[Clinical and neurophysiological manifestations of sluggish cognitive tempo in children]. / Kliniko-neirofiziologicheskie proyavleniya nizkogo kognitivnogo tempa u detei.

OBJECTIVE: To study the clinical and neurophysiological features of children with low cognitive tempo (NCT), as well as the effectiveness of the drug Pantogam in the treatment of this pathology. MATERIAL AND METHODS: A total of 90 children aged 8 to 10 years were examined. Of these, the main study group consisted of 30 children with NCT, the comparison group consisted of 30 children with a combined type of attention deficit hyperactivity disorder ADHD (ADHD-K), the control group consisted of 30 children without neuropsychiatric disorders. The study used clinical, neurophysiological (electroencephalography (EEG)) and parametric methods. The CMAS scale of apparent anxiety (The Children's Form of Manifest Anxiety Scale), the SNAP-IY scale (assessment of the degree of inattention, hyperactivity and impulsivity), the TOVA computer test (the Test of Variables of Attention), the scale «SCT¼ (Sluggish Cognitive Tempo) for assessing manifestations of low cognitive tempo, the «RAM¼ technique for quantifying working memory. Pantogam was used to treat patients at a dose of 750 mg per day for 8 weeks. RESULTS: Patients with NCT are characterized by more pronounced attention disorders compared with healthy peers and with children with ADHD-K, and they have a decrease in mainly not selective attention, but the overall level of functional activity. Also, the group of children with NCT has an increased level of anxiety compared to the group of children with ADHD. A comparative analysis of the level of impulsivity showed that children with NCT are less characterized by a deficit in inhibition processes. According to the quantitative analysis of the EEG, specific changes in functional activity in the frontal and central regions of the cerebral cortex were revealed (a statistically significant increase in the ratio of absolute theta rhythm to beta1 rhythm, compared with other groups), reflecting insufficient cortical arousal and less focused neural states. When re-evaluating the condition of children with NCT after a course of therapy with Pantogam, an improvement in the form of a decrease in the degree of inattention, the severity of memory impairment and a decrease in reaction time was recorded in 60% of cases. According to quantitative EEG analysis, there was a significant decrease in the ratio of absolute theta rhythm to beta1 rhythm in the central leads of both hemispheres and in the parietal-temporal leads of the left hemisphere, indicating an increase in the level of overall activation of the cerebral cortex after a course of treatment. CONCLUSION: Clinical and neurophysiological differences were revealed in patients with NCT and with combined ADHD. It has been shown that the use of Pantogam for the treatment of children with NCT leads not only to a decrease in the main manifestations of this disorder, but also to an improvement in the functional state of the brain.

Use of kersetin and fisetin flavonoids in combination with pregabalin and gabapentin in the treatment of neuropathic pain.

We purposed to explore the consequences of the use quercetin and fisetin alone and in combination with pregabalin and gabapentin, which are used in the management of neuropathic pain, and on neuropathic pain in general. The anti-allodynic effect of various doses (5, 10, and 20 mg/kg) of quercetin and fisetin, both singly and in combination with pregabalin and gabapentin, was evaluated by developing a neuropathic pain model induced by chronic constrictive nerve damage in rats. The effectiveness of these flavonoids was investigated by combining them with gabapentin (50 mg/kg) and pregabalin (15 mg/kg), choosing the effectual dose of 10 mg/kg and the dose of 5 mg/kg, which did not show significant antiallodynic effects. In groups combined with gabapentin and pregabalin, it was determined that they showed a significant antiallodynic effect compared with 50 mg/kg gabapentin and 15 mg/kg pregabalin. In conclusion, in our combination studies, it was observed that the effectiveness of gabapentin and pregabalin, was increased and the duration of effect was prolonged when used with lower doses of flavonoids. Based on these findings; it is possible to say that quercetin and fisetin are potential agents that can be used alone or in combination with other effective treatments to alleviate neuropathic pain.

Potential Mechanisms of Casein Hexapeptide YPVEPF on Stress-Induced Anxiety and Insomnia Mice and Its Molecular Effects and Key Active Structure.

