Abstract
Sub-Saharan African women are still at risk from the human immunodeficiency virus (HIV), and sex with men is the main route of transmission. Vaginal formulations containing antiretroviral drugs are promising tools to give women the power to protect themselves. The aim of this work was to obtain freeze-dried bigels containing pectin, chitosan, or hypromellose for the vaginal controlled release of Tenofovir, which is accelerated in the presence of semen. Nine batches of bigels were formulated using different proportions of these polymers in the hydrogel (1, 2, and 3% w/w). The bigels obtained were freeze-dried and then underwent hardness and deformability, mucoadhesion, swelling, and drug release tests, the last two in simulated vaginal fluid (SVF) and SVF/simulated seminal fluid (SSF) mixture. The formulation containing 3% pectin (fd3P) has the highest values for hardness, resistance to deformation, and good mucoadhesivity. Its swelling is conditioned by the pH of the medium, which is responsive to the controlled release of Tenofovir in SVF, with the fastest release in the SVF/SSF mixture. fd3P would be an interesting smart microbicidal system to allow faster release of Tenofovir in the presence of semen, and thus increase women’s ability to protect themselves from the sexual transmission of HIV.
Highlights
According to 2018 UNAIDS reports, there were about 5000 new infections by the human immunodeficiency virus (HIV) every day in 2017
The nature and proportion of the polymer included in the hydrogel of the freeze-dried bigels based on pectin, chitosan, or HPMC determine the formation and characteristics of the bigel obtained
A system containing 3% w/w of HPMC does not yield a homogeneous bigel since the high viscosity of this hydrogel hinders its interaction with the organogel; and bigels can be obtained from hydrogels containing 1% w/w of pectin or chitosan, freeze-drying produces overly fragile structures impeding their handleability
Summary
According to 2018 UNAIDS reports, there were about 5000 new infections by the human immunodeficiency virus (HIV) every day in 2017. “One in three women worldwide has experienced physical or sexual violence” according to UNAIDS, and this latter factor has a direct bearing on their vulnerability to HIV infection [1]. Vaginal formulations are important as they give women the power they need to protect themselves from the heterosexual transmission of HIV [3]. Tenofovir (TFV), a drug that acts by blocking HIV-1 replication, was the first antiretroviral drug that safely demonstrated PrEP and post-exposure prophylaxis against HIV sexual transmission in animal models [6]. TFV-based microbicide vaginal formulations have already shown efficacy in HIV prevention in women. Clinical trials point to low patient adherence as one of the main reasons for failure [15,16]
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