The safety of combination REBETOL/INTRON A therapy was evaluated in controlled trials of 1010 HCV-infected adults who were previously untreated with interferon therapy and were subsequently treated for 24 or 48 weeks with combination REBETOL/INTRON A therapy and in 173 HCV-infected patients who had relapsed after interferon therapy and were subsequently treated for 24 weeks with combination REBETOL/INTRON A therapy. (See Description of Clinical Studies.) Overall, 19% and 6% of previously untreated and relapse patients, respectively, discontinued therapy due to adverse events in the combination arms compared to 13% and 3% in the interferon arms.
The primary toxicity of ribavirin is hemolytic anemia. Reductions in hemoglobin levels occurred within the first 1-2 weeks of therapy (see WARNINGS). Cardiac and pulmonary events associated with anemia occurred in approximately 10% of patients treated with REBETOL/INTRON A therapy. (See WARNINGS.)
The most common psychiatric events occurring in US studies of previously untreated and relapse patients treated with REBETOL/INTRON A therapy, respectively, were insomnia (39%, 26%), depression (34%, 23%), and irritability (27%, 25%). Suicidal behavior (ideation, attempts, and suicides) occurred in 1% of patients. (See WARNINGS.) In addition, the following spontaneous adverse events have been reported during the marketing surveillance of REBETOL/INTRON A therapy: hearing disorder and vertigo. Very rarely, combination REBETOL/INTRON A therapy may be associated with aplastic anemia.
Selected treatment-emergent adverse events that occurred in the US studies with ≥ 5% incidence are provided in TABLE 5 by treatment group. In general, the selected treatment-emergent adverse events reported with lower incidence in the international studies as compared to the US studies with the exception of asthenia, influenza-like symptoms, nervousness, and pruritus.
TABLE 5. Selected Treatment-Emergent Adverse Events: Previously
Untreated and Relapse Patients
|Patients Reporting Adverse Events*||Percentage of Patients|
|US Previously Untreated Study||US Relapse Study|
|24 weeks of treatment||48 weeks of treatment||24 weeks of treatment|
|Application Site Disorders|
|injection site inflammation||13||10||12||14||6||8|
|injection site reaction||7||9||8||9||5||3|
|Body as a Whole - General Disorders|
|Central & Peripheral Nervous System Disorders|
|Gastrointestinal System Disorders|
|Musculoskeletal System Disorders|
|Respiratory System Disorders|
|Skin and Appendages Disorders|
|Special Senses, Other Disorders|
|* Patients reporting one or more adverse events. A patient may have reported more than one adverse event within a body system/organ class category.|
Changes in selected hematologic values (hemoglobin, white blood cells, neutrophils, and platelets) during combination REBETOL/INTRON A treatment are described below (see TABLE 6).
Hemoglobin decreases among patients on combination therapy began at Week 1, with stabilization by Week 4. In previously untreated patients treated for 48 weeks the mean maximum decrease from baseline was 3.1 g/dL in the US study and 2.9 g/dL in the International study. In relapse patients the mean maximum decrease from baseline was 2.8 g/dL in the US study and 2.6 g/dL in the International study. Hemoglobin values returned to pretreatment levels within 4 - 8 weeks of cessation of therapy in most patients.
There were decreases in neutrophil counts in both the combination REBETOL/INTRON A and INTRON A plus placebo dose groups. In previously untreated patients treated for 48 weeks the mean maximum decrease in neutrophil count in the US study was 1.3 x 109 /L and in the International study was 1.5 x 109 /L. In relapse patients the mean maximum decrease in neutrophil count in the US study was 1.3 x 109 /L and in the International study was 1.6 x 109 /L. Neutrophil counts returned to pretreatment levels within 4 weeks of cessation of therapy in most patients.
In both previously untreated and relapse patients mean platelet counts generally remained in the normal range in all treatment groups, however, mean platelet counts were 10% to 15% lower in the INTRON A plus placebo group than the REBETOL/INTRON A group. Mean platelet counts returned to baseline levels within 4 weeks after treatment discontinuation.
Of patients who entered the previously untreated (24 and 48 week treatment) and relapse (24 week treatment) studies without thyroid abnormalities, approximately 3% to 6% and 1% to 2%, respectively, developed thyroid abnormalities requiring clinical intervention.
Bilirubin and Uric Acid
Increases in both bilirubin and uric acid, associated with hemolysis, were noted in clinical trials. Most were moderate biochemical changes and were reversed within 4 weeks after treatment discontinuation. This observation occurs most frequently in patients with a previous diagnosis of Gilbert's syndrome. This has not been associated with hepatic dysfunction or clinical morbidity.
TABLE 6. Selected Hematologic Values During Treatment with
REBETOL plus INTRON A: Previously Untreated and Relapse Patients
|US Previously Untreated Study||US Relapse Study|
|24weeks of treatment||48 weeks of treatment||24 weeks of treatment|
|Total Bilirubin (mg/dL)|
Read the Rebetron (rebetol and intron a combination therapy) Side Effects Center for a complete guide to possible side effects »
Administration of nucleoside analogues has resulted in fatal and nonfatal lactic acidosis. Coadministration of ribavirin and nucleoside analogues should be undertaken with caution and only if the potential benefit outweighs the potential risks.
Last reviewed on RxList: 3/3/2009
This monograph has been modified to include the generic and brand name in many instances.
Additional Rebetron Information
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Find out what women really need.