Safety, tolerability, and pharmacokinetics of repeated oral doses of 2-hydroxybenzylamine acetate in healthy volunteers: a double-blind, randomized, placebo-controlled clinical trial.

BACKGROUND: 2-Hydroxybenzylamine (2-HOBA) is a selective dicarbonyl electrophile scavenger being developed as a nutritional supplement to help protect against the development of conditions associated with dicarbonyl electrophile formation, such as the cognitive decline observed with Mild Cognitive Impairment or Alzheimer's disease. METHODS: This study evaluated the safety, tolerability, and pharmacokinetics of repeated oral doses of 2-HOBA acetate (500 or 750 mg) administered to healthy volunteers every eight hours for two weeks. The effects of 2-HOBA on cyclooxygenase function and cerebrospinal fluid penetrance of 2-HOBA were also investigated. RESULTS: Repeated oral administration of 2-HOBA was found to be safe and well-tolerated up to 750 mg TID for 15 days. 2-HOBA was absorbed within 2 h of administration, had a half-life of 2.10-3.27 h, and an accumulation ratio of 1.38-1.52. 2-HOBA did not interfere with cyclooxygenase function and was found to be present in cerebrospinal fluid 90 min after dosing. CONCLUSIONS: Repeated oral administration of 2-HOBA was found to be safe and well-tolerated. These results support continued development of 2-HOBA as a nutritional supplement. TRIAL REGISTRATION: Studies are registered at ClinicalTrials.gov (NCT03555682 Registered 13 June 2018, NCT03554096 Registered 12 June 18).

Effect of Wuziyanzong pill on metabolism of dapoxetine in vivo and in vitro.

In vitro incubation of rat liver microsomes with 30 µL of 100 µmol·L-1 dapoxetine and 30 µL of 10, 100, 250, 500, 1000, 2500, or 5000 µg·mL-1 Wuziyanzong pill was performed at 37 °C for 60 min. Dapoxetine concentration was analyzed by high performance liquid chromatography (HPLC). The half maximal inhibitory concentration (IC50) of Wuziyanzong pill on metabolism of dapoxetine was 296.10 µg mL-1in vitro. Twelve SD rats were randomly divided into 2 groups: Control group and Wuziyanzong pill group. The two groups were administrated with 10 mL·kg-1 saline (Control group) or 10 mL·kg-1 Wuziyanzong pill solution (Experimental group, solution contained 200 mg mL-1 Wuziyanzong pill) for 15 consecutive days. Following administration of saline or Wuziyanzong pill on the 15th day, 20 mg kg-1 dapoxetine was administered to all rats. Blood was collected from the tail vein (0.3 mL) at multiple time points, and ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was used to determine the concentration of dapoxetine and its main metabolites, dapoxetine-N-oxide and desmethyldapoxetine in rats. Pharmacokinetic analysis of dapoxetine showed that area under the concentration-time curve (AUC) and mean maximum plasma concentration (Cmax) of the Wuziyanzong pill group were decreased, while plasma clearance (CLz) was increased compared with control group (P < 0.01). The HPLC method for determination of dapoxetine in vitro was accurate and specific. The UHPLC-MS/MS method established for determination of dapoxetine and its major metabolites in rat plasma was rapid and specific, which met the requirements of pharmacokinetic guidelines. Wuziyanzong pill had a weak inhibitory effect on metabolism of dapoxetine in vitro, but had a very strong induction effect in vivo, suggesting the dosage of dapoxetine should be increased when administered in combination with Wuziyanzong pill.

First-in-human study assessing safety, tolerability, and pharmacokinetics of 2-hydroxybenzylamine acetate, a selective dicarbonyl electrophile scavenger, in healthy volunteers.

