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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 your 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 - below 50 copies per millilitre 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 - 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 take treatment
There are many opinions about the best time to 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 antiretrovirals.
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, (eg PCP), your immune system may already be seriously weakened. In this situation, your doctor will strongly advise you to consider taking antiretrovirals.
If you have established HIV infection but have 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 you 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, plans to start a family, relationships, work and travel may influence your decision.
For more information see the booklet HIV Therapy in this series.
Sticking to your drug routine
Taking antiretroviral therapy is a long-term commitment. Once you start the drugs, it is recommended that you 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, or visit NAM’s website aidsmap.com.
For more information see the booklets Adherence and Resistance which are produced by NAM.
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 which have doctors and other health professionals trained in HIV and AIDS. Even if you do not want to take treatments at this stage, regular blood tests will tell you how the disease is progressing.
If you are entitled to free NHS care, antiretroviral drugs provided through NHS HIV clinics and GUM clinics are free.
Monitoring
Before you start on antiretrovirals, 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 assess the effects of the drugs on the normal workings of your body. Your doctor may also test to see if the HIV has developed resistance to any of the antiretrovirals.
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 and some less often once you are well established on treatment and doing well.
For more information, see the booklet Viral Load & CD4 produced by NAM in this series.
Pregnancy
Combinations of antiretrovirals 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 antiretrovirals, 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. You should tell your HIV doctor or another member of your health care team immediately if you become pregnant. The contraceptive pill is less effective in women on anti-HIV drugs due to drug interactions.
There is no evidence that a father's treatment increases the risk of birth defects.
For more information, see the booklets HIV and children and HIV and women, produced by NAM in this series.
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, diarrhoea, 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 are therefore likely to be side-effects of the drug.
Drug interactions
Taking two or more different drugs together may result in an alteration in the effectiveness (or toxicity) 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 that 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. Protease inhibitors are the class of antiretrovirals most likely to interact with recreational drugs, though interactions with both NRTIs and NNRTIs and recreational drugs have been described.
Antiretrovirals can also interact with herbal and alternative treatments. It is known that the herbal antidepressant St John’s wort lowers blood levels of both NNRTIs and protease inhibitors. Garlic capsules stop the protease inhibitor saquinavir from working properly and it is thought that they could have a similar effect on other protease inhibitors as well. Test tube studies have recently indicated that African potato and Sutherlandia, two herbs widely used to treat HIV in Africa, 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 (eg FlixotideTM and FlixonaseTM) causing serious side-effects.
To help increase the chances of all your drugs working effectively and to minimise the possibility of side-effects, make sure you tell your clinic doctor and HIV pharmacist about all the medicines that you are taking. Also check before taking anything new (whether you buy it yourself or have it prescribed by a doctor or dentist).
What's in a name?
Pharmaceutical drugs are given several names:
- First, a research name based on its chemical make-up or manufacturer, eg DMP266.
- Second, a generic name which is common to all pharmaceuticals with that chemical make-up, eg 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, eg Sustiva™.
This booklet lists all three names at the start of a drug entry. The most common name for each drug is used in the text.