Methylxanthines cause a decrease of prolactin plasma levels in healthy non‐pregnant women

The effect of different doses of caffeine and theophylline (2, 4 and 8 mg/kg p.o.) on prolactin plasma levels in volunteer non‐pregnant women has been analysed. The study of basal serum prolactin levels demonstrated great interindividual variation with a good reproducibility of the basal prolactin pattern for all subjects. We found a slight but significant decrease in prolactin levels following xanthine administration. The possible dopaminergic agonism of xanthines and the consequent social implications are discussed. Copyright © 1989 John Wiley & Sons, Ltd.