Crossover Study Comparing Alprazolam and Quetiapine for Generalized Anxiety Disorder
I cannot identify a specific crossover trial comparing alprazolam (Xanax) and quetiapine conducted at the location you mentioned, as no such study appears in the provided evidence base.
What the Evidence Actually Shows
For generalized anxiety disorder, SSRIs and SNRIs are the recommended first-line pharmacotherapy, not alprazolam or quetiapine 1. Both alprazolam and quetiapine lack guideline support for GAD treatment.
Alprazolam (Xanax) Profile
Efficacy:
- Alprazolam demonstrates effectiveness for anxiety symptoms, with 75% of patients showing good recovery in clinical trials 2
- Recent network meta-analysis confirms efficacy superior to placebo for anxiety disorders 3
- All benzodiazepines show similar efficacy for GAD with no significant differences between individual agents 4
Adverse Events (from FDA label):
- Common (>20%): Drowsiness (41%), light-headedness (21%) 5
- Moderate frequency (5-20%): Dry mouth (15%), hypotension (5%) 5
- Serious concerns: Dependence, withdrawal seizures, abuse potential, respiratory depression 5
- Discontinuation symptoms: Insomnia (29.5%), anxiety rebound (19.2%), cognitive impairment (10.3%) 5
Quetiapine Profile
Efficacy:
- Quetiapine XR 50-150 mg/day shows efficacy in GAD with symptom improvement as early as day 4 6
- Mean HAM-A reduction significantly greater than placebo (effect size 0.12-0.20) 7
- Response rates of 50% improvement superior to placebo at 150 mg/day dose 8
Adverse Events (from FDA label):
- Very common (>30%): Somnolence (53%), increased appetite (33%) 9
- Common (10-30%): Dizziness (18%), fatigue (11%), weight gain (27%), constipation (26%) 9
- Metabolic concerns: Weight gain, increased appetite requiring monitoring 9
- Discontinuation rates: Higher than placebo, particularly at doses above 150 mg/day 8
Critical Comparison
Alprazolam advantages:
- Rapid onset of action
- Lower discontinuation rates compared to quetiapine 4
- Fewer metabolic side effects
Alprazolam disadvantages:
- High dependence and withdrawal risk 5
- Not guideline-recommended for GAD 1
- Cognitive impairment concerns 5
Quetiapine advantages:
Quetiapine disadvantages:
- Significant metabolic side effects (weight gain, sedation) 9
- Higher discontinuation rates due to adverse events 8
- Not guideline-recommended as first-line for GAD 1
Clinical Bottom Line
Neither alprazolam nor quetiapine should be first-line treatment for GAD. Japanese guidelines explicitly state that benzodiazepines and antipsychotics "have not been adequately studied" and are "not included in the guideline with or without recommendations" 1.
If you're seeking information about a specific crossover study, it may be unpublished, conducted outside the indexed literature, or you may need to provide additional identifying details. The evidence base does not support routine use of either agent over SSRIs/SNRIs for GAD treatment based on morbidity, mortality, and quality of life outcomes.