New and validated RP-HPLC Method for Quantification of Safinamide Mesylate in Presence of Its Basic Degradate, Levodopa and Ondansetron: Application to Human Plasma.

A simple, precise, rapid and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for analysis of safinamide mesylate (SAF) in presence of its basic degradate, and co-administered drugs levodopa and ondansetron. The mobile phase consisted of acetonitrile and 20 mM potassium dihyrogen orthophosphate buffer having pH = 5 (40: 60 v/v). Quantification was achieved with ultraviolet detector at 226 nm. The linear range was 0.5-10 µg/mL with mean recovery ± SD of 99.72 ± 1.59. The peak purity of SAF in pharmaceutical preparation spiked with its degradate and co-administered drugs revealed symmetry factor (999.8) within the calculated threshold (>998.1). The suggested method was validated in compliance with the International Conference on Harmonization (ICH) guidelines and statistically compared with the manufacturer HPLC method with no significant difference in terms of accuracy and precision. The assay method was successfully used to estimate SAF in tablets with good percentage recoveries. The high sensitivity (lower than Cmax of the drug 0.65 µg/mL) of the proposed HPLC method enabled the determination of SAF in presence of its basic degradate and co-administered drug, ondansetron in human plasma with acceptable accuracy. The suggested HPLC method could be used in Quality Control (QC) lab for analysis of the studied drug in pharmaceutical preparation.

High performance liquid chromatography - Mass spectrometric bioanalytical method for the determination of dapoxetine in human plasma: Application for bioequivalence study.

Dapoxetine is an oral medication used for treatment of premature ejaculation (PE) in men aged (18-64 years). In this study, we present a validated, precise and sensitive method for determination of dapoxetine in human plasma by liquid chromatography/ electrospray ionization-tandem mass spectrometry. Dapoxetine and the internal standard (Dapoxetine- d6) were extracted from plasma via liquid-liquid extraction (LLE). The LC separation was performed utilizing ACE C8 (4.6 X50) mm, 5 µm column. The mobile phase was composed of acetonitrile and buffer (0.01 M Ammonium acetate +0.02% Formic acid solution) (85:15, v/v). The method was linear within the concentration range of 5.0-600 ng/mL for Dapoxetine in human plasma. Short analytical run was achieved with 1.6 min run time. Intra-day and inter-day accuracy was between 97 and 106% with precision (CV, %) of ≤ 5% achieved across all the quality control samples. Dapoxetine was stable in several conditions with recovery rates > 90%. This method was utilized successfully in clinical pharmacokinetic study following oral administration of 60 mg Dapoxetine tablets in 36 healthy male subjects. The result for all 90% confidence intervals were within the preset ranges. The method proved to be highly reproducible and sensitive and thus can be employed in bioequivalence studies and large scale sample analysis of Dapoxetine.

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).

Zein-alpha lipoic acid-loaded nanoparticles to enhance the oral bioavailability of dapoxetine: optimization and clinical pharmacokinetic evaluation.

BACKGROUND: Premature ejaculation (PE) is the most common type of male sexual disorder with important psychological consequences. Dapoxetine (DPX), a recently approved drug for the treatment of PE, suffers from low bioavailability with large variability that ranges from 15-76% (mean 42%) after oral administration. The objective of this study is to optimize the parameters for the preparation of DPX-Zein-alpha lipoic acid (ALA) nanoparticles (NPs) to improve the bioavailability of DPX and consequently decrease therapeutic dose and adverse effect, leading to patient satisfaction and compliance. METHODS: We investigated the effect of ALA concentration, PVA concentration and stirring rate on nanoparticle size (Y1), zeta potential (Y2), initial DPX release (Y3) and cumulative DPX release (Y4). In addition, in vivo pharmacokinetic study was performed for the optimized DPX formulation on human healthy volunteers compared with marketed DPX tablet. RESULTS: The optimized DPX-loaded NPs showed Y1, Y2, Y3, and Y4 of 159.24 nm, 19.14 mV, 25.31% and 95.9 %, respectively. A single oral dose of 30 mg of optimized DPX-loaded NPs to human volunteers resulted in 2-fold improvement of AUC (1376.145±339.592 vs 709.178±146.307 in DPX), 4-fold increase in tmax (2.5±0.314 vs 0.583±0.144), prolongation of MRT (7.637±1.373 compared to 6.031±1.826 h), but with reduction in t1/2 (5.283±1.077 vs 8.452±2.813). CONCLUSION: The clinical findings suggest 194% enhancement of relative bioavailability of the optimized DPX-loaded NPs, potentially leading to a decrease in therapeutic dose and associated side effects in the treatment of PE.

