DEVELOPMENT, MANUFACTURE AND ASSESSMENT OF CLOBETASOL 17- PROPIONATE CREAM FORMULATIONS By Ayeshah Fateemah Beebee Fauzee A Thesis Submitted to Rhodes University in Fulfilment of the Requirements for the Degree of MASTER OF SCIENCE (PHARMACY) January 2011 Faculty of Pharmacy RHODES UNIVERSITY Grahamstown South Africa i ABSTRACT Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic- pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and ii revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI. iii To the Fauzee and Sohawon Families, My late paternal grandparents, maternal grandparents and parents, For inspiration, For motivation & For everlasting support. iv ACKNOWLEDGEMENTS I would like to express my sincere gratitude to the following people: My supervisor, Professor R.B. Walker for his expert guidance, encouragement, continuous support and patience during the research and the writing of this thesis. The Dean and Head, Professor R.B. Walker and the staff of the Faculty of Pharmacy for the use of facilities in the Faculty at Rhodes University. Mr T. Samkange for his technical support and Mr L. Purdon for his assistance and continuous help throughout the duration of this project. Dr M. Skinner for his assistance with the human skin blanching bioequivalence study. My colleagues and friends in the Department of Pharmacy for their help and support: Dr Sandile Khamanga, Dr Kasongo Wa Kasongo, Dr Faith Chaibva, Ms Adrienne Müller, Ms Tinotenda Sachikonye, Ms Henusha Jhundoo, Mr Loti King‟ori, Ms Bianca Dagnolo, Ms Laura Magnus, Ms Natisha Dukhi, Ms Tatenda Munedzimwe, Mr Maynard Chiwakata, Ms Anthonia Afolayan, Ms Catherine luyt, Ms Wai Ling Au, Ms Kirsty-Lee Barford and Ms Rudo Mupfumira. Ms Ameera Limbada, Ms Nazranah Mukadam and Ms Amina Motala for their friendship and encouragement during the trials and tribulations of this research. Uncle Jamiel Kafaar and aunty Zurina Kafaar for making me feel at home when home is so far away, during my undergraduate and postgraduate studies. My grandparents, aunties, uncles and cousins (Sohawon, Keenoo, Khodabux and Husnoo Families) who always had faith in me and motivated me when I needed them most. My sister, Dr Nilufer Jasmine S. Fauzee-Mandarry and my brother-in-law, Dr Tasleem M. Mandarry for all their love, hope and support. My parents, Abdool Raffick and Salmah Bibi Fauzee for their love, motivation and understanding. Without them, nothing would have been possible. Thank you for supporting me financially and for helping me accomplish my dreams and hopes. You have indeed been the most amazing supportive parents. The Almighty for giving me protection, strength and resolve to succeed throughout my life. Alhamdulilah. v STUDY OBJECTIVES Clobetasol 17-propionate (CP) is a class 1 corticosteroid used for the treatment of inflammatory conditions of the skin such as psoriasis, seborrheaic and atopic dermatitis, extreme photodermatitis and eczema [1-3]. Potent corticosteroids are expensive and the prevalence of dermatological conditions in South Africa has increased since the identification of the HIV epidemic in 1982, requiring access to affordable medicines [4]. CP is the drug of choice for the effective treatment of these dermatological conditions since it has a short lag time before an in vivo pharmacological effect is observed, following topical application [5,6]. Although Dovate® is a readily available generic CP cream product on the South African market, there was a need to produce a laboratory and scale-up formulation and to define a manufacturing process that would be suitable for the production of a robust product, prior to consideration of licensing such topical pharmaceutical product. The objectives of this study were: i. To develop and validate a Reversed-Phase High Performance Liquid Chromatographic (RP-HPLC) method that had the necessary sensitivity and selectivity to accurately and precisely quantitate CP, in methanolic solutions and semi-solid dosage forms. ii. To design and develop a 500 g laboratory scale CP cream formulation that would have similar physical and chemical characteristics to an innovator product viz., Dermovate®. iii. To design, develop and optimise a 5000 g batch of CP cream formulation, using a minimum number of trials using experimental design techniques and to evaluate the performance characteristics of the dosage form and compare the results to those obtained for Dermovate®. iv. To assess the rate and extent of CP release from laboratory and scale-up CP cream formulations using a Franz cell diffusion apparatus. v. To study the in vitro release kinetics and release mechanisms for the laboratory and scale-up CP cream formulations. vi. To evaluate the in vivo bioequivalence of a scale-up CP cream formulation, with respect to Dermovate® in healthy human volunteers using the human skin blanching assay. vi TABLES OF CONTENTS ABSTRACT............................................................................................................................................ii ACKNOWLEDGEMENTS..................................................................................................................v STUDY OBJECTIVES.........................................................................................................................vi LISTS OF TABLES.............................................................................................................................xv LISTS OF FIGURES.........................................................................................................................xvii CHAPTER ONE CLOBETASOL 17-PROPIONATE......................................................................1 1.1 INTRODUCTION ........................................................................................................................... 1 1.2 PHYSICO-CHEMICAL PROPERTIES ...................................................................................... 2 1.2.1. Description ................................................................................................................................ 2 1.2.2. Dissociation Constant (pKa) .....................................................................................................