Monograph: |
Nefopam Hydrochloride
Adverse Effects and Treatment
Side-effects occurring with nefopam include nau-
Sea, vomiting, sweating, drowsiness, insomnia, uri-
nary retention, lightheadedness, nervousness,
mental confusion, blurred vision, headache, dry
mouth, and tachycardia. Euphoria, hallucinations.
and convulsions have occasionally been reported, as
has temporary pink discoloration of the urine.
Symptoms of overdosage have included CNS and
cardiovascular toxicity.
Effects on the urinary tract. In January 1989. the UK
Committee on Safety of Medicines' reported that it had re-
ceived 53 reports in which nefopam was associated with the
development of urinary retention or symptoms of hesitancy.
poor stream, or dribbling. In one case there was a history of
prostatism.
Overdoiage. A report of a fatal overdose of nefopam. and
details of 9 patients who recovered with routine supportive
treatment.
Precautions
Nefopam is contra-indicated in patients with a histo-
ry of convulsive disorders. It should be used with
caution in the elderly and in patients with glaucoma.
urinary retention, or impaired hepatic or renal func-
tion.
Interactions
It has been recommended that nefopam should not
be given to patients receiving MAOls and should be
used cautiously in those receiving tricyclic antide-
pressants. The adverse effects of nefopam may be
additive to those of other drugs with antimuscarinic
or sympathomimetic activity.
Pharmacokinetics
Nefopam is absorbed from the gastro-intestinal
tract. Peak plasma concentrations occur I to 3 hours
after administration by mouth and about 1.5 hours
after intramuscular injection. About 73% is bound
to plasma proteins. Nefopam is distributed into
breast milk. It has an elimination half-life of about 4
hours. It is extensively metabolised and excreted
mainly in urine, in which less than 5% of a dose is
excreted unchanged. About 8% of a dose is excreted
via the faeces.
Distribution into breast milk. Studies in 5 healthy nurs-
ing mothers given nefopam for post-episiotomy pain indicat-
ed that nefopam was present in human milk in an equivalent
concentration to that in plasma. It was calculated that on a
body-weight basis a breast-fed infant would receive less than
3% of the maternal dose.
Uses and Administration
Nefopam hydrochloride is a non-opioid analgesic
considered to act centrally, although its mechanism
of action is unclear. It also has some antimuscarinic
and sympathomimetic actions. Nefopam hydrochlo-
ride is used for the relief of moderate acute and
chronic pain. The usual dose range by mouth is 30
to 90 mg three times daily; the suggested initial dos-
es are 60 mg three times daily but 30 mg three times
daily in elderly patients. Nefopam hydrochloride
may also be given in doses of 20 mg by intramuscular injection,
repeated every 6 hours if necessary; it is recommended that the
patient should always be lying down when receiving the injection
and should remain so for 15 to 20 minutes afterwards; it has also
been given by slow intravenous injection.
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