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A new form of interferon involving the attachment of polyethylene glycol to a protein (pegylation) reduces the rate of clearance of this medication and allows for interferon to be used once a week. This is called pegylated interferon of which there are two types: PEG interferon alpha-2A, (Pegasys) and PEG interferon alpha-2B (PEG-Intron). This pegylation provides a higher steady state concentration and more favorable therapeutic effects. There are two formulations of pegylated interferon: Pegylated interferon alpha-2A Pegasys, Roche Pharmaceuticals, and pegylated interferon alpha-2B (PEG Intron, Schering-Plough Corp).
Combination Therapy with Ribavarin
Ongoing studies are evaluating combination with pegylated interferon plus ribavirin. Most studies feel this is the standard of therapy for patients with chronic hepatitis-C.
Dosage
Response Rates
Response rates depend on genotype. In general, both interferons combined with ribavirin have similar response rates.
Genotype I - 40 to 42 percent (versus 33 percent with monotherapy with standard interferon)
Genotype II and III - 80 percent
The optimal dose of ribavirin appears to be 10.5 mg/kg. The benefit of combination therapy was mostly observed in patients infected with genotype I and combination therapy is associated with a higher sustained virological response rate compared to standard interferon alpha-2B plus ribavirin. Pegylated interferon monotherapy appears to be better tolerated than standard interferon. The quality of life during treatment appears to be better with pegylation combination therapy.
Therapy
Dosage: PEG Intron 1.5 mcg/kg once weekly subcutaneously or pegasys 180 mcgrms subcutaneously once a week.
Dosage: Ribavirin 1,000 to 1,200 mg per day, usually in equal and divided doses twice a day.
Patients will be monitored closely for a drop in hemoglobin, white blood cell count, and platelet count. Dose reduction can be done as anemia is common with ribavirin and a drop in white blood cell count, is relatively common in patients who receive the interferon. There are medications that can be given also that keep blood counts out, such as Epogen and Neupogen, that help prevent a dose reduction and keep blood counts in the near-normal range but that will depend on your physician.
Administration Guidelines
Therapy with ribavirin in women of child-bearing potential should only begin after a negative pregnancy test is confirmed.
If a patient becomes pregnant during, or within six months of completing ribavirin therapy,the prescriber or Healthcare professional is encouraged to report the case by calling 1-800-727-7064 as there is a high risk of fetal malformations.
Ribavirin may be stored at room temperature or refrigerated.
Interferon is administered subcutaneously. You should visually inspect the product for particulate matter and discoloration prior to administration.
The Centers for Disease Control and the manufacturer consider ribavirin contraindicated in pregnancy as studies indicate teratogenic (malformations of skull palate, eye, jaw, limbs, skeleton, and GI tract) in most of the animal species tested. The incidence and severity of these affects increased with increasing ribavirin dose. Although, clinical studies have not been performed in humans, ribavirin is classified as FDA Pregnancy Risk Factor-X. Women who are pregnant and the male partners of women who are pregnant should not take ribavirin. Extreme caution must be taken to avoid pregnancy in female patients or in female partners of male patients taking Rebetron. Patients and their partners must use two forms of effective contraception during ribavirin therapy and for six months post-therapy. Patients who are not willing to practice strict contraception should not receive ribavirin. Females should have a pregnancy test prior to use of Rebetron, monthly during therapy, and for six months post therapy. If a woman becomes pregnant during, or within, six months of completing ribavirin, the healthcare professional is encouraged to report the case by calling 1-800-727-7064. Animal studies have indicated that interferon decreases progesterone concentrations, producing changes in the menstrual cycle. Following drug withdrawal, menstruation returned to normal. The importance of this affect on female fertility has not been fully evaluated, but contraceptive methods other than oral contraception are during therapy. The affects on male fertility have not been shown to be detrimental.
It is not known if ribavirin or interferon is excreted in breast milk. Ribavirin has been shown to be toxic in nursing animals. Ribavirin and interferon are not recommended during breast feeding because the benefits do not outweigh the potential risk.
Oral ribavirin should not be used in patients who have some renal insufficiency or renal failure.
Side Effects of Interferon
Side Effects of Ribavirin
Drug interactions with ribavirin include AZT and Zidluvdine so it is very important to notify your physician if you have HIV.
Duration of Therapy
Duration of therapy for hepatitis-C is based on genotype. In genotype-I usually it is 48 weeks of therapy. If it is genotype II or III, it is 24 weeks of therapy. It is important not to stop treatment even if you are feeling better. You may need to have blood tests done during therapy to evaluate your progress
If you have any questions or concerns,call your Doctor's office
You Should Know :Dr. Bhandari specializes in digestive disease disorders. He is triple board certified in Internal Medicine, Medical Nutrition & Gastroenterology. He is a highly trained and skilled Endoscopist. |
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