Pharmacokinetic and pharmacodynamic interaction of Rosuvastatin calcium with guggulipid extract in rats

Background & objectivesRosuvastatin calcium (RC) is a potent and competitive synthetic inhibitor of HMG-CoA reductase used for the treatment of dyslipidemia. Guggulipid obtained from Commiphora mukul is used in the treatment of a wide variety of diseases such as atherosclerosis, hypercholesterolemia, rheumatism, and obesity. The present study evaluates the pharmacokinetic and pharmacodynamic interactions between RC and the standardized guggulipid extract in rats.Materials and methodsThe guggulipid extract was standardized for the presence of guggulsterones. The pharmacokinetic interaction was determined after a single dose administration of RC alone or in combination with the guggulipid extract or after multiple-dose administration of RC alone or RC along with the guggulipid extract for 14 days. To determine the pharmacodynamic interaction, RC and guggulipid extract were administered to hyperlipidemic rats for 14 days. The level of significance was determined using unpaired student’s t-test, one way ANOVA, the post-ANOVA Tukey test.ResultsStandardization of guggulipid extract showed it contains 7.5%w/w of guggulsterones. Guggulipid extract increased the bioavailability of RC in both single-dose and multiple-dose studies. Guggulipid extract reduced the rate of absorption (Ka) of RC but showed an increase in maximum serum concentration (Cmax). An in-vitro study using isolated rat intestine revealed that guggulipid extract decreased the rate of absorption of RC in the intestinal lumen. The hypolipidemic activity of RC was augmented by the guggulipid extract in hyperlipidemic rats.Interpretation & conclusionTherefore it is concluded that guggulipid extract increases the bioavailability of RC by delaying its Ka and augments its hypolipidemic action. However, it is recommended that a combination of RC with guggulipid extract should be used only after an adverse effect(s) of this combination are determined.     

Pharmacokinetic and pharmacodynamic studies of CD19 CAR T cell in human leukaemic xenograft models with dual-modality imaging

In recent years, chimeric antigen receptor T (CAR T)-cell therapy has shown great potential in treating haematologic disease, but no breakthrough has been achieved in solid tumours. In order to clarify the antitumour mechanism of CAR T cell in solid tumours, the pharmacokinetic (PK) and pharmacodynamic (PD) investigations of CD19 CAR T cell were performed in human leukaemic xenograft mouse models. For PK investigation, we radiolabelled CD19 CAR T cell with ⁸⁹Zr and used PET imaging in the CD19-positive and the CD19-negative K562-luc animal models. For PD evaluation, optical imaging, tumour volume measurement and DNA copy-number detection were performed. Unfortunately, the qPCR results of the DNA copy number in the blood were below the detection limit. The tumour-specific uptake was higher in the CD19-positive model than in the CD19-negative model, and this was consistent with the PD results. The preliminary PK and PD studies of CD19 CAR T cell in solid tumours are instructive. Considering the less efficiency of CAR T-cell therapy of solid tumours with the limited number of CAR T cells entering the interior of solid tumours, this study is suggestive for the subsequent CAR T-cell design and evaluation of solid tumour therapy.     

The combined effect of Raspberry Ketone with Resveratrol against oxidative stress and steatohepatitis in rats: Pharmacokinetic and pharmacodynamic studies

Raspberry Ketone (RK) and Resveratrol (RSV) are natural phenolic antioxidants and anti-inflammatory agents. However, its combined pharmacokinetic and pharmacodynamics potentials are not reported. The study aims to assess the combined effect of RK with RSV to protect rats from carbon-tetrachloride (CCl4) induced oxidative stress and NASH. The toxicant CCl4 was employed at a concentration of 1 mL/kg as a 1:1 (v/v) mixture with olive oil twice weekly for 6 weeks to induce liver toxicity. Animal treatment was followed for 2 weeks. Silymarin was used as a standard control drug to compare the hepatoprotective effect of RK and RSV. Hepatic histology, oxidative stress, MMP, reduced glutathione (GSH), plasma levels of SGOT, SGPT, and lipid profile (total cholesterol and triglycerides) were measured. Anti-inflammation genes (IL-10), and fibrotic genes (TGF-β) were also examined in liver tissue. Oral administration of combined RK with RSV (50 + 50 mg/kg for 2 weeks) showed significantly more hepatoprotection by significantly decreasing elevated plasma markers and lipid profile than alone RK and RSV (100 mg/kg daily for 2 weeks). It also significantly alleviated the hepatic lipid peroxidation, restoring the activities of GSH levels in the liver. RT-PCR and Immunoblotting studies confirmed that significantly upregulation of anti-inflammation genes and protein expression (MMP-9) ameliorated the disease. Pharmacokinetic studies confirmed more synergistic stability in simulated gastric-intestinal fluids (FaSSGF, FaSSIF) and rat liver microsomes (CYP-450, NADPH oxidation & glucuronidation. Moreover, coadministration of drugs augmented the relative bioavailability, V_d/F (L/Kg), and MRT_0-∞(h), which leads to more efficacy. This pharmacokinetic and pharmacodynamic reveals a new adjuvant therapy for the treatment of steatohepatitis.     

