Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2020 Publisher: Zentiva Pharma UK Limited, 12 New Fetter Lane, London, EC4A 1JP, United Kingdom
Benzodiazepines have a widespread action as a result of their enhancing the release of gamma-aminobutyric acid (GABA). They are effective as anti-convulsants, muscle relaxants, anti-anxiety agents, pre-medications and sedative hypnotics.
The pharmacokinetics of oral Loprazolam given in a single dose or in repeated doses on 7 consecutive nights were studied in a balanced cross-over trial in six healthy male subjects aged 22-37 years. The subjects were allocated randomly to the treatment phases which were separated by 2-week drug-free intervals. Loprazolam was administered as 1mg tablets.
On the night of administration of the single dose and the seventh repeated dose, venous blood samples were taken before and at intervals after treatment. Serum Loprazolam concentrations were measured using both a radioimmunoassay (RIA) and the more specific high pressure liquid chromatography and gas chromatography (HPLC/GC) technique. Maximum serum levels (Cmax) and the time taken to achieve them (Tmax) were measured, and the half-life (t1/2) was calculated. The area under the serum concentration-time curve (AUC) was determined using the trapezoidal rule. The ratios of AUC and Cmax after repeated doses to AUC and Cmax after single doses were used to assess possible accumulation of Loprazolam.
| MEAN (SD) | ||
|---|---|---|
| SINGLE DOSES | RIA data | HPLC/GC data |
| Cmax (mcg/litre) | 4.0 (1.2) | 4.1 (2.2) |
| tmax (hours) | 4.0 (2.1) | 5.0 (3.6) |
| t1/2 (hours) | 11.7 (4.7) | 8.0 (3.4)* |
| AUC (mcg/litre hour) | 60.0 (20.9) | 35.5 (22.2) |
| REPEATED DOSES | RIA data | HPLC/GC data |
| Cmax (mcg/litre) | 5.1 (1.2) | 4.6 (2.1) |
| tmax (hours) | 5.3 (3.7) | 5.5 (2.7) |
| t1/2 (hours) | 12.8 (4.9) | 3.5 (0.2)** |
| AUC (mcg/litre hour) | 75.6 (21.1) | 50.0 (26.9) |
n=6 subjects, except for *n=5, **n=3.
No additional data of relevance to the prescriber.
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