Essays in Toxicology, Volume 4 covers three essays on habituating drugs, on the kinetics of the active-site-directed irreversible inhibition, and the hidden effects of trace elements. The first essay examines certain dependence-producing drugs; the mechanism of tolerance to barbiturates by changes in drugs metabolism; the distribution of barbiturates to the central nervous system; and the urinary excretion of barbiturates. The formation of morphine from heroin and codeine, and the dealkylation to form normorphine and to reduce naloxone to another compound is also considered in the first essay. The second essay discusses the time-course of enzyme inhibition at single-inhibitor concentrations and the effect of various inhibitor concentrations on the rate constants governing inhibition. The third essay is about the recondite toxicity of trace elements, taking into consideration the effects of these trace elements on body weight, survival, and longevity, clues to mechanisms of toxicity, and the production of chronic diseases simulating human disorders. Toxicologists, oncologists, biochemists, and pharmacologists will find the book invaluable.