Pregabalin and Gabapentin are both gabapentinoids with the same mechanism — but Pregabalin has 90 percent linear bioavailability vs Gabapentin's unpredictable 33 to 60 percent. Pregabalin has Phase III RCT evidence for GAD and European regulatory approval. Gabapentin has neither. This complete comparison covers the pharmacological differences, the anxiety evidence base, side effects, and a clear indication guide for which to choose.