3TC

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 one larger grey 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 Kivexa. 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: nausea, vomiting, abdominal pain, diarrhoea, headache, muscle pains, cough, nasal symptoms, fever, tiredness, rash, hair loss and difficulty sleeping.  

Rare side‑effects include: blood disorders, peripheral neuropathy 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. Although it is not recommended to use 3TC with intravenous foscarnet or ganciclovir, the drugs are frequently used together. 

abacavir

Names: abacavir, Ziagen 

Approved dosage: 600mg daily, either as one 300mg yellow tablet twice daily or two 300mg tablets once a day. Abacavir and 3TC are also available in a combined formulation called Kivexa. The combined Kivexa pill contains 600mg of abacavir and 300mg of 3TC and the dose is one tablet taken once daily. Also available in a combined form with AZT and 3TC called Trizivir, taken as one tablet twice daily.

Children: liquid formulation available. 

Tips on taking it: take with or without food. 

Common side‑effects: nausea and vomiting, diarrhoea, headaches, high temperature, fatigue and loss of appetite.

Special warning: an allergic reaction (often involving fever and rash) occurs in approximately 5% of people taking abacavir, usually within four weeks of starting the drug. See your doctor immediately if you develop a rash, fever, shortness of breath or abdominal pain while on abacavir. You should never 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 (called a HLA‑B*5701 test) to see if a person is likely to have an allergic reaction to abacavir. If this test is positive you should not take abacavir. If it is negative, it is highly unlikely that an allergic reaction will occur, but you should still report symptoms like a fever, rash or headache to your doctor immediately. 

Rare side‑effects include: inflammation of the pancreas. 

Resistance to abacavir: may affect your response to AZT, 3TC, ddI and possibly tenofovir. 

Key drug interactions: abacavir may result in reduced levels of ribavirin (a drug used to treat hepatitis C infection).

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. Also available in a combined tablet with 3TC called Combivir, taken twice a day, and in a combined tablet with 3TC and abacavir, called Trizivir, taken twice a day.

Children: approved for use in children. Liquid formulation available. 

Tips on taking it: take with or after food to reduce nausea. Anti‑nausea drugs may be used up‑front in the first few weeks. 

Common side‑effects: nausea, dizziness, vomiting, abdominal pain, diarrhoea, muscle aches, headache and blood disorders. Fat loss (lipoatrophy) has been recognised as a long‑term side‑effect of AZT. For this reason, treatment with AZT is not recommended if you have other treatment options available to you.  

Rare side‑effects include: liver problems and insomnia. 

Resistance to AZT: is likely to cause resistance to d4T and possibly also to abacavir and tenofovir. 

Key drug interactions: other drugs (e.g. hydroxyurea, ganciclovir, and ribavirin) 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. 

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 but is not available in the UK. 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 which is made into a liquid. 

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, lipodystrophy, fatigue, depression and rash. Fat loss has been recognised as a long-term side-effect of d4T. For this reason d4T is not recommended if you have other treatment options available to you.

Rare side‑effects include: pancreatitis and liver problems. 

Resistance to d4T: likely to cause resistance to AZT. 

Key drug interactions: do not take with AZT or ddI. Drugs that may cause peripheral neuropathy or pancreatitis (e.g. 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. 

ddI

ddI is available in two formulations, as a tablet and capsule. Advice on taking ddI differs depending upon which formulation you are taking, so it is very important to check that you are following the advice that relates to the form you are taking. 

ddI (tablet)

Names: ddl, didanosine, Videx 

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 once daily. 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 (not licensed in the UK). 

Tips on taking it: take on an empty stomach to maximise the amount of ddI that gets into your blood. Take ddI tablets or liquid 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, rash, fatigue, nausea, vomiting and abdominal pain. 

Rare side‑effects include: pancreatitis (greater risk if you have high alcohol consumption) and liver problems, particularly with long‑term use. 

