Ritonavir / Norvir®

Please read this factsheet together with the patient information leaflet carefully before taking your medicine. If you have any questions or are unsure about anything, ask your doctor or pharmacist.

Ritonavir is also known as Norvir®. It belongs to a class of drugs called protease inhibitors.

Protease inhibitors are used in the treatment of HIV infection in combination with other anti-HIV drugs. If you would like more information about how these drugs work in the body, a leaflet is available. Please ask your doctor and the pharmacist for details.

Before taking ritonavir
Tell your doctor about:

* All other drugs that you are taking, including any that you buy over the counter in a community
pharmacy, herbal medicines and recreational drugs;
* Previous allergy to any medicines;
* If you have ever had any liver disease;
* If you are diabetic;

Taking your ritonavir

* Ritonavir is available as an off-white capsule containing 100mg of ritonavir and also as a liquid containing 80mg per ml;
* Ritonavir is now mainly used in small doses to boost the levels of other protease inhibitors in the body, so making them more effective. If you are taking ritonavir to ‘boost’ the levels of another Protease inhibitor the two drugs must be taken at the same time;
* The doses should be divided equally throughout the day: if you take ritonavir twice daily, try to take the doses as close as possible to 12 hours apart, and at the same times each day. If you are taking ritonavir once daily try to take the doses as close as possible to twenty four hours apart and at the same time each day;
* Ritonavir should preferably be taken with or just after food to ensure enough is being absorbed into the body. It should be taken at the same time as your other protease inhibitors;
* Ritonavir works best if there is a constant amount in your bloodstream. It is therefore very important to take the drug regularly. If you forget a dose, take it as soon as you remember, but do not double-up the next dose;

Do not run out of ritonavir. If you are going on holiday and need additional supplies, tell your doctor. When receiving a supply from pharmacy, ensure that you have an adequate supply to last until your next appointment.

Other drugs and ritonavir
Ritonavir is metabolised (processed in the body) by the liver. Some other drugs are metabolised in the same way. This is why it is important to tell your doctor about all the medicines that you take even if you only take them occasionally, including herbal and recreational drugs. Examples of some drugs that are metabolised in the same way as ritonavir and should NOT be taken are rifampicin, Phenytoin, Simvastatin, Ergotamine, certain benzodiazepines and St. Johns Wort.

Other examples of drugs that are metabolised in the same way as ritonavir include warfarin, rifabutin, fluticasone propionate, methadone, drugs for erectile dysfunction (e.g. Viagra®), NNRTIs and other protease inhibitors. Your doctor may alter your doses if you are taking one of these drugs.

Ritonavir can stop hormonal contraceptives from working effectively, so you must use an alternative form of contraception, e.g. barrier methods. If you are taking the chewable tablet form of didanosine (ddI) or antacids (for indigestion) in combination with ritonavir you should take the two drugs at least one hour apart. Ritonavir liquid contains a small amount of alcohol. You should not take the antibiotics metronidazole or tinidazole whilst on ritonavir liquid.

Side effects
Ritonavir like all other medicines has some side effects. The most important are:

* Nausea and vomiting;
* Diarrhoea;
* Abdominal pain;
* Changes in taste;
* Tiredness;
* Headaches;
* A burning sensation of the skin, including tingling around the mouth and tongue;

Combination regimes containing protease inhibitors have been associated with redistribution of body fat in some patients. They are also associated with metabolic abnormalities such as raised cholesterol, increased risk of diabetes and heart disease. Your clinic doctor will monitor you for all of these.

If you experience any of these side effects or any new symptoms after you start ritonavir, tell your doctor who will advise you what to do. If you decide to stop taking ritonavir, it is important that you tell your doctor so that he or she can discuss other treatment options with you.

Admission to hospital
If you are admitted to hospital please bring all your medicines with you. This is especially important for anti-HIV drugs, as they have to be taken regularly. Thomas Macaulay Ward operates a self medication programme. Some people are able to self administer their own medicines to enable them to stick to the routine they have been used to at home.

Storing your ritonavir
Ritonavir capsules should be stored in the fridge; however they can be left at room temperature for
up to one month. Ritonavir liquid should be stored at room temperature.