scholarly journals Pharmacodynamics of (−)-β-2′,3′-Dideoxy-3′-Thiacytidine in Chronically Virus-Infected Woodchucks Compared to Its Pharmacodynamics in Humans

1998 ◽  
Vol 42 (11) ◽  
pp. 2804-2809 ◽  
Author(s):  
Selwyn J. Hurwitz ◽  
Bud C. Tennant ◽  
Brent E. Korba ◽  
John L. Gerin ◽  
Raymond F. Schinazi
Keyword(s):  
Half Life ◽  
Hepatitis Virus ◽  
Time Curve ◽  
Virus Load ◽  
First Order ◽  
Antiviral Effects ◽  
B Virus ◽  
Drug Regimens ◽  
Dose Dependent ◽  
Previous Clinical Study

The pharmacodynamics of (−)-β-2′,3′-dideoxy-3′-thiacytidine (3TC) was studied in chronically woodchuck hepatitis virus-infected woodchucks and compared to that in previous studies in hepatitis B virus (HBV)-infected humans. Net depletion rates of serum virus DNA in woodchucks receiving 3TC were modeled as a sum of an exponentially declining virus input and a first-order elimination. Preceding shoulders and pseudo-first-order virus half-lives in serum ranged from 1 to 7 days and were dose dependent. Higher plasma 3TC concentrations were needed in woodchucks for virus depletion similar to that attained in humans. Human HBV depletion curves from a previous clinical study with 3TC (≥100 mg per day) were described by a biexponential relationship. The average half-life value in humans, normalized to fraction of area under the serum virus load-time curve, was similar to the average half-life value observed in woodchucks given the highest 3TC dose (2.4 and 2.0 days, respectively). On cessation of therapy, virus load rebounds in woodchucks were dose dependent and resembled posttherapy virus “flares” reported to occur in humans. The estimates of drug exposures that could lead to optimal antiviral effects presented indicate that 3TC should not be underdosed and compliance should be monitored. The study of chronically infected woodchucks may prove useful for optimizing drug regimens for hepadnavirus infections.

Pharmacokinetics and Tolerability of a New Low Molecular Mass Heparin (RO-11) in Healthy Volunteers – A Dose-Finding Study within the Therapeutical Range

1997 ◽  
Vol 77 (01) ◽  
pp. 133-136 ◽  
Author(s):  
Liliana Falkon ◽  
Miriam M Bayés ◽  
Guillem Frontera ◽  
Mercè Garí ◽  
Manel Barbanoj ◽  
...  
Keyword(s):  
Phase I ◽  
Molecular Mass ◽  
Half Life ◽  
Dose Finding ◽  
Dose Effect ◽  
Efficacy And Safety ◽  
First Order ◽  
Finding Study ◽  
Dose Finding Study ◽  
Dose Dependent

SummaryThis paper reports on the results of a Phase I, dose-finding study with a new low molecular mass heparin (LMMH) called RO-11. The study focused on pharmacokinetics, dose-effect relationship and on tolerability of three single subcutaneous (SC) doses within the therapeutical range. After the injection of 7,500, 9,000 and 12,500 anti-FXa IU, the anti-FXa effect peaked between 3-6 h and showed a dose-dependent response. The absorption and elimination were first-order processes and the long half-life (>5 h) kept constant after increasing doses. The compound was tolerated very well and no clinically relevant prolongation of APTT, prothrombin and thrombin clotting tests was observed. At the dose of 7,500 IU, which corresponded to 110 anti-FXa IU/Kg, RO-11 exerted anti-FXa effect for at least 18-20 h. We recommend using this dose in a single SC injection, to evaluate the efficacy and safety of RO-11 in the initial treatment of DVT or PE.

scholarly journals Compartmental Pharmacokinetics and Tissue Drug Distribution of the Pradimicin Derivative BMS 181184 in Rabbits

1998 ◽  
Vol 42 (10) ◽  
pp. 2700-2705 ◽  
Author(s):  
Andreas H. Groll ◽  
Tin Sein ◽  
Vidas Petraitis ◽  
Ruta Petraitiene ◽  
Diana Callender ◽  
...  
Keyword(s):  
Single Dose ◽  
Half Life ◽  
Peak Plasma ◽  
Volume Of Distribution ◽  
Multiple Dosing ◽  
Time Curve ◽  
Dose Administration ◽  
Single Dose Administration ◽  
Elimination Half ◽  
Dose Dependent

