Ribasphere

Name: Ribasphere

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of ribavirin in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems, which may require an adjustment in the dose for patients receiving ribavirin.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Didanosine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Abacavir
  • Azathioprine
  • Mercaptopurine
  • Stavudine
  • Zalcitabine
  • Zidovudine

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Interferon Alfa-2b

What should I discuss with my healthcare provider before taking ribavirin?

You should not take ribavirin if you are allergic to it, or if you have:

  • a hemoglobin blood cell disorder such as sickle-cell anemia or thalassemia;

  • autoimmune hepatitis;

  • severe kidney disease;

  • if you are also taking didanosine (Videx); or

  • if you are pregnant, or if you are a man whose sexual partner is pregnant.

You should not take ribavirin with peginterferon alfa-2a if you have:

  • autoimmune hepatitis; or

  • severe liver disease (especially cirrhosis).

To make sure ribavirin is safe for you, tell your doctor if you have:

  • heart disease;

  • a blood cell disorder such as anemia (low red blood cells);

  • breathing problems;

  • vision problems;

  • liver problems other than hepatitis C;

  • a thyroid disorder;

  • kidney disease;

  • human immunodeficiency virus (HIV or AIDS);

  • diabetes;

  • a history of depression, mental illness, or suicide attempt;

  • a history of organ transplant; or

  • if you have ever received treatment for hepatitis C that did not work well.

Ribavirin can cause birth defects or death in an unborn baby. You may need to have a negative pregnancy test before taking this medicine and every month during your treatment.

  • If you are a woman, do not take ribavirin if you are pregnant.

  • If you are a man, do not take ribavirin if your sexual partner is pregnant. An unborn baby could also be harmed if a man fathers the child while he is taking ribavirin.

  • Use at least 2 effective forms of birth control to prevent pregnancy while either sexual partner is taking ribavirin. Keep using 2 forms of birth control for at least 6 months after treatment ends.

  • Tell your doctor right away if a pregnancy occurs while either the mother or the father is taking ribavirin.

If a pregnancy occurs, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of ribavirin on the baby.

It is not known whether ribavirin passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

Ribavirin is not approved for use by anyone younger than 3 years old.

Ribavirin can affect growth in children. Tell your doctor if your child is not growing at a normal rate while using this medicine.

Uses For Ribasphere

Ribavirin is used in combination with injectable interferon alfa-2b, peginterferon alfa-2a, or peginterferon alfa-2b to treat chronic hepatitis C infection. The combination of ribavirin and peginterferon alfa-2b is used to treat adults and children 3 years of age and older who show symptoms of liver damage. Ribavirin is an antiviral agent that treats hepatitis C virus.

This medicine is available only with your doctor's prescription.

Precautions While Using Ribasphere

It is very important that your doctor check the progress of you or your child at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. The medicine may also cause birth defects if the father is using it when his sexual partner becomes pregnant. If a pregnancy occurs while you are using this medicine, tell your doctor right away.

It is important to tell your doctor if you or your female sexual partner become pregnant. Your doctor may want you to join a pregnancy registry for patients taking this medicine.

A negative pregnancy test is needed in women who are of childbearing age before starting treatment with this medicine. Two forms of birth control must be used together during treatment and for 6 months after treatment ends. You will need to have pregnancy tests done regularly to make sure you are not pregnant while being treated with this medicine and after your treatment ends.

Do not use Copegus® in combination with didanosine (Videx®, Videx® EC). Using these medicines together may cause serious medical problems.

Ribavirin may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.

Check with your doctor right away if you or your child have back, leg, or stomach pains; bleeding gums; chills; dark urine; difficulty breathing; fever; general body swelling; headache; loss of appetite; nausea or vomiting; nosebleeds; pale skin; sore throat; unusual tiredness or weakness; or yellowing of the eyes or skin. These could be symptoms of a blood disorder called anemia.

This medicine may cause serious types of allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Stop taking this medicine and call your doctor right away if you or your child have itching, hives, hoarseness, trouble with breathing, trouble with swallowing, or any swelling of the hands, face, or mouth while you are using this medicine.

Serious skin reactions can occur with this medicine. Check with your doctor right away if you or your child have blistering, peeling, or loosening of the skin; fever or chills; hives or welts; red skin lesions; a severe skin rash or acne; or sores or ulcers on the skin while you are using this medicine.

Pancreatitis may occur while you are using this medicine. Stop using this medicine and check with your doctor right away if you or your child have sudden and severe stomach pain, chills, constipation, nausea, vomiting, fever, or lightheadedness.

You or your teenager should not drink alcoholic beverages (including beer, wine, or liquor) while you are taking this medicine.

This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you or your teenager drive, operate machinery, or do anything else that could be dangerous if you are not alert.

Check with your doctor if blurred vision, decreased vision, or any other change in vision occurs while you or your child are using this medicine. Your doctor may want you to have your eyes checked by an ophthalmologist (eye doctor).

Peginterferon injection combined with ribavirin can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets in the blood, which are necessary for proper blood clotting. If this occurs, there are certain precautions you or your child can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising; black, tarry stools; blood in the urine or stools; or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

This medicine may cause teeth and gum problems. This medicine may cause dryness of the mouth, and a dry mouth may damage your teeth and gums if you take the medicine for a long time. To help prevent this condition, carefully brush your teeth at least two times a day and have regular visits with your dentist. For temporary relief of mouth dryness, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute.

