STUDIES ON ANTIDOTES AGAINST ORGANOPHOSPHORUS POISONING——A PRELIMINARY REPORT ON THE PHARMACOLOGY OF PYRIDINE-2-ALDOXINE METHIODIDE(2-PAM)

The value of pyridine-2-aldoxine methiodide (2-PAM) as an antidote for organo- phosphorus poisoning has been well established. Here we intend to get an insight into some of its pharmacological actions other than its cholinesterase reactivating activity. In urethane anaesthetized cats, it caused excitation of respiration, elevation of blood pres- sure, contraction of nictitating membrane, and inhibition of intestinal movement. These effects were gradually weakened on repeated administration of the drug at short intervals and were much reduced or even abolished by bilateral adrenalectomy, pretreatment with tolazoline, reserpine, or large doses of atropine but not with C₆. Besides, it stimulated the toad-heart and excited isolated guinea-pig ileum. The mechanism of its action was briefly discussed.