A sustained release dosage form of acyclovir for buccal application: an experimental study in dogs

Acyclovir is an antiviral agent and it has been particularly used for the treatment of herpes simplex infections. The treatment of infection in the oral cavity is often difficult, because of insufficient drug concentration in saliva when acyclovir is administered via the oral route in conventional tablet form for systemic uptake. Therefore, it was aimed to prepare a tablet for buccal administration and to investigate its effectiveness by performing in vitro and in vivo experiments.The solubility (1.559-4.584) and octanol/water partition coefficients ( - 2.176 to - 1.625) of the acyclovir were investigated at different pH conditions. A series of tablet formulations were prepared for buccal application and their dissolution properties were determined in artificial saliva medium. The effect of tablet ingredients on the release rate and mucoadhesion force was investigated. The dissolution properties of commercially available acyclovir tablets were also determined in the artificial gastric juice. Franz type diffusion cells were used to determine acyclovir penetration through buccal mucosa from prepared buccal tablets. Selected buccal tablets, commercial tablets and intravenous acyclovir solutions were administered to mongrel dogs and drug levels in the blood determined by HPLC.A pharmacokinetic model for buccal application was also developed and blood concentrations were calculated theoretically and compared with the experimental results. Prepared buccal tablets were found to be effective for the treatment of viral infections locally within the oral cavity and also for systemic treatment.