BACKGROUND: 2-Hydroxybenzylamine (2-HOBA) is a selective scavenger of dicarbonyl electrophiles that protects proteins and lipids from being modified by these electrophiles. It is currently being developed for use as a nutritional supplement to help maintain good health and protect against the development of conditions associated with dicarbonyl electrophile formation, such as the cognitive decline associated with Mild Cognitive Impairment and Alzheimer's disease. METHODS: In this first-in-human study, the safety, tolerability, and pharmacokinetics of six ascending single oral doses of 2-HOBA acetate were tested in eighteen healthy human volunteers. RESULTS: Reported adverse events were mild and considered unlikely to be related to 2-HOBA. There were no clinically significant changes in vital signs, ECG recordings, or clinical laboratory parameters. 2-HOBA was fairly rapidly absorbed, with a tmax of 1-2 h, and eliminated, with a t1/2 of approximately 2 h. Both tmax and t1/2 were independent of dose level, while Cmax and AUC increased proportionally with dose level. CONCLUSIONS: 2-HOBA acetate was safe and well-tolerated at doses up to 825 mg in healthy human volunteers, positioning it as a good candidate for continued development as a nutritional supplement. TRIAL REGISTRATION: This study is registered at ClinicalTrials.gov (NCT03176940).

Bumepamine, a brain-permeant benzylamine derivative of bumetanide, does not inhibit NKCC1 but is more potent to enhance phenobarbital's anti-seizure efficacy.

Based on the potential role of Na-K-Cl cotransporters (NKCCs) in epileptic seizures, the loop diuretic bumetanide, which blocks the NKCC1 isoforms NKCC1 and NKCC2, has been tested as an adjunct with phenobarbital to suppress seizures. However, because of its physicochemical properties, bumetanide only poorly penetrates through the blood-brain barrier. Thus, concentrations needed to inhibit NKCC1 in hippocampal and neocortical neurons are not reached when using doses (0.1-0.5 mg/kg) in the range of those approved for use as a diuretic in humans. This prompted us to search for a bumetanide derivative that more easily penetrates into the brain. Here we show that bumepamine, a lipophilic benzylamine derivative of bumetanide, exhibits much higher brain penetration than bumetanide and is more potent than the parent drug to potentiate phenobarbital's anticonvulsant effect in two rodent models of chronic difficult-to-treat epilepsy, amygdala kindling in rats and the pilocarpine model in mice. However, bumepamine suppressed NKCC1-dependent giant depolarizing potentials (GDPs) in neonatal rat hippocampal slices much less effectively than bumetanide and did not inhibit GABA-induced Ca2+ transients in the slices, indicating that bumepamine does not inhibit NKCC1. This was substantiated by an oocyte assay, in which bumepamine did not block NKCC1a and NKCC1b after either extra- or intracellular application, whereas bumetanide potently blocked both variants of NKCC1. Experiments with equilibrium dialysis showed high unspecific tissue binding of bumetanide in the brain, which, in addition to its poor brain penetration, further reduces functionally relevant brain concentrations of this drug. These data show that CNS effects of bumetanide previously thought to be mediated by NKCC1 inhibition can also be achieved by a close derivative that does not share this mechanism. Bumepamine has several advantages over bumetanide for CNS targeting, including lower diuretic potency, much higher brain permeability, and higher efficacy to potentiate the anti-seizure effect of phenobarbital.

Pharmacokinetic drug evaluation of safinamide mesylate for the treatment of mid-to-late stage Parkinson's disease.

INTRODUCTION: Patients with Parkinson's disease suffer from a heterogeneous expression of neurotransmitter deficits. They cause an individual variable expression of motor and non-motor symptoms. Thus, drugs with various mechanisms of actions are suitable to counteract these disease related neurotransmitter alterations. Areas covered: This invited review suggests safinamide as an ideal compound for therapy of Parkinson's disease, as its pharmacological profile includes reversible monoamine oxidase B inhibition, blockage of voltage-dependent sodium channels, modulation of calcium channels and abnormal glutamate release. Safinamide may provide benefits effects on non-motor symptoms in addition to the demonstrated amelioration of motor impairment in levodopa treated patients with Parkinson's disease. Safinamide was well tolerated and safe when administered in dose of 50 or 100 mg daily in pivotal trials. Expert opinion: Clinical handling, safety and tolerability of Safinamide are better than of dopamine agonists or levodopa. Safinamide supplements the existing armamentarium of drugs for Parkinson's disease. Safinamide will help to reduce dosing of levodopa but also of dopamine agonists during long term treatment in patients with Parkinson's disease.

