Influence of a niosomal formulation on the oral bioavailability of acyclovir in rabbits
- 462 Downloads
The purpose of this research was to prepare acyclovir niosomes in a trial to improve its poor and variable oral bioavailability. The nonionic surfactant vesicles were prepared by the conventional thin film hydration method. The lipid mixture consisted of cholesterol, span 60, and dicetyl phosphate in the molar ratio of 65:60:5, respectively. The percentage entrapment was ∼11% of acyclovir used in the hydration process. The vesicles have an average size of 0.95 µm, a most probable size of 0.8 µm, and a size range of 0.4 to 2.2 µm. Most of the niosomes have unilamellar spherical shape. In vitro drug release profile was found to follow Higuchi’s equation for free and niosomal drug. The niosomal formulation exhibited significantly retarded release compared with free drug. The in vivo study revealed that the niosomal dispersion significantly improved the oral bioavailability of acyclovir in rabbits after a single oral dose of 40 mg kg−1. The average relative bioavailability of the drug from the niosomal dispersion in relation to the free solution was 2.55 indicating more than 2-fold increase in drug bioavailability. The niosomal dispersion showed significant increase in the mean residence time (MRT) of acyclovir reflecting sustained release characteristics. In conclusion, the niosomal formulation could be a promising delivery system for acyclovir with improved oral bioavailability and prolonged drug release profiles.
KeywordsAcyclovir niosomes oral acyclovir bioavailability of acyclovir
Unable to display preview. Download preview PDF.
- 4.Vergin H, Kikuta C, Mascher H, Metz R. Pharmacokinetics and bioavailability of different formulations of acyclovir.Arzneim Forsch. 1995;45:508–515.Google Scholar
- 6.US FDA. Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid dosage forms based on a biopharmaceutics classification system. 2000; Available at: www.fda.gov/cder/guidance/2062dft.pdf. Accessed November 2, 2007.Google Scholar
- 7.Avdeef A. pH-metric solubility. I. Solubility-pH profiles from Bjerrum plots, Gibbs buffer and pKa in solid state.Pharm Pharmacol Commun. 1998;4:165–178.Google Scholar
- 8.Lund W.The Pharmaceutical Codex, Principles and Practice of Pharmaceutics. London, UK: The Pharmaceutical Press; 1994.Google Scholar
- 14.McIntosh TJ. The effect of cholesterol content on the structure of phosphatidylcholine bilayers.Biochim Biophys Acta. 1978;51:43–58.Google Scholar
- 17.Brigden D, Fowle A, Rosling A. Collier LH, Oxford J, eds.Developments in Antiviral Therapy. London, UK: Academic Press; 1980:53–62.Google Scholar