Table 6.

Delivery formats for anti-HIV microbicides.^[209]

Delivery format	Advantages	Limitations
Gels (semi-solid), rectal and vaginal	Greater ease of formulation and manufacture, lower cost of production Ease of administration by the user Rapid dispersal of the active compound, conferring protection shortly after placement High localized drug concentrations can be attained Additional functionality as a lubricant for sexual intercourse	Timing of device application is coitally dependent Limited duration of retention at the site of application, requiring more frequent dosing Leakage and potential user discomfort Vulnerability of active compounds to extremes of temperatures and humidity
Vaginal tablets and films	Rapid release of the active compound, providing protection shortly after placement Precise, consistent dosing Lower manufacturing costs Ease of application by the user Improved stability of active compounds to extreme temperatures and humidity	Timing of device application is coitally dependent Shorter retention time of active compounds in the site of application, requiring more frequent dosing For films, their low overall mass limits the amount of active compound that can be incorporated into a single dose
Vaginal rings (VRs)	Sustained release of the microbicide over weeks or months, requiring less frequent user intervention Timing of device application is coitally independent	Increased complexity of manufacture and production costs User discomfort with device insertion/removal Only useful for the vaginal (and not rectal) compartment
Nanoparticles (NPs)	Protection and stabilization of active compounds against degradation Enhanced solubilization of incorporated active compounds Permeation through cervicovaginal mucus to better reach HIV susceptible sites in the epithelium	Increased complexity of manufacture and production costs Clinical safety and efficacy studies are still needed
Electrospun fibers (EFs)	Dry, solid dosage form that can stabilize drugs that may be less stable in a liquid format Base polymers used are often mucoadhesive, potentially increasing residence time of the microbicide at the site of application	Increased complexity of manufacture, low manufacturing production capacity at present, thus higher cost per dose Clinical safety and efficacy studies are still needed
Live microbicides (commensals)	Sustained release of the microbicide over weeks, months, or longer, requiring less frequent user intervention Timing of device application is coitally independent Lactobacilli themselves may positively impact the vaginal mucosal environment	Long-term clinical data are still needed to demonstrate safety and efficacy Limited to delivery of biologic microbicides that can be stably expressed in bacteria User concern about GMOs

GMOs, genetically modified organisms.