Adjuvant therapies for Parkinson's disease: critical evaluation of safinamide.

Safinamide (SAF) is a new drug developed for the treatment of Parkinson's disease (PD). It is a benzylamino derivative with multiple mechanisms of action and antiparkinsonian, anticonvulsant, and neuroprotective properties. SAF inhibits monoamine oxidase B and dopamine reuptake and glutamate release, blocks voltage-dependent sodium channels, and modulates calcium channels. Although the antiparkinsonian effect can be ascribed in part to the inhibition of the monoamine oxidase B, which is complete at 50 mg, the enhanced benefit seen at the 100 mg dose is probably due to nondopaminergic mechanisms. SAF will represent an important option for patients with both early and advanced PD. In early PD patients, the addition of SAF to dopamine agonists may be an effective treatment strategy to improve motor function, prolong the use of dopamine agonists, and/or delay the introduction of levodopa. In advanced parkinsonian patients, SAF has been demonstrated to significantly increase on time with no, or nontroublesome dyskinesias. All studies performed have demonstrated its efficacy in benefiting both short-term and long-term quality-of-life outcomes in both early and advanced PD patients. SAF has been investigated in long-term (24 months), double-blind, placebo-controlled studies, where it showed a very good safety profile. SAF has not been studied in de novo PD patients, and its potential positive effect on dyskinesia deserves further dedicated studies.

Effects of Evodiamine on the Pharmacokinetics of Dapoxetine and Its Metabolite Desmethyl Dapoxetine in Rats.

The objective of this work was to investigate the effect of orally administered evodiamine on the pharmacokinetics of dapoxetine and its active metabolite desmethyl dapoxetine in rats. Twelve healthy male Sprague-Dawley rats were randomly divided into 2 groups: the control group (received oral 10 mg/kg dapoxetine alone) and the combination group (10 mg/kg dapoxetine orally co-administered with 100 mg/kg evodiamine). The plasma concentration of dapoxetine and desmethyl dapoxetine were estimated by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and different pharmacokinetic parameters were calculated using the Drug and Statistics 2.0 software. Compared to the control group, the pharmacokinetic parameter of t1/2, AUC(0-∞) and Tmax of dapoxetine in combination group was significantly increased by 63.3% (p < 0.01), 44.8% (p < 0.01) and 50.4% (p < 0.01), respectively. Moreover, evodiamine had significantly decreased the pharmacokinetic parameter of t1/2 and AUC(0-∞) of desmethyl dapoxetine. This study demonstrated that evodiamine inhibits the metabolism of dapoxetine. Henceforth, the pharmacodynamic influence of this interaction should be taken into consideration while prescribing dapoxetine to the patients already taking evodiamine.

Comparison of the effects of pelargonic acid vanillylamide and capsaicin on human vanilloid receptors.

Pelargonic acid vanillylamide is like capsaicin a natural capsaicinoid from chili peppers and commonly used in food additives to create a hot sensation, even in self-defense pepper sprays and as an alternative to capsaicin in medical products for topical treatment of pain. Although the chemical structures of both compounds are similar, preclinical data suggest that capsaicin is the more potent compound. We therefore performed voltage-clamp recordings using cells transfected with the human vanilloid receptor TRPV1 in order to assess the responses of pelargonic acid vanillylamide and capsaicin at the receptor level. We provide evidence that at the molecular target TRPV1, the concentration-response curves, kinetics of current activation, as well as inhibition by the competitive antagonist capsazepine were not significantly different between the two capsaicinoids. We suggest that the different effects of the two capsaicinoids observed in previous studies may rather be due to different physicochemical or pharmacokinetic properties than to different pharmacological profiles at the receptor level.

