Progestin permeation through polymer membrane V: Progesterone release from monolithic hydrogel devices

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Monolithic devices are used for controlled drug release.
• Hydrogels offer unique swelling properties that can influence release kinetics.
• Understanding release mechanisms is crucial for effective drug delivery.

Purpose of the Study:

• To investigate progesterone release kinetics from poly(hydroxyethyl methacrylate) based hydrogels.
• To analyze the impact of polymer composition and water absorption on drug release.
• To determine the aqueous solubility of progesterone.

Main Methods:

• Preparation of monolithic devices from copolymers of poly(hydroxyethyl methacrylate) and poly(methoxyethoxyethyl methacrylate) or poly(methoxyethyl methacrylate).
• Measurement of progesterone release profiles over time.
• Analysis of release kinetics using plots of fraction released versus (time)1/2.
• Determination of permeability coefficients and equilibrium water content.
• Cross-membrane diffusion studies.
• Measurement of progesterone aqueous solubility.

Main Results:

• Early drug release often followed linear kinetics with respect to the square root of time.
• Water absorption by hydrogels led to observed breakpoints in release curves.
• Release rates were influenced by initial progesterone load and the polymer's equilibrium water content.
• Progesterone aqueous solubility was determined to be 38 micrograms/ml at 23°C.

Conclusions:

• The release of progesterone from these hydrogel devices is complex, influenced by both diffusion and polymer swelling.
• Water absorption significantly affects early-stage drug release kinetics in these hydrogels.
• Controlling initial drug load and polymer water content is key for optimizing progesterone delivery from these monolithic systems.