Verapamil hydrochloride (Vp-HCl) is a calcium channel blocker and class IV antiarrythmic drug. Its oral bioavailability is about 20-
30% because of the extensive first-pass metabolism, so it is advisable to prepare the drug in a buccoadhesive dosage forms to bypass
first-pass metabolism and thus achieving constant plasma concentrations during treatment of chronic hypertension. Certain
bioadhesive polymers were used either singly or in combinations at different ratios in order to select the best matrix forming tablets
with satisfactory drug release, characteristic bioadhesiveness and swelling properties.
It was found that the drug release decreased by increasing the concentration of the polymer in all the studied formulations and the drug
release from using polymer blends is slower than those containing single polymer. Tablet formula containing either 30% (w/w)
hydroxypropyl methyl cellulose 15000(HPMC 15000) & 10% (w/w) sodium carboxymethyl cellulose (SCMC), or containing 5%
(w/w) carbopol 934P (Cp934P) with either 15% (w/w) HPMC 15000 or 30% (w/w) sodium alginate (NaAlg) was developed to a
satisfactory level in terms of drug release, bioadhesive performance and swelling properties.
Plasma concentration time curves obtained following buccal administration of the optimal prepared buccoadhesive tablets to rabbits
showed evidence of sustained release of Vp-HCl. Bioavailability of Vp-HCl formulated tablets formulae (T31, T35 & T38) was
approximately two times higher than that achieved after oral administration of commercial tablets.