Optimised transdermal delivery of pravastatin

Area of Science:

• Pharmaceutical Sciences
• Dermatology
• Drug Delivery Systems

Background:

• The "Formulating for Efficacy" program introduced a novel strategy to optimize topical formulations for enhanced transdermal drug delivery.
• The "Delivery Gap Theory" provides a framework for assessing the potential of active pharmaceutical ingredients (APIs) to improve transdermal transport.

Purpose of the Study:

• To investigate the "Delivery Gap Principle" by formulating six semi-solid topical pravastatin formulations (creams and emulgels) with varying polarities.
• To determine which formulation exhibits optimal transdermal delivery of 2% pravastatin to the systemic circulation.

Main Methods:

• Six semi-solid formulations (three creams, three emulgels) with 2% pravastatin were prepared, varying in polarity (optimized, lipophilic, hydrophilic).
• Franz cell diffusion studies were conducted over 12 hours to measure drug permeation.
• Tape stripping was employed post-diffusion to quantify pravastatin concentration in different skin layers (stratum corneum-epidermis and epidermis-dermis).

Main Results:

• The optimized emulgel formulation achieved the highest median amount of pravastatin per area (2.578 μg/cm²) after 12 hours of diffusion.
• In the stratum corneum-epidermis, the hydrophilic emulgel showed the highest median pravastatin concentration (1.448 μg/ml).
• The optimized emulgel exhibited the highest median pravastatin concentration in the epidermis-dermis (0.849 μg/ml).
• Emulgel formulations consistently demonstrated enhanced pravastatin delivery compared to cream formulations.

Conclusions:

• Optimized emulgels are highly effective for enhancing transdermal pravastatin delivery.
• Formulation polarity significantly influences the transdermal delivery of pravastatin.
• Emulgels represent a superior vehicle for topical pravastatin delivery compared to conventional creams.