Implementation of a Mathematical Model for the Photochemical Kinetics of a Solid Form Active Pharmaceutical Ingredient

We present here the development of a photochemical model used to quantify the risk to photo-degradation of a solid drug substance. A key feature of the proposed model development is streamlined estimation of the dependence of the absorption spectra and the quantum yield to the wavelength. A mathematical description of the relationship between the quantum yield and the wavelength enables estimation of photo-degradation kinetics under any light anticipated to be encountered in the manufacturing environment. The system studied here consisted of a first order irreversible transformation (A → B(1Φ)) and the formalism strongly suggested the quantum yield was constant over the relevant wavelength range. The predictive power of the model enabled the design of a control strategy to limit the formation of the photo-degradant to very low levels. Also presented are insights obtained from quantum mechanical modeling of the electronic transitions associated with the UV absorption spectra.
Source: International Journal of Pharmaceutics - Category: Drugs & Pharmacology Source Type: research