HIV and anti-HIV drugs

HIV is a virus which attacks the immune system – the body’s defence 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 gradually but continually and the immune system is weakened. If nothing is done to slow or halt this destruction of the immune system, a condition called AIDS (Acquired Immune Deficiency Syndrome) follows, as the immune system is no longer able to fight infections. 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 millilitre of blood. The aim of treatment is to reduce the amount of HIV to very low levels (this is called an ‘undetectable’ level) – below 50 copies per millilitre of blood, although some HIV treatment centres are now using tests that can measure as low as 40 copies/ml. 

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

When to start treatment

It’s not known for certain what is the best time to start treatment with anti-HIV drugs. This means you need to weigh up with your doctor the likely benefits and risks for you of starting treatment now as opposed to waiting until later.

However, it’s currently recommended in UK HIV treatment guidelines that you start taking HIV treatment immediately if you are ill because of HIV, or if you have an AIDS-defining illness.

If you do not have any symptoms, then the UK treatment guidelines (published by the British HIV Association, or BHIVA, in 2008) recommend that you start treatment when your CD4 cell count is around 350. Your doctor should start discussing HIV treatment with you when your CD4 cell count is around this figure and you are advised to start treatment as soon as you are ready.

You can find out more about CD4 counts and viral load testing in the NAM booklet CD4, viral load and other tests.

The importance of regular check-ups

If you have HIV, you should see a doctor regularly for a check-up. Most people with HIV attend GUM clinics or specialist HIV clinics that have doctors and other health professionals trained in HIV care. Even if you do not want to take HIV treatment at this stage, regular blood tests will tell you about the health of your immune system and if the disease is progressing. 

If you are entitled to free NHS care, this care and the antiretroviral drugs provided through NHS HIV clinics and GUM clinics are free.

Monitoring the safety and effectiveness of HIV treatment

Before you start taking antiretroviral drugs, 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 your HIV disease is progressing.

Your doctor may also test to see if your HIV has developed resistance to any of the antiretroviral drugs. Clinics also do a genetic test (called HLA-B*5701) to see if you may be more likely to develop an allergic reaction to the anti-HIV drug abacavir (Ziagen, also in the combination pills Kivexa and Trizivir). This test is most accurate in white people; more information is still needed about its accuracy in people of African or Asian origin. 

When you start or change a drug 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 often to begin with and less frequently once you are well established on treatment and doing well. 

Once you are on HIV treatment, you may have tests to measure liver and kidney function and fat and sugar levels in your blood, to assess the effects of the drugs on the normal workings of your body.

Your HIV care will also involve a number of other routine tests. These will be to monitor your general health and to see if your treatment is causing any side-effects.

For more information, see the NAM booklet CD4, viral load and other tests. 

Preparing to start your HIV treatment

Taking antiretroviral therapy is a long-term commitment. Once you start the drugs, it is recommended that you continue treatment for the foreseeable future. 

You are more likely to take your HIV treatment correctly if you are involved in the decisions about when to start treatment and about which drugs to start treatment with.

Being honest about your lifestyle with yourself and with your doctor can help ensure that you start on a drug combination that is right for you. So it's a good idea not to make unrealistic demands on yourself, and to think about how taking medication will fit in with your eating and sleeping patterns, and with your work, family and social life. The chances are that there will be a combination of HIV treatment available that will mean you don’t have to change your lifestyle at all, or make only modest alterations to your routine.

Taking your HIV treatment

It is very important not to miss doses of your anti-HIV drugs and to take them exactly 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 them. This will reduce their long-term effectiveness. 

To help make sure that you take the right combination of anti-HIV drugs, you should have a test to see if you already have any drug resistance before you start treatment (it is possible to be infected with a strain of HIV that has built-in resistance to some drugs).

If you need to change HIV treatment because your viral load becomes detectable again (see The aim of treatment), then your choice of new drugs should be guided by having another resistance test at this stage.

Even if you have resistance to several drugs, it’s good to know that important new anti-HIV drugs have become available in the past few years. An undetectable viral load is a realistic objective for nearly all patients, including those who have taken a lot of different treatments in the past and have drug-resistant virus.

If you are having difficulty sticking to your drug routine, discuss alternative combinations that may be easier to take with your doctor or pharmacist. There are many tips and aids which may improve your ability to take your drugs as required. For more information, speak to your healthcare team, or visit NAM’s website for people living with HIV: www.namlife.org. 

Further information can also be found in NAM’s booklet Adherence and resistance. 

Side-effects

Quite often people experience side-effects when taking antiretroviral drugs, especially during the first few weeks of treatment. Your doctor can prescribe a number of drugs to help you cope with this initial period. 

Side-effects most commonly reported include headache, nausea, diarrhoea, and tiredness. You don’t have to ‘grin and bear’ side-effects – report them, especially rash and fever, to your doctor promptly.

