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Nucleoside analogue reverse transcriptase inhibitors (NRTIs)
Names: 3TC, lamivudine, Epivir™
Approved dosage: 300mg daily, either as one white 150mg tablet twice a day or two white 150mg tablets once a day or once white 300mg tablet once a day. The dose may be altered if you have impaired kidney function. Also available in a combined form with AZT called Combivir™ and in a combined form with AZT and abacavir called Trizivir™. 3TC and abacavir are also available in a combined formulation called KivexaTM. Combivir and Trizivir are both taken as one tablet twice a day and Kivexa is taken as one tablet once a day.
Children: approved for use in children. Liquid suspension available.
Tips on taking it: take with or without food.
Common side-effects: headache, tiredness.
Rare side-effects: rash, diarrhoea, nausea, abdominal pain, blood disorders, peripheral neuropathy, insomnia and liver problems.
Resistance to 3TC: may affect your response to abacavir. Drug-resistant 3TC may continue to have an antiviral effect. People who have virus resistant to 3TC are unlikely to respond to FTC.
Key drug interactions: few significant drug interactions. Any drug that causes neutropenia may increase side-effects. 3TC should not be taken with intravenous foscarnet or ganciclovir.
abacavir
Names: abacavir, Ziagen™
Approved dosage: 600mg daily, either as one 300mg yellow tablet twice daily or two 300mg tablets once a day. Also available in a combined form with AZT and 3TC (TrizivirTM, taken as one tablet twice daily). Abacavir and 3TC are also available in a combined formulation called KivexaTM. The combined KivexaTM pill contains 600mg of abacavir and 300mg of 3TC and the dose is one tablet taken once daily.
Children: liquid formulation available.
Tips on taking it: take with or without food.
Common side-effects: nausea and vomiting, headaches, weakness, diarrhoea, insomnia, dizziness, and abdominal pain.
Rare side-effects: An allergic reaction (often involving fever and rash) occurs in 3% - 8% of people taking abacavir, usually within four weeks of starting the drug. See your doctor immediately if you develop a rash, fever or abdominal pain while on abacavir. You should not re-try abacavir, or take Trizivir™ or Kivexa™ if you have had an allergic reaction to abacavir previously. Many clinics now conduct a genetic test to see if a person is likely to have an allergic reaction to abacavir. Liver problems can also be a rare side-effect of the drug.
Resistance to abacavir: may affect your response to AZT, 3TC, ddI and possibly tenofovir.
Key drug interactions: no significant drug interactions yet identified.
Brain: abacavir may cross the blood-brain barrier and may be effective against HIV in the brain.
AZT
Names: AZT, zidovudine, Retrovir™
Approved dosage: one white and blue 250mg capsule taken twice a day. A 100mg capsule is available for dose variations.
Children: approved for use in children. Liquid formulation available.
Tips on taking it: try to take the doses twelve hours apart. Take with or after food to reduce nausea. Anti-nausea drugs may be used up-front.
Common side-effects: nausea, vomiting, fatigue, headache, insomnia, blood disorders.
Rare side-effect: liver problems.
Resistance to AZT: is likely to cause resistance to d4T and possibly also to abacavir and tenofovir.
Key drug interactions: other drugs (eg hydroxyurea, ganciclovir) that cause blood disorders may worsen side-effects. Do not take with d4T. Drug levels may be affected if methadone, phenytoin, or probenecid are taken with AZT. Doses of clarithromycin and AZT should be taken one hour apart.
Brain: AZT is effective against HIV in the brain and the central nervous system.
Combivir™
AZT is also available in a combined form with 3TC called Combivir™. Dosage of Combivir™ is one white tablet (150mg 3TC and 300mg AZT) twice a day. See the entry for AZT and 3TC for side-effects.
KivexaTM
Abacavir and 3TC are available in a combined form called Kivexa. The dosage of KivexaTM is one orange tablet (600mg abacavir and 300mg 3TC) once a day. See the entries for abacavir and 3TC for side-effects.
Trizivir™
AZT is also available in a combined form with 3TC and abacaviR called Trizivir™. Dosage of Trizivir™ is one green tablet (300mg AZT, 150mg 3TC and 300mg abacavir) taken twice a day. See the entries for AZT, 3TC and abacavir for side-effects.
d4T
Names d4T, stavudine, Zerit™, Zerit PRC™
Approved dosage: for people over 60kg (9 1/2 stone): one dark orange 40mg capsule twice a day; for people under 60kg: usually one light and dark orange 30mg capsule twice a day. Note: people with impaired kidney function or peripheral neuropathy may take 15 or 20mg twice a day. d4T is available as 40mg, 30mg, 20mg and 15mg capsules.
Zerit PRC™ is approved for once daily dosing. The dose for people weighing over 60kg is 100mg, and for people weighing less than 60kg, 75mg a day.
Children: approved for use in children. d4T comes in a powder form.
Tips on taking it: although the product information advises taking d4T on an empty stomach, this does not affect absorption of the drug and it is possible to take with or without food. However, taking it with food reduces nausea.
Common side-effects: peripheral neuropathy, headache, nausea, diarrhoea or constipation.
Rare side-effects: pancreatitis, liver problems.
Resistance to d4T: likely to cause resistance to AZT.
Key drug interactions: do not take with AZT. Drugs that may cause peripheral neuropathy or pancreatitis (eg ddI) may increase the risk of these side-effects.
