The products in question are Temodar (temozolomide) for brain cancer and hepatitis C and cancer drugs PegIntron (pegylated interferon alfa-2b) and Intron A (interferon alfa-2b), according to Merck's just-published quarterly report. All three of the drugs were acquired when Merck bought Schering-Plough in 2009.
Overall, 49% of patients discontinued their medication before the end of the four-year study, with 36% due to failure to comply and 13% due to side effects. Peginterferon alfa-2b was generally well tolerated. Among patients who discontinued due to interferon side effects (17.1%, 49/286), the most common reason (45%, 22/49 patients) was general intolerance to interferon (e.g., due to flu-like symptoms, malaise, and other common interferon side effects).
http://www.nature.com/eye/journal/v17/n4/full/6700391a.html
"INF-alpha therapy has been known to cause a variety of ocular lesions.1,2 Typical lesions include cottonwool spots and retinal haemorrhages at the posterior fundus, particularly around the optic disc, secondary to retinal ischaemia, which usually appear within 3 months of the onset of therapy.
A small trial failed to demonstrate that interferon alfa-2b prevented cirrhosis in HBeAg-positive patients. Another small RCT found no significant difference in histologically confirmed cirrhosis after interferon alfa-2b alone or with simultaneous prednisone. No data were available from RCTs for other antiviral drugs or longer followup.
Hepatic decompensation was not prevented by lamivudine compared to placebo or entecavir compared to lamivudine in three underpowered trials.
I am on the alfa-2b product and have been looking at the papers on how its absorbed and metabolized. Lo and behold, a graph in a review (Zeuzem, S et al. Pharmacokinetics of Peginterferons. Seminars Liver Disease 23(1),23-28) shows something interesting.
It's a concentration vs time profile i.e. Give PegIFN at time 0; measure PegIFN concentration in the blood every hour and plot time on the horizontal and concentration on the vertical axis.
The maximum blood levels are reached ~24hrs.
More than 1400 participants enrolled in this prospective study were treated with 1.5 mcg/kg/week pegylated interferon alfa-2b (PegIntron) plus 800-1400 mg/day weight-adjusted ribavirin. More than half (61%) were men, the mean age was about 43 years, and more than 95% were white. At baseline, about 80% had HCV RNA > 800,000 IU/mL.
Slow response was defined as achieving at least a 2 log drop but still having detectable HCV RNA at week 12 of treatment, but undetectable HCV RNA at week 24.
I'm the opposite of Frijole. I did 2b first and failed treatment, 2a the second time. Although successful it was not due to the 2a. But, I found that the side effects were much less than 2b.
Pegylation of interferon alfa-2b produces a product (PegIntron) whose clearance is lower than that of nonpegylated interferon alfa-2b. When compared to INTRON A, PegIntron (1 mcg/kg) has approximately a 7-fold lower mean apparent clearance and a 5-fold greater mean half-life, permitting a reduced dosing frequency. At effective therapeutic doses, PegIntron has approximately 10-fold greater Cmax and 50-fold greater AUC than interferon alfa-2b.
Ribavirin dosage normally is weight based, with a normal maximum of 12,000 (6 pills) a day. I weigh 144 lbs, so I started out at 1,000 mg a day, 3 in the morning and 2 at night. The doctor may do a lot of adjustments during the treatment also.
Here is some info:
http://www.drugs.com/dosage/ribavirin.
I am GT 1 and my md only wants to give me 800 mg of riba because I weigh 115 lbs. Why ?!
•for the treatment of chronic hepatitis C infection (monoinfection) in combination with interferon alfa-2b in patients previously untreated with interferon alpha:
NOTE: Consider response prognostic factors, HCV genotype, viral load, and disease progression evidence such as hepatic inflammation and fibrosis when deciding to treat a pediatric patient.
The treatment with most promising results is a combination of pegylated interferon alfa (Pegasys, PEG-Intron) and the antiviral drug, ribavirin. Interferon alfa is a protein which the human body produces naturally as a defense response to viral infections. Pegylation describes a chemical process that makes the interferon last longer in the body. Interferon increases the potency of ribavirin in the treatment of HCV.
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