Tramadol is a synthetic analogue of codeine that binds to mu opiate receptors and inhibits norepinephrine and serotonin reuptake. It is rapidly and extensively absorbed after oral doses and is metabolized in the liver.
Analgesia begins within one hour and starts to peak in two hours.
In patients with moderate postoperative pain, i.v. Oral tramadol can also be effective after certain types of surgery. Tramadol and meperidine are equally effective in postoperative patient-controlled analgesia. In epidural administration for pain after abdominal surgery, tramadol is more effective than bupivacaine but less effective than morphine. In patients with ureteral calculi, both dipyrone and butylscopolamine are more effective than tramadol.