Poly(dimethylsiloxane) coatings for controlled drug release--polymer modifications

Area of Science:

• Materials Science
• Pharmaceutical Technology
• Polymer Chemistry

Background:

• End-hydroxylated poly(dimethylsiloxane) (PDMS) formulations require modification for controlled drug delivery applications.
• Spray-coating processes necessitate specific material properties for effective tablet coating.

Purpose of the Study:

• To investigate modified PDMS formulations for spray-coating tablet cores.
• To achieve zero-order drug release kinetics using these modified coatings.
• To evaluate the impact of crosslinker and channeling agent variations on coating properties and drug release.

Main Methods:

• Modified PDMS formulations using different crosslinkers (TEOS, SIG) and channeling agents (lactose, MCC, PEG).
• Characterization of dispersion properties (particle size, viscosity) and mechanical properties of free films.
• In vitro release studies of hydrochlorothiazide from coated tablets in a conventional coating pan.

Main Results:

• All PDMS dispersions were suitable for spray-coating.
• Copolymer addition negatively impacted mechanical properties, precluding its use in free films.
• Formulations with polyethylene glycol (PEG) were most effective for controlling drug release, even at low coating weights (5%).
• Constant release rates were achieved with up to 25% PEG, with 50% PEG yielding 63% drug release over 24 hours.

Conclusions:

• Modified PDMS formulations, particularly those incorporating PEG, are promising for developing controlled-release tablet coatings.
• PEG acts as an effective channeling agent, enabling tunable zero-order drug release profiles.
• Further optimization of PEG concentration can achieve sustained drug release over extended periods.