Source: Pharmaceutical Benefits Scheme (AU) Revision Year: 2019 Publisher: Alphapharm Pty Ltd, Level 1, 30 The Bond, 30-34 Hickson Road, Millers Point NSW 2000, www.mylan.com.au
Flunitrazepam is a member of the benzodiazepine group of drugs and is closely related to nitrazepam, flurazepam and clonazepam. It has marked sedative and hypnotic properties with a rapid onset of action. In experimental animals, flunitrazepam has also been shown to possess anticonvulsant, anxiolytic and muscle-relaxant properties.
Given orally, flunitrazepam induces sleep and maintains and deepens it. The intensity of the effect depends both on the dose taken and on the aetiology of the sleep disturbance.
No data available.
Following oral administration, flunitrazepam is almost completely absorbed. Peak blood levels of flunitrazepam occur usually 45 minutes after ingestion. 10% to 15% is metabolised by a liver first-pass effect, resulting in bioavailability of 64-77%.
Chronic oral administration of flunitrazepam leads to slight accumulation of flunitrazepam in the plasma. The accumulation ratio of flunitrazepam given once daily is approximately 2. Steady-state concentrations are reached after 3 to 5 days for flunitrazepam, and after 5 to 7 days for N-desmethyl-flunitrazepam. Subsequently, the minimum and maximum concentrations remain constant, even on prolonged administration.
The distribution of flunitrazepam is rapid and extensive. About 77 to 80% of absorbed flunitrazepam is bound to plasma proteins over a concentration range of 1 to 20 ng/mL.
Flunitrazepam is extensively metabolised, and both the major metabolites, 7-amino-flunitrazepam and N-desmethyl-flunitrazepam, are pharmacologically active in humans but less so than the parent drug. Both metabolites are eliminated as glucuronides, largely through the kidneys.
Following intravenous administration, the elimination half-life for flunitrazepam is 20 to 30 hours, 10 to 16 hours for 7-amino-flunitrazepam and 23 to 33 hours for N-desmethyl-flunitrazepam. However, due to extensive distribution of the drug and metabolites out of the plasma into body tissues, the long elimination half-lives are not reflected in the duration of clinical effect.
Studies have not been performed to assess the mutagenic potential of flunitrazepam.
Studies have not been performed to assess the carcinogenic potential of flunitrazepam.
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