Monograph: |
Racemethionine
The properties are same as of l-methionine , so see below at l-methionine record for the
details.
DL-Methionine
NOTE. The name methionine is often applied to DL-methionine.
An almost white crystalline powder or small flakes. Sparingly
soluble in water: very slightly soluble in alcohol; practically
insoluble in ether: dissolves in dilute acids and in dilute solu-
tions of alkali hydroxides. A 2% solution in water has a pH of
5.4 to 6.1. Protect from light.
Adverse Effects and Precautions
Methionine may cause nausea, vomiting, drowsi-
ness, and irritability. Methionine should not be used
in patients with acidosis. Methionine may aggravate
hepatic encephalopathy in patients with established
liver damage: it should be used with caution in pa-
tients with severe liver disease.
Interactions
Orally administered methionine may be adsorbed by
activated charcoal leading to a diminished effect of
methionine if they are given concurrently.
For the antagonism of the antiparkinsonian effect of levodopa
by methionine, see levodopa record.
Uses and Administration
L-Methionine is an amino acid which is an essential
constituent of the diet and is incorporated into ami-
no-acid solutions for parenteral nutrition .
Methionine also enhances the synthesis of glutath-
ione and is used as an alternative to acetylcysteine in
the treatment of paracetamol poisoning to prevent
hepatic damage. The literature relating to
the use of methionine in paracetamol poisoning is,
in general, imprecise as to the form of methionine
used. In the UK the usual dose of DL-methionine is
2.5 g by mouth every 4 hours for 4 doses starting
less than 10 to 12 hours after ingestion of the para-
cetamol. Methionine has also been given intrave-
nously. Preparations containing both methionine
and paracetamol have been formulated for use in sit-
uations where overdosage may occur. However, the
issue of whether methionine should be routinely
added to paracetamol preparations is contentious for
medical and ethical reasons.
Methionine has also been given by mouth to lower
urinary pH and as an adjunct in the treatment of liver
disorders.
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