Old versus new anticoagulants: focus on pharmacology.

Heparin, low molecular weight heparin (LMWH) and warfarin are well-established anticoagulants still in widespread use despite their well known drawbacks. Heparin requires continuous monitoring, has serious side-effects such as haemorrhage, thrombosis and osteoporosis, and lacks an oral route of administration. LMWH is a safer, more convenient anticoagulant to use but it cannot be given orally, does not have an antidote and may be difficult to administer in patients with renal failure. Warfarin has a narrow therapeutic window, interacts with other drugs and foods and requires monitoring like heparin. The limitations of all three of these established anticoagulants have prompted the search for better more convenient agents. The major examples of these newer anticoagulants are the direct and indirect factor Xa inhibitors and the direct thrombin inhibitors. These new agents tend to have more predictable pharmacokinetic properties, superior efficacy and safety and some can be administered orally. In this review, we summarise the advantages and disadvantages of three established anticoagulants (heparin, LMWH and warfarin) and the most promising new anticoagulants (fondaparinux, idraparinux, rivaroxaban, apixaban, dabigatran and ximelagatran) by discussing their pharmacodynamics and pharmacokinetics. We also discuss recent patents in the field of anticoagulation, which aim to improve the safety and effectiveness of antithrombotic agents currently in use or offer alternative ways for anticoagulation.

Dapoxetine: a novel treatment for premature ejaculation.

Premature ejaculation (PE) is a common problem worldwide and has significant impact not only on the sufferer but on the partner in terms of self-esteem, interpersonal distress and sexual satisfaction. A variety of psychological, topical and oral therapies have been tried in this condition with varying degrees of success. The selective serotonin reuptake inhibitors (SSRIs) are known to cause delayed ejaculation but require daily administration, have a relatively slow onset of action and may cause SSRI discontinuation syndrome on withdrawal. In addition, they are currently unlicensed for PE. Dapoxetine hydrochloride, an SSRI, has been specifically developed for on-demand use in PE. Its pharmacokinetic profile is characterized by rapid absorption, a short initial half-life of 1.3-1.4 h and rapid elimination with minimal accumulation even after multiple dosing. Several large phase III studies have demonstrated that dapoxetine can increase intravaginal ejaculatory latency time and improve several patient-reported outcomes relevant to control of ejaculation and satisfaction with intercourse. Dapoxetine is generally well tolerated with a low incidence of discontinuations due to adverse events. There were no signals for treatment-emergent anxiety or SSRI discontinuation syndrome after abrupt withdrawal.

Midbrain serotonin transporter binding potential measured with [11C]DASB is affected by serotonin transporter genotype.

BACKGROUND: Homozygote carriers of two long (L) alleles of the serotonin transporter (5-HTT) regulatory region displayed in vitro a twofold increase in 5-HTT expression compared with carriers of one or two short (S) alleles. However, in vivo imaging studies yielded contradictory results. Recently, an A > G exchange leading to differential transcriptional activation of 5-HTT mRNA in lymphobalstoid cell lines was discovered in the 5-HTT regulatory region. In vitro and in vivo evidence suggests that [(11)C]DASB, a new 5-HTT ligand offers some advantages over the ligands used in previous studies in measuring 5-HTT density independent of synaptic levels of serotonin. METHOD: We assessed 5-HTT binding potential (BP (2)) in the midbrain of 19 healthy subjects with positron emission tomography and [(11)C]DASB. Accounting for the hypothesized functional similarity of L (G) and S in driving 5-HTT transcription, we assessed whether L (A) L (A) homozygotes display increased midbrain BP (2) compared with carriers of at least one S allele. RESULTS: BP (2) in the midbrain was significantly increased in L (A) L (A) homozygotes compared with carriers of at least one S allele. Interestingly, the genotype effect on the midbrain was significantly different from that on the thalamus and the amygdala where no group differences were detected. CONCLUSIONS: This in vivo study provides further evidence that subjects homozygous for the L (A) allele display increased expression of 5-HTT in the midbrain, the origin of central serotonergic projections.

