Sulphonylureas first generation

Instead of first-generation sulphonylureas, second-generation drugs must be preferred in cardiac glycoside-treated diabetics (Ballagi-Pordany et al., 1989). In rabbits and rats, glibenclamide decreased, while tolbutamide and carbutamide increased, strophantidin toxicity and myocardial ischaemia-induced transitory ventricular fibrillation in a dose-dependent manner (Pogatsa et al., 1988). 

Absorption of both first- and second-generation sulphonylureas is rapid and complete except for gliclazide and tolazamide, which are absorbed more slowly. The maximal plasma concentrations are usually reached within 2-4 h. The kinetics of absorption depend on the formulation and crystalline structure of the drug. Absorption of chlorpropamide may also depend on pH and therefore on food intake, which appears not to be true for the other sulphonylureas (Sartor et al., 1980). The absorption of glibenclamide, although rapid and almost complete, can be improved by an appropriate formulation (Haupt et al., 1984) which leads to a reduction in the daily dosage required. 

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