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17 Central nervous systemDiazepam
*TemazepamConjugated with
glucuronic acidRenal excretionKidneyOxazepamDesmethyldiazepamFigure 17.2.Metabolism of diazepam.∗Less than 5% of temazepam is metabolized to
oxazepam.Itmay also be used in status epilepticus (50–100μg.kg−^1 i.v., s.l. or p.r. from 1 to 12
years, maximum dose 4 mg; >12 years, 4 mg).
Itis well absorbed following oral or intramuscular administration, highly plasma
protein bound (approximately 95%) and conjugated with glucuronic acid producing
inactive metabolites, which are excreted in the urine (Figure17.2).Temazepam
Temazepam is used as a nighttime sedative and as an anxiolytic premedicant. It
has no unique features within the BDZ family. It is well absorbed in the gut, is 75%
protein bound and has a volume of distribution of 0.8 l.kg−^1 .Eighty percent is excreted
unchanged in the urine while glucuronidation occurs in the liver. Only a very small
amount is demethylated to oxazepam. It has a half-life of about 8 hours and may
result in some hangover effects.Flumazenil
Flumazenil is an imidazobenzodiazepine.Uses
Flumazenil is used to reverse the effects of BDZs, that is, excessive sedation following
minor procedures or in the treatment of BDZ overdose. However, its use is cautioned
in mixed drug overdose as it may precipitate fits. It is given by intravenous injection
in 100μg increments and acts within 2 minutes. Its relatively short half-life (about
1 hour) compared with many BDZs means that further doses or an infusion may be
needed.