Effect of Nigella sativa oil on pharmacokinetics and pharmacodynamics of gliclazide in rats.

Nigella sativa oil (NSO) has been used widely for its putative anti-hyperglycemic activity. However, little is known about its potential effect on the pharmacokinetics and pharmacodynamics of antidiabetic drugs, including gliclazide. This study aimed to investigate herb-drug interactions between gliclazide and NSO in rats. Plasma concentrations of gliclazide (single oral and intravenous dose of 33 and 26.4 mg/kg, respectively) in the presence and absence of co-administration with NSO (52 mg/kg per oral) were quantified in healthy and insulin resistant rats (n = 5 for each group). Physiological and treatment-related factors were evaluated as potential influential covariates using a population pharmacokinetic modeling approach (NONMEM version 7.4). Clearance, volume of distribution and bioavailability of gliclazide were unaffected by disease state (healthy or insulin resistant). The concomitant administration of NSO resulted in higher systemic exposures of gliclazide by modulating bioavailability (29% increase) and clearance (20% decrease) of the drug. A model-independent analysis highlighted that pre-treatment with NSO in healthy rats was associated with a higher glucose lowering effect by up to 50% compared with that of gliclazide monotherapy, but not of insulin resistant rats. Although a similar trend in glucose reductions was not observed in insulin resistant rats, co-administration of NSO improved the sensitivity to insulin of this rat population. Natural product-drug interaction between gliclazide and NSO merits further evaluation of its clinical importance.

Correlation between gut microbiota composition, enteric infections and linear growth impairment: a case-control study in childhood stunting in Pidie, Aceh, Indonesia.

BACKGROUND: Gut microbiota is pivotal in maintaining children's health and well-being. The ingestion of enteric pathogens and dysbiosis lead to Environmental Enteric Dysfunction (EED), which is essential in stunting pathogenesis. The roles of gut microbiome and enteric infections have not been explored comprehensively in relation to childhood stunting in Indonesia. This study aimed to determine the correlation between gut microbiota composition, enteric infections, and growth biomarker, Insulin-like Growth Factor 1 (IGF-1), in stunted children from Pidie, Aceh, Indonesia. METHODS: This study was a case-control study involving 42 subjects aged 24 to 59 months, comprising 21 stunted children for the case and 21 normal children for the control group. The IGF-1 serum level was quantified using ELISA. The gut microbiome profiling was conducted using 16S rDNA amplicon sequencing. The expression of enteric pathogens virulence genes was determined using quantitative PCR (qPCR) assay. The correlations of observed variables were analysed using suitable statistical analyses. RESULTS: The result showed that the IGF-1 sera levels in stunted were lower than those in normal children (p ≤ 0.001). The abundance of Firmicutes (50%) was higher than Bacteroidetes (34%) in stunted children. The gut microbiome profile of stunted children showed enriched genera such as Blautia, Dorea, Collinsella, Streptococcus, Clostridium sensu stricto 13, Asteroleplasma and Anaerostipes. Meanwhile the depleted genera comprised Prevotella, Lactococcus, Butyrivibrio, Muribaculaceae, Alloprevotella, Akkermansia, Enterococcus, Terrisporobacter and Turicibacter. The abundance of water biological contaminants such as Aeromonas, Stappiaceae, and Synechococcus was also higher in stunted children compared to normal children. The virulence genes expression of Enteroaggregative Escherichia coli (aaiC), Enterotoxigenic E. coli (estA), Enteropathogenic E. coli (eaeA), Shigella/Enteroinvasive E. coli (ipaH3) and Salmonella enterica (ompC) in stunted was higher than in normal children (p ≤ 0.001), which negatively correlated to height and level of IGF-1. CONCLUSION: The present study showed the distinctive gut microbiome profile of stunted and normal children from Pidie, Aceh, Indonesia. The gut microbiota of stunted children revealed dysbiosis, comprised several pro-inflammatory, metabolic abnormalities and high-fat/low-fiber diet-related taxa, and expressed virulence genes of enteric pathogens. These findings provide evidence that it is imperative to restore dysbiosis and preserve the balance of gut microbiota to support linear growth in children.

