Healthy Male Human Volunteers Research Articles

Glucose and lipopolysaccharide differentially regulate fibroblast growth factor 21 in healthy male human volunteers - Aprospective cross-over trial.

Fibroblast growth factor 21 (FGF21) affects the regulation of metabolism. Additionally, anti-inflammatory properties are attributed to FGF21, and studies in animals and humans show conflicting results. This study aimed to investigate how FGF21 is affected by glucose and lipopolysaccharide (LPS) in humans. Therefore, FGF21 was measured eight times at different time points within 48 h in this prospective cross-over trial after glucose and LPS on two different study days. The study included ten healthy, non-smoking male subjects aged 18-40. Repeated measures analysis of variance and paired t-test as post hoc analysis were applied. The administration of glucose and LPS resulted in a significant difference in regulating FGF21 (p< 0.001). After glucose administration, FGF21 declined sharply at 360 min, with a subsequent steep increase that exceeded baseline levels. LPS induced a drop in FGF21 after 180 min, while the baseline concentrations were not reached. After 180min and 24 h, a statistically significant difference was demonstrated after adjusting the Bonferroni-Holm method. So, our results support the hypothesis that glucose and LPS differentially affect the human expression of FGF21 over 48 h.

PHARMACOKINETIC DETERMINATION OF METHYLPREDNISOLONE IN INDIAN HEALTHY VOLUNTEERS BY LC-MS/MS

Methylprednisolone is a synthetic glucocorticoid. It relieves inflammation and uses to treat thyroid, colitis, allergies, asthma, and many more. This study aims to develop a bio-analytical method for measuring methylprednisolone in human plasma, accurate, sensitive, rapid, precise and simple. In this study, Propranolol used as an Internal Standard (IS). Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) instrument was used to identify and quantify the drug. Gradient conditions were used to establish the method; with a flow rate of 0.5 ml/min, we used 0.1 % formic acid in Milli-Q water and 0.1 % formic acid in methanol as mobile phases. A C18 Phenomenex Kinetex (50x3 mm, 5µ) column was used to isolate the analyte and the IS. The total chromatographic run time 7.0 min. The extraction of analyte and IS from plasma is done by a simple protein precipitation technique. The method was very selective and sensitive. Lower limit of quantification was 12.50 ng/ml. Linearity range between 12.50 ng/ml - 800ng/ml. The precision and accuracy results from 5 validation batches at five different concentration levels were well within acceptable ranges. The analyte was stable under different stability conditions. The developed method was found reproducible and very simple. The Retention Time of the analyte and IS was 3.53 min and 3.24 min, respectively. The methodology was validated in accordance with EMEA and USFDA regulations. The particular study has been carried out expertly on the pharmacokinetic study and BA/BE study in healthy human male volunteers. No Serious Adverse Events were noted in the clinical phase.

Transcutaneous Vagus Nerve Stimulation in Humans Induces Pupil Dilation and Attenuates Alpha Oscillations

Vagus nerve stimulation (VNS) is widely used to treat drug-resistant epilepsy and depression. While the precise mechanisms mediating its long-term therapeutic effects are not fully resolved, they likely involve locus coeruleus (LC) stimulation via the nucleus of the solitary tract, which receives afferent vagal inputs. In rats, VNS elevates LC firing and forebrain noradrenaline levels, whereas LC lesions suppress VNS therapeutic efficacy. Noninvasive transcutaneous VNS (tVNS) uses electrical stimulation that targets the auricular branch of the vagus nerve at the cymba conchae of the ear. However, the extent to which tVNS mimics VNS remains unclear. Here, we investigated the short-term effects of tVNS in healthy human male volunteers (n= 24), using high-density EEG and pupillometry during visual fixation at rest. We compared short (3.4 s) trials of tVNS to sham electrical stimulation at the earlobe (far from the vagus nerve branch) to control for somatosensory stimulation. Although tVNS and sham stimulation did not differ in subjective intensity ratings, tVNS led to robust pupil dilation (peaking 4–5 s after trial onset) that was significantly higher than following sham stimulation. We further quantified, using parallel factor analysis, how tVNS modulates idle occipital alpha (8–13Hz) activity identified in each participant. We found greater attenuation of alpha oscillations by tVNS than by sham stimulation. This demonstrates that tVNS reliably induces pupillary and EEG markers of arousal beyond the effects of somatosensory stimulation, thus supporting the hypothesis that tVNS elevates noradrenaline and other arousal-promoting neuromodulatory signaling, and mimics invasive VNS.SIGNIFICANCE STATEMENTCurrent noninvasive brain stimulation techniques are mostly confined to modulating cortical activity, as is typical with transcranial magnetic or transcranial direct/alternating current electrical stimulation. Transcutaneous vagus nerve stimulation (tVNS) has been proposed to stimulate subcortical arousal-promoting nuclei, though previous studies yielded inconsistent results. Here we show that short (3.4 s) tVNS pulses in naive healthy male volunteers induced transient pupil dilation and attenuation of occipital alpha oscillations. These markers of brain arousal are in line with the established effects of invasive VNS on locus coeruleus–noradrenaline signaling, and support that tVNS mimics VNS. Therefore, tVNS can be used as a tool for studying how endogenous subcortical neuromodulatory signaling affects human cognition, including perception, attention, memory, and decision-making; and also for developing novel clinical applications.

