The increasing incidence of sexually transmitted bacterial infections (STIs) is a major public health problem worldwide. Currently, among the therapies being studied is the use of the antibiotic doxycycline as a method of post-exposure prophylaxis after unprotected sex - known as DoxyPEP. Now, the University of Barcelona and the NGO Stop have carried out the first study in Spain on the use of DoxyPEP as a preventive strategy among the gay, bisexual and other men who have sex with men (GBHSH) community in Spain."The results suggest that, although medical and scientific associations rarely endorse the community use of DoxyPEP as a prevention strategy, the GBHSH community is already integrating it as a preventive measure", explains Sergio Villanueva, who led the study and is a professor at the UB's Faculty of Information and Audiovisual Media and a researcher at the UB Centre for Research in Information, Communication and Culture (CRICC). The study, published in the journal Infections, has been promoted by Stop, an NGO dedicated to the sexual health of the GBHSH community, of which Professor Villanueva is a member.
DoxyPEP, a promising tool but at risk of increasing bacterial resistance
Several clinical research studies recently - such as the IPERGAY clinical trial in France in 2015; DoxyPEP in the United States, or DoxyVac in France in 2022 - have evaluated the efficacy of doxycycline as a method of post-exposure prophylaxis - known as DoxyPEP - with promising results against syphilis (Treponema pallidum), chlamydia (Chlamydia trachomatis) and, to a lesser extent, gonorrhoea (Neisseria gonorrhoeae). Despite this evidence, most medical and scientific associations do not recommend its use in the community, mainly because of concerns about the potential impact of this therapy on the growing antibiotic resistance.
The researchers say that "the European AIDS Clinical Society (EACS) indicates that DoxyPEP can be proposed to people with repeated sexually transmitted infections (STIs) living with human immunodeficiency virus (HIV) and only on a case-by-case basis. Following these recommendations, several national associations in European countries have issued similar guidelines, such as the Spanish Association of Infectious Diseases and Clinical Microbiology (SEIMC), which recommends DoxyPEP on a case-by-case basis".
Data consistent with studies in other countries
In this context, the experts tried to get an overview of the penetration of this pharmacological tool in the GBHSH community. To this end, they surveyed 150 members of the community through the NGO's social networks. The results revealed that 35.4% of the respondents had used doxycycline as DoxyPEP, 17.2% of whom did not follow the dosing regimens evaluated in clinical trials - i.e. 200 mg within seventy-two hours of condomless sex.
Villanueva acknowledges that "these findings are consistent with those observed in a similar study in Germany, where a comparable proportion of GBHSH community members sampled had taken doxycycline in the past year and were using it as DoxyPEP (35.4% vs. 23%)". Regarding the most common methods of obtaining doxycycline, according to the study, the most common are through a specialist's prescription or using tablets left over from a previous treatment; in some cases they also obtain it by ordering it online or through unofficial channels.
Moreover, the study also showed that using DoxyPEP is associated with a decrease over the past year in the frequency of diagnosis of diseases such as syphilis and gonorrhoea, but significantly only for chlamydia. However, the researchers stress that these findings should be interpreted "with caution, as they are based on self-reported data, and crucial factors such as duration or adherence to DoxyPEP were not adequately captured in the survey".
Need for regulation and guidelines for safe use of DoxyPEP
In any case, for the researchers, "lack of regulation and decision-making can lead to the misuse of doxycycline as a preventive strategy in medication regimens that are not based on solid evidence, on the one hand, and the acquisition of the drug through unregulated channels or by providing false information to healthcare professionals, on the other".
In this sense, the authors stress the need for "a medical and scientific discourse that, in collaboration with civil society organizations dedicated to sexual health, formulates systematic and evidence-based guidelines for this preventive tool, to guarantee the quality of treatments and the training of the professionals responsible for prescribing them".
