Meds and you

30 September 2013


Ritonavir is an antiretroviral. Antiretrovirals are drugs that suppress the activity or replication of retroviruses such as HIV.


Ritonavir is the active ingredient of Norvir Capsules (Nappi Code: 836095-014) and Norvir Solution (Nappi Code: 838527-035).

General information
Ritonavir is an antiretroviral. Antiretrovirals are drugs that suppress the activity or replication of retroviruses such as HIV.

This specific antiviral is classified as a protease inhibitor, meaning that it blocks an enzyme which plays an essential role in viral multiplication. It interferes with the ability of the virus to make copies of itself.

In South Africa ritonavir is registered for the treatment of infection with the human immunodeficiency virus (HIV), often in combination with other antiretroviral drugs.

If not treated, HIV will advance to weaken the body's immune system, gradually chipping away to create grounds for other infections, which the body will find more and more difficult to protect itself against. HIV develops into acquired immune deficiency syndrome (AIDS) when your immune system has been severely weakened.

For ritonavir to be effective it has to be taken regularly. By skipping even a few doses the risk for treatment failure increases substantially. Try to ensure that you take all your doses, and at the correct time.

It should be understood that ritonavir is not a cure for HIV or AIDS, but is one of a variety of drugs that only restricts the advance of the virus, keeping the immune system up-and-running. It is used in combination with other antiretroviral drugs and should not be prescribed on its own.

Ritonavir does not reduce transmission of HIV; you can still infect another person with the virus and the use of appropriate precautions to prevent spread to other persons is highly recommended.

How does ritonavir work?
After a human T cell is infected with HIV, the virus needs to multiply to spread to other cells. A crucial part of HIV multiplication is the production of an enzyme called protease which is essential for the assembly of new viral copies. This drug interferes with the working of this enzyme, thereby leaving the new copies of the virus immature and non-infectious.

Fast facts

Drug schedule: schedule 4
Available as: ritonavir is available as capsules and as an oral solution.
What does it do? Ritonavir is an anti-viral drug.
Overdose risk: medium
Dependence risk: low
Is Ritonavir available as a generic? no
Is Ritonavir available on prescription only? yes

User information Dietary advice: ritonavir should be taken with or after a meal.
Stopping this medicine: do not stop taking this drug without consulting your doctor.
Prolonged use: side-effects may develop with long-term use; frequent blood tests may be required with prolonged therapy to prevent serious blood disorders and to determine liver function.

Special precautions
Consult your doctor before using this drug if:

  • you have known liver or kidney problems

  • you have been diagnosed with a condition that increases your risk of bleeding

  • you have diabetes

  • you have porphyria

  • you are taking other medication.

Pregnancy: avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.
Breastfeeding: avoid. Not only can HIV infection be passed to your baby through breast milk, but ritonavir is also present and transmitted in breast milk.
Porphyria: avoid. This medication may cause serious adverse effects. Consult your doctor before use.
The elderly: caution is advised in the elderly as side effects may be more severe.
Infants and children: this medication is not intended for use in children under the age of 2 years.
Driving and hazardous work: caution is advised as use of this medication may lead to dizziness or light-headedness. Avoid such activities until you know how this medication affects you.
Alcohol: avoid concomitant use of alcohol with this medication.

Possible side effects

Side Effect
Consult your doctor

Only if severe
In all cases


dry mouth




loss of appetite


abdominal pain


taste disturbance




mouth ulcers






abnormal body fat distribution


skin rash


sore throat


muscle weakness


muscle pain




carbamazepine, phenytoin, phenobarbitone reduced effect of ritonavir
benzodiazepines increased risk of toxicity
Ketoconazole increased risk of ritonavir toxicity
dexamethasone reduced effect of ritonavir
didanosine take the 2 drugs at least 2 hours apart
ergotamine increased risk of toxicity
verapamil increased risk of verapamil toxicity
erythromycin/clarithromycin increased risk of toxicity of these agents
astemizole/cisapride/ pimozide/ terfenadine ncreased risk of cardiac toxicity
simvastatin and other similar cholesterol lowering drugs increased risk of muscle wasting
risperidone/haloperidol increased risk of toxicity of these agents

Many other drugs may interact with ritonavir. It is important to consult your doctor or pharmacist before combining any drug with ritonavir.

Disease interactions
Contact your doctor in case of liver/kidney disease, if you have diabetes or porphyria, or you have been diagnosed with a condition that increases your risk of bleeding.

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose seek emergency medical attention.

Recommended dosage
Adults: oral, 600 mg 12 hourly

This material is not intended to substitute medical advice, but is for informational purposes only. Please consult a physician for specific treatment and recommendations.

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