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).

Self-assembled biodegradable polymeric micelles to improve dapoxetine delivery across the blood-brain barrier.

BACKGROUND: Dapoxetine (DPX) is the drug of choice for the specific treatment of premature ejaculation. DPX is characterized by relatively low bioavailability (42%) and short half-life (1.5 h). The aim of this study was to improve DPX bioavailability and delivery across the blood-brain barrier (BBB) using a nanostructured DPX formulation for improved DPX efficacy and patient satisfaction. MATERIALS AND METHODS: DPX-loaded polymeric micelles (PMs) formulations (F1-F3) were characterized for particle sizes, entrapment efficiencies, and Fourier transform infrared spectroscopic and transmission electron microscopic evaluations. In addition, diffusion profiles of the prepared formulations were investigated. Animal model pharmacokinetic parameters in plasma and brain tissues were investigated and compared with commercial DPX tablets. RESULTS: Particle size analysis revealed that formulations of DPX PMs showed a narrow range of 62.7±9.3-45.45±9.1 nm for F1-F3. In addition, DPX PMs showed a sustained release pattern with 91.27%±7.64%, 79.43%±7.81%, and 63.78%±5.05% of DPX content permeated after 24 h for F1, F2, and F3, respectively. Plasma pharmacokinetic parameters for DPX PMs showed significant increase (P<0.05) for the area under drug concentration-time curves in plasma and brain tissues compared with commercial DPX tablets. CONCLUSION: DPX formulations in the form of PMs improved bioavailability and efficacy across the BBB. This DPX formulation provided improved brain delivery in order to enhance the convenience and compliance of patients.

Detection of 25C-NBOMe in Three Related Cases.

An accidental death associated with the use of the designer drug, 2-(4-chloro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine (25C-NBOMe), is reported. A 23-year-old Caucasian male experienced severe respiratory distress and died after being subdued by military law enforcement. At autopsy, remarkable findings upon internal examination included mild to moderate coronary atherosclerosis, biventricular dilation, mild right ventricular hypertrophy and bilateral pulmonary edema and congestion. The decedent's blood contained no drugs, ethanol or other volatile compounds. Pseudoephedrine, nicotine and cotinine were detected in his urine. A LC-QTOF designer drug screen, employing a basic solid-phase extraction, was used to isolate 25C-NBOMe, 25C-NBOH and 2C-C from both blood and urine specimens. Quantitative analysis was performed by LC-MS-MS operating in multiple reaction monitoring mode. 25C-NBOMe and 2C-C were present in the blood (2.07 and 0.12 ng/mL) and in the urine (27.43 ng/mL and 0.38 ng/mL), respectively. 25C-NBOMe concentrations were determined by standard addition in the brain (19.10 ng/g), spleen (27.13 ng/g), lung (25.21 ng/g), liver (15.20 ng/g), kidney (25.06 ng/g) and gastric contents (30.24 µg total in 100 mL submitted). On the basis of decedent case history, autopsy and toxicological findings, the medical examiner ruled the cause of death as 25C-NBOMe toxicity temporally associated with excited delirium and forcible restraint. The manner of death was ruled accidental.

In Vivo Evaluation of Blood Based and Reference Tissue Based PET Quantifications of [11C]DASB in the Canine Brain.

This first-in-dog study evaluates the use of the PET-radioligand [11C]DASB to image the density and availability of the serotonin transporter (SERT) in the canine brain. Imaging the serotonergic system could improve diagnosis and therapy of multiple canine behavioural disorders. Furthermore, as many similarities are reported between several human neuropsychiatric conditions and naturally occurring canine behavioural disorders, making this tracer available for use in dogs also provide researchers an interesting non-primate animal model to investigate human disorders. Five adult beagles underwent a 90 minutes dynamic PET scan and arterial whole blood was sampled throughout the scan. For each ROI, the distribution volume (VT), obtained via the one- and two- tissue compartment model (1-TC, 2-TC) and the Logan Plot, was calculated and the goodness-of-fit was evaluated by the Akaike Information Criterion (AIC). For the preferred compartmental model BPND values were estimated and compared with those derived by four reference tissue models: 4-parameter RTM, SRTM2, MRTM2 and the Logan reference tissue model. The 2-TC model indicated in 61% of the ROIs a better fit compared to the 1-TC model. The Logan plot produced almost identical VT values and can be used as an alternative. Compared with the 2-TC model, all investigated reference tissue models showed high correlations but small underestimations of the BPND-parameter. The highest correlation was achieved with the Logan reference tissue model (Y = 0.9266 x + 0.0257; R2 = 0.9722). Therefore, this model can be put forward as a non-invasive standard model for future PET-experiments with [11C]DASB in dogs.