Some patients who have used this medicine have had vomiting. If you vomit during your treatment, rinse your mouth out with water. This may also help prevent damage to your teeth and gums.

Ribavirin used together with injectable peginterferon alfa-2a or peginterferon alfa-2b may affect your child's growth. Your doctor may need to check your child's height and weight during and after treatment with these medicines.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Warnings and Precautions

Pregnancy

Ribasphere (ribavirin capsules) may cause birth defects and death of the unborn child. Ribasphere therapy should not be started until a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy. Patients should use at least two forms of contraception and have monthly pregnancy tests during treatment and during the 6-month period after treatment has been stopped. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients. Ribavirin has demonstrated significant teratogenic and embryocidal effects in all animal species in which adequate studies have been conducted. These effects occurred at doses as low as one twentieth of the recommended human dose of ribavirin. Ribasphere therapy should not be started until a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy [see Boxed Warning, Contraindications (4), Use in Specific Populations (8.1), and Patient Counseling Information (17.2)].

Anemia

The primary toxicity of ribavirin is hemolytic anemia, which was observed in approximately 10% of Ribasphere/interferon alfa-2b treated subjects in clinical trials. The anemia associated with Ribasphere capsules occurs within 1 to 2 weeks of initiation of therapy. Because the initial drop in hemoglobin may be significant, it is advised that hemoglobin or hematocrit be obtained before the start of treatment and at Week 2 and Week 4 of therapy, or more frequently if clinically indicated. Patients should then be followed as clinically appropriate [see Dosage and Administration (2.4, 2.5)].

Fatal and nonfatal myocardial infarctions have been reported in patients with anemia caused by ribavirin. Patients should be assessed for underlying cardiac disease before initiation of ribavirin therapy. Patients with pre-existing cardiac disease should have electrocardiograms administered before treatment, and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be suspended or discontinued [see Dosage and Administration (2.4, 2.5)]. Because cardiac disease may be worsened by drug-induced anemia, patients with a history of significant or unstable cardiac disease should not use Ribasphere.

Pancreatitis

Ribasphere and interferon alfa-2b or peginterferon alfa-2b therapy should be suspended in patients with signs and symptoms of pancreatitis and discontinued in patients with confirmed pancreatitis.

Pulmonary Disorders

Pulmonary symptoms, including dyspnea, pulmonary infiltrates, pneumonitis, pulmonary hypertension, and pneumonia, have been reported during therapy with ribavirin with alpha interferon combination therapy; occasional cases of fatal pneumonia have occurred. In addition, sarcoidosis or the exacerbation of sarcoidosis has been reported. If there is evidence of pulmonary infiltrates or pulmonary function impairment, the patient should be closely monitored, and if appropriate, combination therapy should be discontinued.

Ophthalmologic Disorders

Ribavirin is used in combination therapy with alpha interferons. Decrease or loss of vision, retinopathy including macular edema, retinal artery or vein, thrombosis, retinal hemorrhages and cotton wool spots, optic neuritis, papilledema, and serous retinal detachment are induced or aggravated by treatment with alpha interferons. All patients should receive an eye examination at baseline. Patients with pre-existing ophthalmologic disorders (e.g., diabetic or hypertensive retinopathy) should receive periodic ophthalmologic exams during combination therapy with alpha interferon treatment. Any patient who develops ocular symptoms should receive a prompt and complete eye examination. Combination therapy with alpha interferons should be discontinued in patients who develop new or worsening ophthalmologic disorders.

Laboratory Tests

Peginterferon alfa-2b in combination with ribavirin may cause severe decreases in neutrophil and platelet counts, and hematologic, endocrine (e.g., TSH), and hepatic abnormalities.

Patients on peginterferon alfa-2b/ Ribasphere combination therapy should have hematology and blood chemistry testing before the start of treatment and then periodically thereafter. In the adult clinical trial, complete blood counts (including hemoglobin, neutrophil, and platelet counts) and chemistries (including AST, ALT, bilirubin, and uric acid) were measured during the treatment period at Weeks 2, 4, 8, 12, and then at 6-week intervals, or more frequently if abnormalities developed. In pediatric subjects, the same laboratory parameters were evaluated with additional assessment of hemoglobin at treatment Week 6. TSH levels were measured every 12 weeks during the treatment period. HCV-RNA should be measured periodically during treatment [see Dosage and Administration (2)].

Dental and Periodontal Disorders

Dental and periodontal disorders have been reported in patients receiving ribavirin and interferon or peginterferon combination therapy. In addition, dry mouth could have a damaging effect on teeth and mucous membranes of the mouth during long-term treatment with the combination of ribavirin and pegylated or nonpegylated interferon alfa-2b. Patients should brush their teeth thoroughly twice daily and have regular dental examinations. If vomiting occurs, they should be advised to rinse out their mouth thoroughly afterwards.

Concomitant Administration of Azathioprine

Pancytopenia (marked decreases in red blood cells, neutrophils, and platelets) and bone marrow suppression have been reported in the literature to occur within 3 to 7 weeks after the concomitant administration of pegylated interferon/ribavirin and azathioprine. In this limited number of patients (n=8), myelotoxicity was reversible within 4 to 6 weeks upon withdrawal of both HCV antiviral therapy and concomitant azathioprine and did not recur upon reintroduction of either treatment alone. Peginterferon alfa-2b, Ribasphere and azathioprine should be discontinued for pancytopenia, and pegylated interferon/ribavirin should not be reintroduced with concomitant azathioprine [see Drug Interactions (7.4)].

