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

This medication is a combination of several medications: ombitasvir, paritaprevir, and ritonavir combined in one tablet and dasabuvir as a second tablet. Together, these medications belong to the class of medications called antivirals. This medication is used alone or with ribavirin to treat Chronic Hepatitis C (CHC) infection.

Ombitasvir, paritaprevir, and dasabuvir each work in different ways to reduce the reproduction of the Hepatitis C virus. Ritonavir contributes to this effect by increasing the amount of paritaprevir available to be used by the body with each dose.

This medication does not prevent the spread of Hepatitis C through sexual contact or blood contamination and it does not prevent you from being reinfected with the Hepatitis C virus.

If you are taking this medication with ribavirin, please refer to the information article for ribavirin, in addition to this article.

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?

Each pink, film-coated, oblong, biconvex tablet, debossed with "AV1" on one side, contains ombitasvir 12.5 mg, paritaprevir 75 mg and ritonavir 50 mg. Nonmedicinal ingredients: colloidal silicon dioxide/anhydrous colloidal silica, copovidone, propylene glycol monolaurate, sodium stearyl fumarate, sorbitan monolaurate, and vitamin E polyethylene glycol succinate. Film coating: iron oxide red, polyethylene glycol/macrogol, polyvinyl alcohol, purified water, talc, and titanium dioxide.

Each beige, film-coated, oval tablet, debossed with "AV2" on one side, contains dasabuvir 250 mg. Nonmedicinal ingredients: colloidal silicon dioxide/anhydrous colloidal silica, copovidone, croscarmellose sodium, lactose monohydrate, magnesium stearate, and microcrystalline cellulose. Film coating: iron oxide black, iron oxide red, iron oxide yellow, polyethylene glycol/macrogol, polyvinyl alcohol, purified water, talc, and titanium dioxide.

How should I use this medication?

The recommended adult dose of ombitasvir - paritaprevir - ritonavir is 2 tablets taken once daily, in the morning. The dasabuvir dose is one tablet taken in the morning and one tablet taken in the evening.

Both tablets should be swallowed whole, with water if needed. Do not chew, crush, or break the tablets. Take this medication with food in order for your body to absorb as much medication as possible from each dose.

A course of treatment with these medications is 12 weeks long. It is important to take this medication exactly as prescribed by your doctor. The effectiveness of the medication depends on there being the right amount of these medications in the bloodstream. Finish all this medication, even if you have started to feel better. Stopping this medication early can allow the infection to return and it may become harder to treat.

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.

If you miss a dose of ombitasvir - paritaprevir - ritonavir, and it is less than 12 hours since your missed dose, take it as soon as possible and continue with your regular schedule. If you miss a dose of dasabuvir and it is less than 6 hours since the missed dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next 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, 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 this medication if you:

  • are allergic to ombitasvir, paritaprevir, ritonavir, dasabuvir, or any ingredients of the medication
  • are pregnant and also taking ribavirin
  • are taking any of the following medications:
    • alfuzosin
    • bosentan
    • carbamazepine
    • cisapride
    • efavirenz
    • ergot derivatives (e.g., ergotamine, dihydroergotamine)
    • ethinyl estradiol
    • etravirine
    • gemfibrozil
    • lovastatin
    • midazolam taken by mouth
    • modafinil
    • phenytoin
    • phenobarbital
    • pimozide
    • rifampin
    • St. John's wort
    • salmeterol
    • sildenafil (when used for pulmonary hypertension)
    • simvastatin
    • triazolam

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.

  • headache
  • tiredness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)

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.