Simultaneous HPLC Assay of Gliclazide and Ciprofloxacin in Plasma and its Implementation for Pharmacokinetic Study in Rats.

A simple and reliable high-performance liquid chromatography method for simultaneous quantitation of gliclazide and ciprofloxacin in plasma sample has been developed and validated. This method implements protein precipitation, a simple and practical pretreatment method by the addition of acetonitrile that gives a clean supernatant. The separation was carried out in a system consisted of a C18 column with acetonitrile and KH2PO4 (0.01 M, 0.1% v/v of triethylamine, pH 2.7) as the mobile phase in a gradient elution at a total flow-rate of 1 mL/min. Gliclazide and ciprofloxacin were quantitated using an ultraviolet detector set at wavelengths of 229 and 277 nm, respectively, which ensures optimal sensitivity for both compounds. This method possesses an excellent linearity at concentration ranges of 0.5-50 mg/L for gliclazide and 0.1-10 mg/L for ciprofloxacin. High within- and between-run accuracy for both gliclazide (% error of -8.00 to 0.45%) and ciprofloxacin (% error of -10.00 to 7.63%) were demonstrated. The intra- and inter-day precision (expressed as %CV) was <8 and 12% for gliclazide and ciprofloxacin, respectively. Both analytes were stable during storage and sample processing. The method reported in this study can be implemented for pharmacokinetic interaction study in rats.

Imaging of cyclosporine inhibition of P-glycoprotein activity using 11C-verapamil in the brain: studies of healthy humans.

UNLABELLED: The multiple-drug resistance (MDR) transporter P-glycoprotein (P-gp) is highly expressed at the human blood-brain barrier (BBB). P-gp actively effluxes a wide variety of drugs from the central nervous system, including anticancer drugs. We have previously demonstrated P-gp activity at the human BBB using PET of (11)C-verapamil distribution into the brain in the absence and presence of the P-gp inhibitor cyclosporine-A (CsA). Here we extend the initial noncompartmental analysis of these data and apply compartmental modeling to these human verapamil imaging studies. METHODS: Healthy volunteers were injected with (15)O-water to assess blood flow, followed by (11)C-verapamil to assess BBB P-gp activity. Arterial blood samples and PET images were obtained at frequent intervals for 5 and 45 min, respectively, after injection. After a 60-min infusion of CsA (intravenously, 2.5 mg/kg/h) to inhibit P-gp, a second set of water and verapamil PET studies was conducted, followed by (11)C-CO imaging to measure regional blood volume. Blood flow was estimated using dynamic (15)O-water data and a flow-dispersion model. Dynamic (11)C-verapamil data were assessed by a 2-tissue-compartment (2C) model of delivery and retention and a 1-tissue-compartment model using the first 10 min of data (1C(10)). RESULTS: The 2C model was able to fit the full dataset both before and during P-pg inhibition. CsA modulation of P-gp increased blood-brain transfer (K(1)) of verapamil into the brain by 73% (range, 30%-118%; n = 12). This increase was significantly greater than changes in blood flow (13%; range, 12%-49%; n = 12, P < 0.001). Estimates of K(1) from the 1C(10) model correlated to estimates from the 2C model (r = 0.99, n = 12), indicating that a short study could effectively estimate P-gp activity. CONCLUSION: (11)C-verapamil and compartmental analysis can estimate P-gp activity at the BBB by imaging before and during P-gp inhibition by CsA, indicated by a change in verapamil transport (K(1)). Inhibition of P-gp unmasks verapamil trapping in brain tissue that requires a 2C model for long imaging times; however, transport can be effectively measured using a short scan time with a 1C(10) model, avoiding complications with labeled metabolites and tracer retention.

Rapid solid-phase extraction method to quantify [(11)C]-verapamil, and its [(11)C]-metabolites, in human and macaque plasma.

