Efavirenz

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

Efavirenz, also known as Sustiva, belongs to a class of drugs called non-nucleoside reverse transcriptase inhibitors (NNRTIs). NNRTIs are used for the treatment of HIV infection, in combination with other anti-HIV drugs. Please speak to your clinic doctor or pharmacist if you would like more information about how these drugs work.

Before taking efavirenz
Tell your doctor about:

* All other drugs you are taking, including any that you buy over the counter in a community pharmacy and any herbal medicines or recreational drugs;
* Any previous allergy to any medicines;
* If you have ever had any liver disease;
* If you have a history of a mental health illness;
* If you are pregnant or planning a pregnancy. Efavirenz should not be taken by pregnant women;
* If you are breastfeeding;

Taking your efavirenz

* Efavirenz is available as a capsule containing 200 mg of efavirenz and a tablet containing 600mg.
Efavirenz is also available in a liquid formulation;
* The usual dose is 600mg once each day - at night;
N.B. if you are taking the liquid formulation, you need to take a slightly higher dose of 720mg
(24mls). This is because the liquid form is not absorbed from the stomach as well as the capsule and
tablet forms.
* The dose should be taken at the same time each day. You may take efavirenz at any time during the day, although taking it at bedtime may help to reduce the side-effects during the first few weeks;
* Efavirenz may be taken before, with or after food. Less drug is actually absorbed when efavirenz is taken on an empty stomach, but there is still sufficient quantities absorbed for the drug to be effective, which is why you are given the choice of how to take it. Because there is less drug absorbed when the drug is taken on an empty stomach there is some evidence to suggest that this may reduce the incidence of nervous system side effects (vivid dreams, hallucinations, dizziness etc.);
If you find that you suffer from these side effects, try taking efavirenz on an empty stomach at bedtime.
* Efavirenz works best if there is a constant amount in your blood stream. It is therefore important to take it 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 efavirenz. If you are going on holiday and need additional supplies - tell your doctor. Your pharmacist will check that you have enough to last until your next appointment.

Other drugs and efavirenz
Efavirenz 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 efavirenz and therefore should NOT be taken are phenytoin, phenobarbitone, carbamazepine, simvastatin, ergotamine, certain benzodiazepines, St. John’s Wort and terfenadine (Triludan). Other examples of drugs that are metabolised in the same way as efavirenz include rifampicin, rifabutin, warfarin, methadone and the protease inhibitors. Your doctor may alter your doses if you are taking one of these drugs.

Efavirenz can stop hormonal contraceptives from working effectively so you must use an alternative form of contraception e.g. barrier methods.

Side effects
Efavirenz, like all other medicines, has some side effects. The most important ones are:

* Dizziness/light-headedness: This appears to be the most common side effect of efavirenz. It occurs after the first dose and usually resolves after a few days or weeks, although it can persist for longer in some people. If you are affected by these symptoms you should not drive or operate machinery. The likelihood of experiencing dizziness and light-headedness is reduced if you take the dose at bedtime;
* Skin rash: This is a common side effect of all the NNRTI's and usually resolves after 4 weeks with continuation of treatment. There is a decreased incidence of skin rash with efavirenz compared with the other NNRTI's such as nevirapine. Efavirenz can very rarely cause a severe skin reaction which is associated with blistering and ulceration. If this occurs consult your doctor immediately;
* Vivid dreams/nightmares: You may find that taking efavirenz at bedtime can lead to vivid dreams. If this becomes troublesome try taking the dose earlier in the evening.;
If you experience any of these side effects or any other new symptoms after starting efavirenz, tell your doctor who will advise you what to do. If you decide to stop taking efavirenz it is important that you tell your doctor so that he or she can discuss other treatment options with you.

Stopping efavirenz therapy
If you decide you would like to stop taking efavirenz it is very important that you discuss this with your doctor rather than stop on your own accord. Efavirenz can last for a long time in your bloodstream after you have stopped taking it – much longer than other drugs. This means that your body may be exposed to a single drug and your virus may become resistant. If you do wish to stop therapy you should discuss this with your doctor, so that it can be stopped in a controlled manner to minimise the risk of resistance.

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 now operate a selfmedication 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 you Efavirenz
Efavirenz should be stored at room temperature.