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Direct-acting antivirals

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Direct-acting antivirals (DAAs) are a collection of medications that directly attack the ability of a virus, such as hepatitis C, to make copies of itself (replicate). There are different kinds of DAAs that interfere at different stages of the replication cycle. Telaprevir (Incivek) and boceprevir (Victrelis)—the first DAAs available for hepatitis C—are both called protease inhibitors (PIs).

Telaprevir and boceprevir are new medications that can be added to a peg-interferon/ribavirin regimen for people with genotype 1 chronic hepatitis C infection.

Telaprevir and boceprevir are new medications that can be added to a peg-interferon/ribavirin regimen for people with genotype 1 chronic hepatitis C. This is called “triple therapy”—since it is a combination of three medications: peg-interferon, ribavirin and either telaprevir or boceprevir. Telaprevir and boceprevir are not prescribed on their own (without peg-interferon and ribavirin) and they are not prescribed together.

This article provides information on the following topics:

Are telaprevir and boceprevir available in Canada?

Telaprevir and boceprevir have both been approved by Health Canada as safe and effective for people with genotype 1 chronic hepatitis C infection. This means that healthcare providers can prescribe them to patients.

Each province and territory is now considering when and how the cost of these medications will be covered by its public health insurance program. Federal health insurance programs and many private insurance companies are doing the same. As more information becomes available you will be able to find it in the Treatment coverage in your region section of this website.  

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What is drug resistance and why is adherence important?

Drug resistance occurs when a virus is able to make more copies of itself (replicate) despite proper doses of a medication—because the virus can resist the medication. Resistance does not happen with peg-interferon and ribavirin but it can happen with direct-acting antivirals such as telaprevir and boceprevir.

Medication schedules and correct doses are designed to keep enough drugs in the bloodstream to stop the virus from replicating. Missing doses means that drug levels in the body may, at least temporarily, drop too low to keep the virus under control. If the virus keeps making copies of itself while exposed to those low drug levels, it can quickly figure out how to make copies of itself even at the proper doses.

Research suggests that the amount of resistant virus declines over time after stopping to take the protease inhibitor. However, it is not clear if there are any long-term consequences if resistance develops.

Adherence—taking all the medications at the right times, every time, as prescribed by a healthcare provider—is one way to prevent resistance from developing. This helps maximize a person’s chance of clearing the virus.

Adherence can be difficult but there are many things a person (and the people supporting them) can do to make it easier. For more information, see Tips for staying on track with treatment.

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What are some considerations for starting triple therapy?

Adding a protease inhibitor to a peg-interferon and ribavirin regimen has some benefits. It can:

  • increase the chances of clearing the virus for people with genotype 1 chronic hepatitis C
  • shorten the length of treatment for some people with genotype 1 chronic hepatitis C
  • improve treatment response for people with genotype 1 chronic hepatitis C infection who tried treatment before and treatment was not successful for them

Still, triple therapy is not the right option for everyone. There are important potential challenges to consider, such as:

  • Adding a PI makes the regimen more complicated, which might make adherence more difficult for some people. Both PIs increase the number of pills a person has to take and how many times a day treatment is taken. Adding a PI can also cause or increase certain side effects. How well a person adheres to a treatment regimen impacts treatment success.
  • It may be difficult to access PIs in some parts of Canada. When, how and for whom the cost of new drugs is covered by public health insurance programs is decided by each individual province/territory.
  • PIs may not be an acceptable treatment option for some women. Ribavirin can cause birth defects so if pregnancy is possible, both partners must use two forms of birth control during treatment and for six months after. However, protease inhibitors decrease the effectiveness of hormonal forms of birth control (such as birth control pills, injections, implants and skin patches). Intra-uterine devices, diaphragms with spermicide and barrier methods such as condoms are not affected by protease inhibitors.
  • PIs and other medicines can affect each other and can also cause serious side effects. There are certain medicines that people cannot take with triple therapy that includes a PI. It is important for people to talk to their healthcare providers about any prescription and non-prescription drugs, vitamins and herbal supplements they take.

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What if someone is co-infected with HIV?

Currently, telaprevir and boceprevir are only approved for people with hepatitis C mono-infection. Studies are ongoing to explore the safety and effectiveness of these medications for people who are co-infected with HIV and genotype 1 hepatitis C.

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About telaprevir

Telaprevir is taken orally three times a day (every 8 hours) in a pill form. It is taken during or right after a meal. Choosing foods with some fat content, such as cheese or toast with butter or peanut butter, will help the medication get into the bloodstream.

Telaprevir is made by Vertex. 

Length of treatment

For people who have never received HCV treatment before, treatment with telaprevir, peg-interferon and ribavirin lasts for 12 weeks. Then, peg-interferon and ribavirin are continued for at least another 12 weeks. During those 24 weeks, a healthcare provider will monitor how treatment is working. Depending on how the virus is responding to treatment:

  • treatment might be stopped (if the virus is not responding)
  • a 24-week regimen might be enough to clear the virus
  • treatment with peg-interferon and ribavirin (and not telaprevir) might continue for another 24 weeks

A similar approach is used for people who previously cleared their HCV virus while on peg-interferon and ribavirin but then had it return after the completion of treatment (this is called a relapse).

For people who previously started peg-interferon and ribavirin but stopped because treatment was not working, triple therapy lasts for 12 weeks and then peg-interferon and ribavirin are continued for another 36 weeks.

In clinical trials, about 70% of people who never received hepatitis C treatment before cleared the virus when the regimen included peg-interferon, ribavirin and telaprevir. 

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About boceprevir

Boceprevir is taken orally three times a day (every 7-9 hours) in a pill form. It is taken during or right after a meal.

Boceprevir is made by Merck Frosst Canada Ltd.

Length of treatment

People start off with four weeks of peg-interferon and ribavirin before adding boceprevir to their regimen on week 5. A healthcare provider will monitor how treatment is working. Depending on how the virus is responding to treatment:

  • treatment might be stopped (if the virus is not responding)
  • a person with a very good virological response to treatment might be able to stop treatment:
    • at week 28 if the person has never tried hepatitis C treatment before; or
    • at week 36 if the person tried treatment with interferon and ribavirin before but did not clear the infection
  • the healthcare provider might recommend continuing treatment with peg-interferon and ribavirin (with or without boceprevir) for a total of 48 weeks of treatment

In clinical trials, about two-thirds of the people who never received hepatitis C treatment before cleared the virus when the regimen included peg-interferon, ribavirin and boceprevir.

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Published 2011.