Acebutolol: ten years of experience

Pharmacologically active drug metabolites: impact on drug discovery and pharmacotherapy

Metabolism represents the most prevalent mechanism for drug clearance. Many drugs are converted to metabolites that can retain the intrinsic affinity of the parent drug for the pharmacological target. Drug metabolism redox reactions such as heteroatom dealkylations, hydroxylations, heteroatom oxygenations, reductions, and dehydrogenations can yield active metabolites, and in rare cases even conjugation reactions can yield an active metabolite. To understand the contribution of an active metabolite to efficacy relative to the contribution of the parent drug, the target affinity, functional activity, plasma protein binding, membrane permeability, and pharmacokinetics of the active metabolite and parent drug must be known. Underlying pharmacokinetic principles and clearance concepts are used to describe the dispositional behavior of metabolites in vivo. A method to rapidly identify active metabolites in drug research is described. Finally, over 100 examples of drugs with active metabolites are discussed with regard to the importance of the metabolite(s) in efficacy and safety.

Stereospecific high-performance liquid chromatographic assay of acebutolol in human plasma and urine

A sensitive high-performance liquid chromatographic technique is described for the separation of R- and S-acebutolol in human plasma and urine. The procedure involves derivatization with the chiral reagent S-(+)-1-(1-naphthyl)ethyl isocyanate. The resulting diastereoisomers are quantified using normal-phase high-performance liquid chromatography with fluorescence detection (220/389 nm). Virtual baseline separation, free from interference, with achieved (resolution factor = 1.45). Excellent linearity (r greater than 0.998) was observed throughout the range 10-500 ng/l and 2-100 mg/l in plasma and urine, respectively. Inter-assay variability was less than 5% for each enantiomer at concentrations of 10 ng/ml. This method is applicable for the determination of the pharmacokinetics, in man, of acebutolol enantiomers in plasma and urine.

Qualities of an ideal beta-adrenoceptor antagonist and comparison of existing agents with a new cardioselective hydrophilic vasodilator beta-adrenoceptor antagonist, celiprolol

Beta-adrenoceptor blockade is established therapy for cardiovascular conditions including hypertension and angina pectoris. The important qualities of a beta-adrenoceptor antagonist relate to cardioselectivity, hydrophilicity, peripheral vasodilation, ideal pharmacokinetics and maintenance of the quality of life. Celiprolol, with its known cardioselectivity, hydrophilicity and peripheral vasodilator capacity, measures well by several of these criteria; more data on pharmacokinetics are required. Further testing is indicated, particularly in relation to effects on epinephrine-induced hypokalemia, blood lipid profiles, clinical vasodilatory properties and effects on the quality of life, especially in geriatric patients.