atazanavir

Names: atazanavir, Reyataz 

Approved dosage: 300mg (two light and dark blue 150mg capsules) plus one cream 100mg ritonavir capsule taken together once a day. If the combination also contains efavirenz or nevirapine the dose is 400mg (two turquoise 200mg capsules) plus one 100mg ritonavir capsule taken together once a day. 

Tips on taking it: take with a snack to improve absorption. 

Common side‑effects: non‑dangerous yellowing of the skin caused by increased levels of bilirubin, peripheral neuropathy, headache, insomnia, vomiting, diarrhoea, abdominal pain, nausea, indigestion, rash, tiredness. 

Rare side‑effects include: abnormal liver function, kidney stones and pancreatitis. 

Resistance to atazanavir: there is conflicting evidence. Early studies suggested that atazanavir would be effective in people resistant to other protease inhibitors. However, more recent evidence shows that as many as 40% of people who had previously used a protease inhibitor have reduced sensitivity to the drug. This is one of the reasons why it is recommended to boost atazanavir levels with ritonavir. 

Key drug interactions: when taken with efavirenz or tenofovir, levels of atazanavir drop. However, adding 100mg of ritonavir counters this. Take ddI tablets at least two hours before or one hour after atazanavir (not necessary if taking Videx EC capsules). Doses of the anti‑TB drug rifabutin should be reduced by 75%. Reduce doses of clarithromycin by half if taken at the same time as atazanavir. Reduce doses of Cialis, Viagra, or Levitra by half. Don’t take with St John’s wort. Don’t take antacids within four hours of atazanavir. Don’t take lansoprazole, omeprazole, rifampicin, phenytoin, carbamazepine, or simvastatin with atazanavir. Take ranitidine once a day only, twelve hours apart from atazanavir (for example take atazanavir in the morning and ranitidine at night). 

darunavir

Names: darunavir, Prezista 

Approved dosage: 600mg (two orange 300mg) tablets plus one 100mg cream ritonavir capsule taken together twice a day.  

Tips on taking it: must be taken with food to improve absorption. 

Common side‑effects: diarrhoea, nausea, rash and headache. 

Resistance to darunavir: the drug works well in many people with resistance to other protease inhibitors. However, resistance to amprenavir/fosamprenavir can reduce the effectiveness of darunavir. 

Key drug interactions: Astemizole; carbamazepine; dihydroergotamine; ergometrine; ergotamine tartrate; hypericin (St John’s wort); midazolam; phenytoin; pimozide; rifampicin; and simvastatin. Careful monitoring required if taken with methadone, rifabutin, Viagra, Cialis, and Levitra. 

fosamprenavir

Names: fosamprenavir, Telzir 

Approved dosage: one pink 700mg tablet with one cream 100mg capsule of ritonavir twice daily. 

Tips on taking it: take with or without food.  

Common side‑effects: diarrhoea, increased blood fats, nausea, vomiting, pain in the stomach, loose stools, rash, headache, feeling dizzy, tiredness, changes in liver and pancreas function. 

Rare side‑effects include: changes in cholesterol levels, Stevens‑Johnson Syndrome 

Resistance to fosmaprenavir: is likely to cause resistance to ritonavir, and possibly also to saquinavir, indinavir and nelfinavir. 

Key drug interactions: Viagra, Cialis, Levitra, Zyban, simvastatin. 

indinavir

Names: indinavir, Crixivan 

Approved dosage: 800mg (two cream 400mg capsules) every eight hours. 

Experimental dosage: with ritonavir: 400mg of both drugs twice daily. Alternatively, two 400mg capsules of indinavir and 100mg of ritonavir twice a day, or two 400mg capsules of indinavir and 200mg of ritonavir (other doses have been used in conjunction with drug level monitoring studies). 

Tips on taking it: if indinavir is taken with ritonavir, there are no food restrictions. When indinavir is taken without ritonavir it should ideally be taken on an empty stomach (avoiding food for two hours before and one hour after each dose). Alternatively it can be taken with a light, low‑fat snack, e.g. 30g cereal with 100g skimmed milk or a tea or coffee with sugar and skimmed milk plus one biscuit, or two small slices of toast with low‑fat spread and 15g of jam per slice. For more suggestions, see NAM’s Nutrition booklet, or discuss your options with an HIV dietitian or pharmacist. Drink 1.5 litres of water of a non‑caffeinated drink in addition to your usual fluid intake, to reduce the risk of kidney stones. Indinavir must be stored with a desiccant to keep the capsules dry. Can be kept in a dosette box without a desiccant for up to three days. 