Enhanced oral bioavailability of diltiazem by resveratrol in healthy human subjects: An open-label, two-period, sequential study

Background: The purpose of this study was to investigate the bioavailability enhancing potential of resveratrol (RSV) on diltiazem (DLT) treatment in healthy human volunteers. Materials and Methods: An open-label, two-period, sequential study was conducted in 12 healthy human male volunteers. A single dose of RSV 500 mg was administered daily for 10 days during the treatment phase. A single dose of DLT 30 mg was administered during the control phase and after treatment phases under fasting conditions. The blood samples were collected at predetermined time intervals after DLT dosing and analyzed using high-performance liquid chromatography. Results: Treatment with RSV significantly enhanced maximum plasma concentration, area under the curve, whereas the volume of distribution and apparent clearance (CL/F) of DLT was significantly decreased when compared to control. Conclusions: The results suggested that enhanced bioavailability of DLT might be attributed by bio enhancing the potential of RSV resulted by inhibition of P-gp and CYP3A4. Further, the dosage of DLT should be readjusted when it is used concomitantly with RSV supplements or food containing RSV.

Influence of Altitude on Pulmonary Function A Comparative Study on Indian and Kyrgyz Healthy Males

Variation in lung function at high altitude (HA) impacts the working capacity of individuals and may predispose body towards hypoxia induced illness. So, we investigated the changes in pulmonary function of healthy human male volunteers belonging to two different ethnicities i.e. Indian and Kyrgyz. Twenty, age and BMI matched, volunteers (Indian=10 and Kyrgyz=10) were recruited for the study. Measurement for pulmonary functions (FVC, FEV1, FEV1/FVC ratio, PEF, FEF 25-75%, MEF 25%, MEF 50%, MEF 75%, MVV) were performed on each individual at basal (800 m) and high altitude (4,111 m) on day 3,7,14 and 21. Results indicate that Kyrgyz has comparatively higher FVC, FEV1, PEF and MVV values and lower FEV1/FVC ratio upon altitude induction than those of Indian counterparts. Mid expiratory flow FEF25-75% was significantly increased in Kyrgyz upon altitude induction indicate more proficient lung emptying while only moderate increase at day 7 in Indian. MEF25% was significantly increased in Kyrgyz, while no change is observed in Indians at high altitude which indicates that 75% of lung emptying through small airways is better in Kyrgyz. MEF 50% and MEF 75% increased with altitude in both groups. For MVV, the maximum increase was ~17% in Indian at HA14 (p&lt;0.01) and in Kyrgyz ~33% (p&lt;0.001) at HA14 as compared to basal. Difference in lung function response observed, indicates that Kyrgyz has better pulmonary dynamics during altitude exposure as compared to Indian counterparts. The varied result observed may be due to different ethnic origin of the groups.

The Effect of Chronic Alprazolam Intake on Memory, Attention, and Psychomotor Performance in Healthy Human Male Volunteers.

