ABSTRACT
We have already discussed in detail how the size of the dose administered, the pharmaceutical formulation, and the route and frequency of administration modify the effects produced by a drug. Although these four factors are the most important variables attributable to the conditions of administration, several others may also profoundly affect the response to a drug. All these other factors have one condition in common: the effects they produce are dependent on the previous administration of the same or a different drug. We shall discuss first the modified drug effects that may be seen following the repeated administration of a single agent and then how the sequential or concurrent administration of two different drugs may enhance or diminish the effects of either or both.
