Effect of thermal gelation on dissolution from coated tablets

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Tablet coatings are crucial for drug delivery and dissolution.
• Methylcellulose and hydroxypropyl methylcellulose are common coating polymers.
• Understanding coating behavior under physiological conditions is essential.

Purpose of the Study:

• To investigate the cause of lower dissolution profiles observed with methylcellulose coatings compared to hydroxypropyl methylcellulose coatings at 37°C.
• To elucidate the mechanism behind the altered dissolution behavior.

Main Methods:

• Comparative dissolution testing of tablets with methylcellulose and hydroxypropyl methylcellulose coatings at 37°C.
• Investigating the effect of temperature and agitation on dissolution profiles.
• Analysis of coating properties related to thermal gelation.

Main Results:

• Methylcellulose coatings exhibited significantly lower dissolution rates than hydroxypropyl methylcellulose coatings at 37°C.
• Thermal gelation of methylcellulose near 37°C was identified as the primary cause for reduced dissolution.
• The retarded dissolution effect was reversible and disappeared at temperatures below the gel point or with increased agitation.
• This phenomenon was independent of the specific drug formulation.

Conclusions:

• The thermal gelation property of methylcellulose at physiological temperatures significantly impacts tablet dissolution.
• Hydroxypropyl methylcellulose offers superior dissolution performance at 37°C due to its resistance to thermal gelation.
• Coating material selection is critical for achieving desired drug release profiles, especially at body temperature.