Safety, Tolerability, and Pharmacokinetics of SUVN-G3031, a Novel Histamine-3 Receptor Inverse Agonist for the Treatment of Narcolepsy, in Healthy Human Subjects Following Single and Multiple Oral Doses.

BACKGROUND AND OBJECTIVE: SUVN-G3031 is a novel, potent, and selective histamine-3 receptor (H3R) inverse agonist in development for the treatment of narcolepsy. Our objective was to characterize the safety, tolerability, and pharmacokinetics of SUVN-G3031 in healthy young adults after single and multiple doses, and to evaluate the effect of food, gender, and age on the pharmacokinetics. METHODS: A single ascending dose (SAD) and a multiple ascending dose (MAD) study for 14 days was conducted in healthy young adults using a randomized, double-blind study design. The effect of food, gender, and age on SUVN-G3031 pharmacokinetics (6 mg as a single dose) was evaluated using an open-label, two-period, randomized, crossover design in fed and fasted states. Pharmacokinetics and safety assessments were conducted throughout the study. RESULTS: Single doses of SUVN-G3031 up to 20 mg and multiple doses up to 6 mg once daily were found to be safe and well tolerated in healthy young adults. The most frequently reported adverse events were abnormal dreams, dyssomnia, and hot flushes. SUVN-G3031 exposure was dose proportional across the tested doses. Steady state was achieved on day 6 after once-daily dosing. Renal excretion (~ 60%) of unchanged SUVN-G3031 was the major route of elimination. Food, gender, and age did not have any clinically meaningful effect on SUVN-G3031 exposure. CONCLUSION: SUVN-G3031 was found to be safe and well tolerated in healthy human subjects without any effect of age, gender, and food on the pharmacokinetics and safety profile. Clinical Trials Registration (https://clinicaltrials.gov): NCT04072380 and NCT02342041.

Safety, Tolerability and Pharmacokinetics of the Serotonin 5-HT6 Receptor Antagonist, SUVN-502, in Healthy Young Adults and Elderly Subjects.

BACKGROUND AND OBJECTIVE: SUVN-502, a selective 5-HT6 receptor antagonist, was found to be active in preclinical models of cognitive deterioration suggesting a potential role in the treatment of dementia related to Alzheimer's disease. The objective of this study was to characterize the safety, tolerability and pharmacokinetics of SUVN-502 in healthy young adults and elderly subjects following single and multiple oral doses. METHODS: Single doses (5, 15, 50, 100 and 200 mg SUVN-502) and multiple doses (50, 100 and 130 mg SUVN-502 once daily for 7 days) were evaluated in healthy young adults and multiple doses (50 and 100 mg SUVN-502 once daily for 14 days) were evaluated in elderly subjects using randomized, double-blind, placebo-controlled, dose-escalating study designs. The effect of food, gender and age on SUVN-502 pharmacokinetics (100 mg single dose) was evaluated using an open-label, two-period, randomized, fed and fasted in a crossover design. SUVN-502 and M1 (major metabolite of SUVN-502) were monitored using validated analytical methods. RESULTS: SUVN-502 is safe and well tolerated up to the highest tested single dose of 200 mg in healthy young adults and multiple doses up to 130 mg for 7 days and 100 mg for 14 days in healthy young adults and elderly subjects, respectively. Exposures of SUVN-502 and M1 were more than dose-proportional over the evaluated dose range. Food and gender did not have a clinically meaningful effect on SUVN-502 exposure. The mean SUVN-502 total (AUC0-∞, and AUC0-last) and peak exposures (Cmax) were 2.9- and 2.2-fold higher, respectively, in elderly subjects compared to young subjects. Steady-state was achieved for SUVN-502 and M1 within 7 days after once-daily dosing of SUVN-502. CONCLUSIONS: SUVN-502 exhibited an acceptable safety, tolerability and pharmacokinetic profile in healthy young adults and elderly subjects. Based on the above results, 50 and 100 mg once-daily doses of SUVN-502 were advanced to Phase 2 evaluation in patients with moderate AD.

Pharmacokinetic profiling of efavirenz-emtricitabine-tenofovir fixed dose combination in pregnant and non-pregnant rats.

