Quantity of phenibut in dietary supplements before and after FDA warnings

Phenibut: A drug with one too many "buts"

Phenibut is a gamma aminobutyric acid derivative with activity at γ-aminobutyric acid (GABA)B, A and β-phenethylamine receptors. It was developed as a drug in the former Soviet Union to overcome anxiety and improve cognitive function in military personnel. In the last decade, it has made inroads into the European and U.S. markets, being marketed for purported nootropic properties. Here, we summarize the current knowledge on phenibut, its toxicology, pharmacology, adverse health effects, and patterns of use. Publications in peer-reviewed journals were searched in PubMed, Web of Science, and Google Scholar databases. Available literature points to adverse side effects associated with intoxication, withdrawal, and addiction to phenibut. Some of these effects can be life-threatening, requiring hospitalization and therapeutic interventions. Supportive efforts are often complicated by a lack of knowledge regarding phenibut's toxicology and pharmacology. Ingestion of phenibut was often associated with concomitant use of other substances of abuse. As control over its online marketing seems unrealistic, current efforts need to be focused on the addition of phenibut to current drug screening tests and the development of generally accepted treatment strategies for phenibut-associated toxicities.

Phenibut: Review and Pharmacologic Approaches to Treating Withdrawal

β-Phenyl-γ-aminobutyric acid (phenibut) is an analog of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) that was first synthesized in Russia in the early 1960s. It is marketed as a nootropic (smart drug) to improve cognitive performance, and to treat generalized and social anxiety, insomnia, and alcohol withdrawal. The use of phenibut is legal in the USA and it is widely available online without a prescription. Increased public awareness of phenibut has led to a growing number of reports of acute intoxication and withdrawal. In this review, we describe the pharmacology of phenibut, the presentation and management of acute intoxication, and regulatory issues, placing particular emphasis on the treatment of acute withdrawal, for which there are no comparative studies. Among 29 cases of phenibut withdrawal, patients were successfully treated with baclofen, benzodiazepines, and phenobarbital, as individual agents or in various combinations. Ancillary medications included antipsychotics, dexmedetomidine, gabapentin, and pregabalin. After stabilization, a number of patients did well on baclofen tapers, whereas others were weaned off benzodiazepines or phenobarbital. Phenobarbital may be preferred over baclofen, or used as an added agent, in patients at risk for seizures. As long as phenibut remains legal, cases of phenibut intoxication and withdrawal are likely to increase. As urine or plasma drug screening for phenibut is not widely available, it is vital that clinicians obtain a detailed medication history in patients presenting to the emergency department with nonspecific symptoms that may represent phenibut intoxication or withdrawal. Further, clinicians may wish to consult an addiction specialist or toxicologist in these situations.

Unauthorized ingredients in "nootropic" dietary supplements: A review of the history, pharmacology, prevalence, international regulations, and potential as doping agents

The first nootropic prohibited in sport was fonturacetam (4-phenylpiracetam, carphedon) in 1998. Presented here 25 years later is a broad-scale consideration of the history, pharmacology, prevalence, regulations, and doping potential of nootropics viewed through a lens of 50 selected dietary supplements (DS) marketed as "cognitive enhancement," "brain health," "brain boosters," or "nootropics," with a focus on unauthorized ingredients. Nootropic DS have risen to prominence over the last decade often as multicomponent formulations of bioactive ingredients presenting compelling pharmacological questions and potential public health concerns. Many popular nootropics are unauthorized food or DS ingredients according to the European Commission including huperzine A, yohimbine, and dimethylaminoethanol; unapproved pharmaceuticals like phenibut or emoxypine (mexidol); previously registered drugs like meclofenoxate or reserpine; EU authorized pharmaceuticals like piracetam or vinpocetine; infamous doping agents like methylhexaneamine or dimethylbutylamine; and other investigational substances and peptides. Several are authorized DS ingredients in the United States resulting in significant global variability as to what qualifies as a legal nootropic. Prohibited stimulants or ß2-agonists commonly used in "pre-workout," "weight loss," or "thermogenic" DS such as octodrine, hordenine, or higenamine are often stacked with nootropic substances. While stimulants and ß2-agonists are defined as doping agents by the World Anti-Doping Agency (WADA), many nootropics are not, although some may qualify as non-approved substances or related substances under catch-all language in the WADA Prohibited List. Synergistic combinations, excessive dosing, or recently researched pharmacology may justify listing certain nootropics as doping agents or warrant additional attention in future regulations.

