In a preliminary prospective study, eleven outpatients undergoing fibreoptic bronchoscopy using a titrated dose of topical lignocaine anaesthesia were studied. Patient comfort, lignocaine dosage and resultant plasma concentrations were measured at four stages during the procedure. Large total doses, mean 512 (SD 55) mg lignocaine, were frequent and systemic absorption was unpredictable with two patients having plasma concentrations in the toxic range (>5JAg/ml). Peak plasma concentrations, mean 2.3 (SD 1.4) JAg/ml, occurred 30 to 40 minutes after commencement of topical application and coincided with completion of the procedure. No correlation was found between the individual dose of lignocaine administered and either the resultant plasma concentration or patient comfort scores. In an effort to minimise potential lignocaine toxicity, a fixed total dose technique (lignocaine 370 mg) was studied in a further twenty-one patients. No change in patient comfort scores and no toxic plasma concentrations were observed. Mean completion plasma concentration was 2.0 (SD 1.0) JAg/ml. No clinical toxicity was observed in either group. Fibreoptic bronchoscopy in both groups using topical lignocaine anaesthesia without premedication or intravenous supplementation was well tolerated.

Summary Although calcium antagonists such verapamil are used primarily in cardiovascular disease, they appear to relax smooth muscle generally. Therefore, the possibility that verapamil might have bronchodilator properties was explored using the guinea‐pig tracheal ring technique. Verapamil was found to produce considerable tracheal smooth muscle relaxation from a threshold concentration of 2 × 10−7M and with maximum effect at 10−3M. The responses to the contractile agonists histamine and prostaglandin F2α and especially methacholine and serotonin were substantially reduced by prior administration of verapamil. Verapamil 2 × 10−4M was equally effective as isoprenaline 10−8M in producing 50% maximum direct relaxation but was more effective than isoprenaline as an antagonist of the contractile agonists, methacholine, histamine and serotonin, but not prostaglandin F2α. Verapamil abolished the contractile responses to barium chloride. It is concluded that, although verapamil was not very potent as a direct bronchodilator, it could potentially be of prophylactic benefit in asthma because of its efficacy as an antagonist of common contractile agonists.