I ordered some F-Phenibut
the first day it came out (from the company I usually order from). It is said to be around 5-10x more potent than Phenibut HCL. I tested a 200mg dose of F-Phenibut, and it felt like 2-3 grams of Phenibut HCL. The onset started to come on at the 1 hour mark, and gradually 'built up' until it peaked at 3-4 hours after dosing. The total duration was about 8-9 hours. It seemed like it was less stimulating and more sedating than Phenibut HCL, but I'm 95% sure it was due to the potency: 200mg F-Phenibut felt like 2-3 grams Phenibut HCL, while I usually take 1.2 grams Phenibut HCL, so this was probably the reason why I was more sedated.
Today (2nd time testing) I tried 130 mg F-Phenibut. It felt like my normal 1.2 gram dose of Phenibut HCL, although it didn't hit me as fast as the HCL, which usually gives me an energy boost and makes me super talkative. It sort of reminds me of a cross between Phenibut HCL and F.A.A. in terms of duration and intensity.
Not many people have tested this compound yet, so I thought I'd let our DF family know about it! Feel free to ask any questions. It might take me a few days to respond, so please be patient. Thanks!