Resistance to ddI: low risk of resistance to 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 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 should only be taken in combination with ddI if no other options are available. If you do need to take ddI and tenofovir, you should be very closely monitored by your clinic. In this case the ddI dose will usually be reduced (250mg for weight >60kg, 200mg for weight <60kg) and the ddI and tenofovir can be taken together, with or without food. 

ddI (capsule)

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. Some people find taking the capsules before bedtime is more convenient. During this fasting period avoid all liquids except water.  

Common side‑effects: diarrhoea, peripheral neuropathy, rash, fatigue, nausea, vomiting and abdominal pain. 

Rare side‑effects include: pancreatitis and liver problems, particularly with long‑term use. 

Resistance to ddI: low risk of resistance to 3TC and abacavir. 

Key drug interactions: it is okay to take ddI EC at the same time as other antiretrovirals so long as they do not need to be taken with food. ddI EC does not interact with medicines that should not be taken at the same time as indigestion remedies. 

Tenofovir increases ddI levels and should only be taken in combination with ddI if no other options are available. If you do need to take ddI and tenofovir, you should be very closely monitored by your clinic. In this case the ddI dose will usually be reduced and the ddI and tenofovir can be taken together, with or without food. 

FTC

Names: FTC, emtricitabine, Emtriva 

Approved dosage: one blue and white 200mg capsule once a day.  FTC is also available in a combination tablet with tenofovir called Truvada. This is taken once a day and consists of 200mg of FTC and 300mg of tenofovir. Also in a combination tablet with tenofovir and efavirenz called Atripla. This is taken once a day and consists of 200mg of FTC, 300mg of tenofovir and 600mg of efavirenz. Note: people who have kidney abnormalities 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. Atripla should be taken on an empty stomach.

Common side‑effects: headache, diarrhoea, nausea, increased creatinine kinase in the blood leading to muscle pain and weakness, dizziness, difficulty sleeping, problems with digestion, rash, changes in skin colour (mainly seen in people with non‑white skin), changes in the blood and disturbance of function of the liver, kidney and pancreas. 

Rare side‑effects include: reduced kidney and liver function, lactic acidosis. 

Resistance to FTC: unlikely to be beneficial for people who are already resistant to 3TC or abacavir. 

Tenofovir

Names: tenofovir, Viread 

Approved dosage: one blue, pear shaped film‑coated 300mg tablet daily. Dose may be adjusted if kidney function impaired. Also available in a combination tablet with FTC called Truvada. This is taken once a day and consists of 300mg of tenofovir and 200mg of FTC. Also in a combination tablet with FTC and efavirenz called Atripla. This tablet is taken once a day and consists of 300mg of tenofovir, 200mg of FTC and 600mg of efavirenz.

Tips on taking it: take with food, to increase absorption. However, recommendations in the US say the drug can be taken with or without food. Atripla should be taken on an empty stomach.

Common side‑effects: dizziness, diarrhoea, nausea, vomiting, flatulence, bone problems and changes in blood phosphates. 

Rare side‑effects include: pancreatitis and rash. Longer‑term side‑effects of tenofovir are not yet clearly established, however there are reports of kidney problems, particularly in people who are on other medicines that can affect the kidneys, or those who have other reasons to experience kidney problems such as high blood pressure or diabetes. Creatinine monitoring advised to spot kidney damage, especially in patients with impaired kidney function. 

Resistance to tenofovir: may cause resistance to all NRTIs with the possible exception of AZT. 

Key drug interactions: tenofovir increases levels of ddI. Should only be used with atazanavir if it is boosted by ritonavir. 

Atripla

In December 2007 a tablet called Atripla that combines 200mg of FTC, 300mg of tenofovir and 600mg of efavirenz 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. 

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 entries for AZT and 3TC for side‑effects and further information.

Kivexa

Abacavir and 3TC are available in a combined form called Kivexa. The dosage of Kivexa is one orange tablet (600mg abacavir and 300mg 3TC) once a day. See the entries for abacavir and 3TC for side‑effects and further information. 

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 and further information. 

Truvada

FTC (emtricitabine) and tenofovir are also available in a combined pill called Truvada . The dose is one blue tablet (200mg FTC and 300mg tenofovir) once a day. For side‑effects see the entries for FTC and tenofovir.