Alprazolam is used as an anxiolytic drug for generalized anxiety disorder and it has been reported to produce sedation and anterograde amnesia. In the current study, we randomly divided 26 healthy male volunteers into two groups: one group taking alprazolam 0.5 mg and the other taking placebo daily for two weeks. We utilized the Cambridge Neuropsychological Test Automated Battery (CANTAB) software to assess the chronic effect of alprazolam. We selected Paired Associates Learning (PAL) and Delayed Matching to Sample (DMS) tests for memory, Rapid Visual Information Processing (RVP) for attention, and Choice Reaction Time (CRT) for psychomotor performance twice: before starting the treatment and after the completion of the treatment. We found statistically significant impairment of visual memory in one parameter of PAL and three parameters of DMS in alprazolam group. The PAL mean trial to success and total correct matching in 0-second delay, 4-second delay, and all delay situation of DMS were impaired in alprazolam group. RVP total hits after two weeks of alprazolam treatment were improved in alprazolam group. But such differences were not observed in placebo group. In our study, we found that chronic administration of alprazolam affects memory but attentive and psychomotor performance remained unaffected.

The effect of five day dosing with THCV on THC-induced cognitive, psychological and physiological effects in healthy male human volunteers: A placebo-controlled, double-blind, crossover pilot trial.

Cannabis is mostly grown under illegal and unregulated circumstances, which seems to favour a product increasingly high in its main cannabinoid ∆-9-tetrahydrocannabinol (THC). ∆-9-tetrahydrocannabivarin (THCV) is a relatively untested cannabinoid which is said to be a cannabinoid receptor neutral antagonist, and may inhibit the effects of THC. To explore the safety and tolerability of repeated THCV administration and its effects on symptoms normally induced by THC in a sample of healthy volunteers. Ten male cannabis users (<25 use occasions) were recruited for this within-subjects, placebo-controlled, double-blind, cross-over pilot study. 10mg oral pure THCV or placebo were administered daily for five days, followed by 1mg intravenous THC on the fifth day. THCV was well tolerated and subjectively indistinguishable from placebo. THC did not significantly increase psychotic symptoms, paranoia or impair short-term memory, while still producing significant intoxicating effects. Delayed verbal recall was impaired by THC and only occurred under placebo condition (Z=-2.201, p=0.028), suggesting a protective effect of THCV. THCV also inhibited THC-induced increased heart rate (Z=-2.193, p=0.028). Nine out of ten participants reported THC under THCV condition (compared to placebo) to be subjectively weaker or less intense (χ(2)=6.4, p=0.011). THCV in combination with THC significantly increased memory intrusions (Z=-2.155, p=0.031). In this first study of THC and THCV, THCV inhibited some of the well-known effects of THC, while potentiating others. These findings need to be interpreted with caution due to a small sample size and lack of THC-induced psychotomimetic and memory-impairing effect, probably owing to the choice of dose.

&lt;i&gt;In vivo&lt;/i&gt; Evaluation of a Cosmetic Emulsion Containing Soybean Extract for Anti-Aging

Purpose: To develop and assess the anti-aging potential of a cosmetic W/O emulsion containing an extract of soybean, Glycine max (L.) Merr. Fabaceae. Methods: This single-blind placebo-controlled study was performed in 11 healthy male human volunteers. A formulation comprising of 4 % of concentrated extract of soybean was prepared by loading the extract in the internal aqueous phase of the emulsion. A control (base), consisting of the emulsion without the extract, was also prepared. Both formulations were applied to the cheeks of all volunteers for 12 weeks and their effect on different skin parameters, i.e., moisture contents, elasticity and surface evaluation of living skin (SELS) were assessed. Results: The formulation containing 4 % soybean extract showed significant (p ≤ 0.05) effects on skin elasticity and moisture contents but the base showed insignificant effect (p > 0.05). There was significant (p ≤ 0.05) decline in SELS, i.e., SEsc (skin scaliness, from 1.73 ± 0.05 to 1.66 ± 0.06), SEw (skin wrinkles, from 71.74 ± 1.52 to 68.51 ± 1.64), SEsm (skin smoothness, from 109.01 ± 4.77 to 102.03 ± 4.23), and SEr (skin roughness, from 4.04 ± 0.09 to 3.82 ± 0.08) parameters after application of the extract formulation for 12 weeks. Conclusion: Topical application of the cosmetic emulsion containing soybean extract exerts potential skin anti-aging effects.