During pregnancy, the disposition of various drugs is altered due to changes in physiological condition, maternal gastrointestinal absorption, gastric secretion and motility. A fixed dose combination of antiretrovirals is commonly prescribed for the treatment of HIV infection. There is a need to understand the pharmacokinetics and placental transfer of efavirenz-emtricitabine-tenofovir in fixed dose combination during pregnancy. The pharmacokinetics and placental transfer of efavirenz-emtricitabine-tenofovir fixed dose combination was evaluated in timed pregnant and non-pregnant Sprague-Dawley rats at 30, 10, 15 mg/kg p.o., respectively. The plasma, placental tissue, amniotic fluid and fetal tissue concentrations were measured using high performance liquid chromatography combined with tandem mass spectrometric detector (LC-MS/MS). To summarize, the pharmacokinetic profile of efavirenz remained similar in the pregnant and non-pregnant rats. However, a considerable difference in the pharmacokinetics of emtricitabine and tenofovir was observed in pregnant and non-pregnant rats. Efavirenz and emtricitabine showed appreciable placental, amniotic fluid and fetal exposure compared with tenofovir. The present study suggests that a profound impact on antiretroviral pharmacokinetics was observed during pregnancy and there is a need to monitor the exposure levels of each drug when administered as a fixed dose combination during pregnancy. Further studies to explore the pharmacokinetic parameters of fixed dose antiretrovirals during the preclinical stage in a timed-pregnancy rat model are required. Such studies can help in the development of safe and effective medications with a reduced risk of perinatal transmission of HIV-1 infection.

Simultaneous extraction of acetylsalicylic acid and salicylic acid from human plasma and simultaneous estimation by liquid chromatography and atmospheric pressure chemical ionization/tandem mass spectrometry detection. Application to a pharmacokinetic study.

A simple analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in atmospheric chemical ionization mode (APCI) for the simultaneous estimation of acetylsalicylic acid (ASA, CAS 50-78-2) and its active metabolite salicylic acid (SA, CAS 69-72-7) in human plasma has been developed and validated. ASA and SA were analyzed simultaneously despite differences in plasma concentration ranges of ASA and SA after oral administration of ASA. In spite of having different chemical, ionization and chromatographic properties, ASA and SA were extracted simultaneously from the plasma sample using acetonitrile protein precipitation followed by liquid-liquid extraction. The analytes were separated on a reversed phase column with rapid gradient program using mobile phase consisting of ammonium acetate buffer and methanol. The structural analogue diclofenac was used as an internal standard. The multiple reaction monitoring (MRM) transitions m/z 179 --> 137 for ASA, m/z 137 --> 65 for SA and m/z 294 --> 250 for IS were used. The assay exhibited a linear dynamic range of 0.02-10 microg/mL for ASA and 0.1-50 microg/mL for SA. The between-batch precision (%CV) ranged from 2.1 to 7.9% for ASA and from 0.2 to 5.2% for SA. The between-batch accuracy ranged from 95.4 to 96.7% for ASA and from 94.6 to 111.3% for SA. The validated method was successfully applied for the evaluation of pharmacokinetics of ASA after single oral administration of 650 mg test formulation versus two 325 mg reference formulations of ASA in human subjects.

Liquid chromatography tandem mass spectrometry method for the quantification of sarpogrelate, a selective 5-HT(2A) receptor antagonist, in plasma: application to a pre-clinical pharmacokinetic study.

A simple LC-MS/MS method was developed and validated for the estimation of sarpogrelate in 50 µL of rat plasma. The analyte and internal standard (IS) were extracted from rat plasma by acetonitrile precipitation and they were separated on a reversed-phase C8 column with gradient program. The MS acquisition was performed with multiple reaction monitoring mode using m/z 430.2 to m/z 135.0 for analyte and m/z 448.2 to m/z 285.3 for IS. The calibration curves were linear over the range of 1-1000 ng/mL with the correlation coefficient greater than 0.999. With dilution integrity up to 20-fold, the upper limit of quantification was extendable up to 15,000 ng/mL. The method was successfully applied to the analysis of rat plasma samples after single dose oral administration of sarpogrelate at 5 mg/kg to rats for the determination of its pharmacokinetics. Following oral administration the maximum mean concentration in plasma (C(max), 11514 ng/mL) was achieved at 0.25 h (T(max)) and the area under curve (AUC0-24) was 11051 ± 3315 ng h/mL. The half-life (t(¹/2)) and clearance (Cl) were 2.9 ± 1.1 h and 490 ± 171 mL/h/kg, respectively. We believe that development of a method in rodent plasma would facilitate the ease of adaptability of sarpogrelate in human plasma.

