Antidepressants augmentation with another drug

An adequate trial of antidepressant medication is defined as treatment with therapeutic doses of a drug for a total of 4 weeks. After 4 weeks of antidepressant treatment, patients can be divided into three groups those who have achieved a full response, those who have achieved a partial response, and those who have not responded. In the case of patients who achieve full remission, treatment should continue for a minimum of 4-6 months, or longer if the patient has a history of recurrent depression (see Maintenance Treatment of Major Depression later in this chapter). If a partial response has been achieved by 4 weeks, a full response may be evident within an additional 2 weeks without further intervention. If the symptoms do not respond at all, the dose should be increased, a different antidepressant should be used, or the therapy should be augmented with another medication (see Treatment-Resistant Depression later in this chapter). 

Augmentation, i.e. the addition of another drug, is used to enhance the effects of standard antidepressants when two or more have successively failed to alleviate depressive symptoms despite treatment at an adequate dose for an adequate time. The therapeutic efficacy of new agents, e.g. venlafaxine, has provided clinicians with further options which now tend to be employed before augmentation but the following may be used. 

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