ABSTRACT The pharmacokinetics of the antifungal pradimicin derivative BMS 181184 in plasma of normal, catheterized rabbits were characterized after single and multiple daily intravenous administrations of dosages of 10, 25, 50, or 150 mg/kg of body weight, and drug levels in tissues were assessed after multiple dosing. Concentrations of BMS 181184 were determined by a validated high-performance liquid chromatography method, and plasma data were modeled into a two-compartment open model. Across the investigated dosage range, BMS 181184 demonstrated nonlinear, dose-dependent kinetics with enhanced clearance, reciprocal shortening of elimination half-life, and an apparently expanding volume of distribution with increasing dosage. After single-dose administration, the mean peak plasma BMS 181184 concentration (C max) ranged from 120 μg/ml at 10 mg/kg to 648 μg/ml at 150 mg/kg; the area under the concentration-time curve from 0 to 24 h (AUC0–24) ranged from 726 to 2,130 μg · h/ml, the volume of distribution ranged from 0.397 to 0.799 liter/kg, and the terminal half-life ranged from 4.99 to 2.31 h, respectively (P < 0.005 toP < 0.001). No drug accumulation in plasma occurred after multiple daily dosing at 10, 25, or 50 mg/kg over 15 days, although mean elimination half-lives were slightly longer. Multiple daily dosing at 150 mg/kg was associated with enhanced total clearance and a significant decrease in AUC0–24 below the values obtained at 50 mg/kg (P < 0.01) and after single-dose administration of the same dosage (P < 0.05). Assessment of tissue BMS 181184 concentrations after multiple dosing over 16 days revealed substantial uptake in the lungs, liver, and spleen and, most notably, dose-dependent accumulation of the drug within the kidneys. These findings are indicative of dose- and time-dependent elimination of BMS 181184 from plasma and renal accumulation of the compound after multiple dosing.

scholarly journals Effect of Oral Administration of Emtricitabine on Woodchuck Hepatitis Virus Replication in Chronically Infected Woodchucks

2000 ◽  
Vol 44 (6) ◽  
pp. 1757-1760 ◽  
Author(s):  
Brent E. Korba ◽  
R. F. Schinazi ◽  
Paul Cote ◽  
Bud C. Tennant ◽  
John L. Gerin
Keyword(s):  
Cell Culture ◽  
Antiviral Activity ◽  
Oral Administration ◽  
Hepatitis Virus ◽  
Controlled Study ◽  
Woodchuck Hepatitis Virus ◽  
Dependent Manner ◽  
Effective Inhibitor ◽  
B Virus ◽  
Dose Dependent

ABSTRACT Emtricitabine [(−)FTC] [(−)-β-2′,3′-dideoxy-5-fluoro-3′-thiacytidine] has been shown to be an effective inhibitor of hepatitis B virus (HBV) in cell culture, with a potency and selectivity that are essentially identical to those of lamivudine. The antiviral activity of oral administration of (−)FTC against WHV replication in chronically infected woodchucks, an established and predictive model for antiviral therapy against HBV, was examined in a placebo-controlled study. (−)FTC significantly reduced viremia and intrahepatic WHV replication in a dose-dependent manner that was comparable to the antiviral activity of lamivudine observed in previous studies conducted by our laboratories. No effect on the levels of hepatic WHV RNA or the levels of woodchuck hepatitis surface antigen or anti-woodchuck hepatitis surface and core antibodies in the serum of the treated animals was observed. No evidence of drug-related toxicity was observed in any of the animals treated.

Viral Pharmacodynamic Model for (–)-β-2′,3′-Dideoxy-5-Fluoro-3′-Thiacytidine (Emtricitabine) in Chronically Infected Woodchucks

2002 ◽  
Vol 13 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Selwyn J Hurwitz ◽  
Bud C Tennant ◽  
Brent E Korba ◽  
Irina Liberman ◽  
John L. Gerin ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Half Life ◽  
Day Treatment ◽  
Dose Range ◽  
Pharmacodynamic Model ◽  
Nucleoside Triphosphate ◽  
Effect Compartment ◽  
Virus Load ◽  
B Virus

There is a need for adequate models of virus depletion in animals and humans as a function of drug dose in order to plan starting dose regimens in the clinic for new antiretroviral nucleoside agents. An indirect response pharmacodynamic model was fitted to link the plasma pharmacokinetics from a 28 day treatment with the nucleoside reverse transcription inhibitor emtricitabine [(–)-FTC], with the resulting virus depletion and recovery profiles in woodchucks chronically infected with woodchuck hepatitis B virus. In this approach it is assumed that the virus is eliminated from serum in a first order fashion and that the fraction of serum virus load produced per day is inhibited by the accumulation of nucleoside triphosphate in a manner that could be described using a Hill equation. Nadir virus load values were inversely related to pretreatment virus load levels within each dose group. A median inhibitory concentration value of 1.5 μM for (–)-FTC triphosphate, previously measured against the isolated viral polymerase of woodchuck hepatitis, was used in model fitting. The fitted value for concentration exponent η of 3.46 indicated a greater than linear sensitivity of virus inhibition with dose. Since the post-treatment virus rebound was much greater than predictions of an initial model, a dose-dependent rebound factor was incorporated in the final model. The rebound factor was maximal at the end of (–)-FTC treatment and decayed mono-exponentially with a rate constant Kreb of 0.11/day. The model inferred decay half-life of (–)-FTC triphosphate in the apparent ‘effect compartment’ of the model was similar to the half-life value previously estimated for human hepatitis B virus-infected hepatocytes. The model described adequately the virus depletion and recovery profiles for the dose range tested and could be adapted for the selection of starting doses for future animal and human studies with emtricitabine and other nucleoside analogues in development.