Impact on Growth - Pediatric Use

Data on the effects of peginterferon alfa-2b and ribavirin on growth come from an open-label study in subjects 3 through 17 years of age, in which weight and height changes are compared to US normative population data. In general, the weight and height gain of pediatric subjects treated with peginterferon alfa-2b and ribavirin lags behind that predicted by normative population data for the entire length of treatment. Severely inhibited growth velocity (less than 3rd percentile) was observed in 70% of the subjects while on treatment. Following treatment, rebound growth and weight gain occurred in most subjects. Long-term follow-up data in pediatric subjects, however, indicates that peginterferon alfa-2b in combination therapy with ribavirin may induce a growth inhibition that results in reduced adult height in some patients [see Adverse Reactions (6.1)].

Similarly, an impact on growth was seen in subjects after treatment with ribavirin and interferon alfa-2b combination therapy for one year. In a long-term follow-up trial of a limited number of these subjects, combination therapy resulted in reduced final adult height in some subjects [see Adverse Reactions (6.2)].

Usage Safeguards

Based on results of clinical trials, ribavirin monotherapy is not effective for the treatment of chronic hepatitis C virus infection; therefore, Ribasphere capsules must not be used alone. The safety and efficacy of ribavirin capsules have only been established when used together with interferon alfa-2b or peginterferon alfa-2b (not other interferons) as combination therapy.

The safety and efficacy of ribavirin/interferon alfa-2b and peginterferon alfa-2b therapy for the treatment of HIV infection, adenovirus, RSV, parainfluenza, or influenza infections have not been established. Ribasphere capsules should not be used for these indications. Ribavirin for inhalation has separate labeling, which should be consulted if ribavirin inhalation therapy is being considered.

There are significant adverse reactions caused by ribavirin/interferon alfa-2b or peginterferon alfa-2b therapy, including severe depression and suicidal ideation, hemolytic anemia, suppression of bone marrow function, autoimmune and infectious disorders, pulmonary dysfunction, pancreatitis, and diabetes. Suicidal ideation or attempts occurred more frequently among pediatric patients, primarily adolescents, compared to adult patients (2.4% versus 1%) during treatment and off-therapy follow-up. Labeling for interferon alfa-2b and peginterferon alfa-2b should be reviewed in their entirety for additional safety information prior to initiation of combination treatment.

Ribasphere - Clinical Pharmacology

Mechanism of Action

Ribavirin is an antiviral agent [see Microbiology (12.4)].

Pharmacokinetics

Single- and multiple-dose pharmacokinetic properties in adults are summarized in Table 11. Ribavirin was rapidly and extensively absorbed following oral administration. However, due to first-pass metabolism, the absolute bioavailability averaged 64% (44%). There was a linear relationship between dose and AUCtf (AUC from time zero to last measurable concentration) following single doses of 200 to 1200 mg ribavirin. The relationship between dose and Cmax was curvilinear, tending to asymptote above single doses of 400 to 600 mg.

Upon multiple oral dosing, based on AUC12 hr, a 6-fold accumulation of ribavirin was observed in plasma. Following oral dosing with 600 mg twice daily, steady-state was reached by approximately 4 weeks, with mean steady-state plasma concentrations of 2200 ng/mL (37%). Upon discontinuation of dosing, the mean half-life was 298 (30%) hours, which probably reflects slow elimination from nonplasma compartments.

Effect of Antacid on Absorption of Ribavirin

Coadministration of ribavirin capsules with an antacid containing magnesium, aluminum, and simethicone resulted in a 14% decrease in mean ribavirin AUCtf. The clinical relevance of results from this single-dose study is unknown.

Table 11: Mean (% CV) Pharmacokinetic Parameters for Ribavirin Capsules When Administered Individually to Adults
* N=11 † Data obtained from a single-dose pharmacokinetic study using 14C labeled ribavirin; N=5. ‡ N=6.

Parameter

Ribavirin Capsules

Single Dose
   600 mg Capsules   
(N=12)

Multiple Dose
   600 mg Capsules   
twice daily
(N=12)

Tmax (hr)

1.7 (46)*

3 (60)

Cmax (ng/mL)

782 (37)

3680 (85)

AUCtf (ng∙hr/mL)

13,400 (48)

228,000 (25)

T1/2 (hr)

43.6 (47)

298 (30)

Apparent Volume of Distribution (L)   

2825 (9)†

Apparent Clearance (L/hr)

38.2 (40)

Absolute Bioavailability

64% (44)‡

Tissue Distribution: Ribavirin transport into nonplasma compartments has been most extensively studied in red blood cells, and has been identified to be primarily via an es-type equilibrative nucleoside transporter. This type of transporter is present on virtually all cell types and may account for the extensive volume of distribution. Ribavirin does not bind to plasma proteins.

Metabolism and Excretion: Ribavirin has two pathways of metabolism: (i) a reversible phosphorylation pathway in nucleated cells; and (ii) a degradative pathway involving deribosylation and amide hydrolysis to yield a triazole carboxylic acid metabolite. Ribavirin and its triazole carboxamide and triazole carboxylic acid metabolites are excreted renally. After oral administration of 600 mg of 14C-ribavirin, approximately 61% and 12% of the radioactivity was eliminated in the urine and feces, respectively, in 336 hours. Unchanged ribavirin accounted for 17% of the administered dose.

