Comparison of infusions of morphine and lysine acetyl salicylate for the relief of pain after surgery.

The effect of a constant i.v. infusion of lysine acetyl salicylate (LAS) on pain after operation was compared with that of a constant infusion of morphine in 30 patients undergoing unilateral inguinal herniorrhaphy. LAS provided analgesia equivalent to that provided by morphine and was associated with significantly less drowsiness, nausea and vomiting. No patient in either group was noted to suffer from respiratory depression. No untoward side effects were noted during or following the administration of LAS.