Stabilization of dithranol in topical formulations

Area of Science:

• Pharmaceutical Sciences
• Dermatology
• Drug Formulation

Background:

• Dithranol is a key antipsoriatic drug used in topical formulations.
• Understanding factors affecting dithranol stability is crucial for effective treatment.
• Previous research has not fully elucidated the complex interactions influencing its degradation in various bases.

Purpose of the Study:

• To investigate the influence of various factors on the stability of dithranol in topical formulations.
• To evaluate the efficacy of different stabilizers in preventing dithranol degradation.
• To determine the optimal conditions for maintaining dithranol integrity in pharmaceutical preparations.

Main Methods:

• Dithranol stability was assessed in lipophilic, hydrophilic, and cream bases.
• Factors studied included drug concentration, temperature, pH, humidity, solubility, and stabilizers.
• Drug degradation was quantified using a selective High-Performance Liquid Chromatography (HPLC) system.

Main Results:

• Dithranol degradation showed a strong dependency on drug concentration.
• Solubility in the ointment base was identified as a critical factor, with higher solubility accelerating degradation.
• Temperature had a less significant impact compared to pH and buffer system choice.
• Succinic acid and tartaric acid were found to be highly effective stabilizers.

Conclusions:

• Dithranol stability in topical formulations is significantly influenced by drug concentration and solubility.
• Optimizing formulation pH, buffer system, and incorporating specific stabilizers are essential for enhancing dithranol stability.
• Succinic acid and tartaric acid show promise as effective agents for protecting dithranol from degradation.