The marked tendency toward habit formation which is so conspicuous and deplorable in connection with the use of morphin is associated with an enormously increased tolerance for the drug. How this is acquired and what is signified by the ability to take doses of a substance which ordinarily would prove highly toxic or even fatal to the nonhabituated individual have been the subject of much discussion. To say that the tissues become adapted to the presence of morphin merely clothes in words our ignorance of the real nature of the tolerance which develops.
In extreme tolerance, the daily quantity used may reach ten times the ordinary toxic dose. A favorite explanation holds that the oxidative powers of the organism are increased with the prolonged use of the drug. The evidence for this view is sought in Faust's well known experiments showing that dogs which have become accustomed to morphin reach
ACQUIRED TOLERANCE OF MORPHIN. JAMA. 1916;LXVI(9):657. doi:10.1001/jama.1916.02580350045024