Effects of chronic treatment with ethanol on the development of cross-tolerance to other alcohols and pentobarbital.

The development of cross-tolerance to various alcohols and pentobarbital was examined in ethanol (EtOH)-treated mice. Chronic EtOH treatment (dosage rising in steps from 3.5-4.5 g/kg i.p. daily during a 23-day period) produced tolerance to its hypnotic effect. Such tolerance was seen as a reduction in the duration of loss of righting reflex (LRR), as well as higher blood EtOH levels at the offset of LRR, in EtOH-treated mice as compared to saline-treated controls. Cross-tolerance was shown by shifts in dose-response curves for the LRR induced by n-propanol and t-butanol. Such treatment, however, did not confer functional cross-tolerance to n-butanol and pentobarbital. Because n-butanol and pentobarbital are more lipid-soluble, whereas EtOH, n-propanol and t-butanol have low degrees of lipid solubility, the development of cross-tolerance among these sedative-hypnotic drugs might be related to their relative degrees of lipid solubility.