Journal of the Autonomic Nervous System vol:24 issue:1-2 pages:147-55
An investigation was undertaken into possible vagolytic effects of chloroquine. A single oral dose of chloroquine was given to healthy human volunteers and its influence on vagally mediated heart rate changes studied. Chloroquine at a dose of 600 mg significantly increased lying and standing heart rates, reduced the beat-to-beat variation of the R-R interval and reduced the heart rate changes induced by deep breathing, by the Valsalva manoeuvre and by standing. Chloroquine at a dose of 225 mg did not produce significant changes of these parameters. The effects of 600 mg chloroquine resemble those obtained with atropine and are consistent with an antimuscarinic receptor effect.