1. A contingent dosing device for controlling the dispensing of a drug to a patient, comprising: a time counter capable of recording one or more starting times and of measuring at least one elapsed time period from the one or more starting times; means for recording an initial dispensing regimen, said regimen including information concerning the times for taking doses in a specified sequence and information regarding acceptable deviations therefrom; means for relating the start of said dispensing regimen to a time recorded or measured by the time counter; means for determining when the patient requests to take a dose of the drug; means for calculating the actual deviation of the request from the recorded dosing time of said regimen; means for comparing the actual deviation with the acceptable deviation set forth in the regimen and deriving the time difference therebetween; and means for informing the patient as to the acceptability of said time difference, whereby if said actual deviation is less than or equal to said acceptable deviation, a dose is dispensed and whereby if said actual deviation is greater than or equal to said acceptable deviation, a dose is refused.