Halothane Verapamil

Halothane and enflurane have direct cardiac inhibitory effects similar to verapamil and diltiazem and these effects may summate. Interaction may also cause an additive effect on conduction with, e.g. isoflurane or halothane. 

The studied molecules include such diverse compounds as volatile anesthetics (halothane), local anesthetics of the cocaine type, calcium channel-blocking agents such as verapamil, antidepressants (chlorpromazine), and anti cancer drugs such as adriamycin. It is argued that the factor of interest to the physiological effect may not... 

Clinically important, potentially hazardous interactions with alcohol, amiodarone, beta-blockers, cimetidine, donidine, digoxin, diltiazem, disopyramide, ephedrine, epinephrine, ergot alkaloids, guanethidine, halothane, isoprenaline, lidocaine, noradrenaline, NSAIDs, phenylephrine, quinidine, reserpine, verapamil... 

Impaired myocardial conduction has been seen in two patients taking diltiazem after they were anaesthetised with enflurane, and prolonged anaesthesia has been seen with verapamil and eto-midate, but it has been suggested that chronic administration of oral calcium-channel blockers up to the day of surgery is usually beneficial. Intravenous dihydropyridines have been used to control peri-operative hypertension, but the use of intravenous verapamil is not recommended in patients anaesthetised with either halothane or enflurane. 

The authors of a review concluded that intravenous verapamil or diltiazem are not recommended in patients anaesthetised with either halothane or enflurane, especially if the patients have eardiac failure or eonduction disturbanees. ... 

---