Special Populations:

Renal Dysfunction

The pharmacokinetics of ribavirin were assessed after administration of a single oral dose (400 mg) of ribavirin to non HCV-infected subjects with varying degrees of renal dysfunction. The mean AUCtf value was threefold greater in subjects with creatinine clearance values between 10 to 30 mL/min when compared to control subjects (creatinine clearance greater than 90 mL/min). In subjects with creatinine clearance values between 30 to 60 mL/min, AUCtf was twofold greater when compared to control subjects. The increased AUCtf appears to be due to reduction of renal and nonrenal clearance in these subjects. Phase 3 efficacy trials included subjects with creatinine clearance values greater than 50 mL/min. The multiple-dose pharmacokinetics of ribavirin cannot be accurately predicted in patients with renal dysfunction. Ribavirin is not effectively removed by hemodialysis. Patients with creatinine clearance less than 50 mL/min should not be treated with Ribasphere [see Contraindications (4)].

Hepatic Dysfunction

The effect of hepatic dysfunction was assessed after a single oral dose of ribavirin (600 mg). The mean AUCtf values were not significantly different in subjects with mild, moderate, or severe hepatic dysfunction (Child-Pugh Classification A, B, or C) when compared to control subjects. However, the mean Cmax values increased with severity of hepatic dysfunction and was twofold greater in subjects with severe hepatic dysfunction when compared to control subjects.

Elderly Patients

Pharmacokinetic evaluations in elderly subjects have not been performed.

Gender

There were no clinically significant pharmacokinetic differences noted in a single-dose trial of 18 male and 18 female subjects.

Pediatric Patients

Multiple-dose pharmacokinetic properties for ribavirin capsules and interferon alfa-2b in pediatric subjects with chronic hepatitis C between 5 and 16 years of age are summarized in Table 12. The pharmacokinetics of ribavirin and interferon alfa-2b (dose-normalized) are similar in adults and pediatric subjects.

Table 12: Mean (% CV) Multiple-dose Pharmacokinetic Parameters for Interferon alfa-2b and Ribavirin Capsules When Administered to Pediatric Subjects with Chronic Hepatitis C
Note: numbers in parenthesis indicate % coefficient of variation.
* AUC12 (ng•hr/mL) for ribavirin; AUC0-24 (IU•hr/mL) for interferon alfa-2b † ND=not done

Parameter

   Ribavirin    15 mg/kg/day as
2 divided doses
(N=17)

Interferon alfa-2b
3 MIU/m2
   three times weekly   
(N=54)

Tmax (hr)

1.9 (83)

5.9 (36)

Cmax (ng/mL)

3275 (25)

51 (48)

AUC*

29,774 (26)

622 (48)

Apparent Clearance L/hr/kg   

0.27 (27)

ND†

A clinical trial in pediatric subjects with chronic hepatitis C between 3 and 17 years of age was conducted in which pharmacokinetics for peginterferon alfa-2b and ribavirin capsules were evaluated. In pediatric subjects receiving body surface area-adjusted dosing of peginterferon alfa-2b at 60 mcg/m2/week, the log transformed ratio estimate of exposure during the dosing interval was predicted to be 58% [90% CI: 141%, 177%] higher than observed in adults receiving 1.5 mcg/kg/week. The pharmacokinetics of ribavirin (dose-normalized) in this trial were similar to those reported in a prior study of ribavirin in combination with interferon alfa-2b in pediatric subjects and in adults.

Effect of Food on Absorption of Ribavirin

Both AUCtf and Cmax increased by 70% when ribavirin capsules were administered with a high-fat meal (841 kcal, 53.8 g fat, 31.6 g protein, and 57.4 g carbohydrate) in a single-dose pharmacokinetic study [see Dosage and Administration (2)].

Microbiology

Mechanism of Action

The mechanism by which ribavirin contributes to its antiviral efficacy in the clinic is not fully understood. Ribavirin has direct antiviral activity in tissue culture against many RNA viruses. Ribavirin increases the mutation frequency in the genomes of several viruses and ribavirin triphosphate inhibits HCV polymerase in a biochemical reaction.

Antiviral Activity in Cell Culture

The antiviral activity of ribavirin in the HCV-replicon is not well understood and has not been defined because of the cellular toxicity of ribavirin. Direct antiviral activity has been observed in tissue culture of other RNA viruses. The anti-HCV activity of interferon was demonstrated in cell containing self-replicating HCV-RNS (HCV replicon cells) or HCV infection.

Resistance

HCV genotypes show wide variability in their response to pegylated recombinant human interferon/ribavirin therapy. Genetic changes associated with the variable response have not been identified.

Cross-resistance

There is no reported cross-resistance between pegylated/non-pegylated interferons and ribavirin.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

Ribavirin did not cause an increase in any tumor type when administered for 6 months in the transgenic p53 deficient mouse model at doses up to 300 mg/kg (estimated human equivalent of 25 mg/kg based on body surface area adjustment for a 60 kg adult; approximately 1.9 times the maximum recommended human daily dose). Ribavirin was noncarcinogenic when administered for 2 years to rats at doses up to 40 mg/kg (estimated human equivalent of 5.71 mg/kg based on body surface area adjustment for a 60 kg adult).

