Comparative effects of placebo and plain and slow-release tablets of xanthinol nicotinate on exercise tolerance in normal human subjects.

The effects of placebo and plain and slow-release xanthinol nicotinate on exercise tolerance were studied in 6 normal human subjects. Placebo administration had no significant effect on exercise tolerance. Administration of plain and slow-release xanthinol nicotinate significantly increased exercise tolerance at 1 hour and 1--9 hours respectively from ingestion of the drug. The intensity and duration of action correlated well with the blood levels of nicotinic acid reported earlier. Four subjects experienced moderate to severe side-effects with plain xanthinol nicotinate. Only 1 subject experienced mild side-effects with slow-release xanthinol nicotinate. Slow-release tablets of xanthinol nicotinate may prove useful in the treatment of angina pectoris.