Pharmacokinetic and -dynamic modelling of G-CSF derivatives in humans

ABSTRACT: BACKGROUND: The human granulocyte colony-stimulating factor (G-CSF) is routinely applied to support recovery of granulopoiesis during the course of cytotoxic chemotherapies. However, optimal use of the drug is largely unknown. We showed in the past that a biomathematical compartment model of human granulopoiesis can be used to make clinically relevant predictions regarding new, yet untested chemotherapy regimen. In the present paper, we aim to extend this model by a detailed pharmacokinetic and -dynamic modelling of two commonly used G-CSF derivatives Filgrastim and Pegfilgrastim. RESULTS: Model equations are based on our physiological understanding of the drugs which are delayed absorption of G-CSF when applied to the subcutaneous tissue, dose-dependent bioavailability, unspecific first order elimination, specific elimination in dependence on granulocyte counts and reversible protein binding. Pharmacokinetic differences between Filgrastim and Pegfilgrastim were modelled as different parameter sets. Our former cell-kinetic model of granulopoiesis was essentially preserved, except for a few additional assumptions and simplifications. We assumed a delayed action of G-CSF on the bone marrow, a delayed action of chemotherapy and differences between Filgrastim and Pegfilgrastim with respect to stimulation potency of the bone marrow. Additionally, we incorporated a model of combined action of Pegfilgrastim and Filgrastim or endogenous G-CSF which interact via concurrent receptor binding. Unknown pharmacokinetic or cell-kinetic parameters were determined by fitting the predictions of the model to available datasets of G-CSF applications, chemotherapy applications or combinations of it. Data were either extracted from the literature or were received from cooperating clinical study groups. Model predictions fitted well to both, datasets used for parameter estimation and validation scenarios as well. A unique set of parameters was identified which is valid for all scenarios considered. Differences in pharmacokinetic parameter estimates between Filgrastim and Pegfilgrastim were biologically plausible throughout. CONCLUSION: We conclude that we established a comprehensive biomathematical model to explain the dynamics of granulopoiesis under chemotherapy and applications of two different G-CSF derivatives. We aim to apply the model to a large variety of chemotherapy regimen in the future in order to optimize corresponding G-CSF schedules or to individualize G-CSF treatment according to the granulotoxic risk of a patient.     

Chronic sodium cyanate treatment induces "hypoxia-like" effects in rats

Three weeks of sodium cyanate (NaCNO) intraperitoneal treatment in rats (n = 15) induced high hemoglobin O2 affinity, i.e., low PO2 at 50% hemoglobin saturation (P50), 20.5 +/- 1.4 Torr, in comparison with the mean control values, 34.5 +/- 1.6 Torr (n = 15). NaCNO rats showed a reduction in mean body weight, 376 +/- 27 g, in comparison with controls, 423 +/- 23 g (P less than 0.001). Despite arterial O2 partial pressure (PaO2) within normal limits NaCNO-treated rats had a higher systolic right ventricular pressure (SRVP), 33.7 +/- 3.1 Torr, in comparison with control value, 29.0 +/- 2.5 Torr (P less than 0.001). Right ventricle weights were significantly increased (P less than 0.001). After 60 min of an hypoxic challenge (fractional concentration of inspired O2 = 0.10) NaCNO-treated rats increased SRVP of only 7 +/- 4% compared with 46 +/- 9% in the control animals. Inducing high hemoglobin affinity in rats (n = 10; 6 wk NaCNO treatment) resulted in increases in hematocrit ratio and hemoglobin concentration (P less than 0.001). The characteristics of the red blood cell (RBC) itself changed; values of mean cell volume, mean cell hemoglobin, and mean cell hemoglobin concentration being significantly increased (P less than 0.001) when compared with mean control values. The count of nucleated RBC's appeared to be significantly higher from the 2nd wk of NaCNO treatment. Chronic NaCNO treatment was demonstrated to exert "hypoxia-like" effects since it induced prevention of normal growth, polycythemia, pulmonary hypertension, right ventricular hypertrophy, and blunted pulmonary pressor response to acute hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Longevity of cold-exposed rats: a reevaluation of the "rate-of-living theory"

