Tramadol
28. What is the purported advantage of tramadol (Ultram) over other opioid analgesics and NSAID?
Tramadol, a centrally acting analgesic with weak opioid agonist properties, activates monoaminergic spinal inhibition of pain. The O-demethylated metabolite of tramadol has a higher affinity for opioid receptors than the parent drug; however, after a single oral dose, the binding of tramadol to the µ-opioid receptor is overshadowed by its nonopioid analgesic effects.114 The tolerance and dependence potential of tramadol during treatment for up to 6 months appear to be low; however, the possibility of dependence with long-term use cannot be excluded entirely.115 Tramadol is indicated for the treatment of moderate to severe pain, but analgesia is not superior to other opiate analgesics.116,117 It, however, has a lower incidence of respiratory depression or significant GI dysmotility than most traditional opioids.
Tramadol is well tolerated in short-term use. Doses range from 50 to 100 mg orally every 4 to 6 hours and should not exceed 400 mg/day.118 As with other opiate agonists, the principal adverse effects are sedation, dizziness, nausea, vomiting, dry mouth, constipation, and sweating; however, the potential for respiratory depression is low. Seizures have occurred during therapy with recommended doses. Seizure risk increases with doses >500 mg/day and in patients taking concurrent selective serotonin-reuptake inhibitors (SSRI), tricyclic antidepressants (TCA), and other opiate agonists.119,120 Tramadol should be used cautiously in patients taking drugs known to lower the seizure threshold, such as monoamine-oxidase inhibitors or antipsychotic agents. In addition, patients with epilepsy, head trauma, metabolic disorders, alcohol or drug withdrawal, or CNS infections may be at increased risk for seizures with tramadol therapy.118 Tramadol also has SSRI-like properties that can initially overshadow the opiate effect in some patients. Therefore, instead of sedation, patients may experience excitation. For more on drug interactions with tramadol, see Question 69.
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