Common side‑effects: headache, dizziness, nausea, vomiting, diarrhoea, rash, kidney stones, fatigue, alerted taste, abdominal pain, sleep disturbance, flatulence, dry mouth, acid regurgitation, in‑growing toenails, dry skin and muscle pain. 

Rare side‑effects include: diabetes and liver abnormalities. 

Resistance to indinavir: causes resistance to ritonavir, and is likely to cause resistance to saquinavir, nelfinavir and fosamprenavir. 

Key drug interactions: do not take indinavir with St John’s wort, terfenadine, astemizole, cisapride, alprazolam, pimozide, rifampicin, amiodarone, quinidine and ergot alkaloids. Careful monitoring and dose adjustments may be needed if indinavir is taken with drugs including: rifabutin, ketoconazole, the NNRTIs, Viagra, Cialis, Levitra and simvastatin. Large doses of vitamin C have been shown to reduce indinavir concentrations in the blood. 

lopinavir/ritonavir (Kaletra)

Names: lopinavir/ritonavir, ABT‑378/r, Kaletra 

Note: Kaletra is available in two formulations, soft gel capsules and hard tablets. Advice on how to take Kaletra varies depending on which you take.  

Approved dosage: 400mg lopinavir plus 100mg ritonavir. Hard tablets contain 200mg lopinavir and 50mg ritonavir so two yellow tablets are required twice a daily. There is an, as yet unapproved, once‑daily dose of Kaletra hard tablets consisting of four tablets once a day.  

For soft‑gel capsules, this means three orange 133.3mg/33.3mg capsules, twice daily. The dose is usually increased to four capsules when taken with efavirenz or nevirapine. Production of soft‑gel capsules is expected to cease in 2008. 

Children:a tablet containing 100mg of lopinavir and 25mg of ritonavir is close to approval for use in children. Liquid formulation available. 

Tips on taking it: the tablet can be taken with or without food, but must not be broken, chewed or crushed. The capsules need to be taken with food and stored in the fridge. But they can be kept at room temperature (below 25 degrees C)  for up to six weeks.

Common side‑effects: diarrhoea, insomnia, headache, nausea, vomiting, abdominal pain, abnormal stools, indigestion, flatulence, rash, feeling weak and changes in blood fats and sugars. It is possible that lipodystrophy, a side‑effect of other protease inhibitors, will also affect lopinavir/ritonavir users. 

Rare side‑effects include: abnormal kidney or liver function. 

Resistance to lopinavir/ritonavir: likely cross‑resistance with indinavir and ritonavir and, to some extent, fosamprenavir. High level resistance to other protease inhibitors may reduce the effectiveness of lopinavir/ritonavir. 

Key drug interactions: due to the presence of ritonavir, avoid all drugs which negatively interact with ritonavir (see ritonavir entry). Efavirenz and nevirapine reduce levels of lopinavir/ritonavir and dose adjustments are recommended. Do not take with St John’s wort. Monitoring and dose adjustment may be necessary when lopinavir/ritonavir is taken in conjunction with amiodarone, bepredil, quinidine, systemic lidocaine, warfarin, calcium channel blockers, Viagra, Cialis, Levitra, Zyban, tacrolimus, cyclosporin, methadone, rifabutin, rifampicin, oral contraceptives, ketoconazole, intraconazole and simvastatin.  

nelfinavir

NB: Problems with the manufacture of nelfinavir led to the drug being taken off the market in June 2007 and the temporary suspension of the drug’s licence. The licence was returned in September 2007, but supplies of nelfinavir are likely to be interrupted.

Names: nelfinavir, Viracept 

Approved dosage: five blue 250mg tablets twice a day, or three blue 250mg tablets three times a day. 

Children: nelfinavir is approved for use in children. Available in powder form. 

Tips on taking it: it is very important that you take nelfinavir with food to increase absorption. 

Common side‑effects: diarrhoea, nausea, flatulence, rash and metabolic abnormalities. 

Rare side‑effects include: jaundice and diabetes.  

Resistance to nelfinavir: is likely to cause resistance to saquinavir and may cause resistance to ritonavir and indinavir. 