The hexapeptide YPVEPF with strong sleep-enhancing effects could be detected in rat brain after a single oral administration as we previously proved. In this study, the mechanism and molecular effects of YPVEPF in the targeted stress-induced anxiety mice were first investigated, and its key active structure was further explored. The results showed that YPVEPF could significantly prolong sleep duration and improve the anxiety indexes, including prolonging the time spent in the open arms and in the center. Meanwhile, YPVEPF showed strong sleep-enhancing effects by significantly increasing the level of the GABA/Glu ratio, 5-HT, and dopamine in brain and serum and regulating the anabolism of multiple targets, but the effects could be blocked by bicuculline and WAY100135. Moreover, the molecular simulation results showed that YPVEPF could stably bind to the vital GABAA and 5-HT1A receptors due to the vital structure of Tyr-Pro-Xaa-Xaa-Pro-, and the electrostatic and van der Waals energy played dominant roles in stabilizing the conformation. Therefore, YPVEPF displayed sleep-enhancing and anxiolytic effects by regulating the GABA-Glu metabolic pathway and serotoninergic system depending on distinctive self-folding structures with Tyr and two Pro repeats.

Phenibutan-an Illegal Food Supplement With Psychotropic Effects and Health Risks.

BACKGROUND: Phenibut (ß-phenyl-γ-aminobutyric acid) is an analog of the neurotransmitter gamma-aminobutyric acid (GABA). Like abapentin and pregabalin, it inhibits α2-δ-subunits of voltagedependent presynaptic calcium channels. The potential harm resulting from the use of these gabapentinoids is currently a matter of debate. METHODS: This review is based on pertinent publications retrieved by a selective literature search and on cases reported to the Giftinformationszentrum-Nord (GIZ-Nord), a poison information center at the University of Göttingen, Germany. RESULTS: Phenibut is a prescription drug in Russia but its production, possession, use, trafficking, or administration is illegal in Germany. The phenibut toxicity syndrome resembles that of gabapentinoids and GABA mimetics: benzodiazepine-like with - drawal symptoms including epileptic seizures, delirium and paradoxical activation have been described, as have cases of abuse and dependence. A few cases of use in the setting of multidrug abuse, and of phenibut-related death, have been described to date in the USA. The GIZ-Nord received 17 inquiries about phenibut, 55 about gabapentin, and 126 about pregabalin over the period 2008-2022. Over the same period, the GIZ-Nord was informed of 1207 cases involving Z substances and 4324 involving benzodiazepines. In the majority of the registered intoxications, including those with phenibut, the symptoms were mild. Overdoses of phenibut (2-100 g) were reported in 15 of the 17 cases; 8 of the persons who had taken an overdose were somnolent. In such cases, observation in intensive care was recommended. Respiratory depression or coma was not encountered in any case, not even in the patient who had taken 100 g of phenibut. CONCLUSION: Phenibut causes symptoms resembling those of gabapentinoid and benzodiazepine use. There have been reports of phenibut use in combination with other psychotropic drugs; in particular, its use together with opiates could increase the risk of coma and respiratory depression. No deaths due to phenibut intoxication have been published in Germany or elsewhere in Western Europe, although such cases may have been overlooked, as this drug is still largely unknown to Western medicine.

Phenibut: Review and Pharmacologic Approaches to Treating Withdrawal.

ß-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.

Monitoring the use of novel psychoactive substances in Australia by wastewater-based epidemiology.

Users of novel psychoactive substances (NPS) are at risk, due to limited information about the toxicity and unpredictable effects of these compounds. Wastewater-based epidemiology (WBE) has been used as a tool to provide insight into NPS use at the population level. To understand the preferences and trends of NPS use in Australia, this study involved liquid chromatography mass spectrometry analysis of wastewater collected from Australian states and territories from February 2022 to February 2023. In total, 59 different NPS were included across two complementary analytical methods and covered up to 57 wastewater catchments over the study. The NPS detected in wastewater were 25-B-NBOMe, buphedrone, 1-benzylpiperazine (BZP), 3-chloromethcathinone, N,N-dimethylpentylone (N,N-DMP), N-ethylheptedrone, N-ethylpentylone, eutylone, 4F-phenibut, 2-fluoro deschloroketamine, hydroxetamine, mephedrone, methoxetamine, methylone, mitragynine, pentylone, phenibut, para-methoxyamphetamine (PMA), alpha-pyrrolidinovalerophenone (α-PVP) and valeryl fentanyl. The detection frequency for these NPS ranged from 3 % to 100 % of the sites analysed. A noticeable decreasing trend in eutylone detection frequency and mass loads was observed whilst simultaneously N,N-DMP and pentylone increased over the study period. The emergence of some NPS in wastewater pre-dates other sources of monitoring and provides further evidence that WBE can be used as an additional early warning system for alerting potential NPS use.

