Conditions: Anxiety Disorder
Keywords: generalized anxiety disorder pharmacotherapy treatment refractory double-blind
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 50
Healthy volunteers: no

Brief summary:
The purpose of this study is to examine the safety and efficacy of quetiapine for generalized anxiety disorder patients who remain symptomatic despite treatment with paroxetine CR.

Detailed description:
Generalized anxiety disorder (GAD) is a relatively common condition affecting 5% of the population, with a typically chronic course and associated with significant psychosocial impairment and decreased quality of life (Schweizer, 1995). Although a number of therapeutic agents demonstrate some efficacy in the treatment of generalized anxiety disorder, only a minority of anxious patients experience remission with initial treatment.

The purpose of this study is to examine the efficacy of one strategy, the addition of quetiapine, for the treatment of patients with GAD who remain refractory despite an adequate treatment trial with a selective serotonin reuptake inhibitor (SSRI). This is an investigator-initiated augmentation study of an already approved drug for a different indication. Quetiapine is a novel antipsychotic agent with potent effects at the serotonergic, as well as dopaminergic receptor, and a more favorable side effect profile than standard neuroleptics, including a low potential to cause extrapyramidal symptoms.

This is a two phase, 18-week research study in which participants who remain symptomatic at the end of one phase (10 weeks) enter into the next phase. In phase I, all participants receive paroxetine CR (Paxil CR) for 10 weeks. Participants who continue to have anxiety symptoms will enter the 8-week Phase II, in which they continue taking Paxil CR and they will also be randomly assigned (by chance, like a flip of a coin) to receive quetiapine (Seroquel) or placebo (contains no active medication).

Arms:
arm 1: Eleven individuals were randomized to plaecbo augmentation of continued paroxetine CR at the week 10 dose level. In the first phase of the study, individuals started at 12.5 mg/day of paroxetine and flexibly titrated up to a maximum of 62.5 mg/day by week 10. Individuals who did not achieve remission and were randomized into the placebo group received placebo augmentation of continued paroxetine CR at the week 10 dose level. arm 2: Eleven individuals were randomized to quetiapine augmentation of continued paroxetine CR at the week 10 dose level. In the first phase of the study, individuals started at 12.5 mg/day of paroxetine and flexibly tirated up to a maximum of 62.5 mg/day by week 10. Individuals who did not receive remission and were randomized to receive quetiapine started at 25 mg at bedtime for the first week, then flexibly dosed based on response and tolerability to a maximum of 200 mg BID by week 16.

Interventions: intervention 1: Continued Paroxetine CR intervention 2: Quetiapine intervention 3: Placebo
Intervention descriptions: intervention 1: None intervention 2: None intervention 3: None

Protocol document: