Absorption characteristics of lignocaine following intravesical instillation

The systemic absorption of topical lignocaine applied intravesically was studied in 11 patients with indwelling catheters. Group A patients (n = 9) had lignocaine 400 mg (as 40 ml of a 1% solution) instilled into the bladder for 1 hour whilst in Group B patients (n = 2) the application was for 2 hours. The mean maximum lignocaine concentration measured in Group A patients was 121 ng ml-1 with a time to maximum concentration of 60-90 minutes. The two patients in Group B had corresponding values of 410 and 1580 ng ml-1 respectively at 120 minutes. Transitional cell epithelium, like intact skin, constitutes a significant barrier to the uptake of topically applied lignocaine which, from the bladder, is both slow and limited. Intravesical application is safe (maximum levels in Group A patients being x 30 less than the minimal toxic level of lignocaine) but its clinical efficacy remains to be determined.