Thermosensitive and mucoadhesive pluronic-hydroxypropylmethylcellulose hydrogel containing the mini-CD4 M48U1 is a promising efficient barrier against HIV diffusion through macaque cervicovaginal mucus.

To be efficient, vaginal microbicide hydrogels should form a barrier against viral infections and prevent virus spreading through mucus. Multiple particle tracking was used to quantify the mobility of 170-nm fluorescently labeled COOH-modified polystyrene particles (COOH-PS) into thermosensitive hydrogels composed of amphiphilic triblock copolymers with block compositions EOn-POm-EOn (where EO refers to ethylene oxide and PO to propylene oxide) containing mucoadhesive hydroxypropylmethylcellulose (HPMC). COOH-PS were used to mimic the size and the surface charge of HIV-1. Analysis of COOH-PS trajectories showed that particle mobility was decreased by Pluronic hydrogels in comparison with cynomolgus macaque cervicovaginal mucus and hydroxyethylcellulose hydrogel (HEC; 1.5% by weight [wt%]) used as negative controls. Formulation of the peptide mini-CD4 M48U1 used as an anti-HIV-1 molecule into a mixture of Pluronic F127 (20 wt%) and HPMC (1 wt%) did not affect its anti-HIV-1 activity in comparison with HEC hydrogel. The 50% inhibitory concentration (IC50) was 0.53 µg/ml (0.17 µM) for M48U1-HEC and 0.58 µg/ml (0.19 µM) for M48U1-F127-HPMC. The present work suggests that hydrogels composed of F127-HPMC (20/1 wt%, respectively) can be used to create an efficient barrier against particle diffusion in comparison to conventional HEC hydrogels.

Note on the formulation of thermosensitive and mucoadhesive vaginal hydrogels containing the miniCD4 M48U1 as anti-HIV-1 microbicide.

The miniCD4 M48U1 was formulated into thermosensitive and mucoadhesive pluronic(®) hydrogels as anti-HIV-1 microbicide. The release kinetics of M48U1 from F127/HPMC (20/1 wt%) and F127/F68/HPMC (22.5/2.5/1 wt%) studied during 24h by using Franz diffusion cells showed that HEC hydrogel (1.5 wt%) used as control released 93% of the peptide, while about 25% of M48U1 remained in pluronic(®) hydrogels. The formulation of M48U1 in pluronic(®) hydrogels ensures a local delivery because no diffusion of the peptide was detected through vaginal Cynomolgus macaque mucosa using Ussing chamber. Finally, toxicological studies showed no significant difference in the HeLa cell viability of the pluronic(®) hydrogels in comparison with HEC and phosphate buffer saline.

Formulation of mucoadhesive vaginal hydrogels insensitive to dilution with vaginal fluids.

The main objective of this work was to design thermosensitive and mucoadhesive vaginal hydrogels able to keep their rheological and mucoadhesive properties after dilution with vaginal fluids. Formulations were composed of pluronic F127 or a mix of two pluronics F127 and F68. Both formulations contained hydroxypropylmethyl cellulose (HPMC) as a mucoadhesive polymer. The determination of gelling temperature (T(gel)) after dilution with simulated vaginal fluid (SVF) demonstrated that hydrogels were resistant to dilution and T(gel) values were close to 30°C. Ex vivo mucoadhesion experiments conducted on porcine vaginal mucosa founded on the technique of traction of the adhesive/adherent joint allowed the characterization of mucoadhesive properties of hydrogels by measuring work of adhesion (W) and maximum force of detachment (F(max)). In the case of F127-based hydrogels, W and F(max) were lowered after dilution with SVF. However, in the case of F127/F68-based hydrogels, W, F(max) and mucoadhesion profiles were weakly affected by dilution. These differences could be attributed to the higher elasticity of F127/F68/HPMC (22.5/2.5/1% w/w) hydrogel in comparison with F127/HPMC one (20/1% w/w). Indeed, rheological analyses of the formulations showed that both elastic (G') and viscous moduli (G'') were higher for F127/F68/HPMC (22.5/2.5/1% w/w) than for F127/HPMC hydrogel (20/1% w/w). However, we demonstrated that the higher elasticity of the hydrogel was due to the higher total pluronic concentration and not due to the presence of F68 in the formulation.