It has been postulated that increased energy expenditure results in shortened survival. To test this "rate-of-living theory" we examined the effect of raising energy expenditure by means of cold exposure on the longevity of rats. Male 6-mo-old SPF Long-Evans rats were gradually accustomed to immersion in cool water (23 degrees C). After 3 mo they were standing in the cool water for 4 h/day, 5 days/wk. They were maintained on this program until age 32 mo. The cold exposure resulted in a 44% increase in food intake (P less than 0.001). Despite their greater food intake, the cold-exposed rats' body weights were significantly lower than those of control animals from age 11 to 32 mo. The average age at death of the cold-exposed rats was 968 +/- 141 days compared with 923 +/- 159 days for the controls. The cold exposure appeared to protect against neoplasia, particularly sarcomas; only 24% of the necropsied cold-exposed rats had malignancies compared with 57% for the controls. The results of this study provide no support for the concept that increased energy expenditure decreases longevity.     

Pharmacokinetic and pharmacodynamic interactions between simvastatin and diltiazem in patients with hypercholesterolemia and hypertension

Pharmacokinetic and pharmacodynamic interactions between simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and diltiazem, a calcium antagonist, were investigated in 7 male and 4 female patients with hypercholesterolemia and hypertension. The patients were given, for one in a three consecutive 4-week periods, oral simvastatin (5 mg/day), oral simvastatin (5 mg/day) combined with diltiazem (90 mg/day), and then oral diltiazem (90 mg/day), respectively. The area under the plasma concentration versus time curve up to 6 hours post-dose (AUC0-6h) and maximum plasma concentrations (Cmax) of the drugs, serum lipid profiles, blood pressures and liver functions were assessed on the last day of each of the three 4-week periods. After the combined treatment period, Cmax of HMG-CoA reductase inhibitor was elevated from 7.8 +/- 2.6 ng/ml to 15.4 +/- 7.9 ng/ml (P < 0.01) and AUC0-6h from 21.7 +/- 4.9 ng x hr/ml to 43.3 +/- 23.4 ng x hr/ml (P < 0.01), while Cmax of diltiazem was decreased from 74.2 +/- 36.4 ng/ml to 58.6 +/- 18.9 ng/ml (P < 0.05) and its AUC0-6h from 365 +/- 153 ng x hr/ml to 287 +/- 113 ng x hr/ml (P < 0.01). Compared to simvastatin monotherapy, combined treatment further reduced LDL-cholesterol levels by 9%, from 129 +/- 16 mg/dl to 119 +/- 17 mg/dl (P < 0.05). No adverse events were observed throughout the study. These apparent pharmacokinetic interactions, namely the increase of HMG-CoA reductase inhibitor concentration by diltiazem and the decrease of diltiazem concentration by simvastatin, enhance the cholesterol-lowering effects of simvastatin during combined treatment.     

Pharmacokinetic and pharmacodynamic responses in adult patients with Chagas disease treated with a new formulation of benznidazole

Pharmacological treatment of Chagas disease with benznidazole (BNZ) is effective in children in all stages, but it is controversial in chronically infected adults. We report the pharmacokinetics and pharmacodynamics in six adult patients with Chagas disease treated with the new BNZ formulation (ABARAX^®) in doses between 2.5-5.5 mg/Kg/day. All but one patient had plasmatic BNZ concentrations within the expected range. All patients finalised treatment with nondetectable Trypanosoma cruziquantitative polymerase chain reaction, which remained nondetectable at the six month follow-up. Our data suggests parasitological responses with the new BNZ and supports the hypothesis that treatment protocols with lower BNZ doses may be effective.     