Phenibut screening and quantification with liquid chromatography-tandem mass spectrometry and its application to driving cases.

An analytical strategy for identification by an LC-MS/MS multitarget screening method and a suitable LC-MS/MS based quantification were developed for the psychotropic drug phenibut. The samples analyzed were collected during traffic control and were associated with driving under the influence of drugs. A positive sample for phenibut was identified in a single case of driving under the influence. The quantification revealed a drug concentration of 1.9 µg/mL. An interaction with blood alcohol (BAC = 0.10%) was discussed as the explanation of the way of driving and deficit manifestations observed (swaying, nystagmus, quivering of the eyelid, and reddened eyes). According to the available information, the quantified phenibut concentration could be explained by an intake of four tablets (self-reported) during the day containing 250 mg of the drug. Chromatography was performed with a Luna 5 µm C18 (2) 100 A, 150 mm × 2 mm analytical column, and a buffer system consisted of 10 mM ammonium acetate and 0.1% acetic acid (v/v) included in mobile phases marked as A (H2 O/methanol = 95/5, v/v) and B (H2 O/methanol = 3/97, v/v). An effective limit of detection (LOD = 0.002 µg/mL) could be achieved for the multitarget screening method. The quantification of phenibut was performed on a second LC-MS/MS system with LOD/LOQ values of 0.22/0.40 µg/mL. Since phenibut quantification data are rare, the presented information can be used with caution for evaluation of positive cases in the future.

Picamilon, a γ-aminobutyric acid (GABA) analogue and marketed nootropic, is inactive against 50 biological targets.

Picamilon is an analogue of the neurotransmitter γ-aminobutyric acid (GABA), which is marketed as a nootropic claiming to enhance cognition. There is a lack of in silico, in vitro and in vivo data on the safety of picamilon. Therefore, to ascertain potential physiological effects of picamilon, it was screened against 50 safety-related biological targets (receptors, ion channels, enzymes and transporters) by in silico and in vitro methods. Using two in silico tools, picamilon was not predicted to bind to the targets. Similarly, picamilon exhibited weak or no binding to the targets when measured in vitro at 10 µM. Overall, this data shows that picamilon, although structurally similar to other GABA analogues, has a different biological target binding profile. Picamilon's lack of binding to the 50 targets fills important data gaps among GABA analogues, a group of structurally related substances found in drugs and other consumer products.

[Treatment of patients with chronic cerebral ischemia: experience of using the combined neuroprotective drug Picamilon Ginkgo]. / Lechenie bol'nykh s khronicheskoi ishemiei golovnogo mozga: opyt primeneniya kombinirovannogo neiroprotektivnogo preparata Pikamilon Ginkgo.

OBJECTIVE: To compare the clinical efficacy and safety of Picamilon Ginkgo and ginkgo biloba in patients with cognitive impairment in vascular diseases of the brain (chronic cerebral ischemia). MATERIAL AND METHODS: An open multicenter randomized comparative study involved 278 patients over 45 years of age with a diagnosis of chronic cerebral ischemia and cognitive impairment. 139 of them received Picamilon Ginkgo and 139 received monotherapy with ginkgo biloba extract for 90 days. Dynamics were compared on the MoCA, MMSE, Hamilton scale for assessing depression and the quality of life of EQ-5D, and the subjective effectiveness of therapy by patients and doctors was evaluated. RESULTS: Combination therapy resulted in significantly greater regression of cognitive impairment compared to monotherapy. At the end of the study, the differences between the groups were significant both on the MMSE scale (p=0.007) and on the MoCA scale (p=00003). At the same time, significant differences between the groups in the magnitude of cognitive improvement on the MoCA scale were noted already from the 30th day of treatment. Combination therapy also contributed to a more significant improvement in the patient's quality of life: dynamics on the EQ-5D scale significantly (p<0.05) differed in the groups, also starting from the 30th day of therapy. There were no significant differences in the dynamics of the Hamilton scale for assessing depression between the compared groups. Both Picamilon Ginkgo and monotherapy with ginkgo biloba extract were safe and were not accompanied by significant adverse events. CONCLUSION: The combination of standardized ginkgo biloba extract with Picamilon has an advantage over monotherapy with ginkgo biloba extract in patients with chronic cerebral ischemia, as it contributes to a more significant regression of cognitive impairment and improvement of quality of life.

