HIV and anti-HIV drugs

HIV is a virus, which attacks the immune system (the body’s defense system against infection and illness). If you have HIV, you can take drugs to reduce the level of HIV in your body. By reducing the amount of HIV in your body, you can slow or prevent damage to your immune system. These drugs are not a cure, but they can help you stay well and extend your life. Anti-HIV drugs are known as antiretroviral drugs.

How antiretroviral drugs work

HIV mainly infects cells in the immune system called CD4 cells. Over many years of HIV infection, the number of CD4 cells drops and the immune system is weakened. If noting is done to slow or halt this destruction of the immune system, a condition called AIDS follows. Antiretroviral drugs work by interrupting this process.

The aim of treatment

An untreated person with HIV may have thousands or even millions of HIV particles in every milliliter of blood. The aim of treatment is to reduce the amount of HIV to very low levels eg below 50 copies per milliliter of blood.

To provide you with the best chance of reducing the amount of HIV in your blood to very low levels, your doctor may recommend that you take a powerful combination of at least three antiretroviral drugs. Once your viral load has dropped, your immune system should begin to recover and your ability to fight infections is likely to improve.

When to take treatment

There are many opinions about when is the best time start taking antiretroviral therapy but there is no general rule that applies to everyone. Some people take treatment early on, before there is much damage to the immune system; others start later, when blood tests show they are likely to become sick in the near future. Some people wait until they are sick before taking antiretroviral.

Your decision about when to start therapy should be made in consultation with your doctor. If you are getting persistent ‘minor’ infections, or if you have had an AIDS-defining illness, (e.g. PCP), your immune system may already be seriously weakened. In this situation, your doctor will strongly advise you to consider taking antiretroviral.

If you have established HIV infection but no symptoms, current guidelines recommend beginning therapy before your CD4 count falls below 200.

If your CD4 count is between 200 and 350 it is recommended that your consider starting therapy. In such circumstances you should use your recent viral load measurements and the number of CD4 cells you have been losing to guide your decision.

The final decision about when to begin treatment rests with you. Social factors such as family, relationships, work and travel may influence your decision.

Sticking to your drug routine

Taking antiretroviral therapy is a long-term commitment. Once you start the drugs, it is recommended that your continue treatment for the rest of your life.

It is very important not to miss doses and to take the drugs as prescribed. If you miss doses, or you do not take the drugs as you are supposed to, the HIV in your body is more likely to develop resistance to the drugs. This will reduce their long-term effectiveness.

If you are having difficulty sticking to your drug routine, discuss alternative combinations that may be easier for you to take with your doctor.

There are many tips and aids which may improve your ability to take your drugs as required. For more information, speak to your health care team.

Regular check-ups

If you have HIV, you should see a doctor regularly for a check-up. Most people with HIV attend specialist HIV clinics, which have doctors and other health professionals trained in HIV and AIDS.

Monitoring

Before you start on antiretroviral, or before you switch to a new combination, you should have a number of blood tests. Viral load and CD4 tests will tell you how advanced your HIV disease is. Once you have begun treatment, tests to measure liver function, and fat and sugar levels in the blood may be conducted to show the effects of the drugs on the normal working of your body. Your doctor may also test for drug resistance.

Once you are on a new combination, a viral load and CD4 count will be done within the first month of treatment. This is to check that the drugs are working. Testing is generally performed every three months, although some doctors may perform tests more regularly.

Pregnancy

Combinations of antiretroviral are now commonly used during pregnancy as an effective means of preventing the transmission of HIV from a mother to her baby. However, the long-term effects on the Child are not yet clear. Generally, anti-HIV drugs are not recommended during the first three months of pregnancy unless the woman is already on treatment.

As a woman’s health improves on antiretroviral, her fertility may also increase. It is recommended that women considering pregnancy, or women, who may conceive, discuss their treatment options with their doctor. The contraceptive pill may be less effective among women on anti-HIV drugs due to drug interactions.

Whether a father’s treatment increases the risk of birth defects is not known.

Side-effects

It is very common for people to experience side effects to antiretroviral therapy, especially during the first few weeks of treatment. Your doctor can prescribe a number of drugs to help you cope with this initial period.

Common side effects of many medications include headache, nausea, diarrhea, and tiredness. Report side effects, especially rash and fever, to your doctor promptly.