November 10, 2015

Health Canada has issued new restrictions concerning the use of Holkira Pak (ombitasvir/paritaprevir/ritonavir). To read the full Health Canada Advisory, visit Health Canada's web site at

Heart rhythm: Ombitasvir - paritaprevir - ritonavir and dasabuvir can cause changes to the normal rhythm of the heart, including an irregular heartbeat called QT prolongation. QT prolongation is a serious life-threatening condition that can cause fainting, seizures, and sudden death. If you are at risk for heart rhythm problems (e.g., people with heart failure, angina, low potassium or magnesium levels), 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.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, 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. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

This medication has been reported to cause signs of decreased liver function. This most commonly appears with women who are taking other medications that contain ethinyl estradiol, such as some birth control pills. Medications containing ethinyl estradiol should be stopped before starting to take ombitasvir - paritaprevir - ritonavir and dasabuvir.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if ombitasvir - paritaprevir - ritonavir and dasabuvir passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

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 ombitasvir - paritaprevir - ritonavir and dasabuvir and any of the following:

  • abiraterone acetate
  • aliskiren
  • alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
  • amantadine
  • amiodarone
  • anti-cancer medications (e.g., cabazitaxel, docetaxel, doxorubicin, etoposide, ifosfamide, irinotecan, vincristine)
  • antihistamines (e.g., cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
  • antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
  • apixaban
  • apomorphine
  • aprepitant
  • atomoxetine
  • atovaquone
  • "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
  • benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
  • birth control pills
  • bosentan
  • buprenorphine
  • buspirone
  • calcitriol
  • calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
  • captopril
  • carbamazepine
  • carvedilol
  • celecoxib
  • chloral hydrate
  • chloroquine
  • cisapride
  • clopidogrel
  • colchicine
  • conivaptan
  • inhaled corticosteroids (e.g., budesonide, ciclesonide, fluticasone)
  • oral corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
  • cyclosporine
  • dabigatran
  • dantrolene
  • dapsone
  • deferasirox
  • dextromethorphan
  • diabetes medications (e.g., chlorpropamide, glipizide, glyburide, insulin, metformin, nateglinide, rosiglitazone)
  • digoxin
  • dipyridamole
  • domperidone
  • dronedarone
  • eltrombopag
  • enzalutamide
  • eplerenone
  • ergot alkaloids (e.g., dihydroergotamine, ergonovine,  ergotamine, methylergonovine)
  • estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
  • ethosuximide
  • everolimus
  • famotidine
  • flecainide
  • flutamide
  • formoterol
  • galantamine
  • gemfibrozil
  • guanfacine
  • hepatitis protease inhibitors (e.g., boceprevir, simeprevir, telaprevir)
  • HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delaviridine, efavirenz, etravirine, nevirapine)
  • HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
  • indapamide
  • irbesartan
  • lidocaine
  • lithium
  • loperamide
  • losartan
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • lurasidone
  • macitentan
  • maprotiline
  • maraviroc
  • mefloquine
  • mestranol
  • methadone
  • methamphetamine
  • metoprolol
  • metronidazole
  • mexiletine
  • mifepristone
  • mirtazapine
  • modafinil
  • montelukast
  • nadolol
  • nateglinide
  • nefazodone
  • nitrates (e.g., isosorbide dinitrate,  isosorbide mononitrate)
  • octreotide
  • ondansetron
  • oxybutynin
  • oxycodone
  • pentamidine
  • perampanel
  • phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
  • pimozide
  • prasugrel
  • praziquantel
  • primaquine
  • procainamide
  • progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
  • propafenone
  • propranolol
  • proton pump inhibitors (e.g., lansoprazole, omeprazole)
  • prucalopride
  • quinidine
  • quinine
  • quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
  • ranitidine
  • repaglinide
  • reserpine
  • rifabutin
  • rilpivirine
  • rivaroxaban
  • romidepsin
  • St. John's wort
  • salmeterol
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
  • serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
  • sirolimus
  • sotalol
  • "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
  • sulfamethoxazole
  • tacrolimus
  • tamoxifen
  • teniposide
  • tetrabenazine
  • tetracycline
  • theophylline
  • ticagrelor
  • ticlopidine
  • timolol
  • tocilizumab
  • tolterodine
  • tolvaptan
  • trabectedin
  • tramadol
  • trazodone
  • tretinoin
  • trimethoprim
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
  • tyrosine kinase inhibitors (e.g., dasatinib, imatinib, nilotinib)
  • valproic acid
  • venlafaxine
  • zidovudine
  • zolpidem
  • 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.