Urethral anaesthesia with topical bupivacaine. A role for a longer-acting agent.

Objective: To assess the efficacy and toxicity of bupivacaine as a topical urethral anaesthetic.

Patients And Methods: This prospective two-part study comprised a pilot study of 10 men (mean age 73 years, range 39-86), to determine the toxicology, pharmocokinetics and suitable preparation of bupivacaine gel, and a study of 40 men (mean age 76 years, range 59-92) to compare the efficacy of bupivacaine with lignocaine gel. All patients were undergoing treatment for benign prostatic hyperplasia by transurethral radiofrequency heating using the Direx Thermex II system.

Results: There were no major adverse events. Bupivacaine provided good topical anaesthesia with a mean duration of 141 min, compared with 29 min for lignocaine. Serum samples taken from patients showed that the drug was absorbed slowly, and with a dose of 50 mg there was a wide margin between serum drug concentrations and toxic levels.

Conclusion: Bupivacaine is safe and effective as a topical anaesthetic agent in the urethra in circumstances where prolonged duration of action is desirable. For lower urinary tract procedures 20-22 mL of anaesthetic gel is required, giving 2-3 h of analgesia/anaesthesia with no significant toxicity or adverse effect. The application of longer-acting anaesthetic agents need not be only during surgical intervention, but might usefully be extended post-operatively to provide early management of pain.