Simeprevir (Galexos)


Simeprevir is a medication used to treat Hep C. It is used in combination with other medications to cure people of the Hep C virus. It is approved in Canada for people with genotype 1 hepatitis C virus. Simeprevir is taken at a dose of 150 mg once per day, with peg-interferon once per week and ribavirin twice per day. A skin rash is one of the few side effects linked to simeprevir. Other side effects such as fatigue, nausea and depression are mainly caused by peg-interferon and ribavirin. Hep C treatment can cure a person of Hep C. However, a person could be infected again.

What is simeprevir?

Simeprevir is a medication used to treat hepatitis C (Hep C). It is sold under the brand name Galexos. It is used in combination with other medications to cure people of the hepatitis C virus.

How does simeprevir work?

Hep C is a disease of the liver that is caused by a virus. A virus is a very tiny germ that makes copies of itself to survive by a process called replication. The Hep C virus has at least six different strains, which are also known as genotypes.

Simeprevir is a direct-acting antiviral (DAA) medication. DAAs are a group of medications that directly attack the ability of a virus, such as hepatitis C, to make copies of itself.

Simeprevir is a type of DAA called a protease inhibitor. It interferes with the production of the pieces needed to build new virus particles, stopping the production of new Hep C virus.

Hep C treatment can cure a person of Hep C. However, a person could get infected again.

How do people use simeprevir?

Simeprevir is taken as a 150-mg pill once per day. Simeprevir is used in combination with peg-interferon and ribavirin. Simeprevir needs to be taken with food, but it does not matter what kind of food.

Simeprevir is approved in Canada for people over the age of 18 with genotype 1 hepatitis C virus.

How long is treatment?

Hep C virus genotype

Treatment combination

Treatment length

genotype 1

simeprevir  + peg-interferon + ribavirin

12 weeks of simeprevir + peg-interferon + ribavirin, followed by 12 to 36 weeks of peg-interferon + ribavirin

Your doctor will test the amount of Hep C virus in your blood (Hep C viral load) at four weeks and 12 weeks after the start of treatment to determine if you should continue treatment and how long it should last.

In clinical trials, most participants were eligible for a shortened treatment of 24 weeks.

Sticking to treatment

All medications work best when they are taken exactly as prescribed and directed. This means taking the medications in the right amount and at the right time for the entire time that your treatment lasts.  Skipping doses or stopping treatment altogether means that the treatment may not work as well and that the chance of being cured is lower.

With some Hep C medications, there is also a chance that the virus can become resistant to the medication if it is not taken as prescribed and directed. In this case, the medication will not be effective against the virus and cannot be used to treat the infection. See the “Resistance” section to learn about the potential for resistance to simeprevir.

What can you do if you forget to take your medication?

If you miss the time when you were supposed to take simeprevir, as long as you are not more than 12 hours late, you can take it with food as soon as possible. Take your next dose at the regularly scheduled time.

If more than 12 hours have passed since you were supposed to take simeprevir, skip your dose and take it at the next regularly scheduled time.

If you find that you are not able to take your medication as prescribed and directed, talk to your nurse or doctor. You can also check out the section “Tips for staying on track with treatment” in CATIE’s Hepatitis C: An In-Depth Guide.

How likely is a cure from treatment that includes simeprevir?

Hep C treatment can cure a person of Hep C.

In late-stage clinical trials of simeprevir and peg-interferon and ribavirin, participants had approximately the following cure rates:

People with virus genotype

Cure rate

genotype 1

80% to 81%

People with severe liver damage (cirrhosis) had cure rates of 60% in clinical trials.

Sometimes in real life the cure rates can be lower than in clinical trials.

A cure for Hep C is also known as a sustained virological response (SVR). This is when the Hep C virus is no longer detected in the blood 12 or 24 weeks after treatment ends.


Combination therapy

Simeprevir must be taken in combination with peg-interferon and ribavirin, so all of the warnings that apply to peg-interferon and ribavirin also apply to people considering simeprevir. For more information on peg-interferon and ribavirin, see the Pegasys or Pegetron factsheets.

The Q80K mutation

Some people with genotype 1a Hep C virus have a version of the virus that contains a change in its genetic material called the Q80K mutation. The Q80K mutation reduces the chance of being cured when treated with simeprevir. If a person has this baseline viral mutation they should not be treated with simeprevir. People with this mutation should talk to their doctor about their treatment options.

