Diclofenac and pirprofen modify pituitary and hypothalamic beta-endorphin concentrations.

We provide evidence that both Diclofenac and Pirprofen, two cyclooxygenase inhibitors with a potent analgesic effect both in the experimental animal and in man, induce a significant and long lasting decrease in pituitary beta-endorphin concentrations, together with an increase of the hypothalamic concentrations of the peptide. We suggest that this effect might participate in the potent analgesic effect of the two compounds, that exceeds the one expected by drugs of this class.