[Effects of Skin Environmental Changes by Steam Towel, Ethanol, l-Menthol and Carpronium on the Drug Behavior in the Minoxidil Nanoparticles-applied Mice].

We previously designed the formulation containing minoxidil (MXD) nanoparticles (MXD-NPs), and found that the MXD-NPs can mainly deliver MXD into hair bulbs via hair follicles pathway, and that the therapeutic efficiency for hair growth is higher in comparison with the formulation containing dissolved MXD. In this study, we investigated whether the skin environmental changes by the treatment of steam towel, ethanol, l-menthol and commercially available (CA) carpronium affect the drug behavior in the MXD-NPs-applied mice. The steam towel, ethanol, l-menthol and CA-carpronium were pre-treated 3 min before MXD-NPs application, and the MXD content in the hair bulge, bulb, skin tissue and blood of mice were measured 4 h after MXD-NPs application. No significant difference of MXD levels in the blood was observed by the pre-treatment of steam towel, ethanol, l-menthol and CA-carpronium. On the other hand, the pre-treatment of steam towel and l-menthol enhanced the MXD levels in hair bulge and/or bulb. Although, the MXD levels in hair bulge and bulb were not changed by the pre-treatment of ethanol, the MXD levels in skin tissue was higher than that of saline-pre-treated group (control). The MXD levels in hair bulge, bulb and skin tissue of mice pre-treated with CA-carpronium were remarkably higher in comparison with control. In conclusion, we showed that the changes in skin environment by the steam towel, ethanol, l-menthol and CA-carpronium affected the absorption of MXD-NPs, and these increased MXD levels in the hair bulb and blood by the combination may enhance the therapeutic efficiency without side effects.

Chronic Phenibut Use: Symptoms, Severe Withdrawal, and Recovery.

INTRODUCTION: Phenibut is a psychoactive drug with GABAB agonism. It remains unregulated and easily attainable in the United States, where it has become a novel drug of abuse. CASE PRESENTATION: We present the case of a 34-year-old man who used phenibut consistently for 3 years. After 6 months of use, he developed signs of dependence and failed outpatient detoxification. While taking high doses, he experienced parasomnia-like symptoms and periods of dysexecutive function. After abrupt cessation, he developed severe withdrawal symptoms, was hospitalized, and required intubation. His condition improved after 1 week of treatment. After recovery and discharge, he remains stable utilizing an extended taper of acamprosate and baclofen. DISCUSSION: Phenibut is not detected on urine drug screen and withdrawal symptoms are nonspecific. Optimal treatment of withdrawal remains unknown. Baclofen and phenobarbital have been successful for treatment of dependence. CONCLUSION: Clinicians should be aware of phenibut abuse and the potential for dependence and withdrawal.

Effects of Gabapentin Enacarbil on Postoperative Pain After Hip and Knee Arthroplasty: A Placebo-controlled Randomized Trial.