Management of Phenibut Use Disorder and Withdrawal in a Geriatric Patient

Phenibut is a misused substance which has shown an increase in use over the past decade. Marketed as a "dietary supplement," it is not approved in the United States for use and is not regulated by the Food and Drug Administration. The substance, however, is readily available for purchase through online markets. It has a similar drug profile as alcohol, gabapentin and benzodiazepines. Clinical effects of this drug include physiologic dependence, euphoria, anxiolysis, antispasticity, sedation, and possible nootropic properties. While there are emerging new cases of managing phenibut withdrawal, no cases currently feature phenibut addiction and withdrawal management in the geriatric population. Here we discuss such a case of phenibut addiction and withdrawal in a 68-year-old male who initially began misusing phenibut to alleviate anxiety and insomnia precipitated by worsening affective disorder, sedative, hypnotic, or anxiolytic use disorder, and alcohol use disorder.

Effects of Gabapentin and Pregabalin on Calcium Homeostasis: Implications for Physical Rehabilitation of Musculoskeletal Tissues

PURPOSE OF REVIEW

In this review, we discuss the mechanism of action of gabapentinoids and the potential consequences of long-term treatment with these drugs on the musculoskeletal system.

RECENT FINDINGS

Gabapentinoids, such as gabapentin (GBP) and pregabalin (PGB) were designed as antiepileptic reagents and are now commonly used as first-line treatment for neuropathic pain and increasingly prescribed off-label for other pain disorders such as migraines and back pain. GBP and PGB exert their analgesic actions by selectively binding the α₂δ₁ auxiliary subunit of voltage-sensitive calcium channels, thereby inhibiting channel function. Numerous tissues express the α₂δ₁ subunit where GBP and PGB can alter calcium-mediated signaling events. In tissues such as bone, muscle, and cartilage, α₂δ₁ has important roles in skeletal formation, mechanosensation, and normal tissue function/repair that may be affected by chronic use of gabapentinoids. Long-term use of gabapentinoids is associated with detrimental musculoskeletal outcomes, including increased fracture risk. Therefore, understanding potential complications is essential for clinicians to guide appropriate treatments.

The unapproved drug centrophenoxine (meclofenoxate) in cognitive enhancement dietary supplements

INTRODUCTION

Centrophenoxine (meclofenoxate) is prescribed in China and elsewhere to treat a variety of conditions including alcoholism and dementia, but the US Food and Drug Administration has not approved the drug for any indication. We designed our study to determine the presence and quantity of centrophenoxine in dietary supplements sold over-the-counter in the US.

METHODS

Supplements were included in our study if the label included (a) the term "dietary supplement" and (b) "centrophenoxine" as a declared ingredient. Supplements were purchased online, and powder from each dietary supplement product was reconstituted in methanol and analyzed using ultra high-performance liquid chromatography.

RESULTS

Seven products were analyzed. Centrophenoxine was present in all products in dosages ranging from 79 to 251 mg per serving. Consumers following the maximum recommended daily intake on the label would be exposed to 237 to 752 mg of centrophenoxine per day. Only 1 of 7 products (14%) listed a quantity of centrophenoxine on the label within ±10% of the actual amount.

CONCLUSION

Clinicians should be aware and advise patients that cognitive enhancement supplements may contain unapproved and prohibited drugs.