Considerations on the quinine actinometry calibration method used in photostability testing of pharmaceuticals

Abstract

This paper addresses two critical issues concerning the guidelines adopted by the ICH on the photostability testing: the quinine actinometry method and the light/radiation exposure map distribution of the photostability chamber. Using a qualified non-commercial photostability chamber tests were performed using quinine and physical actinometry and compared the results to those which are used as the basis of the ICH guidelines. The statistical analysis on the results showed that: (i) the calibration curve of the quinine solution depends on its concentration and on its location in the chamber; (ii) the quinine actinometry method currently recommended by the ICH guidelines should not be generalized to any photostability chamber.

Determination of Dacarbazine Φ-Order Photokinetics, Quantum Yields, and Potential for Actinometry

“…Indeed, the Φ‐order equations are flexible enough to bring forward the potential and facilitate the development of new drug actinometers based on the kinetic data of their photodegradations. In the context of pharmaceutics, proposing new actinometers is important as the one recommended by ICH, namely, the quinine hydrochloride actinometer presents various drawbacks that seriously hamper its application to photostability testing purposes …”

Studies on photodegradation process of psychotropic drugs: a review

“…The radiation dose is calculated from change in quinine solution absorbance at 400 nm (ICH 1996 ). Some tests proved that quinine actinometry is concentration dependent, and the calibration curve may vary depending on the location of the solution in the photostability chamber, so ICH guidelines should not be generalized (de Azevedo Filho et al 2011 ).…”

Quantification of Unimolecular Photoreaction Kinetics: Determination of Quantum Yields and Development of Actinometers—The Photodegradation Case of Cardiovascular Drug Nisoldipine

“…These drawbacks seriously hamper the reliability of this actinometer. It is also noticeable that quinine hydrochloride has rarely been employed for the investigations of drugs' photodegradation in solution [22,29,30]. and irr NIS for data collected for both TRZ and QY various concentrations (Table 3) Nevertheless, no alternative actinometers have thus far been proposed.…”