Reactogenicity and immunogenicity of inactivated poliovirus vaccine produced from Sabin strains: A phase I Trial in healthy adults in Cuba

BackgroundTo ensure that developing countries have the option to produce inactivated poliovirus vaccine (IPV), the Global Polio Eradication Initiative has promoted the development of an IPV using Sabin poliovirus strains (Sabin IPV). This trial assessed the reactogenicity and immunogenicity of Sabin IPV and adjuvanted Sabin IPV in healthy adults in Cuba. MethodsThis is a randomized, controlled phase I trial, enrolling 60 healthy (previously vaccinated) male human volunteers, aged 19–23 years to receive one dose of either Sabin IPV (20:32:64 DU/dose), adjuvanted Sabin IPV (10:16:32 DU/dose), or conventional Salk IPV (40:8:32 DU/dose). The primary endpoint for reactogenicity relied on monitoring of adverse events. The secondary endpoint measured boosting immune responses (i.e. seroconversion or 4-fold rise) of poliovirus antibody, assessed by neutralization assays. ResultsSixty subjects fulfilled the study requirements. No serious adverse events reported were attributed to trial interventions during the 6-month follow-up period. Twenty-eight days after vaccination, boosting immune responses against poliovirus types 1–3 were between 90% and 100% in all vaccination groups. There was a more than 6-fold increase in median antibody titers between pre- and post-vaccination titers in all vaccination groups. DiscussionBoth Sabin IPV and adjuvanted Sabin IPV were well tolerated and immunogenic against all poliovirus serotypes. This result suggests that the aluminum adjuvant may allow a 50% (or higher) dose reduction.

Quantification of dapaconazole in human plasma using high-performance liquid chromatography coupled to tandem mass spectrometry: Application to a phase I study

A simple, selective and sensitive method based on high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) has been developed for the determination of dapaconazole in human plasma using tioconazole as internal standard. The drugs were extracted from plasma by liquid-liquid extraction with ether/hexane (80/20, v/v). The chromatography separation was performed on a Genesis(®) C18 reversed phase analytical column 4μm (100×2.1mm i.d.) with a mobile phase of methanol/acetonitrile/water (80/10/10, v/v/v)+ammonium acetate (0.5mM). Dapaconazole was quantified using a mass spectrometer with an electrospray source in the ESI positive mode (ES+) configured for multiple reaction monitoring (MRM) to monitor the transitions 415.1>159.2 and 387.0>131.0 for dapaconazole and tioconazole, respectively. The method had a chromatography run time of 3.8min and a linear calibration curve over the range 0.2-100ng/mL (r=0.9998). The lower limit of quantification (LLOQ) was 0.2ng/mL. The precision and accuracy values of the assay were within ±10%. The stability tests indicate no significant degradation under the conditions of the experiment. This method was used for a phase I study of topical administration of dapaconazole tosylate in healthy human male volunteers.

High‐performance liquid chromatography tandem mass spectrometry method for quantification of endothelin receptor antagonist drug, ambrisentan, in human plasma and its application in a pharmacokinetic study

A simple and sensitive liquid chromatography tandem mass spectrometry method has been developed for the quantification of ambrisentan (AMB) in human plasma using midazolam (MID) as an internal standard (IS). Chromatographic separation was performed using a Beta Basic-8 (50 × 4.6 mm, 5 µm) column with an isocratic mobile phase. AMB and MID were detected with proton adducts at m/z 379.09 → 303.12 and 326.15 → 291.14 in multiple reaction monitoring-positive mode, respectively. A solid-phase extraction method was used for extraction of the analyte and IS from the plasma samples. The method was shown to be reproducible and reliable with within-run precision <11%, between-run precision <14% and linear concentration range from 10.0 to 2000.2 ng/mL, with a correlation coefficient (r(2) ) of >0.995. The method was successfully applied to a pharmacokinetic study of oral administration of AMB (10 mg) in 24 healthy Indian male human volunteers under fasting conditions.

Resveratrol Enhances the Bioavailability of Fexofenadine in Healthy Human Male Volunteers: Involvement of P-Glycoprotein Inhibition

