pregabalin have been approved by FDA and european union for treatment of fibromyalgia. For GAD it is effective but not the most effective treatment as per my knowledge

As a clinical researcher who participated in the clinical trials for pregabalin for GAD, it certainly does work but in higher doses (300mg +), when the risk of weight gain increases

COMPARING MEDICATION TO CBT — There is insufficient evidence directly comparing the effectiveness of medication for GAD to cognitive behavioral therapy (CBT), the best studied and most effective psychotherapy for GAD [56,57]. Meta-analyses comparing the effect sizes of the two modalities have found largely equivalent results [58]. We suggest that the choice between them should be based on treatment availability and patient preference. (See "Psychotherapy for generalized anxiety disorder".)

COMBINED MEDICATION AND CBT — Two trials have found the combination of a benzodiazepine and CBT to be more effective for GAD than a benzodiazepine alone [59,60]. Another trial compared sertraline, CBT or the combination in 448 7 to 17 year olds with separation anxiety, generalized anxiety, or social phobia [61], finding that the combination treatment was superior to either monotherapy, with all three treatment groups showing greater reduction in anxiety compared to placebo. The number of adverse events, including suicidal and homicidal ideation, did not differ across the groups. (See "Psychotherapy for generalized anxiety disorder", section on 'Cognitive behavioral therapy'.)

While they can be beneficial, treatment that integrates medication with CBT should be administered with caution to avoid counterproductive interactions. As an example, benzodiazepines and, to a lesser degree, sedating SSRIs can disrupt the learning of new coping strategies, a mechanism that is fundamental to CBT. Several principals should guide combined treatment:

Stabilization of medications prior to starting CBT

Avoidance of “as needed” or large doses of benzodiazepines

Avoidance of other medications that have sedative effects (eg, sedative SSRIs) while CBT is in progress

ref:www.uptodate.com

I post the answer in a wrong place,how can I delete this post?

Pregabalin is not the first line drug for GAD but sometimes used to treat GAD. Pregabalin inhibits calcium currents via high-voltage-activated channels containing the a2d-1 subunit, though the relationship of this mechanism to its efficacy in GAD is not known. Pregabalin has shown efficacy for GAD compared to placebo in several randomized trials. It has recently been approved for the treatment of anxiety in Europe [39,40]. Pregabalin is not approved for treating GAD by the US FDA. The doses for pregabalin range from 50 to 300 mg. Side effects include sedation and dizziness. Tolerance, withdrawal, and dependence are possible, but pregabalin is generally better tolerated than benzodiazepines

Pregabalin is not the first line of treatment for GAD. Drugs like Venlafaxine is considered best option