FORMULATION DEVELOPMENT AND IN-VIVO EVALUATION OF BUCCOADHESIVE TABLETS OF VERAPAMIL HYDROCHLORIDE

Controlled-released buccoadhesive tablets of verapamil hydrochloride (VH) were
obtained by incorporation of VH in suitable carrier systems standardised based on bioadhesion
and dissolution. The carrier systems were formulated using carbomor 974P (CP974P) and
hydroxypropylmethylcellulose (HPMC) or sodium carboxymethyl cellulose (NaCMC) or sodium
alginate or guar gum as the bioadehsives. Mannitol and polyethylene glycol 6000 (PEG6000)
were used as solubilizers singly or in combination. The effect of polymer concentration on the
release profile and in-vitro bioadhesion of the matrix tablets was studied. Tablet formulations
with carbomor 974P (5%), in combination with sodium alginate (20%) or HPMC (20%) showed
98% or 79% drug release, respectively after 6 h. The dissolution rate of the drug decreased by
increasing CP974P concentration. Controlled-release buccoadhesive tablets containing VH
were prepared and evaluated in order to achieve constant plasma concentrations during
treatment of chronic hypertension and to improve the bioavailability of VH by the avoidance of
hepatic first-pass metabolism. Pharmacological parameters and plasma concentration time
curves obtained following buccal administration to rabbits of buccoadhesive tablets showed
evidence of sustained release of VH. Bioavailability of VH was approximately two times that
achieved after oral administraion of commercial tablets. The formulations were compared using
pharmacokinetic parameters such as AUC, Cmax and Tmax values.