Emerging drugs for premature ejaculation.

Lifelong premature ejaculation (PE) is a frequent male sexual dysfunction and is thought to be mediated in part by disturbances of serotonergic (5-hydroxytryptamine; 5-HT) neurotransmission and ejaculation-mediating 5-HT receptors in the CNS. The aetiology of the dysfunction is unclear, but probably includes neurobiological and environmental factors. Lifelong PE is a syndrome characterised by a cluster of symptoms. Rapid ejaculations become manifest around the first sexual encounters in puberty or adolescence. Intravaginal ejaculation latency time usually occurs within 30-60 s, or maximally within 2 min after vaginal penetration, is present with nearly every sexual partner, and remains similar throughout life or may aggravate during ageing. The syndrome may lead to secondary psychological, sexual and relationship problems. Daily treatment with some selective serotonin re-uptake inhibitors (SSRIs) leads to strong ejaculation delay, but may be accompanied by side effects. New treatment with SSRIs with a short half-life (if approved) for on-demand use 1-2 h prior to coitus exerts less ejaculation-delaying effects than daily SSRI strategies. Animal studies have shown that strong, immediate ejaculation delay may be induced by the combination of an SSRI with a 5-HT(1A) receptor antagonist. The combination of an SSRI and any other compound that immediately strongly raises 5-HT neurotransmission may form the basis for the development of new on-demand drugs to treat PE.

Comparative pharmacokinetics of vitamin K antagonists: warfarin, phenprocoumon and acenocoumarol.

Vitamin K antagonists belong to the group of most frequently used drugs worldwide. They are used for long-term anticoagulation therapy, and exhibit their anticoagulant effect by inhibition of vitamin K epoxide reductase. Each drug exists in two different enantiomeric forms and is administered orally as a racemate. The use of vitamin K antagonists is complicated by a narrow therapeutic index and an unpredictable dose-response relationship, giving rise to frequent bleeding complications or insufficient anticoagulation. These large dose response variations are markedly influenced by pharmacokinetic aspects that are determined by genetic, environmental and possibly other yet unknown factors. Previous knowledge in this regard principally referred to warfarin. Cytochrome P450 (CYP) 2C9 has clearly been established as the predominant catalyst responsible for the metabolism of its more potent S-enantiomer. More recently, CYP2C9 has also been reported to catalyse the hydroxylation of phenprocoumon and acenocoumarol. However, the relative importance of CYP2C9 for the clearance of each anticoagulant substantially differs. Overall, the CYP2C9 isoenzyme appears to be most important for the clearance of warfarin, followed by acenocoumarol and, lastly, phenprocoumon. The less important role of CYP2C9 for the clearance of phenprocoumon is due to the involvement of CYP3A4 as an additional catalyst of phenprocoumon hydroxylation and significant excretion of unchanged drug in bile and urine, while the elimination of warfarin and acenocoumarol is almost completely by metabolism. Consequently, the effects of CYP2C9 polymorphisms on the pharmacokinetics and anticoagulant response are also least pronounced in the case of phenprocoumon; this drug seems preferable for therapeutic anticoagulation in poor metabolisers of CYP2C9. In addition to these vitamin K antagonists, oral thrombin inhibitors are currently under clinical development for the prevention and treatment of thromboembolism. Of these, ximelagatran has recently gained marketing authorisation in Europe. These novel drugs all feature some major advantages over traditional anticoagulants, including a wide therapeutic interval, the lack of anticoagulant effect monitoring and a low drug-drug interaction potential. However, they are also characterised by some pitfalls. Amendments of traditional anticoagulant therapy, including self-monitoring of international normalised ratio values or prospective genotyping for individual dose-tailoring may contribute to the continuous use of warfarin, phenprocoumon and acenocoumarol in the future.

