Stability of dithranol in creams

Area of Science:

• Dermatology
• Pharmaceutical Sciences
• Formulation Chemistry

Background:

• Dithranol is a key anthraquinone derivative used in topical treatments.
• Ensuring the stability of dithranol in cream formulations is crucial for therapeutic efficacy.
• Previous studies have indicated potential degradation issues with dithranol in certain formulations.

Purpose of the Study:

• To evaluate the long-term stability of dithranol in cream formulations.
• To determine the optimal storage conditions and packaging for dithranol creams.
• To assess the impact of different concentrations and container materials on dithranol stability.

Main Methods:

• Dithranol cream formulations at 0.1%, 0.3%, and 0.5% concentrations were prepared.
• Creams were stored in aluminum-coated and polypropylene tubes.
• Samples were stored at controlled temperatures (4°C and 20°C).
• Drug concentration was quantified using high-performance liquid chromatography (HPLC) at various time points (0, 3, 6, 12 months).

Main Results:

• All tested concentrations of dithranol (0.1%, 0.3%, 0.5%) demonstrated stability for 12 months when stored at 4°C in aluminum-coated tubes.
• Dithranol cream stored in polypropylene tubes showed instability, indicating material incompatibility.
• The stability was maintained across all tested concentrations under refrigerated conditions in appropriate packaging.

Conclusions:

• Low concentrations of dithranol in cream formulations are stable for at least 12 months when stored refrigerated (4°C) in aluminum-coated tubes.
• Aluminum-coated tubes are suitable packaging for long-term storage of dithranol creams.
• Polypropylene tubes are unsuitable for storing dithranol cream formulations due to potential degradation.