OBJECTIVES: Total joint arthroplasties are among the most common elective procedures performed in the United States, and they are associated with postoperative pain. Gabapentin enacarbil is a prodrug with an extended-release formulation that has been proposed for multimodal postoperative analgesia, but the drug's efficacy for major arthroplasties remains unclear. MATERIALS AND METHODS: We enrolled 60 adult patients scheduled for primary knee or hip arthroplasty expected to remain hospitalized for at least 3 days. Eligible patients were randomly assigned to placebo or gabapentin enacarbil 600 mg twice daily starting the day before surgery continuing for 3 days thereafter.The primary outcome was analyzed using a joint hypothesis framework of pain (0 to 10 verbal response scores) and cumulative opioid consumption (mg of morphine equivalent) within the first 72 hours. Secondary outcomes were nausea and vomiting, pain persisting 90 days after surgery, duration of hospitalization, and early postoperative health status using quality of recovery score (QoR-15). RESULTS: Twenty-eight patient in gabapentin enacarbil group and 32 in placebo group were analyzed. Since pain scores did not differ significantly (difference of means: -0.2 in pain scores; 95% confidence interval: -1.1, 0.7), nor did opioid consumption, conditions for joint hypothesis testing were not met. Moreover, there were no significant differences between groups for secondary outcomes. DISCUSSION: We did not identify statistically significant or clinically meaningful differences in our primary and secondary outcomes related to perioperative use of gabapentin enacarbil in patients having primary hip or knee arthroplasties.

A Case of Phenibut Directed Detoxification Leading to Toxicity During the COVID-19 Pandemic.

BACKGROUND: Phenibut is a non-Food and Drug Administration-approved gamma-aminobutyric acid analog marketed in the United States as an anxiolytic, cognitive enhancer, and alcohol withdrawal treatment through online supplement vendors. In this case report, we describe a woman's self-directed detoxification with phenibut used to manage withdrawal symptoms from fentanyl and benzodiazepines in March 2020 during the height of the COVID-19 pandemic. CASE: A 38-year-old woman with severe opioid, benzodiazepine, gabapentin, stimulant use disorders developed altered mental status after oral phenibut ingestion intended to help self-manage opioid and benzodiazepine withdrawal. She chose self-directed detoxification as she feared COVID-19 exposure in detoxification facilities. Her altered mental status drove her to jump out a third-story window causing multiple spinal fractures. After a long hospitalization, she self-directed her discharge home due to concerns about COVID-19. Her premature discharge disrupted opioid and benzodiazepine use disorder treatment plans. CONCLUSION: This case highlights the risks of phenibut use for selfdirected detoxification. With COVID-19 related changes in the drug supply, people may be more likely to use online pharmaceuticals, therefore, substance use assessments should inquire about the online acquisition of new psychoactive drugs. Public health messaging regarding the risks of infectious disease transmission in addiction care settings is needed to guide addiction treatment choices among people who use substances.

Quantity of phenibut in dietary supplements before and after FDA warnings.

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.

Interindividual Variability in the Bioavailability of Gabapentin Enacarbil Extended Release in Healthy Adults: An Analysis of Data From 6 Phase I Studies.

BACKGROUND: The absorption and bioavailability of oral gabapentin are associated with a high degree of interindividual variability. Gabapentin enacarbil, a prodrug of gabapentin, is well absorbed and provides sustained, dose-proportional exposure to gabapentin. The aim of this analysis was to describe the interindividual variability in the bioavailability of gabapentin after gabapentin enacarbil administration in healthy subjects. METHODS: Gabapentin pharmacokinetic (PK) parameters after an oral dose of gabapentin enacarbil 1200 mg (2 600-mg tablets) were compared across 6 phase I studies in healthy adults (n = 12 per study). The distribution of bioavailability values was assessed in all studies. RESULTS: The mean PK parameters of gabapentin were consistent across the trials: maximum concentration range: 6.4-7.9 µg/mL, time to maximum concentration range: 5.2-8.2 hours, area under the plasma-concentration curve extrapolated from time 0 to infinity or at steady state range: 70.8-109.4 µg·h/mL, and bioavailability range: 64.8%-82.9%. Overall, the mean bioavailability was 74.1% (SD, 14.1; coefficient of variation, 19.1%). Individual bioavailability across all studies ranged from 42% to 100%. CONCLUSIONS: Gabapentin PK after gabapentin enacarbil administration was consistent across studies, with low interindividual variability in bioavailability. Gabapentin enacarbil may provide more consistent and predictable exposure to gabapentin than oral gabapentin formulations.

[Influence of pantogam and atomoxetine on attention stability and distribution of dopamine D2 and GABAB receptors in the attention deficit mouse model]. / Vliianie pantogama i atomoksetina na ustoichivost' vnimaniia i raspredelenie dofaminovykh D2 i GAMKV-retseptorov u myshei s model'iu defitsita vnimaniia.

