When nalorphine is given in large doses, it causes morphine like automatic changes which may be more pronounced. The respiratory changes which may be more pronounced. The respiratory depression is not similar to what is produced by morphine and related narcotics. In man, the degree of respiratory depression is not similar to what is produced by morphine and related narcotics. In man, the degree of respiratory depression produced by morphine increases progressively as the dose is increased, but with Nalorphine the curve of respiratory depressions flattens out, that is why a dose of 75 mg does not produce significantly greater respiratory depression than is seen with 10 to 20 mg. In man deaths have not been reported but in monkeys lethal doses may produce tremors and periodic colonic seizures with simultaneous respiratory arrest and cardiovascular collapse. Nalorphine does not produce physical or psychological dependence and the withdrawal symptoms and not typical of those observed after morphine withdrawal. Antagonists have little or no abuse liability.