Brain: d4T crosses the blood-brain barrier and may be effective against HIV in the brain.
ddC
Names: ddC, zalcitabine, Hivid™
Approved dosage: one pale blue/grey 0.75mg tablet three times a day.
Children: syrup available for children through a special access scheme.
Tips on taking it: take with or after food to reduce nausea.
Common side-effects: peripheral neuropathy, mouth ulcers, diarrhoea, nausea, rash.
Rare side-effects: pancreatitis (very rare), liver problems.
Resistance to ddC: low risk of resistance to ddI, 3TC and abacavir.
Key drug interactions: do not take with ddI or 3TC. Other drugs that can cause peripheral neuropathy, pancreatitis, or ulcers increase the risk of these side-effects of ddC.
Note: Roche Pharmaceuticals, who make ddC, have announced that they plan to stop making it in 2006 or shortly after.
ddI (Videx™)
ddI is available in two formulations, as a tablet and capsule. Advice on taking ddI differs depending upon which formulation you are taking.
Names
Approved dosage: for people over 60kg (9 1/2 stone): two white, orange-flavoured 200mg tablets once daily; for people under 60kg: one large white, orange-flavoured 200mg tablet plus two large white, orange flavoured 25mg tablets one a day. Note: people who have kidney or liver abnormalities may be advised by their doctor to take a lower dose.
Children: approved for use in children. Liquid formulation available.
Tips on taking it: take on an empty stomach to maximise the amount of ddI that gets into your blood. Take ddI tablets at least two hours after eating and wait another half an hour before eating again. During this fasting period avoid fruit juices (except clear apple juice), fizzy drinks and milk. Smoking may also reduce the absorption of ddI. Crush and dissolve ddI tablets in ice-cold water or clear apple juice. If you take a dose first thing in the morning, dissolve your dose the night before and leave in the fridge. Pill-crushers are available from pharmacies.
Common side-effects: diarrhoea, peripheral neuropathy, nausea.
Rare side-effects: pancreatitis, greater risk if you have high alcohol consumption and/or liver problems.
Resistance to ddI: low risk of resistance to ddC, 3TC and abacavir.
Key drug interactions: ddI tablets should be taken at least two hours apart from any medicines which carry the warning 'not to be taken at the same time of day as indigestion remedies', as the effectiveness of these other medicines may be reduced. Examples of drugs which should not be taken at the same time as ddI tablets are atazanavir, itraconazole, ketoconazole, indinavir, ciprofloxacin, valganciclovir, tetracycline antibiotics and delavirdine (an NNRTI, not licensed in the UK). Do not take with ddC, allopurinol or intravenous pentamidine. Drugs such as H2 blockers, omeprazole, rifampicin, and rifabutin may increase the risk of pancreatitis. ddI tablets should not be taken at the same time of day as some other medications. For example, ddI tablets and protease inhibitors must be taken at least one hour apart. Tenofovir increases ddI levels and they should only be taken in combination with ddI if no other options are available. If you do need to take ddI and tenfovir, you should be very closely monitored by your clinic and ddI should be taken at least two hours after or one hour before tenofovir.
When taken with hydroxyurea, the amount of active ddI in cells increases. Hydroxyurea may therefore both improve the effectiveness of ddI and increase the risk of side-effects, but is not licensed for use in this way.
ddI (Videx EC™)
Names: ddI EC capsules, didanosine enteric coated, Videx EC™
Approved dosage: for people over 60kg (9 1/2 stone): one 400mg white capsule once a day, or one 200mg capsule twice a day; for people under 60kg: one 250mg capsule once a day or one 125mg capsule twice daily. Note: people who have kidney or liver abnormalities may be advised by their doctor to take a lower dose.
Children: ddI EC is approved for use in children.
Tips on taking it: take with water on an empty stomach to maximise the amount of ddI EC that gets into your blood. Take ddI EC capsules at least two hours before and at least two hours after food. Taking the capsules before bedtime may be most convenient. During this fasting period avoid all liquids except water. It is okay to take ddI EC at the same time as other antiretrovirals, including indinavir, so long as they do not need to be taken with food. ddI E does not interact with medicines that should not be taken at the same time as indigestion remedies.
Common side-effects: diarrhoea, nausea, headache, peripheral neuropathy.
Rare side-effects: pancreatitis, liver problems.
Resistance to ddI: low risk of resistance to ddC, 3TC and abacavir.
FTC (emtricitabine, Emtriva™)
Names: FTC, emtricitabine, Emtriva™
Approved dosage: one blue and white 200mg capsule once a day. Note: people who have kidney adnormalities may be advised by their doctor to take a lower dose.
Children: approved for use by children aged four months and over.
Tips on taking it: can be taken with or without food.
Common side-effects: dizziness, headache, diarrhoea, and nausea.
Less common side-effects: rash, vomiting, sleep problems, abnormal kidney and liver function, lactic acidosis, skin discolouration.
Resistance to FTC: unlikely to be beneficial for people who are already resistant to 3TC or abacavir.
TruvadaTM
FTC (emtricitabine) is also available in a combined pill with the nucleotide analogue, tenofovir. The FTC/tenofovir pill is called TruvadaTM. The dose is one blue tablet (200mg FTC and 300mg tenofovir) once a day. For side-effects see the entries for FTC and tenofovir.