The closed enriched cross maze test was employed as a new experimental model of the attention deficit disorder (ADD) for evaluation of the behavioral and neurochemical effects of the nootropic drug pantogam (100 mg/kg, intraperitoneally) and atomoxetine hydrochloride (3 mg/kg, intraperitoneally) administered subchronically to CD-1 outbred mice. Two subpopulations of rodents differed spontaneously in attention to enriched compartments (ED-Low and ED-High), were estimated on the basis of time spent by the mice in the empty or enriched compartments. The ED-Low and ED-High mice insignificantly differed in parameters associated with anxiety, exploratory efficacy and motor activity. Subchronic administration of both drugs in selected doses produced corrective effect on animal behavior seen as a selective increase in the ED-ratio values in the ED-Low subpopulation. Differences in the distribution of dopamine D2 and GABAB receptors (Bmax) between placebo-treated ED-Low and ED-High mice were found in the prefrontal cortex using the radioligand binding method. The neuroreceptor effects of atomoxetine were seen in prefrontal cortex of ED-Low mice as decrease in the Bmax values of D2 receptors by 14%. Pantogam in the prefrontal cortex of ED-Low subpopulation showed a decrease in the Bmax values of D2 receptors by 22% and an increase for GABAB receptors by 44%. Therefore, subchronic administration of pantogam had a positive corrective effect on the behavior parameters and the density of the studied receptor subtypes in animals with severe attention deficit.

The Coenzyme A Level Modulator Hopantenate (HoPan) Inhibits Phosphopantotenoylcysteine Synthetase Activity.

The pantothenate analogue hopantenate (HoPan) is widely used as a modulator of coenzyme A (CoA) levels in cell biology and disease models─especially for pantothenate kinase associated neurodegeneration (PKAN), a genetic disease rooted in impaired CoA metabolism. This use of HoPan was based on reports that it inhibits pantothenate kinase (PanK), the first enzyme of CoA biosynthesis. Using a combination of in vitro enzyme kinetic studies, crystal structure analysis, and experiments in a typical PKAN cell biology model, we demonstrate that instead of inhibiting PanK, HoPan relies on it for metabolic activation. Once phosphorylated, HoPan inhibits the next enzyme in the CoA pathway─phosphopantothenoylcysteine synthetase (PPCS)─through formation of a nonproductive substrate complex. Moreover, the obtained structure of the human PPCS in complex with the inhibitor and activating nucleotide analogue provides new insights into the catalytic mechanism of PPCS enzymes─including the elusive binding mode for cysteine─and reveals the functional implications of mutations in the human PPCS that have been linked to severe dilated cardiomyopathy. Taken together, this study demonstrates that the molecular mechanism of action of HoPan is more complex than previously thought, suggesting that the results of studies in which it is used as a tool compound must be interpreted with care. Moreover, our findings provide a clear framework for evaluating the various factors that contribute to the potency of CoA-directed inhibitors, one that will prove useful in the future rational development of potential therapies of both human genetic and infectious diseases.

Inhibition of Fatty Acid Metabolism Increases EPA and DHA Levels and Protects against Myocardial Ischaemia-Reperfusion Injury in Zucker Rats.

Long-chain ω-3 polyunsaturated fatty acids (PUFAs) are known to induce cardiometabolic benefits, but the metabolic pathways of their biosynthesis ensuring sufficient bioavailability require further investigation. Here, we show that a pharmacological decrease in overall fatty acid utilization promotes an increase in the levels of PUFAs and attenuates cardiometabolic disturbances in a Zucker rat metabolic syndrome model. Metabolome analysis showed that inhibition of fatty acid utilization by methyl-GBB increased the concentration of PUFAs but not the total fatty acid levels in plasma. Insulin sensitivity was improved, and the plasma insulin concentration was decreased. Overall, pharmacological modulation of fatty acid handling preserved cardiac glucose and pyruvate oxidation, protected mitochondrial functionality by decreasing long-chain acylcarnitine levels, and decreased myocardial infarct size twofold. Our work shows that partial pharmacological inhibition of fatty acid oxidation is a novel approach to selectively increase the levels of PUFAs and modulate lipid handling to prevent cardiometabolic disturbances.