Dev et al Journal of Drug Delivery & Therapeutics. 2019; 9(1):237-243 ISSN: 2250-1177 [237] CODEN (USA): JDDTAO Available online on 15.01.2019 at http://jddtonline.info Journal of Drug Delivery and Therapeutics Open Access to Pharmaceutical and Medical Research © 2011-18, publisher and licensee JDDT, This is an Open Access article which permits unrestricted non-commercial use, provided the original work is properly cited Open Access Research Article Formulation and characterization of acyclovir based topical microemulsions by QBD approach Dev Asish * 1, 2 , Dwivedi Jayesh 3 , Momin Munira 4 1 Research scholar, Pacific University, Udaipur, Rajasthan 2 Assistant Professor, Oriental College of Pharmacy, University of Mumbai, Maharashtra 3 Associate Professor, Pacific University, Udaipur, Rajasthan 4 Principal and Professor, Dr. Bhanuben Nanavati College of Pharmacy, University of Mumbai, Maharashtra ABSTRACT Objective: The proposed study is focussed at developing acyclovir microemulsions for topical drug delivery systems. QbD was applied for better understanding of the process and to generate design space, using quality target product profile, critical quality attributes, and risk assessment. The aim of the experiment is to prepare a safe, efficacious, stable and patient compliant microemulsion dosage form of Acyclovir. Materials and methods: Pre-formulation studies were carried out which helped in developing a suitable dosage form. UV, FTIR and DSC studies were done for pre-formulation and post-formulation evaluations. QbD was applied to generate design space, using QTPP, CQA, and risk assessment. Microemulsions of acyclovir were developed by using 3 2 factorial designs. Pseudo terneary phase diagrams were constructed to screen various surfactants and co-surfactants for the preparation of microemulsions. Two independent variables Oil Concentration (X1) and Smix Concentration (X2) at three levels low, medium and high were selected and response surface plots were generated. The microemulsions were prepared by plotting pseudo terneary phase diagrams. Various characterizations that were carried out include % transmittance, Viscosity and % drug release. Statistical analyses of batches and surface response studies were done to understand the effect of various independent variables on the dependent variables. Results and Discussions: The λmax was confirmed at 251 nm by UV spectroscopy. The melting point was determined experimentally to be 246 0 C which confirms the drug to be Acyclovir. FTIR and DSC studies confirmed that the drug is Acyclovir. Conclusion: The study indicates that microemulsions of Acyclovir by QbD approach were successfully developed. Keywords: Microemulsion, Acyclovir, DoE, QbD Article Info: Received 03 Dec 2018; Review Completed 09 Jan 2019; Accepted 11 Jan 2019; Available online 15 Jan 2019 Cite this article as: Asish D, Jayesh D, Munira M, Formulation and characterization of acyclovir based topical microemulsions by QBD approach, Journal of Drug Delivery and Therapeutics. 2019; 9(1):237-243 DOI: http://dx.doi.org/10.22270/jddt.v9i1.2230 *Address for Correspondence: Dev Asish, Assistant Professor, Oriental College of Pharmacy, University of Mumbai, Maharashtra INTRODUCTION Acyclovir is a potent, specific antiviral drug which is active against herpes simplex viruses’ types I and II and varicella zoster virus 1 . Acyclovir is available as various dosage forms in the market which includes capsules, creams, ointments, tablets and suspension. Idea of microemulsions was first presented by Hoar and Schulman in 1940s. It is an arrangement of water, oil and surfactant, which is optically isotropic and thermodynamically stable fluid that have low consistency or interfacial film comprising of surfactant/co- surfactant 2 . It is vehicle for enhancing drug delivery, optimization of dose and bioavailability of drugs 3 . It is well- established that medium chain unsaturated fats impact tight intersections of epithelial cells, and long chain unsaturated fats allow lipoprotein amalgamation and consequential lymphatic absorption. Lately, various investigations have suggested that microemulsion [o/w or w/o] can possibly promote bioavailability of medications by means of topical routes. Quality by design (QbD) is an efficient way to bring quality into both product and process. QbD can be achieved by constructive planning of all the previous data that is accessible. Although it is based on certain amount of risks, it gives results that reduces the risk of end product failure and increases the chances of regulatory acceptance 4 . ICH Q8, ICH Q9 and ICH Q10 do explain the principles of QbD in the best way. They provide guidelines on science and risk based assessment, life cycle of product and various approaches in its development. It is also well known fact that there can be a great deal of unpredictability in scale up of a product from research and development, although the reason for failure is