Capsaicin Microemulsions: Preparation, Characterization and in Vitro Release Study

In this study, pseudoternare phase diagrams were made and oil: water: surfactant: cosurfactant (O:W:S:CoS) weight ratios corresponding to microemulsion states were highlighted. Soybean oil was used as the oily phase (O) and a mixture of water and glycerol in a ratio of 4:1 (wt / wt) was used as the aqueous phase (W). As a surfactant (S) was used sorbitan monooleate (Span 80) and cosurfactants (CoS) were ethanol and 1butanol in the mass ratio S: CoS = 2:1. Viscosimetric and conductometric analyses revealed the transition state of the O/W, W/O microemulsions and bicontinuous structures. In vitro study of capsaicin release and permeability was performed using a Franz cell, with a cellulose membrane. As a liquid receiver was used a liquid mixture 1:1 (v/v) of ethanol and citric acid disodium phosphate buffer, with pH = 7.4 at a temperature of 37C. The drug content of capsaicin was analysed by a HPLC technique. It was determined capsaicin optimal concentration of 0.12% (wt/wt). The microemulsions behaviour as a better vehicle than gel behaviour and ethanol action as a better permeation enhancer than 1-butanol were demonstrated. A clinical trial on capsaicin microemulsions use as improving method of blood collecting for obstructive pulmonary disease (OPD) diagnostic was conducted. The results confirm the high potential of microemulsions as topical drug vehicles. Rezumat În această lucrare s-a realizat un studiu privind prepararea și caracterizarea unor microemulsii cu capsaicină. Microemulsiile s-au preparat folosind uleiul de soia, un amestec de apă și glicerol în raport masic de 4:1 și un amestec de Span 80 și etanol sau 1butanol în raport masic de 2:1. Pentru stabilirea rapoartelor de amestecare corespunzătoare stării de microemulsie s-au construit diagramele pseudoternare de fază. Structura microemulsiilor s-a determinat prin măsurători conductometrice și vîscozimetrice. S-a realizat un studiu in vitro de eliberare a capsaicinei din microemulsii și hidrogel. S-a studiat posibilitatea folosirii microemulsiilor cu capsaicină la îmbunătăţirea metodelor de recoltare de sânge în vederea diagnosticării bolilor pulmonare obstructive cronice. Rezultatele obţinute arată faptul că microemulsiile cu capsaicină, ca forme farmaceutice vasodilatatoare, favorizează prelevarea intracapilară a probelor de sânge.