Pharmacokinetic / pharmacodynamic relationships of liposomal amphotericin B and miltefosine in experimental visceral leishmaniasis

BackgroundThere is a continued need to develop effective and safe treatments for visceral leishmaniasis (VL). Preclinical studies on pharmacokinetics and pharmacodynamics of anti-infective agents, such as anti-bacterials and anti-fungals, have provided valuable information in the development and dosing of these agents. The aim of this study was to characterise the pharmacokinetic and pharmacodynamic properties of the anti-leishmanial drugs AmBisome and miltefosine in a preclinical disease model of VL.Methodology / Principal findingsBALB/c mice were infected with L. donovani (MHOM/ET/67/HU3) amastigotes. Groups of mice were treated with miltefosine (orally, multi-dose regimen) or AmBisome (intravenously, single dose regimen) or left untreated as control groups. At set time points groups of mice were killed and plasma, livers and spleens harvested. For pharmacodynamics the hepatic parasite burden was determined microscopically from tissue impression smears. For pharmacokinetics drug concentrations were measured in plasma and whole tissue homogenates by LC-MS. Unbound drug concentrations were determined by rapid equilibrium dialysis. Doses exerting maximum anti-leishmanial effects were 40 mg/kg for AmBisome and 150 mg/kg (cumulatively) for miltefosine. AmBisome displayed a wider therapeutic range than miltefosine. Dose fractionation at a total dose of 2.5 mg/kg pointed towards concentration-dependent anti-leishmanial activity of AmBisome, favouring the administration of large doses infrequently. Protein binding was >99% for miltefosine and amphotericin B in plasma and tissue homogenates.Conclusion / SignificanceUsing a PK/PD approach we propose optimal dosing strategies for AmBisome. Additionally, we describe pharmacokinetic and pharmacodynamic properties of miltefosine and compare our findings in a preclinical disease model to available knowledge from studies in humans. This approach also presents a strategy for improved use of animal models in the drug development process for VL.     

Pharmacokinetic and pharmacodynamic analyses of cocaine and its metabolites in behaviorally divergent inbred mouse strains

Cocaine (COC) is a psychostimulant with a high potential for abuse and addiction. Risk for COC use disorder is driven, in part, by genetic factors. Animal models of addiction-relevant behaviors have proven useful for studying both genetic and nongenetic contributions to drug response. In a previous study, we examined initial locomotor sensitivity to COC in genetically diverse inbred mouse strains. That work highlighted the relevance of pharmacokinetics (PK) in initial locomotor response to COC but was limited by a single dose and two sampling points. The objective of the present study was to characterize the PK and pharmacodynamics of COC and its metabolites (norcocaine and benzoylecgonine) in six inbred mouse strains (I/LnJ, C57BL/6J, FVB/NJ, BTBR T+ tf/J, LG/J and LP/J) that exhibit extreme locomotor responses to cocaine. Mice were administered COC at one of four doses and concentrations of cocaine, norcocaine and benzoylecgonine were analyzed in both plasma and brain tissue at 5 different time points. Initial locomotor sensitivity to COC was used as a pharmacodynamic endpoint. We developed an empirical population PK model that simultaneously characterizes cocaine, norcocaine and benzoylecgonine in plasma and brain tissues. We observed interstrain variability occurring in the brain compartment that may contribute to pharmacodynamic differences among select strains. Our current work paves the way for future studies to explore strain-specific pharmacokinetic differences and identify factors other than PK that are responsible for the diverse behavioral response to COC across these inbred mouse strains.     

Macrophage-colony stimulating factor and interleukin-34 induce chemokines in human whole blood

The aim of this study is to investigate if macrophage-colony stimulating factor (M-CSF) or interleukin-34 (IL-34) induces cytokines or chemokines using human whole blood (HWB) and if an M-CSF- or IL-34-induced cytokine or chemokine production from HWB is inhibited by soluble M-CSF receptor or c-FMS kinase inhibitors. Among eight cytokines or growth factors tested, only IL-6 level was increased by up to 6-fold by M-CSF or IL-34 in HWB. In contrast, chemokine levels (IP-10/CXCL10, IL-8/CXCL8, and MCP-1/CCL2) were dramatically increased by M-CSF or IL-34 in HWB while exhibiting a large variation among donors. Variability of the MCP-1 signal induced by M-CSF or IL-34 was relatively less among donors compared to the IP-10 and IL-8 signals. The elevation of these chemokine levels was significantly decreased by soluble M-CSF receptor, indicating the elevation of these chemokines was mediated by M-CSF or IL-34. Furthermore, GW2580, a c-FMS kinase inhibitor, inhibited the induction of MCP-1 by M-CSF or IL-34 in a concentration dependent manner. These indicate MCP-1 is the most appropriate chemokine target for a chemokine release assay to evaluate the potency of c-FMS kinase inhibitors and MCP-1 release assay using HWB would be useful, relevant tool for translational pharmacology of c-FMS kinase inhibitors.     

