M. Halsas et al., BIOPHARMACEUTICAL EVALUATION OF TIME-CONTROLLED PRESS-COATED TABLETS CONTAINING POLYMERS TO ADJUST DRUG-RELEASE, European journal of drug metabolism and pharmacokinetics, 23(2), 1998, pp. 190-196
This paper deals with press-coated modified release tablets in which t
he drug dose is situated in the core or is divided between the core an
d the coat. The coat contains polymer (sodium alginate pr hydroxypropy
lmethyl cellulose, HPMC) to control drug release. The main objective w
as to investigate how the pharmacokinetic profile of the model drug co
uld be modified by altering the proportion of the drug between the cor
e and the coat. The effect of the amount of the polymer in the coat wa
s also studied. Bioavailability tests were carried out on healthy volu
nteers. In the absorption curves of the tablets containing 50%, 67% an
d 80% of the drug in the core and 180 mg HPMC in the coat a bimodal pr
ofile was observed. No bimodal release pattern in the in vitro dissolu
tion studies was found. If the whole dose was incorporated in the core
the absorption curve has only one clear t(max) value at about 10 h. D
oubling the amount of HPMC in the coat dramatically decreased drug abs
orption. It was concluded that, if a slightly reduced t(max)-value was
required, the viscosity grade of HPMC used should be lowered.