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Evaluation of the antifibrillatory drug interactions between propranolol and captopril in perfused rabbit hearts In view of the reliability of the serial-shock method of measuring ventricular fibrillation threshold (VFT) in assessing antifibrillatory potency of many antiarrhythmic drugs (Almotrefi & Baker, 1981) and the alarming reports of the proarrhythmic effects of several antiarrhythmic agents (Peters et al., 1994) we decided to use the above technique to study interactions that may occur when antiarrhythmic and antihypertensive drugs from different classes are combined.. Recently, we have presented the antifibrillatory interactions between propranolol and lidocaine (Almotrefi et al., 1999), and with valsartan (Almotrefi & Arif, 2005). This abstract reports its interactions with captopril. Studies were carried out on hearts isolated from New Zealand white rabbits of either sex weighing 1 to 2 Kg. The method used has been described previously (Almotrefi & Baker, 1981). Perfusion with propranolol produced significant, dose-dependent increase in VFT while perfusion with captopril did not cause any significant change. In addition, there was no significant difference in VFT with the combined infusion of 0.34 µmol of propranolol and 1µmol of captopril, in contrast to a synergistic antifibrillatory effect of the combined use of lidocaine and propranolol (Almotrefi et al., 1999). This suggests that captopril does not have antifibrillatory interactions with lidocaine , indicating its safety in combining with class II antiarrhythmic drugs.
Table 1. Effect of propranolol, captopril and combination on VFT in isolated-perfused rabbit heart
Almotrefi,AA & Baker, JBE (1981) Br.J.Pharmacol., 73,373-377 |
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