Herb-drug interaction of Epimedium extract on the pharmacokinetic of dapoxetine in rats.

The aim of study is to develop a high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method to investigate the pharmacokinetic interaction of Epimedium extract on the dapoxetine in rats. Experimental rats were divided into the following four parallel groups: (1) dapoxetine alone (10mg/kg, i.v.); (2) oral administration of Epimedium extract (2g/kg) for 3 consecutive days and on the fourth day dapoxetine was administered (10mg/kg, i.v.); (3) dapoxetine alone (10mg/kg, p.o.); (4) oral administration of Epimedium extract (2g/kg) for 3 consecutive days and on the fourth day dapoxetine was administered (10mg/kg, p.o.). The calibration curves of dapoxetine were acquired over a concentration ranges from 1 to 500ng/mL with the R(2)=0.999. The mean matrix effects and extraction recoveries of dapoxetine at three different concentrations (1, 10, 500ng/mL) ranged from 107.3 to 110.9% and from 25.5 to 28.2% respectively. The interday and intraday relative standard deviation were both <6% while the bias were both <14%. The pharmacokinetic results demonstrated that pretreated with/without Epimedium extract for three consecutive days did not significant alter the pharmacokinetics of dapoxetine in rats. The oral bioavailability of dapoxetine was about 75% in rats.

Development and validation of a sensitive UPLC-MS/MS method for the simultaneous determination of dapoxetine and its two metabolites in human plasma.

A sensitive and rapid ultra performance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) method was developed to determine dapoxetine and its two major metabolites (dapoxetine-N-oxide and desmethyldapoxetine) in human plasma simultaneously. After a simple protein precipitation, the analytes and the combined internal standard (carbamazepine) were separated on an Acquity UPLC BEH C18 column using a mobile phase of acetonitrile and 0.1% formic acid in water with gradient elution. Mass spectrometric analysis was performed using a XEVO TQD triple quadruple mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions are of m/z 306.3→261.2, m/z 322.2→261.2, m/z 292.2→261.2 and m/z 237.1→194.2 for dapoxetine, dapoxetine-N-oxide, desmethyldapoxetine and IS, respectively. The linearity of this method was found to be within the concentration range of 1.0-200ng/mL for dapoxetine; 0.5-100ng/mL for dapoxetine-N-oxide; and 0.1-5.0ng/mL for desmethyldapoxetine in human plasma, respectively. Only 4.0min was needed for an analytical run. Intra-day and inter-day accuracy and precision were within the acceptable limits of ±15% at all of the concentrations. This assay was successfully used to support a clinical pharmacokinetic study following oral administration of dapoxetine tablets in healthy Chinese subjects.

A novel liquid chromatographic method with fluorescence detection for quantitation of tadalafil and dapoxetine hydrochloride in pharmaceutical dosage form and human plasma.

Tadalafil (TAD) and dapoxetine HCl (DAP) are recently co-formulated and both show native fluorescence. Therefore, a novel, accurate, specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard (IS). Separation was achieved using isocratic elution within 7.0 min on C18 column and acetonitrile-0.15% triethylamine (40:60, v/v; pH 4) as a mobile phase. The flow rate was 1.0 mL/min and the detection was time-programmed at 330, 410 and 370 nm for TAD, DAP and IS, respectively, after excitation at 236 nm. The linear ranges from 0.01 to 30.00 µg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP, respectively. The method was validated in accordance to the International Conference on Harmonization (ICH) guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17% and 98.83% for TAD and DAP respectively.

A data-independent acquisition workflow for qualitative screening of new psychoactive substances in biological samples.

Identification of new psychoactive substances (NPS) is challenging. Developing targeted methods for their analysis can be difficult and costly due to their impermanence on the drug scene. Accurate-mass mass spectrometry (AMMS) using a quadrupole time-of-flight (QTOF) analyzer can be useful for wide-scope screening since it provides sensitive, full-spectrum MS data. Our article presents a qualitative screening workflow based on data-independent acquisition mode (all-ions MS/MS) on liquid chromatography (LC) coupled to QTOFMS for the detection and identification of NPS in biological matrices. The workflow combines and structures fundamentals of target and suspect screening data processing techniques in a structured algorithm. This allows the detection and tentative identification of NPS and their metabolites. We have applied the workflow to two actual case studies involving drug intoxications where we detected and confirmed the parent compounds ketamine, 25B-NBOMe, 25C-NBOMe, and several predicted phase I and II metabolites not previously reported in urine and serum samples. The screening workflow demonstrates the added value for the detection and identification of NPS in biological matrices.