Pregnancy and breastfeeding/nursing

Some of the drugs used to treat Hep C can harm a fetus, so talk to a doctor if you are pregnant or thinking about getting pregnant.

People on Hep C treatment who could get pregnant or who are sex partners with someone who could get pregnant should use two forms of reliable contraception.

People with infants who are taking simeprevir should not breastfeed their children.


In clinical trials, a small number of people who took simeprevir developed photosensitivity—a high sensitivity to sunlight in which a person can develop a rash or severe sunburn when exposed to the sun. Avoid excess exposure to the sun and use of tanning devices while taking simeprevir. You may find it useful to wear a long-sleeved shirt, pants, a hat and sunscreen.


Some people who take simeprevir may develop a rash that can range from mild to severe. If you develop a rash, see your doctor.

Hepatitis B

The U.S. Food and Drug Administration (FDA) recommends that all people starting hepatitis C treatment with DAA medications be tested for hepatitis B before starting treatment.

This is because if someone has hepatitis C and hepatitis B and is not receiving treatment for hepatitis B, treatment with DAAs could reactivate hepatitis B during or after treatment. For more information about being tested for hepatitis B, speak to your doctor or nurse.

Special populations

People who should not be treated with simeprevir

  • people with Hep C genotypes other than genotype 1
  • people under the age of 18
  • people who have previously taken boceprevir (Victrelis) or telaprevir (Incivek) and were not cured
  • people who have severe liver damage (Child-Pugh Class C)
  • people with liver failure (decompensated cirrhosis)
  • people who are organ transplant recipients or who are going to have an organ transplant
  • people with galactose intolerance (a rare hereditary condition)

Groups of people for whom there is limited or no information about the effectiveness of simeprevir

There is limited or no data from clinical trials about the effectiveness of simeprevir in combination with peg-interferon and ribavirin in the following groups:

  • people over the age of 65
  • people with severe kidney impairment or end-stage kidney disease
  • people who are co-infected with hepatitis B virus

If you are in one of these groups, the risks and benefits of taking simeprevir need to be carefully weighed, so speak to your doctor about the most appropriate treatment options. Your doctor or specialist may have experience treating these special populations.

People who are co-infected with HIV

In a late-stage trial of simeprevir, peg-interferon and ribavirin for people co-infected with hepatitis C and HIV, cure rates were an average of 74%. Participants with HIV received the same length of treatment as participants without HIV.

Driving or using machines

Treatment with simeprevir, peg-interferon and ribavirin may affect your ability to drive or use machines. If you feel faint or are having trouble seeing, do not drive or use machines.

Side effects

When simeprevir is taken with peg-interferon and ribavirin, the most common side effects are:

In general, most of these side effects are caused by peg-interferon and/or ribavirin.

Drug interactions

Always consult your doctor and pharmacist about taking other prescription and non-prescription drugs, including methadone or opiate substitution therapies, herbs, supplements and street drugs.

Drug interactions occur when one medication affects how another is absorbed, used or flushed out of the body. Some drugs can interact with simeprevir, increasing or decreasing the level of one or both drugs in the body. Increased levels can lead to new or more severe side effects. Decreased levels may mean that the drug won’t be as effective.

When simeprevir is taken with the following medications it could cause significant drug interactions. This is not a complete list of drug interactions with simeprevir.

  • medicine to treat irregular heartbeat, such as amiodarone, digoxin (Toloxin), disopyramide (Rythmoden), flecainide, lidocaine (when given by injection), mexiletine, propafenone, quinidine
  • medicine to treat bacterial infection, such as clarithromycin (Biaxin), erythromycin, telithromycin
  • medicine to prevent blood clots, such as warfarin (Coumadin)
  • medicine to prevent seizures, such as carbamazepine, oxcarbazepine, phenobarbital, phenytoin
  • medicine to treat fungal infection when taken by mouth, such as itraconazole, ketoconazole, posaconazole, voriconazole, fluconazole
  • medicine to treat infections like tuberculosis, such as rifabutin, rifampin, rifapentine
  • medicine to lower blood pressure, such as amlodipine, bepridil, diltiazem, felodipine, nicardipine, nifedipine, nisoldipine, verapamil
  • steroids, such as dexamethasone when administered by injection or when taken by mouth
  • medicine to treat HIV, such as atazanavir (Reyataz), darunavir (Prezista and also in Prezcobix), delavirdine mesylate (Rescriptor), efavirenz (Sustiva, also a component of Atripla), etravirine (Intelence), fosamprenavir (Telzir), indinavir (Crixivan), lopinavir (in Kaletra), nelfinavir (Viracept), nevirapine (Viramune), ritonavir (Norvir), saquinavir (Invirase), tipranavir (Aptivus), cobicistat, a component of Prezista and Stribild
  • medicine to lower cholesterol, such as atorvastatin (Lipitor), lovastatin, pravastatin, rosuvastatin (Crestor), simvastatin
  • medicine to lower immune response or prevent organ transplant failure, such as sirolimus. It is not recommended to take cyclosporine.
  • medicine to treat pulmonary hypertension, such as sildenafil (Revatio), tadalafil (Adcirca)
  • medicine to treat trouble with sleeping and/or anxiety, such as triazolam
  • any medicinal herbs, especially one used to treat depression: St. John’s wort  (Hypericum perforatum), or hyperforin or hypericin, active ingredients in St. John’s wort, and milk thistle (Silybum marianum)