Objective: The purpose of the present study was to assess the influence ofresveratrol onP-glycoprotein mediated drug disposition in humans using fexofenadine as a P-glycoprotein substrate. Methods: A non-blinded, an open label crossover study was conducted in twelve healthy male volunteers aged between 26 and 31 years. A single dose of fexofenadine hydrochloride 120 mg was given to volunteers during control phase and treatment phases. A single dose of resveratrol 500 mg was given to volunteers once daily for period of 10 days. The blood samples were collected at predetermined time intervals during control and treatment phases. The plasma samples containing fexofenadine hydrochloridewere analyzed by LC-MS/MS. The pharmacokinetic parameters were computed by non-compartmental method and the mean pharmacokinetic parameter differences during control and treatment phases were assessed. Results: Treatment with resveratrol significantly increased thearea under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) offexofenadine to 76.7%(2520.92.48 versus 4454.48 ng.h/mL) and 65.2% (415.08 versus 685.58 ng/mL)respectively when compared to control phase. On other hand, apparentoral clearance (CL/F) and apparent volume of distribution (Vd/F) of fexofenadine were significantly decreased by 42.6% (49.46 versus 28.37 L/h) and 42.1 % (591.73 versus 342.62 L) respectively. However, there was no significant change was observed in T1/2, Kel and Tmaxof fexofenadine upon treatment with resveratrol when compared to control phase. Conclusion: The results of the present study showed that multiple doses of resveratrolenhanced the bioavailability of fexofenadine probably by the inhibition of P-glycoprotein mediated drug efflux in humans.

Effect of Carum carvi, a herbal bioenhancer on pharmacokinetics of antitubercular drugs: A study in healthy human volunteers.

Aim and Objectives:The present study was undertaken in 20 healthy human volunteers to evaluate the effect of a herbal bioenhancer, Carum carvi on pharmacokinetics of rifampicin, isoniazid, and pyrazinamide in fixed dose combination (FDC).Materials and Methods:It was a prospective, two-period, open-label, cross-over experiment on 20 healthy human male volunteers. The volunteers were administered a single dose of FDC containing rifampicin (450 mg), isoniazid (300 mg), and pyrazinamide (1000 mg) and after 10 days washout period the same FDC along with C. carvi extract (100 mg) was administered. Blood samples were collected at different time-points and analyzed by high-performance liquid chromatography (HPLC). Detailed pharmacokinetic parameters were calculated, which included Cmax, area under curve (AUC), time to reach maximum plasma concentration (Tmax), clearance (Cl), volume of distribution (Vd), and half-life (t½).Results:Additions of C. carvi extract lead to increase in plasma levels of rifampicin, isoniazid, and pyrazinamide. The bioavailability indices Cmax of rifampicin increased from 4.57 ± 0.19 to 5.95 ± 0.19 (P = 0.000) and AUC increased from 40.11 ± 1.69 to 53.01 ± 1.88 (P = 0.000). Similarly, Cmax of isoniazid increased from 2.66 ± 0.16 to 3.62 ± 0.16 (P = 0.000) and AUC from 17.72 ± 0.78 to 22.87 ± 0.94 (P = 0.000). The bioavailability indices of pyrazinamide also revealed an increase in Cmax from 18.81 ± 0.79 to 25.06 ± 1.14 (P = 0.000) and AUC from 107.65 ± 4.42 to 137.71 ± 5.92 (P = 0.000), respectively.Conclusion:C. carvi acts as a bioenhancer and modifies the kinetics of antitubercular treatment (ATT) favorably.

Evaluation of peripheral blood microsampling techniques in combination with liquid chromatography‐high resolution mass spectrometry for the determination of drug pharmacokinetics in clinical studies

New bioanalytical assays were developed, validated, and applied in a clinical study for quantitative measurement of acetaminophen concentrations in blood and plasma samples. Furthermore, after validation, the bioanalytical assays were used for determination of pharmacokinetics within a group of six healthy male human volunteers after admission of a single oral dose of 500 mg of acetaminophen. Quantitative analyses were done by means of liquid chromatography-high resolution mass spectrometry and blood samples were collected at various sampling time points using different peripheral blood microsampling techniques. Post-dose peripheral collected blood samples were applied for the preparation of dry blood spots, dried matrix on paper discs, and peripheral plasma. Pharmacokinetic parameters determined were clearance (Cl), area under the curve (AUC), volume of distribution (Vd ), peak concentration (Cmax ), time of occurrence of peak concentration (Tmax ) and half-life time (T½ ). Observed pharmacokinetic values were not statistically (ANOVA) different compared to in literature reported values based on venous blood collection. The present pilot study demonstrated the feasibility of peripheral blood microsampling techniques in combination with quantitative liquid chromatography-high resolution mass spectrometry analysis for the determination of pharmacokinetics in clinical studies.