Quantification of iodiconazole by LC-MS/MS, a new topical transdermal cream, in dermatophytosis patients' plasma.

BACKGROUND: A rapid and sensitive LC-MS/MS method was established to measure iodiconazole (ADKZ) in dermatophytosis patients treated topically with 2% ADKZ cream. METHODOLOGY: ADKZ was extracted by liquid-liquid extraction (LLE) and separated by an Agilent Zorbax SB-C18 column (2.1 × 150 mm, 3.5 µm) using methanol - 0.01% formic acid (70:30, v/v) as the mobile phase. All the validation assays met the acceptable criteria and the linearity ranged from 10 to 1000 pg/ml. CONCLUSION: The method has been validated to be simple, sensitive and successfully applied to the study. The average amount of ADKZ absorbed into blood was approximately 0.51 µg daily, and ADKZ blood concentrations were consistent during the four-week treatment course. The cumulation of ADKZ in vivo was almost negligible.

Pathological findings in 2 cases of fatal 25I-NBOMe toxicity.

The research compound 25I-NBOMe, also known as CIMBI-5 or INBMeO, was created in academic laboratories as a potent serotonin 2A receptor agonist. Because of its high affinity and ambiguous legal status, recreational drug enthusiasts have used this compound as a powerful alternative to other hallucinogenic drugs such as lysergic acid diethylamide. We report 2 deaths after 25I-NBOMe ingestion by decedents who attended separate "rave" parties. The first case involved a 21-year-old male who admitted taking "acid" to his friend. A sudden violent rage caused him to flail about, and he subsequently became unresponsive. The postmortem examination revealed numerous external injuries that were consistent with physical aggression. The second case involved a 15-year-old female who was socializing outside a rave party, became ill, and rapidly deteriorated as her friend transported her to the hospital. The postmortem assessment was similar to the first case in that external contusions featured prominently. Comprehensive toxicology screens in both cases revealed only evidence of marijuana use. A deeper analysis using time-of-flight mass spectrometry revealed the presence of 25I-NBOMe, which was further confirmed by tandem-mass spectrometry. The behavior and injuries in these cases reveal a consistent pattern preceding fatal 25I-NBOMe toxicity.

Disposition and metabolism of safinamide, a novel drug for Parkinson's disease, in healthy male volunteers.

BACKGROUND/AIMS: Absorption, biotransformation and elimination of safinamide, an enantiomeric α-aminoamide derivative developed as an add-on therapy for Parkinson's disease patients, were studied in healthy volunteers administered a single oral dose of 400 mg (14)C safinamide methanesulphonate, labelled in metabolically stable positions. METHODS: Pharmacokinetics of the parent compound were investigated up to 96 h, of (14)C radioactivity up to 192/200 h post-dose. RESULTS/CONCLUSIONS: Maximum concentration was achieved at 1 h (plasma, median Tmax) for parent drug and at 7 and 1.5 h for plasma and whole blood (14)C radioactivity, respectively. Terminal half-lives were about 22 h for unchanged safinamide and 80 h for radioactivity. Safinamide deaminated acid and the N-dealkylated acid were identified as major metabolites in urine and plasma. In urine, the ß-glucuronide of the N-dealkylated acid and the monohydroxy safinamide were also characterized. In addition, the glycine conjugate of the N-dealkylated acid and 2-[4-hydroxybenzylamino]propanamide were tentatively identified as minor urinary metabolites.

Severe clinical toxicity associated with analytically confirmed recreational use of 25I-NBOMe: case series.

CONTEXT: 4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe) is a N-methoxybenzyl-substituted phenethylamine with potent serotoninergic effects. We describe seven cases of analytically confirmed toxicity due to the recreational use of 25I-NBOMe in the United Kingdom. CASE SERIES: Seven patients, all young adult males, presented to hospitals in the northeast of England with clinical toxicity after recreational drug use in January 2013. Clinical features included tachycardia (n = 7), hypertension (4), agitation (6), aggression, visual and auditory hallucinations (6), seizures (3), hyperpyrexia (3), clonus (2), elevated white cell count (2), elevated creatine kinase (7), metabolic acidosis (3), and acute kidney injury (1). LC-MS/MS analysis identified 25I-NBOMe as the main active substance in the plasma of all seven cases. CONCLUSIONS: Severe clinical toxicity may occur following recreational use of 25I-NBOMe, with stimulant and serotoninergic features predominating. Clinicians should be alert to this substance, in view of its emergence in Europe as well as in the United States.

