Tramadol in acute pain
by
Lehmann KA
Service d'Anesthesie et de Reanimation Chirurgicale,
Universite de Cologne,
Allemagne.
Drugs 1997; 53 Suppl 2:25-33
ABSTRACT
Tramadol has been in clinical use in Germany since the late 1970s and has
proven effective in both experimental and clinical pain without causing serious
cardiovascular or respiratory side effects. Moreover, the negligible abuse
potential of tramadol has meant that it has never been a restricted drug, and it
therefore very quickly became the most popular analgesic of its class in
Germany. Although tramadol has been used in myocardial emergencies, in trauma
and obstetric pain, or to supplement balanced anaesthesia, most studies have
investigated postoperative patients. The focus of this article is to review
clinical experience with tramadol in the treatment of acute postoperative pain.
Tramadol, a synthetic opioid of the aminocyclohexanol group, is a centrally
acting analgesic with weak opioid agonist properties, and effects on
noradrenergic and serotonergic neurotransmission. In addition, these opioid and
nonopioid modes of action appear to act synergistically. Tramadol has been shown
to provide effective analgesia after both intramuscular and intravenous
administration for the treatment of postoperative pain. The drug is available in
formulations suitable for oral, rectal and parenteral administration. Clinically
effective analgesic doses of tramadol were comparable to those of pethidine
(meperidine) and about 10 times higher than those of morphine. While it is not
recommended as a supplement to general anaesthesia because of its insufficient
sedative activity, tramadol has been successful in the treatment of
postoperative pain. A randomised double-blind study reported acceptable
analgesia with postoperative intravenous tramadol 50mg, repeated once if
required after 30 minutes. It produced an effect similar to that of morphine 5mg
or the alpha 2 agonist, clonidine 150 micrograms. In another study, it was shown
that the 50mg dose of tramadol fulfilled the requirements of an analgesic for
the treatment of moderate postoperative pain, whereas for severe pain a higher
dose was recommended. Tramadol is generally well tolerated, the most common
adverse events being nausea and vomiting. In contrast to agents such as morphine
and pethidine, clinically relevant respiratory depression is rarely observed
during tramadol administration at equipotent doses and consequently it can be
recommended for first-line management of postoperative pain instead of morphine.
It is also associated with a low incidence of cardiac depression and
significantly less dizziness and drowsiness than morphine. Finally, the
dependence and abuse potential with tramadol is negligible. Comparative studies
have generally shown that tramadol is more effective than NSAIDs for controlling
post operative pain. Use of a combination of tramadol and NSAIDs allows the
tramadol dose to be reduced and results in a lower incidence of adverse effects.
Patient controlled analgesia (PCA) with tramadol has been frequently used and is
well accepted by patients. Wide individual variations exist with regard to
analgesic requirements and, nowadays, it is generally accepted that adequate
pain management implies systematic individualisation of the therapy, i.e.
titration of the analgesic effect to individual needs. Demand and loading doses
play a decisive role in the success of PCA. Analgesic failures requiring rescue
medication are rare, but it should be stressed that these can always occur with
weak opioids. In conclusion, tramadol can be recommended as a basic analgesic
for the treatment of moderate to severe pain. In the event of analgesic failure
with tramadol, there is no reason not to switch to more potent opioids. Although
no studies are available regarding its use in the management of postoperative
pain after day case surgery, tramadol is frequently administered with good
results in such patients. The most important side effects of tramadol are nausea
and emesis, which can often be prevented by slow injection and administration of
a prophylactic antiemetic such as metoclopramide.
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