Oxygen diffusion coefficients in commonly used topical semisolid creams.

Area of Science:

• Pharmaceutics
• Physical Chemistry
• Materials Science

Background:

• Oxygen sensitivity is a critical factor in formulating drugs for topical, ophthalmic, and parenteral use.
• Understanding oxygen diffusion in semisolid dosage forms is crucial for drug stability and efficacy.
• Topical ointments and creams require specific formulation considerations to protect oxygen-sensitive ingredients.

Purpose of the Study:

• To determine oxygen diffusion coefficients, permeabilities, and solubilities in oil-in-water (o/w) topical ointments and commercial anthralin creams.
• To investigate the impact of petrolatum concentration on oxygen diffusion in o/w creams.
• To provide data for optimizing the formulation of oxygen-sensitive drugs in semisolid dosage forms.

Main Methods:

• A novel coupled steady-state and unsteady-state analysis for oxygen diffusion was employed.
• Oxygen diffusion through a thin layer of test material on a membrane-covered polarographic oxygen electrode was measured.
• The method, developed by Ju and Ho (1986), was applied to a USP XXI hydrophilic ointment and four 1% anthralin creams.

Main Results:

• Oxygen diffusion coefficients were found to decrease with increasing petrolatum concentration in o/w topical creams.
• The study successfully determined oxygen diffusion coefficients for four commercial 1% anthralin creams.
• Permeability and solubility data were also obtained, contributing to a comprehensive understanding of oxygen transport.

Conclusions:

• The formulation of topical creams significantly influences oxygen diffusion rates.
• Increased petrolatum concentration in o/w creams acts as a barrier to oxygen diffusion.
• This research provides valuable insights for designing stable and effective topical formulations for oxygen-sensitive pharmaceuticals.