The following drugs are not sold in Canada but have been identified by the manufacturers as causing drug interactions when taken with simeprevir. You may come across them when travelling in other countries.

  • medicine to treat some stomach conditions, such as cisapride
  • medicine to lower cholesterol, such as pitavastatin
  • medicine to treat trouble with sleeping and/or anxiety, such as midazolam (when taken by mouth)
  • antihistamines astemizole and terfenadine

Talk to your nurse, doctor and pharmacist if you are taking any of these medicines. Ask them about how to deal with these drug interactions. One way to manage drug interactions is to make sure that your doctor and pharmacist know about everything you are taking. This includes prescription drugs, over-the-counter drugs, street drugs, herbal medications, supplements or anything else. If you have more than one doctor or pharmacist, it is possible for drug interactions to get missed. If more than one doctor is writing prescriptions for you, let each one know about everything you are taking. If possible, use the same pharmacy for all your prescriptions.


Drug resistance develops when a virus mutates, or changes, during the replication process. Some mutations of the virus may be able to resist Hep C medications. When this happens the medication becomes less effective or stops working. Resistance can develop when a person does not take their medication as prescribed and directed.

During clinical trials a small number of people developed resistance to simeprevir; the majority of those people were not cured from treatment with simeprevir. It is not clear what this drug resistance means for future treatment options. If your Hep C becomes resistant to simeprevir, speak to your doctor about possible options for treatment in the future. New combinations of drugs are being developed and will become available in several years. Some of these may be effective against Hep C that is resistant to simeprevir.


Simeprevir, manufactured by Janssen, has been approved by Health Canada and is available in Canada.

Your nurse, doctor or pharmacist can tell you more about the availability and coverage of simeprevir in your region.

CATIE’s online Treatment coverage in your region section of Hepatitis C: An In-Depth Guide also contains information about provincial and territorial drug coverage.


We thank Alnoor Ramji, MD, FRCP(C) for expert review.


  1. Janssen Inc. Galexos (simeprevir) Product monograph. 2014.
  2. Jacobson IM, Dore GJ, Foster GR, et al. Simeprevir with pegylated interferon alfa 2a plus ribavirin in treatment-naive patients with chronic hepatitis C virus genotype 1 infection (QUEST-1) : a phase 3, randomised, double-blind, placebo-controlled trial. The Lancet. 2014 Aug; 384: 403-413.
  3. Manns M, Marcellin P, Poordad F, et al. Simeprevir with pegylated interferon alfa 2a or 2b plus ribavirin in treatment-naïve patients with chronic hepatitis C virus genotype 1 infection (QUEST-2): a randomised, double-blind, placebo-controlled phase 3 trial. The Lancet. 2014 Aug; 384: 414-426.
  4. Dieterich D, Rockstroh JK, Orkin C, et al. Simeprevir (TMC435) plus PegIFN/ribavirin in HCV genotype-1/HIV-1 coinfection (Study C212). Program and abstracts of the 21st Conference on Retroviruses and Opportunistic Infections, March 3-6, 2014, Boston, USA. Abstract 24.
  5. Dieterich D, Rockstroh JK, Orkin C, et al. Simeprevir (TMC435) with Pegintereron/Ribavirin in patients coinfected with HCV genotype-1 and HIV-1: A Phase III study. Clinical Infectious Diseases. 2014; in press.

Author(s): Anderson S

Published: 2014