<p>Labetalol may enhance the hypotensive effects of halothane. Care should be taken if labetalol is used concomitantly with either Class I antiarrhythmic agents or calcium antagonists of the verapamil type. The hypotensive effect of Labetalol may be reduced when used in combination with prostaglandin synthetase inhibitors (NSAIDs). Dosage adjustments may therefore be necessary. Concomitant use of tricyclic antidepressants may increase the incidence of tremor. Cimetidine may increase the bioavailability of Labetalol and care is required in oral dosing of the latter.</p>