Comparison of a novel spray congealing procedure with emulsion-based methods for the micro-encapsulation of water-soluble drugs in low melting point triglycerides.
The particle size characteristics and encapsulation efficiency of microparticles prepared using triglyceride materials and loaded with two model water-soluble drugs were evaluated. Two emulsification procedures based on o/w and w/o/w methodologies were compared to a novel spray congealing procedure. After extensive modification of both emulsification methods, encapsulation efficiencies of 13.04% tetracycline HCl and 11.27% lidocaine HCl were achievable in a Witepsol-based microparticle. This compares to much improved encapsulation efficiencies close to 100% for the spray congealing method, which was shown to produce spherical particles of approximately 58 microm. Drug release studies from a Witepsol formulation loaded with lidocaine HCl showed a temperature-dependent release mechanism, which displayed diffusion-controlled kinetics at temperatures approximately 25 degrees C, but exhibited almost immediate release when triggered using temperatures close to that of skin. Therefore, such a system may find application in topical semi-solid formulations, where a temperature-induced burst release is preferred.
McCarron
Paul A
PA
School of Pharmacy, Queen's University Belfast, Medical Biology Centre, Belfast, UK. p.mccarron@qub.ac.uk
Donnelly
Ryan F
RF
Al-Kassas
Rasil
R
D000279:Administration, Cutaneous; D004339:Drug Compounding / Q000379:methods; D016503:Drug Delivery Systems; D015195:Drug Design; D004655:Emulsions; D004867:Equipment Design; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage; D010316:Particle Size; D012867:Skin / Q000473:pathology; D012995:Solubility; D013752:Tetracycline / Q000008:administration & dosage; D014280:Triglycerides / Q000032:analysis* / Q000737:chemistry; D014867:Water / Q000737:chemistry*
D004655:Emulsions; D014280:Triglycerides; D014867:Water; D008012:Lidocaine; D013752:Tetracycline