International Journal of Cardiology, 6 (1984) 581-584 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK Elsevier 581 IJC 00196 Use of oral verapamil in long-term treatment of neonatal, paroxysmal supraventricular tachycardia. A pharmacokinetic study zyxwvutsrqponmlkjihgfedcbaZYXWVUTS U. de Vonderweid ‘, A. Benettoni I, D. Piovan 2 and R. Padrini 2 ’ Istituto per I’lnfanria, Pediatric Hospital Trieste, Italy; ’ Department of Pharmacology, University of Padova, Italy (Received 6 January 1984; revision received 15 May 1984; accepted 24 May 1984) De Vonderweid U, Benettoni A, Piovan D, Padrini R. Use of oral verapamil in long-term treatment of neonatal, paroxysmal supraventricular tachycardia. zyxwvutsrqponmlkjihgfedc A pharmacokinetic study. Int J Cardiol 1984;6:581-584. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML Efficacy and pharmacokinetics of verapamil were studied in two neonates affected by supraventricular paroxysmal tachycardia, under maintenance treatment with the drug. Verapamii proved to be fully effective in suppressing arrhythmic episodes at the daily doses of 1.5 mg/kg four times a day in case 1 and of 2 mg/kg in case 2. The results of plasma half-life of the drug, calculated in a dose interval, were 3.14 hr and 2.10 hr, respectively. In patient 2, doses -C 0.95 mg/kg four times a day did not produce detectable drug plasma levels, while a further stepwise increase of dose up to 2 mg/kg four times a day produced a steep rise in trough concentration. So, in view of this dose-concentration relationship, caution is recommended in adjusting verapamil oral dosage. (Key words: neonatal tachycardia; drug monitoring; pre-excitation syndrome) Introduction Verapamil has proven very effective in various supraventricular arrhythmias in adult patients and a number of reports exist concerning acute use in pediatric patients [l-3]. At present, information about chronic oral treatment with verapamil in newborn infants is lacking, particularly as far as the relationship between oral dose and Correspondence and reprint requests to: Dr. Roberto Padrini, Dipartimento di Farmacologia “E. Meneghetti”, Largo E. Meneghetti 2, 35100 Padova, Italia. 0167-5273/84/$03.00 0 1984 Elsevier Science Publishers B.V.