Continuing a therapeutic drug after it has reached efficacy to prevent an early relapse or a later recurrence of illness. For instance, in clinical trials of antidepressants, there are three phases of treatment: the acute phase (which usually lasts 6–8 weeks), the continuation phase (2–6 months), and the maintenance phase (more than 6 months).
Reducing the dosage of a therapeutic drug after it has reached its maximum efficacy and sustaining it at the minimum level to prevent a relapse.