Oligonol Supplementation Attenuates Body Temperature and the Circulating Levels of Prostaglandin E2and Cyclooxygenase-2 After Heat Stress in Humans

Oligonol, a phenolic production from lychee, has been reported to exhibit anti-oxidative and anti-inflammatory effects. This study investigated the effect of Oligonol supplementation on circulating levels of prostaglandin E2 (PGE2) and cyclooxygenase (COX)-2, as well as body temperature, after heat stress in 17 healthy human male volunteers (age, 21.6±2.1 years). All experiments were performed in an automated climate chamber (26.0°C±0.5°C, relative humidity 60%±3.0%, air velocity less than 1 m/sec) between 2 and 5 p.m. Subjects ingested an Oligonol (100 mg)-containing beverage or placebo beverage before half-body immersion into hot water (42°C±0.5°C for 30 min). Tympanic and skin temperatures were measured and mean body temperatures were calculated. Serum concentrations of PGE2 and COX-2 were analyzed before, immediately after, and 60 min after immersion. Oligonol intake significantly prevented elevation of tympanic (temperature difference: 0.17°C at Post, P<.05; 0.17°C at Re-60, P<.05) and mean body temperatures (temperature difference: 0.18°C at Post, P<.05; 0.15°C at Re-60, P<.05), and lowered concentrations of serum PGE2 (increased by 13.3% vs. 29.6% at Post, P<.05) and COX-2 (increased by 15.6% vs. 21.8% at Post, P<.05), compared to placebo beverage. Our result suggests that Oligonol has the potential to suppress increases in body temperature under heat stress, and this is associated with decreases in serum levels of PGE2 and COX-2.

Heat acclimation affects circulating levels of prostaglandin E2, COX-2 and orexin in humans

We examined serum levels of prostaglandin E2 (PGE2), cyclooxygenase (COX)-2 and orexin before and after heat acclimation (HA) to test the hypothesis that decreased basal body temperature due to HA correlate with circulating levels of these key thermoregulatory molecules. Nine healthy human male volunteers were recruited (age, 21.9±2.7 years). The subjects were exposed to half-body immersion in hot water (42±0.5°C) at the same time of day (2–5p.m.) on alternate days for 3 weeks. The HA protocol included 10 bouts of 30min immersion. All experiments were performed in an automated climate chamber (temperature, 26.0±0.5°C; relative humidity, 60±3.0%; air velocity, <1m/s). Tympanic and skin temperatures were measured, and mean body temperature was calculated. The difference in body weight was used to estimate total sweat loss. Serum levels of PGE2, COX-2 and orexin were analyzed before and after HA. Body temperature decreased significantly (P<0.05) after HA, whereas sweat volume increased significantly (P<0.01). Serum PGE2, COX-2 and orexin concentrations decreased significantly compared to those at pre-acclimation (P<0.001, P<0.01, P<0.01, respectively). Our data suggest that decreased basal body temperature after HA is associated with decreases in thermoregulatory molecules, such as PGE2, COX-2 and orexin.

Liquid chromatography–tandem mass spectrometry method for simultaneous quantification of urapidil and aripiprazole in human plasma and its application to human pharmacokinetic study

A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of urapidil and aripiprazole in human plasma. A simple liquid-liquid extraction with ethyl acetate was used for the sample preparation. Chromatographic separation was achieved on a Phenomenex C18 (4.6 × 50 mm, 5 µm) column with 0.1% formic acid-acetonitrile (10:90, v/v) as the mobile phase with flow rate of 0.6 mL/min. The quantitation of the target compounds was determined in a positive ion multiple reaction monitoring mode. Calibration plots were linear over the range of 2.0-2503.95 ng/mL for urapidil and 1.0-500.19 ng/mL for aripiprazole. The lower limit of quantitation for urapidil and aripiprazole was 2.0 and 1.0 ng/mL, respectively. Mean recovery was in the range of 69.94-75.62% for both analytes and internal standards. Intra-day and inter-day precisions of the assay at three concentrations were 2.56-5.89% with accuracy of 92.31-97.83% for urapidil, and 3.14-6.84% with accuracy of 91.38-94.42% for aripiprazole. The method was successfully applied to human pharmacokinetic study of urapidil and aripiprazole in healthy human male volunteers.