High-performance liquid chromatographic method for the separation of enantiomeric gatifloxacin.

A high-performance liquid chromatographic method has been developed in normal-phase conditions for the separation of enantiomeric gatifloxacin, (+/-) 1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-quinoline-3-carboxylic acid, an antibiotic in bulk drug. The method involved the use of an amylose-based Chiralpak AD-H (150 mm x 4.6 mm, 5 microm) column using a mobile phase system containing n-hexane-ethanol-diethylamine (85:15:0.1% v/v). The conditions affording the best resolution were found by selection and variation of the mobile-phase compositions and the differences in separation capability of the method is noted. Relative standard deviation of retention times and peak areas were better than 0.2% and 0.4%, respectively, for precision. Gatifloxacin sample solution and mobile phase are found to be stable for at least 48 h.

Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometry.

Chemical neurotransmission has been the subject of intensive investigations in recent years. Acetylcholine is an essential neurotransmitter in the central nervous system as it has an effect on alertness, memory and learning. Enzymatic hydrolysis of acetylcholine in the synaptic cleft is fast and quickly metabolizes to choline and acetate by acetylcholinesterase. Hence the concentration in the extracellular fluid of the brain is low (0.1-6 nm). Techniques such as microdialysis are routinely employed to measure acetylcholine levels in living brain systems and the microdialysis sample volumes are usually less than 50 microL. In order to develop medicine for the diseases associated with cognitive dysfunction like mild cognitive impairment, Alzheimer's disease, schizophrenia and Parkinson's disease, or to study the mechanism of the illness, it is important to measure the concentration of acetylcholine in the extracellular fluid of the brain. Recently considerable attention has been focused on the development of chromatographic-mass spectrometric techniques to provide more sensitive and accurate quantification of acetylcholine collected from in-vivo brain microdialysis experiments. This review will provide a brief overview of acetylcholine biosynthesis, microdialysis technique and liquid chromatography mass spectrometry, which is being used to quantitate extracellular levels of acetylcholine.

Liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry method for the quantification of pregabalin in human plasma.

A sensitive high-performance liquid chromatography positive ion atmospheric pressure chemical ionization tandem mass spectrometry method was developed and validated for the quantification of pregabalin in human plasma. Following liquid-liquid extraction, the analyte was separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H](+) ions, m/z 160-142 for pregabalin and m/z 482-258 for the internal standard. The assay exhibited a linear dynamic range of 1-10,000ng/mL for pregabalin in human plasma. The lower limit of quantification was 1ng/mL with a relative standard deviation of less than 11.4%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 4.0min for each sample made it possible to analyze more than 300 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic studies.

Liquid chromatography-tandem mass spectrometry method for the quantification of dimebon in rat plasma and brain tissue.

A sensitive high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of dimebon in rat plasma and brain tissue. Following liquid-liquid extraction, the analyte was separated using a gradient mobile phase on a reversed phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H](+) ions, m/z 320-277 for dimebon and m/z 407-100 for the internal standard. The assay exhibited a linear dynamic range of 0.25-250 ng/mL for dimebon in rat plasma and brain tissue. Acceptable precision (<11%) and accuracy (100+/-7%) were obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample made it possible to analyze more than 250 samples per day. The method was successfully applied to quantify dimebon concentrations in a rodent pharmacokinetic study. Moreover, it can be believed that the assay method in rat plasma would facilitate the ease of adaptability of dimebon quantification in human plasma for clinical trials.

Sensitive liquid chromatography positive electrospray tandem mass spectrometry method for the quantitation of tegaserod in human plasma using liquid-liquid extraction.

