Abstract:
The objective of this study was to find appropriate compositions to formulate 5% spironolactone topical gel with good stability and physical characteristics for the treatment of hormonal acne. The 5% spironolactone gels were prepared using hydroxypropyl methylcellulose as the gelling agent. The effects of additives (tea tree oil, lactic acid and PEG 400) on the physical characteristics such as clarity, color, pH, viscosity and % drug content, had been investigated after preparing and storing for 1 month at room temperature and under accelerated condition (45C/75%RH). After preparation, the gels were clear, colorless or yellowish in color in some formulas due to the adding of lactic acid. The pH was in between 3.69 - 5.76, the viscosity was in between 311.6 ± 4.2 to 676.4 ± 7.5 centipoises and the drug content was 89.06% to 95.87%. The formulas containing PEG 400 were found to be higher in the viscosity compared to those without PEG 400. After being stored for 1 month, the formulations containing tea tree oil were found to have less mercaptan-like odor of the drug. The lactic acid containing formulation produced more unacceptable odor. After storage at room temperature and under accelerated condition for 1 month, the assay value decreased from the initial time from 2.2% to 17.7% and 3.3% to 23.9%, respectively. It was found that, tea tree oil can be used as a good odor masking while lactic acid should be avoided. The addition of PEG 400 provided higher viscosity and had no advantage on drug stability.
