Rectal Douche as HIV Pre-Exposure Prophylaxis for Receptive Anal Intercourse: An End User Tenofovir Powder Sachet Preparation Feasibility Study (DREAM-04).

Background: Unprotected receptive anal intercourse carries the highest sexual HIV transmission risk. The need for diverse pre-exposure prophylaxis (PrEP) options has encouraged the development of on-demand, topical PrEP products for those preferring nonsystemic or occasional PrEP. We assessed end users' proficiency in preparing tenofovir douches from sachets containing 2 different powder types, lyophilized and spray dried, and evaluated their experience.

Methods: Cisgender adult men with a history of RAI-related douching were consented, screened, and randomized 1:1 to the order of the powder type prepared. All participants prepared at least 3 enema bottles of each powder type. Aliquots from each prepared douche bottle were analyzed for tenofovir (TFV) concentration, osmolality, and pH. User experience and likelihood of future product use were assessed by questionnaire.

Results: Twenty-one eligible participants were enrolled. Most participants reported both products as easy or very easy to prepare and likely or very likely to be used. Participants preferred the lyophilized product. The lyophilized and spray-dried douche bottles prepared met the osmolality specifications 89% and 61% of the time and TFV content specifications 81% and 29% of the time, respectively. Questionnaires indicated the most common challenges were tearing open the sachets and transferring the spray-dried product.

Conclusions: Most participants reported the douches were easy to prepare and indicated likely future use. Although the lyophilized sachets were prepared sufficiently to establish preparation feasibility, the spray-dried sachets often fell outside specifications. Failure analysis provided insights to guide product modifications to improve the proficiency of douche preparation and future product use.