Reological properties of hydroalcoholic ciclopirox gels

Introduction. Reological properties of semi- solid formulations are very important and may indicate their stability. Excipients like menthol, thymol, rosemary oil, juniper oil, cinnamon oil can alter rheology and drug delivery characteristics of topical gels. The objective of this study is to perform detailed and extensive rheological chrarcterization of hydroxypropyl cellulose gel formulated using differnt excipients. Methods. Hydroalcoholic gels with different excioients were prepared by dissolving hydroxypropyl cellulose and ciclopirox in co- solvent. Menthol, thymol, rosemary oil, juniper oil, cinnamon oil were aded to different formulations. Steady and transient shear measurements were performed to measure viscoelastic properties, temperature dependency, yield strength of pharma ceutical gels. Flow curves were constructed for the range of temperature. Flow curves were made after reological measurements and it were described using mathematical model- power law slope. Flow index and consistency coefficient were calculated for all formulations at 3 temperatures: 25, 32 and 37 C. Results. Gels with rosemary oil and thymol show lower consistency coefficients and higher flow index compared to gel without oils. Menthol, juniper oil, cinnamon oil have marginal influence for viscosity. Structural recovery after stress were observed. All formulations are stable when shear rate is changing and structure returns to its original state after the cessation of stress. Changes of temperature can destroy structure and gel do not recover. Gels with menthol and rosemary oil are not resistant to torsional effects. [...].