Epidural morphine in treatment of pain

Epidural injections of a 2 mg morphine were given to 10 patients with severe acute or chronic pain. All cases had considerable amelioration of pain, which commenced within 2-3 min, reached a peak in 10-15 min, and was effective for 6-24 h. It is suggested that the morphine reached the subarachnoid space and produced its effect by direct action on the specific opiate receptors in the substantia gelatinosa of the posterior-horn cells of the spinal cord.