In this booklet, we have listed as common side effects anything which affected more than 5-10% of people in clinical trials of a drug, and which in the opinion of the drug licensing bodies, are side effect of the drug.

Drug interactions

Combining two or more different drugs together may result in an alteration in the effectiveness of one or more of the drugs being taken. This booklet lists the key drug interactions for antiretroviral drugs.

Some antiretroviral drugs lower or increase levels of other antiretroviral drugs. Some antiretroviral drugs interact with other medicines commonly used in the treatment of HIV.

Some drug combinations are contraindicated-which means you definitely should not take them together. Reasons for this include serious toxicity and interactions, which make one or both drugs ineffective.

Other interactions are less serious. Levels of one or both drugs in your blood may be affected and dosing adjustments may be required.

Some drug interactions may mean you have a greater chance of developing certain side-effects such as peripheral neuropathy.

Less is known about interactions with recreational drugs. However, if you use recreational drugs it is sensible to discuss this with your doctor, HIV pharmacist or other health care provider. The protease inhibitors are the most likely to interact with recreational drugs, though interactions with both NRTIs and NNRTIs and recreational drugs have been described.

Types of antiretroviral drugs

There are five main types of antiretroviral drugs:

 Nucleoside analogue reverse transcriptase inhibitors (NRTIs), which target an HIV protein called reverse transcriptase.
 Non-nucleoside reverse transcriptase inhibitors (NNRTIs), which also target reverse transcriptase.
 Nucleotide analogue reverse transcriptase inhibitors (NtRTIs), which also target reverse transcriptase
 Protease inhibitors (Pis), which target an HIV protein called protease.
 Fusion inhibitors, which target the point where HIV binds onto immune system cells.

Each class of drug attacks HIV in a different way. Generally drugs from two (or sometimes three) classes are combined to ensure a powerful attack on HIV.

Summary

 Anti-HIV drugs prevent HIV from damaging your immune system, and so prevent ill health and prolong survival.

 The best time to begin anti-HIV drugs is not known. Decisions are guided by the CD4 count and viral load. It is currently recommended that treatment starts before the CD4 count falls below 200.

 Combinations of at least three anti-HIV drugs provide the best chance of reducing the amount of HIV in your blood to very low levels.

 Taking your anti-HIV drugs as prescribed is extremely important, as this will prolong the benefit you will get from them, and reduce the risk of resistance to the drugs developing.

 Five classes of antiretroviral drugs are now available.

Glossary

AIDS Acquire Immune Deficiency Syndrome.

AIDS-defining illness One of a group of illnesses associated with AIDS. If you are HIV-positive and you have one of these illnesses, you are said to have AIDS. For example, PCP or Kaposi’s sarcoma.

Absorption The amount of drug that gets into the blood.

Approved dosage An effective and safe dose that has been approved by drug licensing authorities.

Blood disorders Refers to conditions such as anaemia (low red blood cells) which causes fatigue, and neutropenia (low white blood cells).

CD4 A molecule on the surface of some cells on to which HIV can bind. The CD4 cell count roughly reflects the state of the immune system.

Experimental dosage Dosage/s being tested in trials and not approved by drug licensing authorities.

GUM clinics Genito-urinary medicine or sexual health clinics.

Lipodystrophy A change to the way the body stores, handles and distributes fat. A side-effect of anti-HIV drug treatment.

Metabolic abnormalities Anti-HIV drugs, particularly protease inhibitors, ae associated with irregularities in the body’s processing of sugar and fat, resulting in increased levels of these substances in the blood.

Pancreatitis Inflammation of the pancreas. A serious, possibly life-threatening condition.

PCP Pneumocystis carinii pneumonia – a type of pneumonia which is diagnostic of AIDS.

Peripheral neuropathy Nerve damage which causes pins and needles, altered sensation and pain, usually in the hands and feet.

Resistance A resistant HIV strain in one which is less susceptible to one or more anti-HIV drugs.

Special access scheme Before a drug is fully approved by drug licensing authorities, a pharmaceutical company may make a new treatment available through a special access scheme. This is sometimes called named patient prescribing or expanded access.

Stevens-Johnson Syndrome A severe or even life-threatening allergic reaction.

Viral load Measurement of the amount of virus in a sample. HIV viral load indicates the extent to which HIV is reproducing in the body.