Mutagenesis

Ribavirin demonstrated increased incidences of mutation and cell transformation in multiple genotoxicity assays. Ribavirin was active in the Balb/3T3 In Vitro Cell Transformation Assay. Mutagenic activity was observed in the mouse lymphoma assay, and at doses of 20 to 200 mg/kg (estimated human equivalent of 1.67 to 16.7 mg/kg, based on body surface area adjustment for a 60 kg adult; 0.1 to 1 times the maximum recommended human 24-hour dose of ribavirin) in a mouse micronucleus assay. A dominant lethal assay in rats was negative, indicating that if mutations occurred in rats they were not transmitted through male gametes.

Impairment of Fertility

Ribavirin demonstrated significant embryocidal and teratogenic effects at doses well below the recommended human dose in all animal species in which adequate studies have been conducted. Malformations of the skull, palate, eye, jaw, limbs, skeleton, and gastrointestinal tract were noted. The incidence and severity of teratogenic effects increased with escalation of the drug dose. Survival of fetuses and offspring was reduced. In conventional embryotoxicity/teratogenicity studies in rats and rabbits, observed no-effect dose levels were well below those for proposed clinical use (0.3 mg/kg/day for both the rat and rabbit; approximately 0.06 times the recommended human 24-hour dose of ribavirin). No maternal toxicity or effects on offspring were observed in a peri/postnatal toxicity study in rats dosed orally at up to 1 mg/kg/day (estimated human equivalent dose of 0.17 mg/kg based on body surface area adjustment for a 60 kg adult; approximately 0.01 times the maximum recommended human 24-hour dose of ribavirin) [see Contraindications (4), and Warnings and Precautions (5.1)].

Fertile women and partners of fertile women should not receive Ribasphere unless the patient and his/her partner are using effective contraception (two reliable forms). Based on a multiple-dose half-life (t1/2) of ribavirin of 12 days, effective contraception must be utilized for 6 months post-therapy (e.g., 15 half-lives of clearance for ribavirin).

Ribasphere should be used with caution in fertile men. In studies in mice to evaluate the time course and reversibility of ribavirin-induced testicular degeneration at doses of 15 to 150 mg/kg/day (estimated human equivalent of 1.25 to 12.5 mg/kg/day, based on body surface area adjustment for a 60kg adult; 0.1-0.8 times the maximum human 24-hour dose of ribavirin) administered for 3 or 6 months, abnormalities in sperm occurred. Upon cessation of treatment, essentially total recovery from ribavirin-induced testicular toxicity was apparent within 1 or 2 spermatogenesis cycles.

Animal Toxicology and/or Pharmacology

Long-term studies in the mouse and rat [18 to 24 months; doses of 20 to 75 and 10 to 40 mg/kg/day respectively, (estimated human equivalent doses of 1.67 to 6.25 and 1.43 to 5.71 mg/kg/day, respectively, based on body surface area adjustment for a 60 kg adult; approximately 0.1 to 0.4 times the maximum human 24-hour dose of ribavirin)] have demonstrated a relationship between chronic ribavirin exposure and increased incidences of vascular lesions (microscopic hemorrhages) in mice. In rats, retinal degeneration occurred in controls, but the incidence was increased in ribavirin-treated rats.

In a study in which rat pups were dosed postnatally with ribavirin at doses of 10, 25, and 50 mg/kg/day, drug-related deaths occurred at 50 mg/kg (at rat pup plasma concentrations below human plasma concentrations at the human therapeutic dose) between study Days 13 and 48. Rat pups dosed from postnatal Days 7 through 63 demonstrated a minor, dose-related decrease in overall growth at all doses, which was subsequently manifested as slight decreases in body weight, crown-rump length, and bone length. These effects showed evidence of reversibility, and no histopathological effects on bone were observed. No ribavirin effects were observed regarding neurobehavioral or reproductive development.

Important information

You should not use Ribasphere if you have autoimmune hepatitis, severe kidney disease, or a hemoglobin blood cell disorder.

Call your doctor at once if you have pale or yellowed skin, dark colored urine, fever, confusion, chest pain, weakness, or trouble breathing.

Ribasphere is not effective when used alone. It must be used together with an interferon alfa product. You should not take ribavirin with didanosine.

Ribavirin can cause birth defects or death in an unborn baby. Do not use this medicine if you are pregnant, or if you are a man and your sexual partner is pregnant. Use 2 forms of birth control to prevent pregnancy while either sexual partner is taking Ribasphere, and for at least 6 months after treatment ends. Tell your doctor right away if a pregnancy occurs while either the mother or the father is taking Ribasphere.

In rare cases, ribavirin can cause fatal heart problems. Get emergency medical attention if you have chest pain.

Ribasphere side effects

Get emergency medical help if you have signs of an allergic reaction to Ribasphere: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Ribavirin can cause anemia. In rare cases, this can lead to fatal heart problems. Get emergency medical attention if you have chest pain.

Call your doctor at once if you have:

  • problems with your vision;

  • severe pain in your upper stomach spreading to your back, nausea, vomiting, diarrhea;

  • stabbing chest pain, wheezing, feeling short of breath;

  • severe depression, thoughts about suicide, or thoughts about hurting someone else;

  • signs of serious anemia - pale or yellowed skin, dark colored urine, confusion or weakness; or

  • other signs of low blood cell counts - fever, chills, flu-like symptoms, swollen gums, mouth sores, skin sores, easy bruising, unusual bleeding, feeling light-headed.

