One important milestone in the treatment of AIDS patients was the implementation of a two-drug combination of nucleoside reverse transcriptase inhibitors (e.g. tenofovir dizoproxil with emtricitabine) into antiretroviral therapy. This combination has been observed to be effective against HIV, inhibit its replication and be an effective antiretroviral drug. Since these two chemical compounds belong to the same group of drugs, their mechanism of action is identical, this has therefore led to the conclusion that they are not suitable for use in HAART therapy (highly effective antiretroviral therapy), which aims to protect the patient by providing drugs with different mechanisms of action. HAART therapy currently uses drugs from the following groups with different mechanisms:
The majority of current HAART therapy uses combination drugs of the above-mentioned groups so that patients can comfortably take 1 tablet of a combination drug per day, which is most acceptable to them.
However, as pharmaceutical companies have invested considerable resources in the development and subsequent registration of binary drugs, currently reluctantly used in HAART therapy due to the need to combine them with another drug (taking 2 or 3 tablets instead of 1), began to question whether the mechanism of action identified in these drugs could be useful in HIV prevention, that is, whether the reverse transcriptase inhibitors (the enzyme responsible for transcribing the genetic code of HIV mRNA into the DNA of the patient's cell) used in them could prevent HIV infection at the cell level. Numerous studies have led to surprising conclusions, which prove that the use of these drugs in healthy, HIV-uninfected patients, when exposed to such infection, inhibits transcription and prevents seroconversion in more than 90 per cent of cases. Thus, drugs previously used to treat HIV-infected patients, in uninfected patients, can prevent infection and can be used as a method of prevention of infection.
PrEP or pre-exposure prophylaxis is, therefore, a drug that healthy people who are not infected with HIV but who are at risk of infection (e.g. who have experienced risky sexual behaviour) use to prevent HIV infection during sex or injection drug use. PrEP can effectively stop HIV infection and its spread in the body. Currently, there are three daily oral drugs approved by drug regulatory authorities worldwide (including the US FDA - Food and Drug Administration and the European EMA - European Medicines Agency) for use as PrEP: emtricitabine in combination with tenofovir dizoproxil (known by the trade name Truvada®), emtricitabine with tenofovir alafenamide fumarate (known by the trade name Descovy®) and cabotegravir (known by the trade name Vocabria®), among others. The US FDA has also approved a long-acting form of PrEP for injection, but so far this is not applicable in Europe. In addition, there are currently 9 ongoing scientific projects in the USA for the implementation of new antiretroviral drug applications for PrEP therapy, 2 projects for injectable PrEP and 1 project related to vaginal PrEP (in a form released from a vaginal disc).
Results from studies in many countries around the world show that PrEP reduces the risk of HIV infection during sex by approximately 99% when taken as prescribed. This is an extremely high result, demonstrating that PrEP should be used universally among people taking HIV risk. Although there is less information on the effectiveness of PrEP among injecting drug users, PrEP is known to reduce the risk of HIV infection by at least 74% when taken as prescribed. Currently, PrEP injections are not recommended for people who inject drugs. PrEP is less effective if not taken as prescribed, hence there are frequent cases of HIV infection in PrEP users with a history of inappropriate drug use (e.g. according to the wrong mechanism and dosage).
PrEP should be used in adults at increased risk of acquiring HIV infection. People at increased risk of HIV infection who should be offered PrEP include those who:
Separate from PrEP, the mechanism for HIV prevention is post-exposure prophylaxis (PEP), which is in fact, by definition, not prophylaxis due to the previous occurrence of a potentially infectious agent. PEP, or post-exposure prophylaxis, is a short course of treatment with antiretroviral drugs, taken very soon after a possible exposure to HIV, to prevent the HIV virus from entering the body and building its genetic material into the DNA of a human cell for subsequent replication. PEP must be taken as soon as possible, optimally within 4 hours, up to a maximum of 48 hours, and in exceptional cases of high-risk sexual exposures no later than 72 hours (3 days) after a possible HIV exposure (stabbing, unprotected sexual intercourse with an HIV-infected person with a detectable viremia, contact of an open wound or mucous membrane with potentially HIV-infected material), otherwise, this method of therapy will not work.
PEP is always ordered by a doctor experienced in the treatment of HIV infection, after a detailed examination and qualification of the patient, and sometimes after a diagnostic examination of the person who is a potential source of contact (e.g. in the case of a patient in the hospital, a person detained by the police), but always with their consent.
In Poland, PEP therapy uses the same drugs as in HIV-infected patients, acting according to similar mechanisms, but in 3 approved regimens, in accordance with the recommendations of the Polish AIDS Society. Once PEP prophylaxis has been implemented, treatment should be continued for 28 days. PEP should be used only in emergency situations. It is not intended for regular use by people who may be frequently exposed to HIV infection, for such cases PrEP prophylaxis is recommended.
