Quantity of phenibut in dietary supplements before and after FDA warnings

Abstract

Introduction: Phenibut is used to treat anxiety, insomnia, alcohol withdrawal and other conditions in Russia. The drug, however, has abuse potential and may cause lethargy, delirium, psychosis and coma. In the United States (US), the US Food and Drug Administration (FDA) has never approved the use of phenibut as a prescription medication, but the drug is available over-the-counter in dietary supplements. More than 80 cases of coma and death have been associated with phenibut consumption and withdrawal, and the FDA recently warned that the drug is not permitted in over-the-counter supplements. We designed our study to determine the presence and quantity of phenibut in over-the-counter supplements before and after the FDA warnings. Methods: Phenibut products were included if they (a) listed phenibut or a synonym as an ingredient on the label, (b) were labeled as a dietary supplement, and (c) were available for sale both before and after the FDA warning. Supplements were analyzed by liquid chromatography time-of-flight mass spectrometry; quantification was performed by isotope dilution method. Results: Four brands of dietary supplements labeled as containing phenibut met the inclusion criteria. Prior to the FDA warnings, two of the four brands contained phenibut, at dosages of 484 mg and 487 mg per serving. After the FDA warning, all four products contained phenibut, ranging in dosages from 21 mg to 1,164 mg per serving. Phenibut was first detected only after the FDA warnings in two brands, and the quantity of phenibut increased in three of four products after the FDA warnings. Quantities detected per dose were as much as 450% greater than a typical 250 mg pharmaceutical tablet manufactured in Russia. Conclusion: Following FDA issuing an advisory that phenibut is not permitted in dietary supplements, the quantity of phenibut increased in 3 of 4 brands of over-the-counter phenibut supplements.

Phenibut: Review and Pharmacologic Approaches to Treating Withdrawal

“…Ironically, after the FDA warning was issued, all 4 products still contained phenibut, ranging between 21 and 1164 mg per product. Of note, none of the products analyzed in this investigation were manufactured by companies who received an FDA warning letter 101 . Although limited in scope, this study suggests that the FDA warning letters regarding phenibut may not be serving as a deterrent to manufacturers who continue to include this prohibited compound in their products, which they label as dietary supplements.…”

“…Prior to the FDA warnings, 2 of the 4 products contained phenibut (484 and 487 mg, respectively). 101 Ironically, after the FDA warning was issued, all 4 products still contained phenibut, ranging between 21 and 1164 mg per product. Of note, none of the products analyzed in this investigation were manufactured by companies who received an FDA warning letter.…”

“…Declaring phenibut in your product (and) labeling (it) as a dietary ingredient causes your product to be misbranded … in that the labeling is false or misleading.” 100 Cohen et al analyzed 4 brands of dietary supplements labeled as containing phenibut before and after the issuance of these warning letters. Prior to the FDA warnings, 2 of the 4 products contained phenibut (484 and 487 mg, respectively) 101 . Ironically, after the FDA warning was issued, all 4 products still contained phenibut, ranging between 21 and 1164 mg per product.…”