Diazepam half life could be observed during rapid absorption from the gastrointestinal tract after oral administration, reaching peak concentrations in about 1 hour in adults and within 15 to 30 minutes in children.
There is rapid uptake of diazepam into the brain, followed by redistribution to inactive tissue sites. The Vd of diazepam is large, reflecting extensive tissue uptake specially in women due to a greater body fat content.
Diazepam rapidly crosses the placenta, and so does diazepam half life achieving foetal concentrations equal to and sometimes greater than those present in the maternal circulation.
Diazepam is an anticonvulsant, not an antiepiicptic. Do not inject diazepam if convulsions have stopped.
IV Lorazepam 4-8 mg (2 mg/min) is almost as rapid acting as but much longer acting (12-24 hours) than diazepam IV (3-4 hours). Midazolam has 3-4 hours of action.
Due to a longer diazepam half life compared to other medicine of its group it is used in cases where the longer action of benzodiazepine in indicated.
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