Chloral hydrate

Chloral hydrate leads to a decrease in sleep latency and in the number of awakenings. A near natural sleep is induced and the REM/Non-REM ratio is not altered.

Chloral hydrate and its metabolite trichloroethanol act as central nervous system depressants. Chloral hydrate is rapidly absorbed from the stomach, and starts to act within 30 minutes. It is widely distributed throughout the body, and is metabolised to trichloroethanol, also an active hypnotic, and trichloroacetic acid in the erythrocytes, liver and other tissues. It is excreted partly in the urine as trichloroethanol and its glucuronide, urochloralic acid, and as trichloroacetic acid. Significant amounts are also excreted in bile. Trichloroethanol has a plasma half life of the order of 8 hours. Trichloroacetic acid has a half-life of several days. In infants the half lives are longer. The value for trichloroethanol is 35 hours whilst for trichloroacetic acid the half life exceeds 6 days, with significant plasma concentrations present at 14 days.

Chloral hydrate induces liver tumours in male mice, with no tumourigenic effects in rats. The mechanism of tumour induction is not known, but in the absence of clear evidence of mutagenic and clastogenic potential it is unlikely to be relevant in man.