Abstract:
Verapamil hydrochloride is a drug from the calcium antagonist group.
Verapamil is widely used in the treatment of coronary heart disease, arterial
hypertension, certain supraventricular tachyarrhythmias and obstructive hypertropic
cardiomyopathy. In oral administration, there is an extensive metabolism in the
liver. Therefore, its bioavailability is only 10 to 30%. The buccal mucosa is an
alternative route for systemic delivery; this route avoids the hepatic first-pass
metabolism and gastrointestinal degradation. In this study, a verapamil
hydrochloride buccal patch was developed by using crab chitosan and chitin
whiskers as a mucoadhesive and absorption enhancer. In vitro mucoadhesive study
found that the increasing concentration of crab chitosan induced increasing
mucoadhesive properties of a buccal patch as compared to HEC, (Hydroxy Ethyl
Cellulose), due to the cationic charge of chitosan interacting with an anionic charge
of surface mucosa. In addition, the chitin whiskers compound, which is nonionic,
reduced the mucoadhesiveness. In vitro penetration study found that the crab
chitosan gave higher drug penetration than HEC and the standard solution within 2
to 4 hr. The incorporation of chitin whiskers reduced the drug penetration. The six
formulations, when arranged from high to low drug penetration were ratio of chitin
whiskers and crab chitosan of 1:4, 1:2. 1.5:1, and crab chitosan concentrations of
1.0%, 1.5% and 2.0%. Increasing concentration of crab chitosan from 1.0 to 2.0%
reduced the drug penetration, whereas reduction of concentration of chitin whiskers
from 60 to 20 ml or increasing concentration of crab chitosan from 0.6 to 1.2% in a
mixture of chitin whiskers and chitosan induced drug penetration. This result
suggests that the concentration of crab chitosan used as an absorption enhancer has
an optimal concentration. These results implied that there was a good linear
relationship between the concentration of crab chitosan and chitin whiskers and the
percent of drug penetration via porcine buccal mucosa. In conclusion, the crab
chitosan and chitin whiskers influenced the mucoadhesive properties and drug
penetration of a verapamil hydrochloride buccal patch