Tramadol is a centrally acting
analgesic which possesses
opioid agonist properties and activates monoaminergic spinal inhibition of
pain. It may be administered orally, rectally, intravenously or intramuscularly. In patients with moderate to severe
postoperative pain, intravenous or intramuscular
tramadol has generally proved to be of equivalent potency to
pethidine (
meperidine) and one-fifth as potent as
nalbuphine. Intravenous
tramadol 50 to 150mg was equivalent in
analgesic efficacy to
morphine 5 to 15mg in patients with moderate
pain following surgery; however, when administered epidurally
tramadol was one-thirtieth as potent as
morphine.
Tramadol has demonstrated efficacy in a few studies in the short term treatment of
chronic pain of various origins. Orally administered
tramadol was found to be an effective
analgesic in step 2 of the World Health Organization's guidelines for the treatment of patients with
cancer pain.
Tramadol is well tolerated in short term use with
dizziness,
nausea, sedation, dry mouth and sweating being the principal adverse effects.
Respiratory depression has been observed in only a few patients after
tramadol infusion anaesthesia. When used for
pain relief during childbirth, intravenously administered
tramadol did not cause
respiratory depression in neonates. The tolerance and dependence potential of
tramadol during treatment for up to 6 months appears to be low, although the possibility of dependence with long term use cannot be entirely excluded. Thus, evidence to date of the
analgesic effectiveness of
tramadol combined with a low respiratory depressant effect and low dependence potential in short term use, suggests that the
drug may become a useful alternative to the
opioid analgesics currently available for the treatment of patients with moderately severe acute or
chronic pain.