*Calcium Channel Blockers DOI: http://dx.doi.org/10.5772/intechopen.90778*

levels within 1 hour of administration. Nevertheless, the sustained-release preparations provide peak plasma levels within 3–4 hours of oral administration.

Diltiazem is metabolized extensively by the first-pass metabolism after oral administration. Hence, its bioavailability is about 40%. It undergoes several biotransformations, including deacetylation, oxidative O- and N-demethylations, and conjugation of the phenolic metabolites. Although it has various metabolites, only deacetyldiltiazem is pharmacologically active, which has about 40–50% of the potency of the parent drug [7].
