Original Article Formulation of saquinavir mesylate loaded microparticle by counterion induced aggregation method: Approach by hyperosmotic technique Harekrishna Roy a, *, Chandan Kumar Brahma a , Ravi Kumar a , Sisir Nandi b a Department of Pharmatechnology, Vikas College of Pharmaceutical Sciences, Suryapet, Nalgonda, Andhra Pradesh 508213, India b Department of Medicinal Chemistry, Global Institute of Pharmaceutical Education & Research, Kashipur, U.S. Nagar, Uttarakhand 244713, India article info Article history: Received 4 May 2013 Accepted 29 July 2013 Keywords: Saquinavir mesylate Hyperosmotic solution Polycation Chitosan Fickian abstract Objective: The objective of present work is to formulate saquinavir mesylate loaded microparticle by counterion induced aggregation method, employing simultaneous cold temperature and hyperosmotic solution treatment as new and novel technique. Method: Chitosan was chosen as polycation and smaller molecular electrolytes such as sodium citrate, sodium sulphate and sodium orthophosphate were chosen as polyanions. The resulted aggregated microparticles were subjected to surface morphology, size dis- tribution, in-vitro release and drug excipient interaction study. Results and discussion: Sodium citrate (SC) and sodium sulphate (SS) were able to form ag- gregates except sodium orthophosphate (SP), as chitosan forms complexes and depends on pH and pKa of medium. Prepared aggregates were subjected to cold hyperosmotic dextrose solution to provide more mechanical strength. The percentage of entrapped drug was more in SC based microparticle as compared to SS. The SS and SC microparticles had average particle size of 1400 mm and 1200 mm respectively. Also, the SEM study revealed more rough and ridges on surface of SC particle as compared to SS. The higher correlation coefficient (r 2 ) was found with Higuchi’s equation for all formulations and formulation SS2 had greater r 2 value of 0.986 compared to all and obeyed fickian diffusion. There was no such major interaction were found during FTIR and DSC study. In addition, stability study was per- formed and data showed no significant change in assay value for SS2. Conclusion: The microparticles prepared by above mentioned method had sufficient me- chanical strength and were able to released drug for a period of 30 h. Furthermore in-vivo study and pharmacokinetic study have to carry out. Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved. * Corresponding author. E-mail address: hareroy@gmail.com (H. Roy). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/dit drug invention today 5 (2013) 259 e266 0975-7619/$ e see front matter Copyright ª 2013, JPR Solutions; Published by Reed Elsevier India Pvt. Ltd. All rights reserved. http://dx.doi.org/10.1016/j.dit.2013.07.002