Microbicides and Pre-exposure prophylaxis (PrEP) are two methods of preventing the spread of HIV that could be used before you have sex. Microbicides are still in development but PrEP is already here although not yet available through the NHS in the UK.
PrEP cannot protect against other sexually transmitted infections (STIs) or an unwanted pregnancy, so it’s best to use a condom as well.
What are microbicides?
A microbicide is a substance that can stop microbes in the form of viruses or bacteria from entering the cells by either destroying them or by acting as a barrier.
Microbicides could therefore be developed to protect against:
- pregnancy (by using spermicides).
Microbicides are usually applied inside a woman’s vagina (possibly a gel, cream or ring that releases a drug).
Challenges in microbicide research
Work is underway to produce microbicides that kill HIV or otherwise stop the virus infecting a partner during sex. Some aim to deliver anti-HIV drugs into the vagina where they may be able to stop the virus infecting the woman.
Research is also underway to develop microbicides for use in the rectum to stop infection in women and men during anal sex. These would most likely have to be formulated in a different way as there are differences in the skin of the anus and that of the vagina. Also the vagina is a contained space and the anus is open ended.
What we know so far
Results from trials of vaginal microbicides have given mixed results, so if an effective product can be developed it ‘s likely to take some time before it’s available. Even then, any microbicide would be unlikely to give 100% protection, so would need to be used together with another HIV prevention method such as condoms.
Results of two recent vaginal ring trials found both products to be moderately effective at preventing HIV infection – with the product offering protection in a third of cases. In fact the rings offered no protection at all to women aged 18-21 years old - which were the groups with the highest rates of infection.
Research is continuing into one of the rings tested with the hope scientists can learn why it was less effective in younger women and how this can be improved.
What is PrEP?
PrEP is a course of HIV drugs taken by someone who is HIV negative, at high risk of HIV and who is finding it hard to use condoms, in order to stop them getting HIV. This means taking HIV medication during the period they’re at risk.
Results in trials have been very successful, with PrEP significantly lowering the risk of becoming HIV positive and without major side effects.
The medication used for PrEP is a tablet called Truvada, which contains tenofovir and emtricitabine (which are drugs commonly used to treat HIV).
The drugs used in PrEP are the same drugs that are prescribed to thousands of people living with HIV every year. They are very safe and have no serious side effects. A few people experience nausea, headaches or tiredness and, very rarely, the medication can affect kidney function. As a precaution people taking PrEP have regular kidney tests.
Where to get PrEP
PrEP is not currently available on the NHS, but it’s available by private prescription from some clinics.
Some people are also ordering a cheaper, generic version of Truvada online - called Tenvir-EM.
If you’re thinking about getting PrEP from outside the NHS, it’s really important that you talk to your sexual health clinic. They should be able to help you with getting safety checks on your kidneys and might be able to suggest ways you can get tests done to make sure the drug is legitimate too.
You can find out more with our full guide to PrEP ››