INTRODUCTION: P-glycoprotein (P-gp), an efflux transporter, is a significant barrier to drug entry into the brain and the fetus. The positron emission tomography (PET) ligand, [(11)C]-verapamil, has been used to measure in vivo P-gp activity at various tissue-blood barriers of humans and animals. Since verapamil is extensively metabolized in vivo, it is important to quantify the extent of verapamil metabolism in order to interpret such P-gp activity. Therefore, we developed a rapid solid-phase extraction (SPE) method to separate, and then quantify, verapamil and its radiolabeled metabolites in plasma. METHODS: Using high-performance liquid chromatography (HPLC), we established that the major identifiable circulating radioactive metabolite of [(11)C]-verapamil in plasma of humans and the nonhuman primate, Macaca nemestrina, was [(11)C]-D-617/717. Using sequential and differential pH elution on C(8) SPE cartridges, we developed a rapid method to separate [(11)C]-verapamil and [(11)C]-D-617/717. Recovery was measured by spiking the samples with the corresponding nonradioactive compounds and assaying these compounds by HPLC. RESULTS: Verapamil and D-617/717 recovery with the SPE method was >85%. When the method was applied to PET studies in humans and nonhuman primates, significant plasma concentration of D-617/717 and unknown polar metabolite(s) were observed. The SPE and the HPLC methods were not significantly different in the quantification of verapamil and D-617/717. CONCLUSIONS: The SPE method simultaneously processes multiple samples in less than 5 min. Given the short half-life of [(11)C], this method provides a valuable tool to rapidly determine the concentration of [(11)C]-verapamil and its [(11)C]-metabolites in human and nonhuman primate plasma.

Six-Month Chronic Toxicity Study of Tamarind Pulp (Tamarindus indica L.) Water Extract.

Tamarind water extract has been shown to demonstrate an anti-obesity effect. In this research, long-term use of tamarind pulp water extract safety was evaluated. Tamarind pulp was extracted by reflux method, followed by freeze-drying to obtain dry extract. Wistar rats were divided into six groups, with 20 animals of each sex per group. The control group and satellite control group received carboxymethylcellulose sodium (CMC-Na) 0.5% 1 mL/100 g bw (body weight) per day. Treatment groups received tamarind pulp extract at doses of 75, 200, 1000, satellite 1000 mg/kg bw per day for six months. After six months, control groups and the treatment group were sacrificed. Satellite groups were sacrificed one month later. Relative organ weights, hematology and clinical biochemistry profiles were determined. After six months, there were no significant change in body weight, hematologic, and clinical biochemistry profiles of the tested group. Body weight of male rats in the satellite 1000 mg/kg bw group was significantly increased in week 30 compared to the satellite control group (p < 0.05). The relative spleen weight of female rats of the 200 mg/kg bw group was reduced (p < 0.05). The relative kidney weight of male rats in the 1000 mg/kg bw group was increased (p < 0.05). This study showed that tamarind pulp extract was generally safe and well tolerated at the tested dose.

Imaging P-glycoprotein transport activity at the human blood-brain barrier with positron emission tomography.

BACKGROUND: Numerous knockout mouse studies have revealed that P-glycoprotein (P-gp) significantly limits drug distribution across the mouse blood-brain barrier (BBB). To determine the importance of P-gp at the human BBB, we developed a state-of-the-art, noninvasive, quantitative imaging technique to measure P-gp activity by use of carbon 11-labeled verapamil as the P-gp substrate and cyclosporine (INN, ciclosporin) as the P-gp inhibitor. METHODS: In brief, 11C-verapamil (approximately 0.2 mCi/kg) was administered to healthy volunteers (n = 12 [6 women and 6 men]) as an intravenous infusion over a period of approximately 1 minute before and after at least a 1-hour infusion of cyclosporine (2.5 mg x kg(-1) x h(-1)). Arterial blood samples and brain positron emission tomography images were obtained at frequent intervals for 45 minutes. Both blood and plasma radioactivity contents were determined in each verapamil sample. The content of verapamil and its metabolites in the 20- and 45-minute plasma samples was determined by a rapid solid-phase extraction method. The brain uptake of 11C-radioactivity (brain area under the curve [AUCbrain ]/blood area under the curve [AUCblood]) was determined in the presence and absence of cyclosporine. RESULTS: The AUCbrain/AUCblood ratio of 11C-radioactivity was increased by 88% +/- 20% (1.02 +/- 0.18 versus 0.55 +/- 0.10, P < .001) in the presence of cyclosporine (mean blood concentration, 2.8 +/- 0.4 micromol/L) without affecting 11C-verapamil metabolism or plasma protein binding. The corresponding increases for the brain white and gray matter were 84% +/- 13% and 84% +/- 18%, respectively. CONCLUSIONS: This is the first time that P-gp activity at the human BBB has been measured. The modest inhibition of human BBB P-gp by cyclosporine has implications for P-gp-based drug interactions at the human BBB. Our method for imaging P-gp activity can be used to identify multidrug-resistant tumors or to determine the contribution of P-gp polymorphism, inhibition, or induction to interindividual variability in drug response.

