Improvement of Transdermal Delivery of Aciclovir Aliphatic Ester Prodrugs by Using Supersaturated System / 中国药房

ABSTRACT

OBJECTIVE：To prepare supersaturated system of lip ophilic aci clovir（ACV）prodrug，and to increase the cutaneous bioavailability of ACV. METHODS ：Three prodrugs of ACV were synthesized by anhydride acylation ，i.e. aciclovir acetate （ACV-Ace），butyrate（ACV-But）and hexanoate （ACV-Hex）. The structures of ACV and three ACV prodrugs were confirmed by 1H-NMR and HRESI-MS ；the concentrations of ACV and three ACV prodrugs were determined by UPLC-triple quadrupole tandem mass spectrometry ，and saturated solubility of them in different volume fractions of propylene glycol-water solution was calculated. The compound with the greatest potential of form supersaturated system was screened out. The supersaturated system of that compound was prepared by co-solvent method. The effect of hydroxypropyl methylcellulose E 3 （HPMC E 3） on its physical stability was observed by light microscope. Vertical Franz diffusion cells were used to study the effects of degree of supersaturation （DS）and HPMC E 3 on the deposited amount of drug in the excised porcine skin after using the supersaturated system for 1 h. The distribution of ACV in the excised porcine skin was determined by frozen slicing stratified quantitative method after using the supersaturated system and marketed aciclovir cream for 1 h. RESULTS ：Three ACV prodrugs were successfully synthesized. The established quantification methods met the requirements of biological sample analysis. Among all of the three ACV prodrugs ， ACV-Hex showed the lowest saturated solubility in water [ （0.5±0.0）mmol/L] a nd the highest saturated solubility in propylene glycol [（53.4 ± 14.2）mmol/L]，which made it potentially feasible to form supersaturated system with high DS. In 10％propylene glycol-water system ，the addition of HPMC E 3 163.com enabled ACV-Hex supersaturated systems ，with DS no morethan 4，to maintain physical stability within 1 h. The total deposited amount （ACV + ACV-Hex ） in skin after the application of ACV-Hex supersaturated system with DS of 4 for 1 h was higher than that after the application of ACV-Hex supersaturated system with DS less than 4 or without HPMC E 3. In addition ，the concentration of ACV in the basal epidermis （skin thickness was 100-160 mm）by supersaturated system was significantly higher than that of the marketed aciclovir cream （P＜0.05）. CONCLUSIONS：ACV-Hex，the lipophilic prodrug of ACV ，can form stable supersaturated system with DS of 4 in 10％ propylene glycol-water system in the presence of HPMC E 3. High concentration of ACV could be accumulated in the basal epidermis after the skin was exposed to supersaturated system for 1 h，which may be valuable for local treatment skin infection of herpes simplex virus .