In this booklet, we have listed the more common side-effects – those affecting between 5 and 10% of people during clinical trials done as part of a drug’s development. We’ve also given details of rarer side-effects if they are potentially dangerous.

You can find out more about side-effects and how to deal with them in NAM’s booklet Side-effects.

Drug interactions

Taking two or more different drugs together may result in an alteration in the effectiveness (or side-effects) of one or more of the drugs being taken. Some prescription drugs and some drugs you can buy over the counter at a chemist should not be taken in combination with certain antiretrovirals.

It’s therefore important that your doctor and pharmacist know about all other medicines and drugs that you are taking – this includes those prescribed by another doctor, over-the-counter remedies, herbal and alternative treatments, and recreational drugs.

Some antiretroviral drugs lower or increase levels of other antiretroviral drugs. Some 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 side-effects or interactions which make one or both drugs ineffective. 

Other interactions are less dangerous, but still need to be taken seriously. Levels of one or both drugs in your blood may be affected and dosing adjustments may be required. 

Some drug interactions may mean that you have a greater chance of developing certain side-effects. 

Your HIV doctor and pharmacist will check for possible interactions before you start treatment with a new drug.

If any other healthcare professional prescribes you medicine, it’s important that they know about the drugs you are taking for your HIV. For example, it’s known that treatments for erectile dysfunction such as Viagra can interact with protease inhibitors and non-nucleoside reverse transcriptase inhibitors (NNRTIs). These interactions can increase blood levels of Viagra and similar drugs, increasing the risk of side-effects.

Some anti-HIV drugs can interact with antihistamines, treatments for indigestion, and statins – drugs that are used to control cholesterol (lipid levels). These treatments can either be prescribed or bought over the counter at high-street chemists. If you are using these drugs, you should tell your HIV doctor or pharmacist so they can check for possible interactions and recommend the most suitable treatment. Or, when you are buying them, you may wish to tell the pharmacist about the anti-HIV drugs you are taking. High-street chemists often have a private area for consultations. Or you could write the name of the drugs down and hand them to him or her. If you do need to mention the name of your anti-HIV drugs, it’s very unlikely that anyone around you will recognise what they are used to treat.

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 healthcare provider.

Antiretrovirals can also interact with herbal and alternative treatments. It is known that the herbal antidepressant St John’s wort lowers blood levels of NNRTIs and protease inhibitors. Garlic capsules stop the protease inhibitor saquinavir (Invirase) from working properly and it is thought that they could have a similar effect on other protease inhibitors as well. Test-tube studies have indicated that African potato and Sutherlandia interfere with the body’s ability to process protease inhibitors and NNRTIs. 

Interactions can even happen with medicines that are not taken by mouth. For example, ritonavir can interact with inhalers and nasal sprays containing fluticasone (e.g. Flixotide, Seretide and Flixonase), causing serious side-effects. 

Make sure you tell your clinic doctor and HIV pharmacist about all the medicines you are taking.

This includes prescribed medicines, medicines you buy from a chemist, herbal or traditional medicines, and recreational drugs. Also check before taking anything new (whether you buy it yourself or have it prescribed by a doctor or dentist). 

HIV treatment and pregnancy

Antiretroviral drugs are now commonly used during pregnancy as an effective means of preventing the transmission of HIV from a mother to her baby. Although the long-term effects on the child are not yet clear, evidence so far suggests that HIV treatment during pregnancy is safe. Taking HIV treatment during pregnancy greatly reduces the risk of passing on HIV to the baby, so the benefits outweigh any risks. Generally, anti-HIV drugs are not used during the first three months of pregnancy unless the woman is already on treatment. Pregnant women usually begin HIV treatment at the beginning of the seventh month of pregnancy, unless they need to take it earlier for their own health. 

As a woman’s health improves, her fertility may also increase. It is recommended that women considering pregnancy, or women who may conceive, discuss their treatment options with their doctor before conceiving. One reason for this is that some anti-HIV drugs (e.g. efavirenz, Sustiva, also in the combination pill Atripla) are not usually recommended for women who are planning a pregnancy. You should tell your HIV doctor or another member of your healthcare team immediately if you become pregnant.

Hormonal contraception is less effective in women on many of the anti-HIV drugs due to drug interactions. Other forms of contraception are unaffected by HIV treatment.

There is no evidence that a father’s treatment increases the risk of birth defects. 

For more information, see the NAM booklet HIV & women. 

Names of anti-HIV drugs

Pharmaceutical drugs are given several names: 

• First, a research name based on its chemical make-up or manufacturer, e.g. DMP266. 
• Second, a generic name which is common to all pharmaceuticals with the same chemical make-up, e.g. efavirenz. 
• Third, a brand name which belongs to a particular company. A brand name starts with a capital letter and is generally written in italics, e.g. Sustiva. 

This booklet lists all names a drug has at the start of a drug entry. The most common name for each drug is used in the text.