Maturation-related changes in tolerance development to hexobarbital after short term treatment with diazepam in the rat.

Male rats at six different ages received diazepam on a 4-day treatment schedule. Cross-tolerance to hexobarbital was tested several times during withdrawal period with an anaesthesia threshold technique. Pattern of cross-tolerance was different at different ages. Thus, age and maturation of the rat is a variable which must be considered in studies of tolerance to diazepam.