Side Effects of the Two New Hep C Drugs
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With the addition of two new medicines approved by the FDA in May 2011, significant progress against chronic Hepatitis C has officially been made. For many years, the standard treatment for this prevalent, infectious virus has been subpar. Hovering at just a 50 percent success rate, Hepatitis C combination therapy is a gamble – with grueling side effects that often prevent people from completing treatment. Adding one of the two new drugs to the Hepatitis C arsenal has greatly increased the likelihood of wiping out this virus. However, the side effects accompanying these new medications could make treatment even more of a challenge than standard combination therapy.
Both of the new Hepatitis C drugs, Victrelis (boceprevir) and Incivek (telaprevir) are explicitly for use in conjunction with the current combination of pegylated interferon and ribavirin. Thus, any side effects occurring with Victrelis or Incivek are in addition to the side effects seen with the previous standard treatment regimen.
Pegylated Interferon and Ribavirin Side Effects
Used to treat Hepatitis C for decades, interferon and ribavirin have been improved upon to enhance their effectiveness at treating chronic Hepatitis C infection. Now, treatment typically includes pegylated interferon (a form that enables it to stay in the bloodstream longer) and weight-based ribavirin (allowing for higher, more effective doses for heavier recipients). These changes have increased combination therapy’s ability to eliminate Hepatitis C from more people, but have done little to ease these drugs’ side effects.
Often emulating flu-like symptoms that can be severe enough to halt treatment, the most common side effects of pegylated interferon and ribavirin include fatigue, headache, myalgia, fever, arthralgia, nausea, anorexia, diarrhea, depression, irritability, insomnia, itching, rash, hair loss, anemia, cough and shortness of breath.
Incivek and Victrelis
Both Victrelis and Incivek boost the chances that Hepatitis C treatment will result in a sustained viral response (SVR), the closest measurement currently available to a Hepatitis C cure. Both of these new drugs target the Hepatitis C protease enzyme, making it nearly impossible for the virus to replicate. Although the virus quickly becomes resistant to either drug used alone, combination therapy with pegylated interferon and ribavirin prevents drug resistance.
Standard treatment with pegylated interferon and ribavirin lasts 48 weeks, yet results in an SVR for fewer than half of patients. As shown in clinical trials, adding Incivek or Victrelis to this regimen boosted SVR rates 20 to 45 percent more than the standard treatment in about half the time (24 weeks). Thus, while Incivek or Victrelis may add to the side effects that must be endured, they typically need to be tolerated for less time than a regimen consisting solely of interferon and ribavirin.
The most common side effects are similar between the two drugs, with some being potentially serious:
- Incivek – Skin rashes (possibly severe), anemia (possibly severe), itching, nausea, diarrhea, vomiting, anal or rectal problems, taste changes and fatigue.
- Victrelis – Fatigue, anemia (possibly severe), low white blood cell count, headaches, nausea and taste changes.
Incivek and Victrelis have not yet been evaluated side-by-side, so there is no evidence yet of which is more effective or which one causes more deleterious side effects.
As with any newly released drug, many questions remain as to the long-term safety profiles of these medications. Regardless of whether tackling HIV, Hepatitis C, cancer or the flu, a greater number of drugs taken equals a greater potential for side effects. Unfortunately, Incivek and Victrelis are not exempt from this natural law. We are hoping that the benefits of these protease enzyme inhibitors overpower their faults so that more people can triumph over chronic Hepatitis C – in spite of any side effects these drugs may cause.
References:
http://www.aidsbeacon.com/news/2011/04/30/new-drugs-for-hepatitis-c-part-2-boceprevir-and-telaprevir-dosing-regimens-and-side-effects/, New Drugs For Hepatitis C: Part 2 – Boceprevir And Telaprevir Dosing Regimens And Side Effects, Courtney McQueen, Retrieved July 24, 2011, Light Knowledge Resources, 2011.
http://www.drugs.com/victrelis.html, Victrelis, Retrieved July 24, 2011, Drugs.com, 2011.
http://www.hepatitis.va.gov/provider/reviews/treatment-side-effects.asp, Interferon and Ribavirin Treatment Side Effects, Retrieved July 24, 2011, US Department of Veteran Affairs, 2011.
http://www.merck.com/product/usa/pi_circulars/v/victrelis/victrelis_mg.pdf, Victrelis, Retrieved July 24, 2011, Merck & Co., Inc., 2011.
http://www.rxlist.com/incivek-drug.htm, Incivek, Retrieved July 24, 2011, RxList, Inc., 2011.
http://www.vrtx.com/current-projects/approved-medicines/incivek.html, Incivek ™, Retrieved July 24, 2011, Vertex, 2011.
http://www.webmd.com/hepatitis/news/20110525/new-hepatitis-c-drug-incivek-gets-fda-approval, New Hepatitis C Drug Incivek Gets FDA Approval, Daniel J. DeNoon, Retrieved July 24, 2011, WebMD, LLC, 2011.
