PHYSICAL-DEPENDENCE TO BARBITAL COMPARED TO PENTOBARBITAL .2. TOLERANCE CHARACTERISTICS

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 204  (3) , 507-513
Abstract
The tolerance characteristics of barbital compared to pentobarbital, the standard drug, during chronically equivalent treatment were studied. Barbiturate tolerance was assessed as the increase in dose from the beginning to the end of treatment required to achieve equieffective peak effect. Dispositional tolerance was assessed as a reduction in the elimination half-life of barbiturate from blood. Functional tolerance was assessed as the increase in blood concentration of barbiturate at the time of peak effect. Greater tolerance was developed to pentobarbital than to barbital. For pentobarbital, tolerance was both dispositional and functional; the dispositional tolerance developed rapidly and was almost complete at 1 wk. For barbital, tolerance was exclusively functional. Functional tolerance to barbital and pentobarbital developed at the same slow rate for chronically equivalent treatment, Functional tolerance development may be independent of the particular barbiturate reflecting the adaptability of the CNS to chronic depression.