Common Ribasphere side effects may include:

  • nausea, flu-like symptoms, tiredness;

  • fever, chills or shaking;

  • headache;

  • mood changes, feeling irritable;

  • muscle pain; or

  • stomach pain, vomiting, loss of appetite.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

For Healthcare Professionals

Applies to ribavirin: compounding powder, inhalation powder for reconstitution, oral capsule, oral solution, oral tablet

General

The most common serious or life-threatening side effects induced or aggravated by ribavirin (the active ingredient contained in Ribasphere) tablets in combination with peginterferon alfa-2a have included depression, suicide, relapse of drug abuse/overdose, and bacterial infections in less than 1% of patients and hepatic decompensation in 2% of chronic hepatitis C (CHC)-HIV coinfected patients. The most common serious side effect in CHC monoinfected (3%) and CHC-HIV coinfected (5%) patients receiving peginterferon alfa-2a alone or in combination with ribavirin tablets was bacterial infection (e.g., sepsis, osteomyelitis, endocarditis, pyelonephritis, pneumonia). Common side effects reported in CHC-HIV coinfected patients receiving ribavirin tablets in combination with peginterferon alfa-2a have included neutropenia, anemia, thrombocytopenia, weight decrease, and mood alteration.

The most common side effects reported in patients receiving ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b were injection site inflammation/reaction, fatigue/asthenia, headache, rigors, fevers, nausea, myalgia, and anxiety/emotional lability/irritability. The most common serious side effects associated with peginterferon alfa-2b in combination with ribavirin capsules/oral solution were depression and suicidal ideation in less than 1% of patients. The most common fatal side effects reported in patients receiving peginterferon alfa-2b in combination with ribavirin capsules/oral solution were cardiac arrest, suicidal ideation, and suicide attempt in less than 1% of patients.[Ref]

Respiratory

Mechanically ventilated patients may be predisposed to respiratory deterioration.

Severe hypoxia was described in a case report of a previously healthy infant who experienced a dramatic drop in transcutaneous oxygen within 1 minute of receiving ribavirin (the active ingredient contained in Ribasphere) Oxygen levels returned to normal promptly following discontinuation of therapy. However, the infant later died, and postmortem examination revealed a high pulmonary arterial pressure and a patent ductus arteriosus. A definitive causal relationship was not established, and equipment failure was not specifically ruled out by the authors.

Most signs and symptoms reported in exposed health care workers resolved within minutes to hours of stopping close exposure to aerosolized ribavirin.[Ref]

Respiratory side effects associated with oral ribavirin in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included dyspnea (up to 26%), cough (up to 23%), and exertional dyspnea (up to 7%). Pharyngitis (up to 13%), rhinitis (up to 8%), and sinusitis (up to 12%) have been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b. Pulmonary symptoms (including dyspnea, pulmonary infiltrates, pneumonitis, pulmonary hypertension, pneumonia, and fatal pneumonia), sarcoidosis, and exacerbation of sarcoidosis have been reported with oral ribavirin in combination with alpha interferon. Pulmonary hypertension has been reported during postmarketing experience with ribavirin capsules/oral solution in combination with interferon alfa-2b or peginterferon alfa-2b. Significant deterioration of pulmonary function in patients with chronic obstructive pulmonary disease or asthma and minor pulmonary function abnormalities in healthy volunteers have been reported with aerosolized ribavirin. Asthmatic patients have also reported dyspnea and chest soreness with aerosolized ribavirin. Worsening of respiratory status, bronchospasm, hypoventilation, cyanosis, dyspnea, bronchoconstriction, bacterial pneumonia, cough, pneumothorax, pulmonary edema, apnea, atelectasis, hypoxia, and ventilator dependence have been reported with aerosolized ribavirin. Rhinitis and pharyngitis, as well as several cases of bronchospasm and/or chest pain (usually in individuals with underlying reactive airway disease), have been reported in health care workers exposed to aerosolized ribavirin.[Ref]

Hypersensitivity

Hypersensitivity side effects have included reactions such as urticaria, angioedema, bronchoconstriction, and anaphylaxis in patients treated with alfa interferon and ribavirin (the active ingredient contained in Ribasphere) Severe skin reactions (including vesiculobullous eruptions, Stevens-Johnson syndrome, erythema multiforme, and exfoliative dermatitis/erythroderma) have been reported in patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Serious skin reactions have been reported during postmarketing experience in patients treated with peginterferon alfa-2a.[Ref]

Dermatologic

Dermatologic side effects have included rash and skin irritation from prolonged drug contact. Alopecia (up to 36%), pruritus (up to 29%), dermatitis (up to 16%), dry skin (up to 24%), increased sweating (up to 11%), rash (up to 34%), and eczema (up to 5%) have been associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b. Grover's disease has been reported in a 55-year-old man 2 weeks after the start of ribavirin therapy. A photoallergic skin reaction was reported to occur 4 months after initiation of ribavirin treatment, and recurred approximately 24 hours after reexposure to ribavirin. Skin disorders associated with ribavirin tablets in combination with peginterferon alfa-2a have included lichenoid eruptions and maculopapular rashes. Rash has been reported in patients treated with and health care workers exposed to aerosolized ribavirin. Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported during postmarketing experience with ribavirin tablets in combination with peginterferon alfa-2a.[Ref]

Grover's disease (suprabasal transient acantholytic dermatosis) secondary to ribavirin use was confirmed upon drug rechallenge in a 55-year-old man with chronic active hepatitis C.

