Selective Serotonin Reuptake Inhibitors: A Class Review

OVERVIEW Many changes and therapeutic advances have occurred in the treatment of depression in recent years, most notably the availability of the selective serotonin reuptake inhibitor (SSRI) class of agents, followed by the introduction of escitalopram oxalate (LexaproTM, Forest), the first agent in what is known as the “second generation” of SSRIs. However, because of the higher acquisition cost of SSRIs, compared with earlier antidepressants, managed care plans have begun to implement cost-containment strategies for these agents. As a result, P&T committee members are being asked not only to review efficacy and safety data but also to focus on available pharmacoeconomic data for this class of drugs. Therefore, in addition to acquisition costs, issues relating to the onset of action, adverse drug events (ADEs), potential drug–drug interactions, and rates of patient discontinuation of treatment, P&T committees must consider expenses when selecting antidepressants for inclusion in the formulary and when determining the level of reimbursement for individual products. Compared with the first-generation SSRIs, escitalopram, which was developed with the use of isomer technology, is associated with a more rapid onset of action, a more favorable ADE profile, fewer drug interactions, and thus a lower rate of therapy discontinuation. These clinical features result from isolating the S-enantiomer of citalopram hydrobromide (CelexaTM, Forest). The isolation process renders escitalopram more selective for serotonin and thereby eliminates the undesirable effects that exist with the racemic compound, a mixture of “optically active” compounds that is not optically active itself. (Material is optically active if it preferentially absorbs or affects the polarization of light passing through it.) The following topics are emphasized in this review: