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

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

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.

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.

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.