efavirenz

Names: efavirenz, Sustiva 

Approved dosage: one dark yellow 600mg tablet once a day or three dark yellow 200mg capsules once a day. Efavirenz is also available in a combination tablet with FTC and tenofovir. This is taken once a day and consists of 600mg efavirenz, 200mg of FTC and 300mg of tenofovir.

Children: approved for use in children aged three years and above, who weigh more than 13kg. Oral solution available (but note that the dose of the solution is different from the dose of the tablets or capsules). 

Tips on taking it: recommended to take on an empty stomach. Avoid taking it with a high fat meal which may increase absorption. If efavirenz causes confusion or dizziness, take before going to bed. 

Common side‑effects: dizziness, headache, sleep disturbances, abdominal pain, diarrhoea, nausea, vomiting, rash and psychological effects (these are most commonly experienced during the first four weeks of treatment and include feeling ‘out of sorts’, confusion, abnormal dreams, disturbance in attention, and depression. In most cases these side‑effects go away by themselves and it isn’t necessary to stop taking efavirenz). 

Rare side‑effects include: Stevens‑Johnson Syndrome (very rare), disturbance in liver function tests, aches and pains, and severe psychological symptoms including paranoia and suicidal thoughts. 

Resistance to efavirenz: is likely to cause resistance to delavirdine (an NNRTI that is not licensed for use in the UK) and nevirapine. 

Key drug interactions: alters blood levels of protease inhibitors. May interfere with oral contraceptives. Do not take efavirenz with St John’s wort, astemizole, triazolam, and midazolam. Efavirenz may affect drug levels of Viagra, Cialis, Levitra, Zyban or rifabutin and so dose adjustments are needed. Dose adjustment is also necessary if taken with clarithromycin and rifampicin. Do not take with simvastatin. 

Brain: efavirenz crosses the blood‑brain barrier and has some action against HIV in the brain and the central nervous system. 

Pregnancy: efavirenz is not recommended during pregnancy or in women planning pregnancy due to a theoretical risk of nervous system abnormalities in the infant. If you become pregnant while taking efavirenz continue taking your medication and contact your clinic for advice.  

nevirapine

Names: nevirapine, Viramune 

Approved dosage: one white 200mg tablet once a day for the first two weeks and then one 200mg tablet twice a day thereafter. Men should not start treatment with nevirapine if their CD4 cell count is above 400, women should not start treatment with nevirapine if their CD4 cell count is above 250 as this increases the risk of potentially dangerous side‑effects. 

Experimental dosage: two white 200mg tablets once a day. This is not normally recommended within the first two months of starting nevirapine. 

Children: syrup available. 

Tips on taking it: take with or without food. 

Common side‑effects: headache, rash (usually in the first six weeks of treatment), fatigue, liver problems (usually in the first six weeks of treatment), muscle pain and nausea. During the first six weeks of treatment with nevirapine the health of your liver will be intensively monitored and you will be advised to have liver function tests every one to two weeks. 

Rare side‑effects include: Stevens‑Johnson Syndrome. 

Resistance to nevirapine: is likely to cause resistance to delavirdine (an NNRTI that is not licensed in the UK) and efavirenz. 

Key drug interactions: nevirapine may reduce levels of a number of drugs including atazanavir, indinavir, lopinavir/ritonavir, ketoconazole, Cialis, Viagra, Levitra. Nevirapine may reduce the effectiveness of oral contraceptives. Nevirapine may worsen side‑effects of clarithromycin, and erythromycin. Do not take with St John’s wort. 

Brain: nevirapine crosses the blood‑brain barrier and has some action against HIV in the brain and central nervous system. 

Atripla

In December 2007 for a tablet called Atripla that combines 600mg of efavirenz with 200mg of FTC and 300mg of tenofovir was approved. The dose is one pink, oval tablet, once a day. See the entries for FTC, tenofovir and efavirenz for side‑effects and interactions. 

In the UK and Europe, it is recommended that Atripla should be taken on an empty stomach.