Effect of hyoscine butylbromide and atropine on heart rate during nocturnal sleep.

This is a single blind crossover study designed to test the effects of hyoscine butylbromide (HBB), an anticholinergic which does not cross the blood brain barrier (BBB), on the temporal changes in heart rate during nocturnal sleep. The effects were compared with atropine sulphate which is known to cross the BBB. Ten healthy male volunteers slept in the JIPMER sleep disorders laboratory for three nights and received either saline, atropine sulphate (0.4 mg, i.v.) or HBB (10 mg, i.v.) just prior to sleep onset. All night polysomnography recording was done to monitor heart rate during the specific stages of sleep. The normal physiological fall in heart rate is blunted by both drugs during slow wave sleep whereas only HBB prevented the fall in rapid eye movement sleep. Therefore, HBB may be a better choice as pre-anaesthetic medication for patients with cardiac abnormalities since it does not alter heart rate during both slow wave sleep and rapid eye movement sleep.