Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
50 mg capsules
50 mg/mL in 2 mL ampoules
AMH Section 3.2
Tramadol is a synthetic opioid. It is thought to act by binding with µ opioid receptors (see 'Opioids - mechanism of action' Aust Prescr 1996;19:63-5). It also weakly inhibits reuptake of noradrenaline and serotonin.
The drug reaches its peak serum concentration 1-3 hours after an oral dose and 45 minutes after an intramuscular injection. The analgesic effect begins within one hour of an oral dose. Part of this effect is due to an active metabolite. The production of this metabolite depends on cytochrome P450 2D6 so there is a possibility of interaction with drugs such as fluoxetine, paroxetine and amitriptyline. Most of the metabolites are excreted in the urine. The half-life is 5-7 hours and is extended by reduced renal or hepatic function.
Tramadol has been available overseas for a few years and has been studied in a variety of clinical situations. For postoperative patients, intravenous tramadol is probably as effective as morphine for moderate pain. Morphine is better at controlling severe pain. Tramadol is not recommended for labour pain.
Oral tramadol (100 mg) is more effective than placebo for the relief of pain after tooth extraction. It may also be more effective than 60 mg codeine, but not as effective as a combination of aspirin and codeine. Studies of patients with chronic pain suggest that tramadol can be considered to be as effective as combinations of paracetamol and codeine or aspirin and codeine. Controlled-release morphine may be more effective in cancer pain.
The adverse effects of tramadol are similar to those of other opioids. They include nausea, dizziness, dry mouth and constipation. The adverse effects associated with intravenous injection can be reduced by giving the injection slowly. Extra caution is required if tramadol is given to patients at risk of seizures or respiratory depression. It is contraindicated in patients who have taken monoamine oxidase inhibitors within the previous two weeks. As tramadol is an opioid, there is potential for dependence and abuse.
Tramadol is effective for moderate pain, but it is not more effective than commonly used drugs. As overseas experience suggests that tramadol will cost more than its competitors, there are no compelling reasons to prescribe it.