Investigation on the photostability of tretinoin in creams.

In this investigation, the photodegradation of some tretinoin cream formulations was evaluated. Several oils were selected to prepare the cream formulations: olive oil, maize oil, castor oil, isopropyl myristate and Miglyol 812. A solubility study showed that tretinoin is best soluble in castor oil (0.

Liposomes with tretinoin: a physical and chemical evaluation.

The comedolytic activity of tretinoin, incorporated in liposomes, is five to ten times higher compared to the conventional preparations and also the local tolerability is much better. This implies the big interest of a study on tretinoin in liposomes. First, the encapsulation capacity of tretinoin in the liposomes was determined.

Determination of hydroperoxides in liposomes by the modified IDF and the modified tiron methods.

Two new methods, the modified International Dairy Federation and the modified Tiron methods, were developed for the determination of hydroperoxides in liposomes. Interferences of alpha-tocoferol and egg-phosphatidylcholine (EPC) required a solid-phase extraction before the analysis to eliminate alpha-tocoferol and a fluid-fluid extraction based on the solvent triangle of Bligh and Dyer to separate EPC. The developed color, using thiocyanate and Tiron, respectively, as complex-formers for the generated ferri-ions, was measured spectrophotometrically.

Investigation on the photostability of a tretinoin lotion and stabilization with additives.

Tretinoin, a drug that is used in topical preparations for the treatment of acne vulgaris, is known to be very susceptible to degradation under daylight. The objective of this work was to investigate the degradation of a tretinoin lotion placed in front of a xenon lamp. Analysis was performed with HPLC.

Investigation of the chemical stability of an erythromycin-tretinoin lotion by the use of an optimization system.

A combination of 2% erythromycin and 0.05% tretinoin in an alcohol-isopropanol lotion was prepared. Two parameters were investigated for their influence on the stability of erythromycin and/or tretinoin, namely pH and the concentration of butylhydroxytoluene (BHT) as antioxidant.