Rash associated with aerosolized ribavirin usually resolved within hours of stopping treatment in patients and within minutes to hours of stopping close exposure in health care workers.[Ref]

Cardiovascular

Cardiovascular side effects have included angina, arrhythmia, and pulmonary embolism in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin (the active ingredient contained in Ribasphere) tablets. Fatal and nonfatal myocardial infarctions have been reported in patients with anemia due to ribavirin capsules/oral solution. Cardiac arrest, hypotension, bradycardia, bigeminy, tachycardia, hypertension (usually slight increases in blood pressure), and digitalis toxicity have been reported with aerosolized ribavirin.[Ref]

Bigeminy, bradycardia, and tachycardia have been reported in patients with underlying congenital heart disease.[Ref]

Hematologic

Hematologic side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included anemia (up to 35%), lymphopenia (up to 14%), neutropenia (up to 40%), thrombocytopenia (up to 8%), and leukopenia (up to 10%). Hemolytic anemia is the most significant toxicity of ribavirin. Aplastic anemia and thrombotic thrombocytopenic purpura have been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Pancytopenia (marked decreases in red blood cells, neutrophils, and platelets) and bone marrow suppression have been reported following concomitant administration of pegylated interferon plus oral ribavirin and azathioprine. Aplastic anemia has been reported during postmarketing experience with ribavirin capsules/oral solution in combination with interferon alfa-2b or peginterferon alfa-2b. Pure red cell aplasia has been reported during postmarketing experience with oral ribavirin in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b. Cases of anemia (type unspecified), reticulocytosis, and hemolytic anemia associated with aerosolized ribavirin have been reported during postmarketing experience and have been reversible with drug discontinuation.[Ref]

Hemolytic anemia is the primary toxicity of ribavirin therapy. Hemoglobin levels generally declined within the first 1 to 2 weeks of oral therapy. Cardiac and pulmonary adverse effects associated with anemia have been reported in 10% of patients.

Hemoglobin less than 10 g/dL was reported in 13% of patients receiving ribavirin tablets in combination with peginterferon alfa-2a. Additional laboratory abnormalities during treatment with ribavirin tablets in combination with peginterferon alfa-2a or interferon alfa-2b have included decreased neutrophils (1000 to less than 1500 cells/mm3: up to 38%; 500 to less than 1000 cells/mm3: up to 49%; less than 500 cells/mm3: up to 5%), platelets (50,000 to less than 75,000 cells/mm3: up to 11%; 20,000 to less than 50,000 cells/mm3: up to 5%), and hemoglobin (8.5 to 9.9 g/dL: 11%; less than 8.5 g/dL: up to 2%).

Changes in laboratory values during treatment with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b have included decreased hemoglobin (9.5 to 10.9 g/dL: up to 32%; 8 to 9.4 g/dL: up to 5%; 6.5 to 7.9 g/dL: up to 0.2%), leukocytes [2 to 2.9 x 10(9)/L: up to 46%; 1.5 to 1.9 x 10(9)/L: up to 24%; 1 to 1.4 x 10(9)/L: up to 5%], neutrophils [1 to 1.49 x 10(9)/L: up to 42%; 0.75 to 0.99 x 10(9)/L: up to 25%; 0.5 to 0.74 x 10(9)/L: up to 18%; less than 0.5 x 10(9)/L: up to 11%], and platelets [70 to 99 x 10(9)/L: up to 15%; 50 to 69 x 10(9)/L: up to 3%; 30 to 49 x 10(9)/L: up to 0.2%; less than 30 x 10(9)/L: up to 1%].[Ref]

Ocular

Ocular side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included blurred vision (up to 6%). Corneal ulcer has been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Conjunctivitis (up to 5%) has been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b. Serous retinal detachment has been reported during postmarketing experience with oral ribavirin in combination with peginterferon alfa-2a, interferon alfa-2b, or peginterferon alfa-2b. Eye irritation and conjunctivitis have been reported in patients treated with and health care workers exposed to aerosolized ribavirin. Lacrimation has been reported in health care workers exposed to aerosolized ribavirin. Damage to contact lenses after prolonged close exposure to aerosolized ribavirin has also been reported.[Ref]

Conjunctivitis associated with aerosolized ribavirin usually resolved within hours of stopping treatment in patients. Most signs and symptoms reported in exposed health care workers resolved within minutes to hours of stopping close exposure to aerosolized ribavirin.

Eye and conjunctival irritation resolved spontaneously when the caregivers left the hospital. In five of six cases, the caregivers were wearing contact lenses. After the staff stopped wearing contact lenses while caring for patients receiving aerosolized ribavirin, the reactions did not occur.[Ref]

Gastrointestinal

Most signs and symptoms reported in exposed health care workers resolved within minutes to hours of stopping close exposure to aerosolized ribavirin (the active ingredient contained in Ribasphere) [Ref]

Gastrointestinal side effects associated with oral ribavirin in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included nausea (up to 47%), nausea and vomiting (up to 29%), diarrhea (up to 22%), vomiting (up to 14%), abdominal pain (up to 13%), dry mouth (up to 12%), dyspepsia (up to 16%), and constipation (5%). Peptic ulcer, gastrointestinal bleeding, pancreatitis, and colitis have been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Nausea has been reported in health care workers exposed to aerosolized ribavirin.[Ref]

Musculoskeletal

Musculoskeletal side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included myalgia (up to 64%), arthralgia (up to 34%), musculoskeletal pain (up to 28%), and back pain (5%). Myositis has been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. At least 6 cases of mild to moderate gout have been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b.[Ref]