Muscle distribution of the neuromuscular blocker gallamine using microdialysis.

Measurement of drug concentrations in target tissue has the potential to provide insight into the pharmacokinetics and pharmacodynamics of a drug. In this study, the distribution of the neuromuscular blocker, gallamine, into muscle tissue was investigated in urethane-anesthetized rats after an intravenous bolus dose (6 mg/kg). Microdialysis sampling was used to continuously determine gallamine concentrations in muscle interstitial fluid (MIF). In vivo microdialysis recovery of gallamine was determined as the relative loss of gallamine from the perfusate into muscle tissue after perfusion with gallamine (2 microg/mL). Recovery was determined in each rat before the pharmacokinetic studies. Terminal muscle sampling followed by homogenization was also performed to examine gallamine distribution within muscle tissue. All samples were assayed for gallamine using a validated high-performance liquid chromatography assay. Gallamine was rapidly distributed into MIF with a MIF-plasma partition coefficient of 0.9 +/- 0.1 (n = 6). By contrast, the estimated gallamine concentration in muscle tissue homogenate was only 23 +/- 5% (n = 5) of the concentration in MIF as estimated by microdialysis sampling at the terminal sampling time. These findings suggest that gallamine is not distributed uniformly within muscle but selectively distributes into MIF. Simulations using a hybrid physiologically based pharmacokinetic model which describes uptake of drug only into the interstitial space showed good agreement between predicted and observed concentration data obtained from microdialysis sampling, supporting the findings that gallamine selectively distributes into MIF. These studies demonstrate microdialysis combined with conventional terminal tissue sampling provides valuable information on intra-tissue drug distribution.

Comparative bioavailability of two irbesartan/hydrochlorothiazide tablet formulations in Indonesian healthy subjects.

AIM: The bioavailability of two 300 mg irbesartan (CAS 138402-11-6)/12.5 mg hydrochlorothiazide (CAS 58-93-5) tablet formulations was compared, using Co-Ir-vell tablets as test formulation and the originator product as reference formulation. METHODS: Twenty-four subjects were included in this single-dose, open-label, randomized two-way crossover study following an overnight fasting. A two-week wash-out period was applied. Blood samples were drawn up to 48 h following drug administrations. Irbesartan and hydrochlorothiazide plasma concentrations were determined by liquid chromatography-tandem mass spectrometry method with TurboIonSpray mode. Pharmacokinetic parameters AUC(0-t), AUC(0-infinity), Cmax and t were determined and used for bioequivalence evaluation after log-transformation, whereas t max ratios were evaluated non-parametrically. RESULTS: The estimated point and 90% confidence intervals (CI) for AUC(0-t), AUC(0-infinity), Cmax and t for irbesartan were 97.74% (85.40-111.86%), 96.36% (83.25-111.55%), 103.30% (90.65-117.71%), 92.38% (82.68-103.21%) and for hydrochlorothiazide, 106.30% (97.72-115.63%), 106.28% (98.14-115.10%), 108.01% (95.48-122.18%), 105.52% (96.70-115.14%), respectively. CONCLUSION: These results indicated that the two formulations of irbesartan/hydrochlorothiazide were bioequivalent; therefore they may be prescribed interchangeably.

