Radioimmunoassay for the new antiarrhythmic agent cibenzoline in human plasma

Cibenzoline. A review of its pharmacological properties and therapeutic potential in arrhythmias

Cibenzoline is a class I antiarrhythmic drug with limited class III and IV activity which can be administered orally or intravenously. An elimination half-life of about 8 to 12 hours permits twice daily administration, although age and renal function must be considered when determining dosage. Cibenzoline has some activity in ventricular and supraventricular arrhythmias, including drug-refractory ventricular tachycardia or ventricular arrhythmias following recent acute myocardial infarction, although results in patients with sustained ventricular tachycardia are less promising. In comparative trials, cibenzoline has demonstrated efficacy similar to or better than that of a variety of other class I antiarrhythmic drugs and was at least as well tolerated, with a more convenient dosage schedule. However, further studies to clarify the proarrhythmic effects of cibenzoline and its use in patients with impaired left ventricular function are required, and the use of cibenzoline (and other class I antiarrhythmic agents) in patients with other than potentially lethal ventricular arrhythmias should be avoided following the results of the CAST studies. Thus, cibenzoline is an effective antiarrhythmic agent with a favourable pharmacokinetic profile that may be considered with other class I drugs in patients requiring therapy for high risk arrhythmias.

Between-lot and within-lot comparisons of bioavailability of macrocrystalline nitrofurantoin capsules

Comparative bioavailability studies should be designed and the resulting data evaluated based on estimates of both intersubject and intrasubject variances in the kinetic parameters for the particular drug products(s) being studied. This report presents the results of two comparative bioavailability studies. In the first study, three production lots of macrocrystalline nitrofurantoin capsules (Macrodantin) were compared in 21 subjects, and in the second study, capsules from one production lot were administered to 21 different subjects on three occasions. Both model-independent kinetic parameters for urinary excretion and a one-compartment model with zero-order absorption were used to evaluate both the rate and the extent of bioavailability. Overall the results showed a very low variance between and within production lots and a relatively large intersubject variance in the rate and extent of absorption.