Design and Evaluation of Metoprolol Tartrate Containing Buccal Tablets

Abstract

Metoprolol tartrate is a selective β-1 adrenergic antagonist used in the treatment of the cardiovascular
system, especially hypertension. It is readily and completely absorbed from the gastrointestinal tract but is subjected
to considerable first- pass metabolism having half-life of 3 to 4 hr. It has 12% oral bioavailability. These
physicochemical properties of metoprolol tartrate (undergoing considerable first- pass metabolism, low molecular
weight) make it suitable candidate for administration by buccal route. Bilayered buccal tablets of metoprolol tartrate
were prepared by direct compression method using combinations of polymers (carbopol 934p along with sodium
carboxy methyl cellulose, sodium alginate and hydroxy propyl methyl cellulose K4M), using mannitol as a
channeling agent and ethyl cellulose as a backing layer. The tablets were evaluated for physical and biological
parameters. Among the 15 formulations, the formulation FA1 containing sodium alginate (34.00% w/w of matrix
layer), Carbopol 934p (6.0% w/w of matrix layer) and mannitol (channeling agent, 8.0% w/w of matrix layer) was
found to be promising, which showed t25%, t50%, t70% values of 0.42, 2.45, 4.48 hr respectively and in vitro drug release
of 86.04% in 8 hr along with satisfactory bioadhesive strength (5.00±0.10 g). Stability studies on the promising
formulations indicated that there are no significant changes in drug content and in vitro dissolution characteristics
(p<0.05). Infra-redspectroscopic studies indicated that there are no drug-excipient interactions. The prepared buccal
tablets of metoprolol tartrate could stay in the buccal cavity for a longer period of time, which indicate a potential use
of mucoadhesive tablets of metoprolol tartrate for treating blood pressure.