Heterogeneous polymer composite nanoparticles loaded in situ gel for controlled release intra-vaginal therapy of genital herpes

Herpes simplex virus causes serious and contagious genital infections in high percentage of female population world-wide. Acyclovir is a clinically successful antiviral molecule till date, in-spite of limitations as poor solubility, low half-life, reduced oral bioavailability and side effects at higher doses. In the present work, controlled release in situ gelling system loaded with polymeric nanoparticles of acyclovir containing a dose of drug equivalent to 105mg/day has been developed. The formulation containing drug loaded polyvinyl pyrrolidone-Eudragit RSPO hybrid polymeric nanoparticles (Size ∼99±3nm, Zeta ∼+26.1±1.5mV) in 15% Pluronic F-127 gel exhibited improved permeability through vaginal membrane (KP=2.20±0.19×10(-6)cm/s). The nanoparticles showed enhanced viability for vaginal epithelial cell lines up to concentration of 100-250μg/mL. The formulation was evaluated for bioavailability and biodistribution through intra-vaginal administration in rat models. The nanoparticle in situ gel formulation maintained an average therapeutic drug level of 0.6±0.2μg/mL in plasma for 24h. Significant improvement in mean residence time of the drug (12.52±1.12h) was observed with a two-fold increase in the relative bioavailability (AUC0-24h=14.92±2.44μgh/mL) compared to that of the pure drug (7.18±1.79μgh/mL). The tissue distribution was 2-3 folds higher in animals treated with nanoparticles in situ gel compared to that of pure drug. Sustained release of drug in vivo was demonstrated, ensuring the suitability of the formulation for clinical therapy in female population.

Dual sustained release delivery system for multiple route therapy of an antiviral drug

CONTEXT

The first successful molecule against herpes infections was Acyclovir, which competes with new generations in the market, with its potential activity. The major physicochemical constraints and pharmacokinetics of Acyclovir such as low solubility, poor permeability, less half-life, high dose has initiated many researchers to develop diverse modified release dosage forms.

OBJECTIVE

The objective of this work was to design polymeric nanoparticles of Acyclovir and then incorporate the drug-loaded nanoparticles within an in situ gelling system to provide dual sustained release effect, whereby the duration of action and bioavailability through different routes of administration could be improved.

MATERIALS AND METHODS

The formulation was designed through 3(2) factorial design, first developing the nanoparticles using Polycaprolactone and Pluronic F127 by Solvent evaporation process, followed by dispersion of the suspended nanoparticles into thermosensitive in situ gelling system of Pluronic F127 with Carbopol.

RESULTS AND DISCUSSION

The characterization of the nanoparticles and its sol-gel system performed through zeta sizer, SEM, XRD, TG-DSC, FTIR and rheology helped to optimize the formulation. The drug release could be sustained to 60% and 30% at eight hours, for the nanoparticles and their in situ gel systems, respectively, with non-Fickian diffusion mechanism of drug release. The test for % cell viability with NIH3T3 cell line revealed low level of toxicity for the nanoparticles.

CONCLUSION

The statistical significance obtained for the trail formulations experimentally proved its suitability for this dosage form design to achieve desired level of drug release.