How does this medication work? What will it do for me?

Simeprevir is an antiviral agent. Specifically, it belongs to the class of medications known as protease inhibitors. Protease is an enzyme that is needed by viruses for reproduction. Simeprevir blocks the action of protease, slowing the growth of the virus.

This medication is used in combination with other medications to treat chronic (long-term) hepatitis C caused by "genotype 1" or "genotype 4" for people who have not been treated before, or who have been treated and not responded well.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Simeprevir is no longer being manufactured for sale in Canada and is no longer available under any brand names. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The recommended dose of simeprevir is 150 mg taken once daily with food. The capsule should be swallowed whole with fluids and not crushed or chewed. Ideally, simeprevir should be taken at the same time each day.

Simeprevir must be taken in combination with other anti-viral medications. It is usually taken for 12 or 24 weeks, depending on your situation. The effectiveness of the combination of medications is determined by your doctor with blood tests.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor and not reduced. Reducing the dose may cause the medication to fail. If you miss a dose, and it is within 12 hours of the missed dose, take it as soon as possible with food and continue with your regular schedule. If it is more than 12 hours past the time of your missed dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature in its original package, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take simeprevir if you:

  • are allergic to simeprevir or any ingredients of the medication
  • cannot take sofosbuvir, peginterferon alfa or ribavirin
  • are pregnant or plan to become pregnant

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • constipation
  • increased sensitivity to sunlight (sunburn, blistering, redness)
  • itchiness
  • skin rash

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.


December 1, 2016

Health Canada has issued new restrictions concerning the use of Galexos® (simeprevir). To read the full Health Canada Advisory, visit Health Canada's web site at

Birth control: The effect of simeprevir on the development of an unborn baby has not been studied, however it is often taken with medications that can cause severe birth defects to an unborn child. Both partners should use a reliable form of birth control while taking this medication and for 6 months afterwards (the time it takes for ribavirin to be cleared from the body).

For women, your doctor will not give you simeprevir until you have had a negative pregnancy test. Your doctor should have you continue to do monthly pregnancy tests to ensure that you do not become pregnant while using this medication.

Methods of birth control that use hormones, such as a birth control pill, patch, or injection, may not be fully reliable as simeprevir interacts with many medications and may change the way that your body uses the hormones. At least 2 forms of non-hormonal birth control (condom, diaphragm) must be used while you are taking this medication.

Hepatitis B Reactivation: If you have had hepatitis B infection in the past, taking simeprevir may cause the hepatitis B to reactivate. This can cause liver damage, possible leading to the liver failure or death. Talk to your doctor if you have a history of hepatitis B infection.

Hepatitis C virus response: Only genotype 1 and genotype 4 hepatitis C virus strains have been studied and determined to respond to simeprevir. The safety and effectiveness of using simeprevir to treat other strains of hepatitis C virus have not been determined.

Infection with Human Immunodeficiency Virus (HIV): The safety and effectiveness of treatment with simeprevir have not been established for people who also have human immunodeficiency virus (HIV).

Lactose intolerance: This medication contains lactose. If you have galactose intolerance (galactosemia, glucose-galactose malabsorption, or Lapp lactase deficiency) you should not take this medication. Talk to your doctor about other alternatives.

Liver function: Simeprevir is not recommended for people with active, worsening liver disease, or moderately-to-severely reduced liver function. If you have a history of reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Organ transplantation: The safety and effectiveness of treatment with simeprevir have not been established for people with liver or other organ transplants. Simeprevir may interact with medications used to prevent rejection of the transplanted organ.

Skin reactions: Simeprevir may cause skin rash or itchiness with or without a rash. It may also make your skin more sensitive to ultraviolet light from the sun or tanning beds. While you are taking simeprevir, avoid unnecessary exposure to sunlight. If you notice any unusual skin rash or peeling, contact your doctor.

Pregnancy: Simeprevir has not been studied for use by pregnant women and it must be taken with other antiviral medications, some of which have been shown to cause serious harm to the developing baby. Tell your doctor immediately if you become pregnant while using this medication.

Breast-feeding: It is not known if simeprevir passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Breast-feeding should be stopped before starting treatment with simeprevir.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between simeprevir and any of the following:

  • abiraterone
  • aliskiren
  • alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
  • amiodarone
  • anticancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
  • antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
  • apixaban
  • aprepitant
  • "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
  • barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
  • benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
  • bicalutamide
  • bosentan
  • bromocriptine
  • buprenorphine
  • buspirone
  • calcitriol
  • calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
  • carvedilol
  • cetirizine
  • chloroquine
  • cimetidine
  • ciprofloxacin
  • cobicistat
  • colchicine
  • conivaptan
  • cyclosporine
  • dabigatran
  • dabrafenib
  • dantrolene
  • dapsone
  • deferasirox
  • desvenlafaxine
  • dexamethasone
  • digoxin
  • disopyramide
  • domperidone
  • dronedarone
  • edoxaban
  • eltrombopag
  • enzalutamide
  • ergot-containing medications (e.g., dihydroergotamine, ergotamine)
  • estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
  • flutamide
  • gemfibrozil
  • "gliptin" diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
  • grapefruit juice
  • hepatitis C antivirals (e.g., daclatasvir, dasabuvir, ledipasvir, paritaprevir, ombitasvir, sofosbuvir)
  • HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
  • HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
  • hydrocortisone
  • ivermectin
  • lidocaine
  • loperamide
  • losartan
  • lumacaftor
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • maraviroc
  • mefloquine
  • methadone
  • mifepristone
  • milk thistle
  • mirtazapine
  • modafinil
  • nadolol
  • nefazodone
  • nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
  • norfloxacin
  • ondansetron
  • oxycodone
  • phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
  • praziquantel
  • primaquine
  • protein kinase inhibitors (e.g., crizotinib, dasatinib, imatinib, nilotinib)
  • proton pump inhibitors (e.g., lansoprazole, omeprazole)
  • prucalopride
  • quinidine
  • quinine
  • ranitidine
  • repaglinide
  • rifabutin
  • rifampin
  • rilpivirine
  • rivaroxaban
  • romidepsin
  • St. John's wort
  • seizure medications (e.g., carbamazepine, gabapentin, levetiracetam, phenytoin, primidone)
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
  • siltuximab
  • sirolimus
  • "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
  • tacrolimus
  • tenofovir
  • teriflunomide
  • ticagrelor
  • ticlopidine
  • tocilizumab
  • tolterodine
  • tolvaptan
  • tramadol
  • trazodone
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
  • venlafaxine
  • zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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