Analgesic and urodynamic effects of epidural meperidine and pentazocine--a comparative study

Meperidine 1 mg kg-1 and pentazocine 0.3 mg kg-1 were administered epidurally to investigate their effect on vesical function in twenty American Society of Anesthesiologists Classification I (ASA-1) adult males. Cystometry was performed before and 45 minutes following epidural administration of meperidine and pentazocine. There was no significant change in maximum cystometric capacity, detrusor pressure at which detrusor reflex occurred and in vesical compliance following epidural administration of meperidine in ten patients and also in ten patients who received epidural pentazocine. The mean onset of analgesia after epidural administration of meperidine was 8 minutes which lasted for more than 360 minutes whereas mean onset of analgesia after epidural administration of pentazocine was 4 minutes which lasted for more than 360 minutes. There was no significant change in heart rate, blood pressure and respiratory rate after epidural administration of either meperidine or pentazocine. None of the subjects in either of the groups experienced any difficulty in passing urine, frequency or urgency of micturition. Side-effects like nausea, vomiting, pruritus and respiratory depression were not observed. It is concluded that epidural administration of meperidine 1 mg kg-1 or pentazocine 0.3 mg kg-1 produces significant analgesia of faster onset without altering vesical function as documented, both subjectively by voiding symptoms and objectively by cystometry.