Determination of dapoxetine in rat plasma by ultra-performance liquid chromatography-tandem mass spectrometry.

In this study, we describe and validate a rapid and sensitive method for quantitation of dapoxetine in rat plasma by using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS). Plasma samples were prepared by protein precipitation with acetonitrile, and sildenafil was used as an internal standard (IS). The mobile phase consisted of 0.5% formic acid/acetonitrile (60:40, v/v); a C18 reversed-phase column (2.0 × 50 mm, 1.7 µm) was used for chromatographic separation. Multiple reaction monitoring (MRM) was used in the positive ion mode for mass spectrometric detection. The calibration curve for dapoxetine was linear (r(2)=0.999) in the concentration range of 1-500 ng/mL. The intra- and inter-day precision was between 3.8% and 8.3%, and the intra- and inter-day accuracy was between 101.1% and 109.0%. Dapoxetine was found to be stable in various conditions with the recoveries>87.0% (RSD <7.2%). The method was found to be specific, precise, and accurate, and no matrix effect was observed. Our results suggest that this method can be successfully applied in pharmacokinetic studies of dapoxetine in rat plasma.

Safinamide reduces dyskinesias and prolongs L-DOPA antiparkinsonian effect in parkinsonian monkeys.

INTRODUCTION: Safinamide is a compound under investigation for use in the treatment of Parkinson's disease for combination with pharmacological therapy currently available. The objective of this study was to test the effects of safinamide in an animal model of l-DOPA-induced dyskinesias (LID), the MPTP lesioned dyskinetic macaque monkey, in comparison to and in combination with amantadine. METHODS: LID and parkinsonian symptoms were measured in dyskinetic monkeys treated with l-DOPA with and without several dose levels of safinamide, amantadine, and the two in combination. Safinamide plasma levels were monitored during the experiments. RESULTS: Safinamide pre-treatment (3, 10, 20 and 30 mg/kg) dose-dependently reduced LID scores, in two acute and one semi-chronic experiment. Intensity and duration of LID were reduced and inversely correlated with safinamide blood levels. All doses of safinamide tested prolonged the duration of the beneficial antiparkinsonian effect of l-DOPA. Amantadine (5 and 20 mg/kg) reduced LID, but reduced duration of antiparkinsonian response to l-DOPA. When added to amantadine (5 mg/kg), safinamide showed no (3 mg/kg) or modest (20 mg/kg) additional beneficial effects on LID while the combined treatment prevented the reduction of the duration of the l-DOPA antiparkinsonian effect observed with amantadine only. CONCLUSIONS: Safinamide and amantadine reduced LID in this primate model while only safinamide increased the duration of the antiparkinsonian response of l-DOPA, suggesting that safinamide may have effects on LID that are pharmacologically distinct from amantadine, which is in current clinical use for control of LID.

Large inter-individual variation of the pharmacodynamic effect of anticoagulant drugs on thrombin generation.

Anticoagulation by a standard dosage of an inhibitor of thrombin generation presupposes predictable pharmacokinetics and pharmacodynamics of the anticoagulant. We determined the inter-individual variation of the effect on thrombin generation of a fixed concentration of direct and antithrombin-mediated inhibitors of thrombin and factor Xa. Thrombin generation was determined by calibrated automated thrombinography in platelet-poor plasma from 44 apparently healthy subjects which was spiked with fixed concentrations of otamixaban, melagatran, unfractionated heparin, dermatan sulfate and pentasaccharide. The variability of the inhibitory effect of the different anticoagulants within the population was determined using the coefficient of variation, i.e. the standard deviation expressed as a percentage of the mean. The inter-individual coefficients of variation of the endogenous thrombin potential and peak height before inhibition were 18% and 16%, respectively and became 20%-24% and 24%-43% after inhibition. The average inhibition of endogenous thrombin potential and peak height (ETP, peak) brought about by the anticoagulants was respectively: otamixaban (27%, 83%), melagatran (56%, 63%), unfractionated heparin (43%, 58%), dermatan sulfate (68%, 57%) and pentasaccharide (25%, 67%). This study demonstrates that the addition of a fixed concentration of any type of anticoagulant tested causes an inhibition that is highly variable from one individual to another. In this respect there is no difference between direct inhibitors of thrombin and factor Xa and heparin(-like) inhibitors acting on the same factors.