A new and simple HPLC method for determination of etamsylate in human plasma and its application to pharmacokinetic study in healthy adult male volunteers

A new and simple HPLC assay method was developed and validated for the determination of etamsylate in human plasma. After protein precipitation with 6% perchloric acid, satisfactory separation was achieved on a HyPURITY C18 column (250mm×4.6mm, 5μm) using a mobile phase comprising 20mM sodium dihydrogen phosphate-2 hydrate (pH was adjusted to 3.5 by phosphoric acid) and acetonitrile at a ratio of 95:5 v/v. The elution was isocratic at ambient temperature with a flow rate of 0.75ml/min. Allopurinol was used as internal standard. The calibration curve was linear over the range from 0.25 to 20μg/ml (r2=0.999). The limit of quantification for etamsylate in plasma was 0.25μg/ml. The within day coefficient of variance (%CV) ranged from 3.9% to 10.2%, whereas the between-day %CV ranged from 3.1% to 8.7%. The assay method has been successfully used to estimate the pharmacokinetics of etamsylate after oral administration of a 500mg tablet under fasting conditions to 24 healthy Egyptian human male volunteers. Various pharmacokinetic parameters including AUC0–t, AUC0–∞, Cmax, Tmax, t1/2, MRT, Cl/F, and Vd/F were determined from plasma concentration–time profile of etamsylate.

Application of Key Events Dose Response Framework to Defining the Upper Intake Level of Leucine in Young Men1–4

Leucine is sold in large doses in health food stores and is ingested by weight-training athletes. The safety of ingestion of large doses of leucine is unknown. Before designing chronic high-dose leucine supplementation experiments, we decided to determine the effect of graded doses of leucine in healthy participants. The Key Events Dose Response Framework is an organizational and analytical framework that dissects the various biologic steps (key events) that occur between exposure to a substance and an eventual adverse effect. Each biologic event is looked at for its unique dose-response characteristics. For nutrients, there are a number of biologic homeostatic mechanisms that work to keep circulating/tissue levels in a safe, nontoxic range. If a response mechanism at a particular key event is especially vulnerable and easily overwhelmed, this is known as a determining event, because this event drives the overall slope or shape of the dose-response relationship. In this paper, the Key Events Dose Framework has been applied to the problem of leucine toxicity and leucine’s tolerable upper level. After analyzing the experimental data vis a vis key events for leucine leading to toxicity, it became evident that the rate of leucine oxidation was the determining event. A dose-response study has been conducted to graded intakes of leucine in healthy human adult male volunteers. All participants were started at the mean requirement level of leucine [50 mg/(kg · d)] and the highest leucine intake was 1250 mg/( kg · d), which is 25 times the mean requirement. No gut intolerance was seen. Blood glucose fell progressively but remained within normal values without any changes in plasma insulin. Maximal leucine oxidation levels occurred at an intake of 550 mg leucine/( kg · d), after which plasma leucine progressively increased and plasma ammonia also increased in response to leucine intakes >500 mg/( kg · d). Thus, the “key determining event” appears to be when the participants reach their maximal leucine oxidation level, after which the risk of metabolic adverse effects progressively increased.

Whole-body distribution and radiation dosimetry of [11C]telmisartan as a biomarker for hepatic organic anion transporting polypeptide (OATP) 1B3

Telmisartan, a nonpeptide angiotensin II AT1 receptor antagonist used as an antihypertensive drug, is specifically taken up by the liver through the OATP1B3. PET imaging with [(11)C]telmisartan is expected to provide information about the whole body pharmacokinetics of telmisartan as well as its transport property by OATP1B3. The purpose of the study was to determine the biodistribution and radiation dosimetry of [(11)C]telmisartan in humans. Biodistribution of [(11)C]telmisartan was measured in three rats and six healthy male human volunteers. In the rat study, a dynamic emission scan was performed for 90 min. In the human study, dynamic whole-body PET images were acquired after intravenous injection of [(11)C]telmisartan. ROIs were defined for source organs on the PET images to measure time-course of [(11)C]telmisartan uptake as percentage injected dose and the number of disintegration for each organ. Radiation dosimetry was calculated with OLINDA/EXM. In the rat study, most radioactivity was rapidly taken up by the liver and part of it was excreted into the biliary tract and intestine. Extrapolating from the rat data, the effective dose for the adult human being was estimated to be 3.65±0.01 microSv/MBq (n=3). In the human study, most of the tracer was taken up by the liver as well, although not as rapidly as in the rat. The activity in the gall bladder and intestine increased gradually. The effective dose for the adult human being was 4.24±0.09 microSv/MBq (n=6). [(11)C]Telmisartan is a safe PET tracer with a dosimetry profile comparable to other common (11)C PET tracers.