A sensitive and rapid high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method is developed and validated for the quantitation of tegaserod in human plasma. Following liquid-liquid extraction, the analytes are separated using an isocratic mobile phase on a reversed-phase column and analyzed by tandem mass spectrometry in the multiple reaction monitoring mode using the respective (M+H)+ ions, m/z 302 to 173 for tegaserod and m/z 409 to 228 for the internal standard. The assay exhibits a linear dynamic range of 100-10000 pg/mL for tegaserod in human plasma. The lower limit of quantitation is 100 pg/mL with a relative standard deviation of less than 7%. Acceptable precision and accuracy are obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample makes it possible to analyze more than 250 human plasma samples per day. The validated method is successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability, or bioequivalence studies.

Simultaneous quantification of a non-nucleoside reverse transcriptase inhibitor efavirenz, a nucleoside reverse transcriptase inhibitor emtricitabine and a nucleotide reverse transcriptase inhibitor tenofovir in plasma by liquid chromatography positive ion electrospray tandem mass spectrometry.

A high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry method for the simultaneous quantification of efavirenz, emtricitabine and tenofovir was developed and validated with 100 microL human plasma. Following solid-phase extraction, the analytes were separated using a gradient mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 316 to 168 for efavirenz, m/z 248-130 for emtricitabine and m/z 288-176 for tenofovir, m/z 482-258 for rosuvastatin (IS), m/z 260-116 for propranolol (IS). The method exhibited a 100-fold linear dynamic range for all the three analytes in human plasma (20-2000, 2-200 and 20-2000 ng/mL for efavirenz, emtricitabine and tenofovir respectively). The lower limit of quantification was 2 ng/mL for emtricitabine and 20 ng/mL for both efavirenz and tenofovir with a relative standard deviation of less than 11%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time of 4 min for each sample made it possible to analyze more than 250 human plasma samples per day. The method is precise and sensitive enough for its intended purpose. The method is also successfully applied to quantify efavirenz, emtricitabine and tenofovir concentrations in a rodent pharmacokinetic study.

A simple and rapid method to collect the cerebrospinal fluid of rats and its application for the assessment of drug penetration into the central nervous system.

Many central nervous system (CNS) drug discovery programs require the successful collection of cerebrospinal fluid (CSF) for assessing CNS penetration and distribution of new chemical entities. The objective of the present investigation was to simplify the technique for collecting maximum CSF from cisterna magna of the rats. Rat was anesthetized with 5% halothane and positioned in a stereotaxic frame. The rat head was flexed downward at approximately 45 degrees , a depressible surface with the appearance of a rhomb between occipital protuberances and the spine of the atlas becomes visible. The 23 G needle was punctured into the cisterna magna for CSF collection without making any incision at this region. The blunt end of the needle was inserted into a 10 in. length of PE-50 tubing and other end of the tubing was connected to a collection syringe. The non-contaminated sample was drawn into the syringe by simple aspiration. This technique is simple and can be performed by one person. The technique has a greater than 95% success rate of CSF collection and it was free of red blood cell contamination. In addition, it yielded 100-120 microL of CSF per rat. This method is simple, effective, and easy to perform and has been successfully applied in preclinical screening of novel chemical entities in neuropharmacotherapy for CNS use. The present method is demonstrated by studying the CSF concentrations of carbamazepine and raclopride.

Enantiomeric separation of Linezolid by chiral reversed-phase liquid chromatography.

A chiral liquid chromatographic method is developed for the enantiomeric resolution of Linezolid, (S)(-)-N-[[-3-(3-fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl] methyl] acetamide, an antibiotic in bulk drugs. The enantiomers of Linezolid are resolved on a Chiralcel OJ-RH column using a mobile phase system containing 150mM di-sodium hydrogen phosphate buffer (pH 4.5)-acetonitrile (86:14, v/v). The resolution between the enantiomers is found to be two. The developed method is extensively validated and proved to be robust. The limit of detection and limit of quantification of (R)-enantiomers are found to be 94 and 375 ng/mL, respectively, for 10 microL injection volume. The percentage recovery of (R)-enantiomer is ranged from 98.9 to 102.9 in bulk drug samples of Linezolid. Linezolid sample solution and mobile phase are found to be stable for at least 48 h. The proposed method is found to be suitable and accurate for the quantitative determination of (R)-enantiomer in bulk drugs.