Biosynthesis and turnover of a 34-kDa protein growth factor in human cytotrophoblasts

Recently we isolated a new protein growth factor of 34 kDa from synctial membranes of human placenta. In its polypeptide molecular mass, antigenic structure, receptor binding specificity and partial amino acid sequence, it is unlike several known growth factors, hormones and other proteins. Here we report studies on its biosynthesis and turnover in cultured cytotrophoblasts from term human placenta. Expression of the 34-kDa protein in these cells was studied by immunoprecipitation and Western blot analyses using a highly specific antibody. The experiments have produced the following results. a) Immunostaining and Western blot analyses have demonstrated the presence of immunoreactive 34-kDa protein in isolated cytotrophoblasts. The protein is present in both freshly isolated cells and in cells that have fused in culture to form multinuclear syncytiotrophoblasts. b) Trophoblastic biosynthesis of the protein has been demonstrated by in vitro translation of cellular mRNA and by metabolic labelling experiments with intact cells. c) Pulse-chase experiments show that biosynthesis of the protein does not involve any detectable precursors of higher or lower molecular mass. d) Studies on turnover indicate that the synthesized protein is unusually stable with a half-life of 50-70 h.     

Homology modelling and H NMR studies of human leukaemia inhibitory factor

Human leukaemia inhibitory factor (LIF) is a glycoprotein with a diverse range of activities on many cell types. A molecular model of LIF has been constructed based mainly on the structure of the related cytokine granulocyte colony-stimulating factor, and refined using simulated annealing and molecular dynamics in water. The model was stable during molecular dynamics refinement and is consistent with known stereochemical data on proteins. It has been assessed by comparison with ¹H NMR data on the ionization behaviour of the six histidine residues in LIF, the imidazolium pK_a values of which range from 3.6 to 7.4. These pK_a values were assigned to individual histidine residues from NMR studies on a series of His → Ala mutants. The environments of the histidine residues in the model account very well for their observed ionization behaviour. Furthermore, the model is consistent with mutagenesis studies which have defined a group of amino acid residues involved in receptor binding.     

Pharmacokinetic interaction with digoxin and glucocorticoids in rats detected by radio-immunoassay using a novel specific antiserum

We previously prepared a more specific antiserum (Antiserum-I) to digoxin (Dx) compared with commercially available anti-Dx antiserum (Antiserum-II), clinically used in the therapeutic drug monitoring of Dx. The aims of this study are to compare Dx disposition kinetics by radio-immunoassay (RIA) using Antiserum-I and Antiserum-II, and evaluate the drug-drug interaction with Dx and glucocorticoids in rats. When Dx metabolites were added to rat serum containing Dx, the recovery ratios using Antiserum-I showed 100 to 110% and were remarkably lower than those using Antiserum-II. In rats, serum concentration-time courses of Dx after a single i.v. or p.o. administration of Dx (0.017 mg/kg) by RIA using Antiserum-I were much lower than those using Antiserum-II. The area under the concentration-time course of Dx was significantly lower than that using Antiserum-II and the total body clearance values were significantly higher, while an obvious change of bioavailability was not observed. When using Antiserum-I, rats twice and six times pretreated with dexamethasone (75 mg/kg/day, i.p.) and prednisolone (69 mg/kg/day, i.p.), respectively, showed significant change of the pharmacokinetic parameters of Dx compared with the control rats. In contrast, using Antiserum-II, it took three and nine times of pretreatment with dexamethasone and prednisolone, respectively, to significantly change the parameters of Dx. In conclusion, these results demonstrate that Antiserum-I is very useful not only to more precisely monitor serum Dx levels, but also to determine earlier the drug-drug interaction with glucocorticoids than Antiserum-II.     

A novel thrombin enhancement factor in human plasma

A protein has been isolated from human plasma by gel filtration followed by affinity chromatography with a derivative of wheat germ agglutinin and ion exchange chromatography. This protein showed one peak in high performance liquid chromatography but in gel electrophoresis, in the presence of sodium dodecyl sulfate and β-mercaptoethanol, revealed two major components of 74 kDa and 55 kDa. These results indicate that the protein probably exists as a complex of the two polypeptides. This protein complex enhanced platelet aggregation by thrombin while aggregation induced by ADP was not significantly affected. Similarly, the rate of thrombin action on fibrinogen and N-benzoylarginine ethyl ester as measured in a spectrophotometer was increased in the presence of this plasma protein. These results suggest the presence of a protein complex in human plasma which can directly interact with thrombin and enhance its reactivity.