A novel accelerated oxidative stability screening method for pharmaceutical solids.

Area of Science:

• Pharmaceutical Science
• Chemical Engineering
• Materials Science

Background:

• Oxidation is a major pharmaceutical degradation pathway, yet effective stress testing methods for solid forms are limited.
• Evaluating oxidative stability is crucial for drug development and formulation.
• Current methods for assessing oxidative degradation in pharmaceutical solids are insufficient.

Purpose of the Study:

• To introduce a novel, simple, and routine experimental method for peroxide-mediated oxidative stress testing on pharmaceutical solids.
• To demonstrate the utility of this method in solid form selection and degradation product identification.
• To provide a more relevant screening condition for solid dosage forms.

Main Methods:

• Utilized urea-hydrogen peroxide as a solid-state source for hydrogen peroxide vapor generation at elevated temperatures (e.g., 30°C).
• Determined hydrogen peroxide vapor pressure using a modified spectrophotometric method.
• Applied the method to assess the oxidative stability of various solid forms of ephedrine.

Main Results:

• Ephedrine hydrochloride showed no degradation after 2 weeks of exposure to hydrogen peroxide vapor.
• Anhydrate and hemihydrate free base forms of ephedrine degraded rapidly under the same conditions.
• Degradation of ephedrine free base forms was faster under dry conditions compared to 75% relative humidity (RH).
• A novel degradation product was identified under dry conditions.

Conclusions:

• The proposed method offers a simple, convenient, and routine approach for peroxide-mediated oxidative stress testing of pharmaceutical solids.
• This technique is valuable for selecting optimal solid forms, identifying potential degradation products, and screening formulations.
• The method provides more relevant screening conditions for solid dosage forms compared to existing methods.