Simultaneous quantification of losartan and active metabolite in human plasma by liquid chromatography-tandem mass spectrometry using irbesartan as internal standard.

A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method employing electronspray ionization was developed and validated for quantification of losartan and its carboxylic acid metabolite in human plasma using irbesartan as internal standard (IS). Following a simple pretreatment procedure, the analytes were separated using a gradient mobile phase on reverse phase C18 column. Selected reaction monitoring was specific for losartan, losartan acid and irbesartan. The method validation demonstrated the specificity, lower limit of quantification, accuracy and precision of measurements. The assay exhibited a linear dynamic range of 2.0-400 ng/mL for losartan and 1.85-370 ng/mL for losartan acid. A run time of 3.5 min for each sample made it possible to analyze more than 200 samples per day. The validated method has been successfully used to analyze human plasma samples for application in bioavailability/bioequivalence studies.

Comparative bioavailability of two dexamethasone tablet formulations in Indonesian healthy volunteers.

AIM: To compare the bioavailability of two dexamethasone (CAS 50-02-2) tablet formulations -- 4 mg Dexmethsone tablets as test formulation and 4 mg tablets of the originator product as reference formulation. METHODS: The study was conducted according to an open-label, randomized two-way crossover design with a one-week washout period. Twenty-four volunteers received a single dose of two tablets of the two different dexamethasone formulations. Blood samples for pharmacokinetic profiling were taken up to 24 h after drug administration in fasting condition. Plasma concentrations of dexamethasone were determined with a validated HPLC method using an ultraviolet detector. Pharmacokinetic parameters were calculated from observed plasma concentration-time profiles. RESULT: The mean AUC0-t, AUC0-infinity, and Cmax were 501.61 ng x h/ml, 518.88 ng x h/ ml and 98.02 ng/ml, respectively for the test formulation and 507.10 ng x h/ml, 525.20 ng x h/ml and 97.82 ng/ml, respectively, for the reference formulation. The median Tmax, for both formulations was 0.75 h. Plasma elimination half-lives (t1/2) were 3.44 h (test) and 3.38 h (reference). The point estimates and 90% confidence intervals (CI) for AUC0-t, AUC0-infinity and Cmax were 98.92% (94.62-103.41%), 98.80% (94.51-103.28%) and 100.20% (91.43-109.81%), respectively, satisfying the bioequivalence criteria of the European Committee for Proprietary Medicinal Products and the US Food and Drug Administration guidelines. CONCLUSION: These results indicate that the two formulations of dexamethasone are bioequivalent and thus may be prescribed interchangeably.

Comparative bioavailability of two estazolam tablet formulations in Indonesian healthy volunteers.

AIM: To compare the bioavailability of two estazolam (CAS 29975-16-4) tablet formulations (Estalin 2 mg tablets as test formulation and 2 mg tablets of the originator product as reference formulation). METHODS: The study was conducted according to an open label, randomized two-way cross-over design with a two-week washout period. Twenty-four subjects received each of the two estazolam formulations. Blood samples for pharmacokinetic profiling were taken up to 72 h after drug administration in fasting condition. Plasma concentrations of estazolam were determined with a validated HPLC method with ultraviolet detection. Pharmacokinetic parameters were calculated from observed plasma concentration-time profiles. RESULTS: The mean AUC(0-t), AUC(0-infinity) and Cmax were 2581.38 ng x h/mL, 2934.37 ng x h/mL and 95.25 ng/mL, respectively for the test formulation and 2835.75 ng x h/ mL, 3207.73 ng x h/mL and 99.32 ng/mL, respectively, for the reference formulation. The median Tmax for both formulations was 1 h. The point estimates and 90% confidence Intervals for AUC(0-t), AUC(0-infinity) and Cmax were 91.03% (87.48-94.72%), 91.48% (86.67-96.55%) and 95.90% (92.60-99.31%) respectively, satisfying the bloequivalence criteria of the European Committee for Proprietary Medicinal Products and the US Food and Drug Administration guidelines. CONCLUSION: These results indicate that two formulations of estazolam are bioequivalent and, thus, may be prescribed interchangeably.

