e Preexposure prophylaxis (PrEP) with 1% tenofovir (TFV) vaginal gel has failed in clinical trials. To improve TFV efficacy in vaginal gel, we formulated tenofovir disoproxil fumarate nanoparticles in a thermosensitive (TMS) gel (TDF-NP-TMS gel). TDF-NPs were fabricated using poly(lactic-co-glycolic acid) (PLGA) polymer and an ion-pairing agent by oil-in-water emulsification. The efficacy of TDF-NP-TMS gel was tested in humanized bone marrow-liver-thymus (hu-BLT) mice. Hu-BLT mice in the treatment group (Rx; n ‫؍‬ 15) were administered TDF-NP-TMS gel intravaginally, having TDF at 0.1%, 0.5%, and 1% (wt/vol) concentrations, whereas the control (Ctr; n ‫؍‬ 8) group received a blank TMS gel. All Rx mice ( Presently, a total of 36.9 million people worldwide are living with HIV-1 (1). Topical preexposure prophylaxis (PrEP) currently is a promising preventative strategy (2). The basic idea is to protect the vagina (and/or rectum) from HIV-1 infection by applying gel containing antiretroviral drug(s) around the time of sexual intercourse. This topical preparation is considered a microbicide, inhibiting infection by blocking viral transmission at the mucosal surface. To date, tenofovir (TFV) is the only drug administered locally as a 1% vaginal gel shown to be effective at preventing heterosexual contraction of HIV-1 (3). TFV tissue concentrations indicate a direct relationship between levels of TFV in genitals and protection (4-7). The minimum amount of TFV in cervicovaginal fluid levels when associated with gel that shows protection against HIV-1 infection has been reported to be Ͼ1,000 ng/ml (4). This level is greater than 10 times that seen in patients receiving oral TDF and emtricitabine (4). In female macaques given 1% TFV gel, the intracellular half-life for the active metabolite, tenofovir diphosphate, is significantly shorter (averaging 25 h) in vaginal lymphocytes than peripheral PBMCs (averaging 49 h) (7). A coitally independent strategy using 1% TFV gel has not shown efficacy in several clinical trials (8,9). Based on the dramatic negative results of the Vaginal and Oral Interventions to Control the Epidemic (VOICE) trial, it is important to consider female attitudes and opinions for a vaginal gel-based prevention delivery system. A safe and effective female-controlled, discrete gel-based delivery system has the potential to prevent millions of HIV-1 infections worldwide annually.When designing female-controlled preventative delivery systems, the gel-based system should have features important for the female user. Namely, the delivery system should be (i) easy to administer; (ii) adherent to the mucosal surface once applied vaginally; (iii) low seepage; and (iv) free of side effects or cytotoxicity to the mucosal surfaces of the female genital tract (10). All of these factors, if not optimized, could diminish gel effectiveness or lead to gel aversion. Finally, a long-acting preparation would be highly desirable if it offered long-term protection from HIV-1 (11).Our laboratory has been developing a nanotechn...

To adequately reduce new HIV infections, development of highly effective pre-exposure prophylaxis (PrEP) against HIV infection in women is necessary. Cellulose acetate phthalate (CAP) is a pH sensitive polymer with HIV-1 entry inhibitory properties. Dolutegravir (DTG) is an integrase strand transfer inhibitor with potent antiretroviral activity. DTG delivered in combination with CAP may significantly improve current PrEP against HIV. In the present study the development of DTG-loaded CAP nanoparticles incorporated in thermosensitive (TMS) gel at vaginal pH 4.2 and seminal fluid pH 7.4 is presented as proof-of-concept for improved PrEP. Water–oil–in–water homogenization was used to fabricate DTG-loaded CAP nanoparticles (DTG–CAP–NPs). Size, polydispersity, and morphological analyses illustrate that DTG–CAP–NPs were smooth and spherical, ≤200 nm in size, and monodispersed with a polydispersity index PDI ≤ 0.2. The drug encapsulation (EE%) and release profile of DTG–CAP–NPs was determined by HPLC analysis. The EE% of DTG in DTG–CAP–NPs was evaluated to be ∼70%. The thermal sensitivity of the TMS gel was optimized and the pH dependency was evaluated by rheological analysis. DTG release studies in TMS gel revealed that DTG–CAP–NPs were stable in TMS gel at pH 4.2 while DTG–CAP–NPs in TMS gel at pH 7.4 rapidly release DTG (≥80% release within 1 h). Cytotoxicity studies using vaginal cell lines revealed that DTG–CAP–NPs were relatively non-cytotoxic at concentration <1 μg/mL. Confocal microscopic studies illustrate that ≥98% cells retained DTG–CAP–NPs intracellularly over seven days. Antiretroviral drug loaded nanocellulose fabrications in TMS gel delivered intravaginally may enhance both microbicidal and antiretroviral drug efficacy and may present a novel option for female PrEP against HIV.

HIV continues to be one of the greatest challenges facing the global health community. More than 36 million people currently live with HIV and, in 2015 2.1 million new infections were reported globally. Pre-Exposure Prophylaxis (PrEP) prevents HIV infection by inhibiting viral entry, replication, or integration at the primary site of pathogenic contraction. Failures of large antiretroviral drug (ARV) PrEP clinical trials indicate the current insufficiencies of PrEP for women in high-risk areas, such as sub-Saharan Africa. A combination of social, adherence, and drug barriers create these insufficiencies and limit the efficacy of ARV. Nanotechnology offers the promise of extended drug release and enhances bioavailability of ARVs when encapsulated in polymeric nano-particles. Nanoparticle encapsulation has been evaluated in vitro in comparative studies to drug solutions and exhibit higher efficacy and lower cytotoxicity profiles. Delivery systems for nanoparticle PrEP facilitate administration of nano-encapsulated ARVs to high-risk tissues. In this mini-review, we summarize the comparative nanoparticle and drug solution studies and the potential of two delivery methods: thermosensitive gels and polymeric nanoparticle films for direct prophylactic applications.

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