Release of theophylline and carbamazepine from matrix tablets - Consequences of HPMC chemical heterogeneity

• The release of theophylline and carbamazepine from matrix tablets composed of microcrystalline cellulose, lactose and hydroxypropyl methylcellulose (HPMC) was studied. The aim was to investigate the effect of different substituent heterogeneities of HPMC on the drug release from matrix tablets composed of either 35% or 45% HPMC. The release of the poorly soluble carbamazepine was considerably affected by the HPMC heterogeneity, and the time difference at 80% drug release was more than 12 h between the formulations of different HPMC batches. This was explained by slower polymer erosion of the heterogeneous HPMC and the fact that carbamazepine was mainly released by erosion. In addition, results from magnetic resonance imaging showed that the rate of water transport into the tablets was similar. This explained the comparable results of the release of the sparingly soluble theophylline from the two formulations even though the polymer erosion and the swelling of the tablets were considerably different. Thus, it can be concluded that the drug release was highly affected by the substituent heterogeneity, especially in the case of carbamazepine, which was released mainly by erosion. (C) 2011 Elsevier B.V. All rights reserved.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

Hydrophilic matrix tablets

hydroxypropyl methylcellulose matrices

MRI

physicochemical properties

hydroxypropylmethylcellulose

Drug solubility

polymer particle-size

Drug release

hydrophilic

HPMC chemical heterogeneity

drug-release

diffusion

matrices

delivery-systems

kinetics

Batch-to-batch variability

dissolution

Publication and Content Type

art (subject category)

ref (subject category)