Key drug interactions: careful monitoring and dose adjustments may be needed if nelfinavir is taken with drugs including: oral contraceptives, rifabutin, methadone, carbamazapine, phenytoin, Viagra, Cialis, Zyban, Levitra and some lipid‑lowering drugs. Do not take nelfinavir with terfenadine, rifampicin, astemizole, cisapride, pimozide, amiodarone, quinidine, midazole, triazolam, simvastatin, ergot alkaloids or St John’s wort. 

ritonavir

Names: ritonavir, Norvir 

Approved dosage: ritonavir is mainly used in small doses (usually 100mg or 200mg once or twice daily) to ‘boost’ other protease inhibitors. It has been approved for use in this way in the following doses: ritonavir/atazanavir 100/300mg once daily; ritonavir/fosamprenavir 100/700mg twice daily; ritonavir/darunavir 100mg/600mg twice daily; ritonavir/lopinavir 100mg/400mg twice daily; ritonavir/saquinavir 100mg/1000mg twice daily; ritonavir/tipranavir 200mg/500mg twice daily. 

Ritonavir is also approved for use as a single protease inhibitor at a dose of 600mg twice a day (six 100mg cream capsules). However it is very rarely used in this way.  

Children: full-dose ritonavir is not formally approved for use in children, although it can be made available. 

Tips on taking it: take with food to reduce nausea. Ritonavir capsules should be stored in a fridge, but can be kept at room temperature (below 25 degrees C) for up to 30 days. Ritonavir liquid should always be stored at room temperature. 

Common side‑effects: diarrhoea, stomach pain, nausea, vomiting, weakness, taste abnormalities, loss of appetite, numbness around the mouth, lipodystrophy and metabolic abnormalities. 

Rare side‑effects: kidney problems, diabetes. 

Resistance to ritonavir: causes resistance to indinavir and is likely to mean some resistance to nelfinavir, saquinavir and fosamprenavir. 

Key drug interactions: ritonavir interacts with many other medications. Consult your doctor or HIV pharmacist before taking any other drugs with ritonavir (including inhalers, medicines bought from a high street chemist, herbal preparations and recreational drugs). Do not take ritonavir with piroxicam, dextropropoxyphene, pethidine; amiodarone, encainide, flecainide, propafenone, quinidine, bupropion (Zyban) , astemizole, terfenadine, clozapine, pimozide, alprazolam, clorazepate, diazepam, estazolam, bepridil, cisapride; fluorazepam, midazolam, triazolam, zolpidem, Viagra, Cialis, Levitra or St John’s wort. 

saquinavir

Names: saquinavir, Invirase 

Approved dosage: two orange 500mg tablets (or five yellow and green 200mg capsules) together with one 100mg capsule of ritonavir twice a day. 

Children: saquinavir is not approved for use by children. 

Tips on taking it: take saquinavir within two hours of a full meal to increase absorption. 

Common side‑effects: fatigue, anaemia, nausea, vomiting, lipodystrophy and metabolic disorders. 

Rare side‑effects include: diabetes and Stevens‑Johnson Syndrome. 

Resistance to saquinavir: may mean resistance to nelfinavir, indinavir and ritonavir. 

Key drug interactions: do not take with rifampicin, rifabutin, astemizole, terfenadine, cisapride or the herbal anti‑depressant St John’s wort. Careful monitoring and dose adjustments may be needed if taking saquinavir with many other drugs including: NNRTIs, methadone, anti‑arrhythmics, some anti‑depressants, some anti‑convulsants, some lipid‑lowering drugs, dapsone, ergotamine, dihydroergotamine, dexamethasone, Viagra, Cialis and Levitra. Do not take with garlic supplements.  

tipranavir

Names: tipranavir, Aptivus 

Approved dosage: approved dosage: two 250mg pink capsules together with 200mg (two 100mg cream capsules) ritonavir, twice daily. 

Tips on taking it: to be taken with food. Tipranavir capsules should be stored in the fridge, but can be kept at room temperature (below 25 degrees C) for up to 60 days. 

Common side-effects: diarrhoea, nausea, vomiting, abdominal pain, flatulence, tiredness, headache, increased blood fats, liver abnormalities and rash.  

Rare side-effects: diabetes and kidney problems. 

Resistance to tipranavir: test tube studies report that resistance to tipranavir is slow to develop, and that there is no clear pattern of cross‑resistance to currently available protease inhibitors. 

Key drug interactions: rifampicin, cisapride pimozide, sertindole, triazolam, ergot derivatives, astemizole, terfenadine, simvastatin, lovastatin, amiodarone, bepridil, flecainide, propafenone, quinidine and St John’s wort. Take special care with Viagra, Cialis and Levitra, disulfiram, fluticasone, atorvastatin and metronidazole. Tipranavir may also interact with other types of medicines, which may lead to a loss of effectiveness of these medicines. These include the morphine‑substitute methadone and oral contraceptives. If you are using oral contraceptives to prevent pregnancy you should use an additional or different type of contraception. If you are taking ddI EC, it should be taken at least two hours apart from tipranavir.