Nervous system

Nervous system side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included headache (up to 66%), dizziness (excluding vertigo; 26%), and memory impairment (up to 6%). Peripheral neuropathy, coma, and cerebral hemorrhage have been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Taste perversion (up to 9%) has been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b. Hearing impairment and hearing loss have been reported during postmarketing experience with ribavirin tablets in combination with peginterferon alfa-2a. Vertigo and hearing disorder have been reported during postmarketing experience with ribavirin capsules/oral solution in combination with interferon alfa-2b or peginterferon alfa-2b. Headache and dizziness have been reported in health care workers exposed to aerosolized ribavirin. Seizures have been reported with experimental intravenous ribavirin.[Ref]

Most signs and symptoms reported in exposed health care workers resolved within minutes to hours of stopping close exposure to aerosolized ribavirin.[Ref]

Metabolic

Metabolic side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included anorexia (up to 32%) and weight decrease (up to 29%). Diabetes mellitus has been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Falsely low hemoglobin A1c levels have been reported. Dehydration has been reported during postmarketing experience with ribavirin tablets in combination with peginterferon alfa-2a. Diabetes has been reported during postmarketing experience with ribavirin capsules/oral solution in combination with interferon alfa-2b or peginterferon alfa-2b.[Ref]

Falsely low hemoglobin A1c levels may be due to ribavirin-induced hemolysis decreasing the number of circulating glycosylated hemoglobin molecules.[Ref]

Psychiatric

Psychiatric side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included irritability/anxiety/nervousness/emotional lability (up to 47%), insomnia (up to 41%), depression (up to 36%), concentration impairment (up to 21%), mood alteration (up to 9%), and agitation (up to 8%). Suicide, suicidal ideation, psychosis, aggression, anxiety, drug abuse/overdose, psychotic disorder, and hallucination have been reported in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin tablets. Impairment of desire and the potential to affect sexual satisfaction have been reported with ribavirin tablets in combination with peginterferon alfa-2a in male patients.[Ref]

Endocrine

Endocrine side effects associated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b have included hypothyroidism (up to 5%).[Ref]

Other

Other side effects frequently associated with ribavirin (the active ingredient contained in Ribasphere) tablets in combination with peginterferon alfa-2a have included influenza-like symptoms (such as fatigue, pyrexia, myalgia, headache, and rigors). Fatigue/asthenia (up to 70%), pyrexia (up to 55%), rigors (up to 48%), chills (up to 39%), influenza-like illness (up to 18%), unspecified pain (up to 13%), right upper quadrant pain (up to 12%), pain (up to 10%), chest pain (up to 9%), and malaise (up to 6%) have been associated with oral ribavirin in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b. Hyperuricemia (in association with hemolysis; up to 38%) and flushing (up to 4%) have been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b. Asthenia has been reported with experimental intravenous ribavirin.[Ref]

Hepatic

Hepatic side effects have included hepatic dysfunction, fatty liver, and cholangitis in less than 1% of patients treated with peginterferon alfa-2a alone or in combination with ribavirin (the active ingredient contained in Ribasphere) tablets. Hepatic decompensation has been reported in 2% of CHC-HIV coinfected patients receiving peginterferon alfa-2a in combination with ribavirin tablets. Hyperbilirubinemia (in association with hemolysis; up to 14%), hepatomegaly (4%), and increased ALT have been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b.[Ref]

Changes in laboratory values during treatment with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b have included increased total bilirubin (1.5 to 3 mg/dL: up to 32%; 3.1 to 6 mg/dL: up to 3%; 6.1 to 12 mg/dL: up to 0.4%) and ALT (2 x baseline: up to 0.6%; 2.1 to 5 x baseline: up to 3%).[Ref]

Immunologic

Immunologic side effects associated with peginterferon alfa-2a alone or in combination with ribavirin (the active ingredient contained in Ribasphere) tablets have included bacterial infection (e.g., sepsis, osteomyelitis, endocarditis, pyelonephritis, pneumonia) in 3% of CHC and 5% of CHC-HIV patients and autoimmune phenomena (such as hyperthyroidism, hypothyroidism, sarcoidosis, systemic lupus erythematosus, rheumatoid arthritis) in less than 1% of patients. Resistance mechanism disorders (overall: up to 12%), including viral infection (12%) and fungal infection (up to 6%), have been associated with oral ribavirin in combination with peginterferon alfa-2a, peginterferon alfa-2b, or interferon alfa-2b. Liver and renal graft rejections have been reported during postmarketing experience with ribavirin tablets in combination with peginterferon alfa-2a.[Ref]

Genitourinary

Genitourinary side effects associated with ribavirin (the active ingredient contained in Ribasphere) tablets in combination with peginterferon alfa-2a have included sexual dysfunction in male patients. Menstrual disorder has been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b.[Ref]

Local

Local side effects have included injection site reactions (up to 58%) in patients treated with oral ribavirin (the active ingredient contained in Ribasphere) in combination with interferon alfa-2b, peginterferon alfa-2b, or peginterferon alfa-2a. Injection site inflammation (up to 25%) has been reported with ribavirin capsules/oral solution in combination with peginterferon alfa-2b or interferon alfa-2b. Skin disorders associated with ribavirin tablets in combination with peginterferon alfa-2a have included cutaneous necrosis at peginterferon alfa-2a injection sites. Hyperpigmentation around/over peginterferon alfa-2a injection sites has been reported.[Ref]

Some side effects of Ribasphere may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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