Development of an in vitro release method for mupirocin-calcium topical emulsion

U ovom istraživanju razvijena je in vitro metoda za ispitivanje oslobađanja djelatne tvari iz topikalne emuzije s mupirocin-kalcijem. Pripremljeni su uzorci kreme s različitim udjelima djelatne tvari i različitim viskoznostima. Reološkim ispitivanjima provedenim pomoću reometra Physica MCR 301 su dobiveni profili viskoznosti te je utvrđeno da su kreme pseudoplastični sustavi. Utvrđen je profil oslobađanja mupirocin-kalcija iz formulacije. Za ispitivanje je korištena aparatura s Franz-difuzijskim ćelijama i komercijalno dostupne sintetičke membrane pri čemu su se membrane izrađene od regenerirane celuloze s veličinom pora 0,2 .m pokazale najprikladnijima. Nakon usporedbe rezultata dobivenih ispitivanjem u čistom acetatnom puferu pH=5,5 i u smjesi jednakih omjera acetatnog pufera pH=5,5 i etilnog alkohola te na temelju ispitane topljivosti mupirocin-kalcija u acetatnom puferu pH=5,5, kao receptorski medij odabran je acetatni pufer pH=5,5. Brzina miješanja pomoću magnetskog mješača bila je 400 okretaja/min, temperatura na kojoj se ispitivanje vršilo bila je 32°C, a trajanje eksperimenta bilo je 5h s ukupno 10 vremena uzorkovanja. Pri toj temperaturi i trajanju ispitivanja oslobodi se oko 30% djelatne tvari. Dokazano je da je razvijena metoda osjetljiva na promjene u formulaciji te stoga korisna za ispitivanje formulacija tijekom razvoja ljekovitog pripravka. Osim toga, vrlo je upotrebljiva za usporedbu i praćenje sličnosti, odnosno uočavanje razlika između formulacija u laboratorijskoj fazi, tijekom uvećavanja postupka (eng. scale up) i u slučaju uvođenja promjena u formulaciji nakon što je već dobiveno odobrenje za stavljanje lijeka u promet. Velika je prednost što se na taj način mogu izbjeći ponovna skupa i dugotrajna in vivo testiranja (bioekvivalencijske i kliničke studije).In this study, in vitro release method of mupirocin-calcium cream was developed. Formulations containing the different amounts of active pharmaceutical ingredient with different viscosity were prepared. Viscosity was measured using a rheometer Physica MCR 301 and viscosity profiles were determined. Based on viscosity profiles, it was concluded that creams have pseudoplastic behavior. The release profile of mupirocin-calcium from cream was determined. A diffusion cell system, Franz diffusion cells, was used for the study. Commercially available synthetic membranes were evaluated and regenerated cellulose membrane with pore of 0,2 Ým was determined as suitable one. Acetate buffer pH=5,5 was chosen as a receptor medium after comparison of release profiles observed from experiments in which acetate buffer pH=5,5 was used and experiments in which mixture of acetate buffer pH=5,5 and ethanol was used. Temperature was set up on 32˘XC and rotational speed at 400 rpm. Duration of the test was 5 hours and samples were taken at ten defined time points. At this temperature and test duration approximately 30% of mupirocin-calcium is released. It has been proved that developed method is able to detect changes in formulation during product development. Further more, it is very applicable in comparing and monitoring sameness or differences between formulations in laboratory phase, during scale up and in case of introducing changes in formulation after approval for marketing of the drug product was already issued. Important advantage of this kind of testing is that it enables avoidance of repeated in vivo trials (bioequivalence and clinical studies) that are very expensive and time-consuming