Synthesis of N,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine as a serotonin transporter imaging agent.

Two 403U76 analogs, N,N-dimethyl-2-(2-nitro-4-bromophenylthio)benzylamine (4) and N,N-dimethyl-2-(2,4-dinitrophenylthio)benzylamine (8) were prepared in multi-steps synthesis as precursors for the synthesis of a new serotonin transporter imaging agent, N,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine (12a). Reaction of 2,5-dibromonitrobenzene (1) with 2-thio-N,N-dimethylbenzamide gave N N-dimethyl-2-(2-nitro-4-bromophenylthio)benzamide (3). N,N-Dimethyl-2-(2,4-dinitrophenylthio)benzamide (6) was synthesized similarly from the reaction of 2-bromo-1,5-dinitrobenzene (2) with 2-thio-N,N-dimethylbenzamide. Reduction of 3 and 6 with BH(3)/THF gave benzylamines 4 and 8 along with their amine boranes 5 and 7. Nucleophilic substitution of 4 or 8 with K[18F]/Kryptofix 2.2.2 in DMSO at 120 degrees C followed by reduction with NaBH(4)- Cu(OAc)(2) in EtOH at 78 degrees C and purification with HPLC gave compound 12a in approximately 5-10% yield in a synthesis time of 150min from EOB. A preliminary biodistribution study in rats showed that the uptake of compound 12a in rat brain was high (approximately 1%/g) and the ratio of the uptake of compound 12a in hypothalamus (a serotonin transporter-rich area) and cerebellum (a serotonin-transporter-devoid area) was 6/1 at 1h post-injection. These results suggest that compound 12a may be a potential new serotonin transporter PET imaging agent.

Anti-Trichophyton mentagrophytes activity and percutaneous permeation of butenafine in guinea pigs.

We examined anti-Trichophyton mentagrophytes activity, cutaneous penetration, and skin localization of butenafine, a novel benzylamine antifungal agent. The following results were obtained. (i) In the guinea pig dorsal skin trichophytosis model, butenafine produced complete eradication of fungi from infected sites. Clotrimazole was active when animals were infected with 10(4) or 10(5) cells but was almost inactive when the inoculum size was 10(6) cells. (ii) The MICs of butenafine and clotrimazole against arthrospores of T. mentagrophytes KD-04 were 0.025 and 0.39 microgram/ml, respectively. (iii) When 0.2 ml of a 1% 14C-butenafine solution was applied for 23 h/day for 7 days, high radioactivity corresponding to 250 to 500 micrograms of butenafine per g of skin in the epidermis, including the horny layer, was observed. (iv) Butenafine penetrates through transepidermal and transfollicular routes. The excellent therapeutic efficacy of butenafine on experimental dermatophytosis may be attributed to its low MIC and good penetration and distribution in the horny layer and hair follicles, where fungi reside.

Effects of butenafine hydrochloride, a new benzylamine derivative, on experimental dermatophytosis in guinea pigs.

Butenafine hydrochloride, N-4-tert-butylbenzyl-N-methyl-1-naphthalenemethylamine hydrochloride (butenafine), is a novel antifungal agent of the class of benzylamine derivatives. Butenafine was investigated for its activity against guinea pig dermatophytosis caused by Trichophyton mentagrophytes or Microsporum canis in comparison with those of naftifine, tolnaftate, clotrimazole, and bifonazole. Topical butenafine showed excellent efficacy against dermatophytosis when it was applied once daily, and the effect was superior to those of all four reference drugs. When applied once at 24 or 48 h before infection, the drug exhibited excellent prophylactic efficacy against experimental T. mentagrophytes infection. The concentrations of butenafine in animal skin at 24 and 48 h after application of 0.2 ml of a 1% solution were several hundred times higher than those required to kill T. mentagrophytes and M. canis. The good efficacy of butenafine against dermatophytosis may be attributable to its fungicidal activity and long retention in the skin after topical application.