Verapamil P-glycoprotein transport across the rat blood-brain barrier: cyclosporine, a concentration inhibition analysis, and comparison with human data.

To predict the magnitude of P-glycoprotein (P-gp)-based drug interactions at the human blood-brain barrier (BBB), rodent studies are routinely conducted where P-gp is chemically inhibited. For such studies to be predictive of interactions at the human BBB, the plasma concentration of the P-gp inhibitor must be comparable with that observed in the clinic. Therefore, we determined the in vivo EC(50) of P-gp inhibition at the rat BBB using verapamil as a model P-gp substrate and cyclosporine A (CsA) as the model P-gp inhibitor. Under isoflurane anesthesia, male Sprague-Dawley rats were administered i.v. CsA to achieve pseudo steady-state CsA blood concentrations ranging from 0 to approximately 12 microM. Then, an i.v. tracer dose of [(3)H]verapamil was administered, and 20 min after verapamil administration, the animals were sacrificed for determination of blood, plasma, and brain (3)H radioactivity by scintillation counting. The percentage increase in the brain/blood (3)H radioactivity (relative to 0 microM CsA) was described by the Hill equation with E(max), 1290%; EC(50), 7.2 microM; and gamma, 3.8. Previously, using [(11)C]verapamil, we have shown that the human brain/blood (11)C radioactivity was increased by 79% at 2.8 microM CsA blood concentration. At an equivalent CsA blood concentration, the rat brain/blood (3)H radioactivity was increased by a remarkably similar extent of 75%. This is the first time that an in vivo CsA EC(50) of P-gp inhibition at the rat BBB has been determined and the magnitude of such inhibition was compared between the rat and the human BBB at the same blood CsA concentration.

Human subcutaneous tissue distribution of fluconazole: comparison of microdialysis and suction blister techniques.

AIMS: To investigate uptake of fluconazole into the interstitial fluid of human subcutaneous tissue using the microdialysis and suction blister techniques. METHODS: A sterile microdialysis probe (CMA/60) was inserted subcutaneously into the upper arm of five healthy volunteers following an overnight fast. Blisters were induced on the lower arm using gentle suction prior to ingestion of a single oral dose of fluconazole (200 mg). Microdialysate, blister fluid and blood were sampled over 8 h. Fluconazole concentrations were determined in each sample using a validated HPLC assay. In vivo recovery of fluconazole from the microdialysis probe was determined in each subject by perfusing the probe with fluconazole solution at the end of the 8 h sampling period. Individual in vivo recovery was used to calculate fluconazole concentrations in subcutaneous interstitial fluid. A physiologically based pharmacokinetic (PBPK) model was used to predict fluconazole concentrations in human subcutaneous interstitial fluid. RESULTS: There was a lag-time (approximately 0.5 h) between detection of fluconazole in microdialysate compared with plasma in each subject. The in vivo recovery of fluconazole from the microdialysis probe ranged from 57.0 to 67.2%. The subcutaneous interstitial fluid concentrations obtained by microdialysis were very similar to the unbound concentrations of fluconazole in plasma with maximum concentration of 4.29 +/- 1.19 microg ml(-1) in subcutaneous interstitial fluid and 3.58 +/- 0.14 microg ml(-1) in plasma. Subcutaneous interstitial fluid-to-plasma partition coefficient (Kp) of fluconazole was 1.16 +/- 0.22 (95% CI 0.96, 1.35). By contrast, fluconazole concentrations in blister fluid were significantly lower (P < 0.05, paired t-test) than unbound plasma concentrations over the first 3 h and maximum concentrations in blister fluid had not been achieved at the end of the sampling period. There was good agreement between fluconazole concentrations derived from microdialysis sampling and those estimated using a blood flow-limited PBPK model. CONCLUSIONS: Microdialysis and suction blister techniques did not yield comparable results. It appears that microdialysis is a more appropriate technique for studying the rate of uptake of fluconazole into subcutaneous tissue. PBPK model simulation suggested that the distribution of fluconazole into subcutaneous interstitial fluid is dependent on tissue blood flow.