Sensitive liquid chromatography tandem mass spectrometry method for the quantification of Quetiapine in plasma.

A sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of quetiapine in rat plasma. Following liquid-liquid extraction, the analyte was separated using a gradient mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 384 to m/z 221 for quetiapine and m/z 327 to m/z 270 for the internal standard. The assay exhibited a linear dynamic range of 0.25-500 ng/mL for quetiapine in rat plasma. The lower limit of quantification was 0.25 ng/mL with a relative standard deviation of less than 7%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated method was successfully used to analyze rat plasma samples for application in pre-clinical pharmacokinetic studies. This method in rodent plasma could be adapted for quetiapine assay in human plasma.

Liquid chromatography tandem mass spectrometry method for the quantification of amisulpride with LLOQ of 100 pg/mL using 100 microL of plasma.

A sensitive and selective high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of amisulpride in 100 microL of human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective (M + H)(+) ions, m/z 370-242 for amisulpride and m/z 341-112 for the internal standard. The assay exhibited a linear dynamic range with a lower range of 0.1-100 ng/mL and a higher range of 1-500 ng/mL of amisulpride in human plasma. The lower limit of quantification was 0.1 ng/mL with a relative standard deviation of less than 10%. Acceptable precision and accuracy were obtained for both linearity ranges. A run time of 2.0 min for each sample made it possible to analyze more than 275 human plasma samples per day. The validated method has been successfully used to analyze plasma samples for application in pharmacokinetic studies.

Liquid chromatography tandem mass spectrometry method for the quantification of clonidine with LLOQ of 10 pg/mL in human plasma.

A sensitive high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of clonidine in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H](+) ions, m/z 230 to 44 for clonidine and m/z 254 to 44 for the internal standard. The assay exhibited a linear dynamic range of 10-2000 pg/mL for clonidine in human plasma. The lower limit of quantification was 10 pg/mL with a relative standard deviation of less than 6.8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample made it possible to analyze more than 250 human plasma samples per day. The validated method was successfully used to analyze human plasma samples for application in pharmacokinetic studies.

Sensitive liquid chromatography tandem mass spectrometry method for the quantification of sitagliptin, a DPP-4 inhibitor, in human plasma using liquid-liquid extraction.

A sensitive high-performance liquid chromatography-positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of sitagliptin, a DPP-4 inhibitor, in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H](+) ions, m/z 408-235 for sitagliptin and m/z 310-148 for the internal standard. The assay exhibited a linear dynamic range of 0.1-250 ng/mL for sitagliptin in human plasma. The lower limit of quantification was 0.1 ng/mL with a relative standard deviation of less than 6%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 300 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic studies.

Rapid and simple liquid chromatography tandem mass spectrometry method for the quantification of zidovudine in rat plasma.

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of zidovudine in rat plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reverse phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 268/127 for zidovudine and m/z 230/112 for the internal standard. The method exhibited a linear dynamic range of 5-500 ng/mL for zidovudine in rat plasma. The lower limit of quantification was 5 ng/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 plasma samples per day. The validated method was applied for pharmacokinetic studies of the novel drug delivery systems of zidovudine in rats.

Liquid chromatography tandem mass spectrometry method for the quantification of rimonabant, a CB1 receptor antagonist, in human plasma.

A sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of rimonabant in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective (M+H)+ ions, m/z 463-363 for rimonabant and m/z 408-235 for the internal standard. The assay exhibited a linear dynamic range of 0.1-100 ng/mL for rimonabant in human plasma. The lower limit of quantification was 0.1 ng/mL with a relative standard deviation of less than 6%. With dilution integrity up to 10-fold, the upper limit of quantification was extendable up to 1000 ng/mL. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 250 human plasma samples per day. The validated method was successfully used to analyze human plasma samples for application in pharmacokinetic studies.

Quantification of pramipexole in human plasma by liquid chromatography tandem mass spectrometry using tamsulosin as internal standard.

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of pramipexole in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H](+) ions, m/z 212/152 for pramipexole and m/z 409/228 for the IS. The method exhibited a linear dynamic range of 200-8000 pg/mL for pramipexole in human plasma. The lower limit of quantification was 200 pg/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 3.5 min for each sample made it possible to analyze more than 200 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.