Analysis and stability study of myristyl nicotinate in dermatological preparations by high-performance liquid chromatography.

Myristyl nicotinate is an ester prodrug under development for delivery of nicotinic acid to skin for treatment and prevention of conditions that involve skin barrier impairment such as chronic photodamage and atopic dermatitis or for mitigating skin barrier impairment that results from therapy such as retinoids or steroids. The formulation stability of myristyl nicotinate is crucial because even small amounts of free nicotinic acid cause skin flushing, an effect that is not harmful but would severely limit tolerability. We report here reversed-phase HPLC methods for the rapid analysis of myristyl nicotinate and nicotinic acid in dermatological preparations. Because of the large differences in polarity, myristyl nicotinate and nicotinic acid were analyzed by different chromatographic conditions, but they can be rapidly extracted from cream formulations using HPLC mobile phase as a solvent followed by HPLC analysis in less than 10 min. The methods were validated in terms of linearity, precision and accuracy and mean recovery of myristyl nicotinate from topical creams ranged from 97.0-101.2%. Nicotinic acid at levels of 0.01% in the formulations could be quantified. Stability studies show that myristyl nicotinate formulations are stable at room temperature for 3 years with less than 0.05% conversion to nicotinic acid. These methods will be effective for routine analysis of myristyl nicotinate stability in dermatological formulations.