Research Progress of Glycyrrhizic Acid on Antiviral Activity

2019 ◽  
Vol 19 (10) ◽  
pp. 826-832 ◽  
Author(s):  
Zhi-Gang Sun ◽  
Ting-Ting Zhao ◽  
Na Lu ◽  
Yong-An Yang ◽  
Hai-Liang Zhu
Keyword(s):  
Hepatitis B ◽  
Glycyrrhizic Acid ◽  
Skin Diseases ◽  
Hepatitis B Surface Antigen ◽  
Research Progress ◽  
Extracellular Secretion ◽  
Antiviral Effects ◽  
B Virus ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome

Glycyrrhizic acid (GA), a triterpene isolated from the roots and rhizomes of licorice, named Glycyrrhiza glabra, is the principal bioactive ingredient of anti-viral, anti-inflammatory and hepatoprotective effects. GA has been used in the clinical treatment of hepatitis, bronchitis, gastric ulcer, AIDS (acquired immunodeficiency syndrome), certain cancers and skin diseases. It has a direct effect on anti-HBV (hepatitis B virus) via affecting the HBsAg (hepatitis B surface antigen) to extracellular secretion, improving liver dysfunction in patients with chronic hepatitis B, and ultimately improving the immune status of HBV. GA can significantly inhibit the proliferation of HIV, showing an immune activation. The clinical application of GA on the prevention and treatments of various diseases may derive from its numerous pharmacological properties. This review provides the summary of the antiviral effects of GA on research progress and mechanism in recent years.

In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

2020 ◽  
Vol 16 ◽  
Author(s):  
M. Alarjah
Keyword(s):  
Half Life ◽  
Hplc Method ◽  
Hydrolysis Rate ◽  
First Order ◽  
First Order Kinetics ◽  
Rp Hplc ◽  
Pharmacokinetic Properties ◽  
Pseudo First Order ◽  
Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

scholarly journals Antiviral Activities of Oral 1-O-Hexadecylpropanediol-3-Phosphoacyclovir and Acyclovir in Woodchucks with Chronic Woodchuck Hepatitis Virus Infection

2000 ◽  
Vol 44 (7) ◽  
pp. 1964-1969 ◽  
Author(s):  
Karl Y. Hostetler ◽  
James R. Beadle ◽  
William E. Hornbuckle ◽  
Christine A. Bellezza ◽  
Ilia A. Tochkov ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Virus Infection ◽  
Hepatitis B ◽  
Hepatitis Virus ◽  
Response To Therapy ◽  
Hydroxyl Group ◽  
Woodchuck Hepatitis Virus ◽  
Acyclovir Treatment ◽  
B Virus ◽  
Hepatitis Virus Infection

ABSTRACT Acyclovir triphosphate is a potent inhibitor of hepatitis B virus DNA polymerase, but acyclovir treatment provides no benefit in patients with hepatitis B virus infection. This is due in part to the fact that hepatitis B virus, unlike herpes simplex virus, does not code for a viral thymidine kinase which catalyzes the initial phosphorylation of acyclovir. We synthesized 1-O-octadecyl-sn-glycero-3-phospho (3-P)-acyclovir and found that it was highly active in reducing hepatitis B virus replication in 2.2.15 cells, while acyclovir was inactive. The greater antiviral activity of 1-O-octadecyl-sn-glycero-3-P-acyclovir appeared to be due to liver cell metabolism of the compound to acyclovir monophosphate (K. Y. Hostetler et al., Biochem. Pharmacol. 53:1815–1822, 1997). However, a closely related compound without a hydroxyl group at the sn-2 position of glycerol, 1-O-hexadecylpropanediol-3-P-acyclovir, was more active and selective in 2.2.15 cells in vitro. In this study, we treated woodchucks chronically infected with woodchuck hepatitis virus with increasing oral doses of 1-O-hexadecylpropanediol-3-P-acyclovir and assessed the response to therapy versus acyclovir or a placebo. At a dosage of 10 mg/kg of body weight twice a day, the test compound significantly inhibited viral replication in vivo, as indicated by a 95% reduction in serum woodchuck hepatitis virus DNA levels and by a 54% reduction in levels of woodchuck hepatitis virus replicative intermediates in the liver. Higher doses were somewhat less effective. In contrast, 20 mg of acyclovir/kg twice daily, a 5.3-fold-higher molar dosage, had no demonstrable activity against woodchuck hepatitis virus. Oral 1-O-hexadecylpropanediol-3-P-acyclovir appeared to be safe and effective in chronic woodchuck hepatitis virus infection.

scholarly journals 1326. Vancomycin Area Under the Concentration-Time Curve (AUC) Estimation Using a Bayesian Approach Versus First-Order Pharmacokinetic Equations: A Pilot Study

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S673-S673
Author(s):  
Jeffrey Pearson ◽  
Yazed S Alsowaida ◽  
B S Pharm ◽  
David W Kubiak ◽  
Mary P Kovacevic ◽  
...  
Keyword(s):  
Pilot Study ◽  
Median Time ◽  
Bayesian Modeling ◽  
Surgical Prophylaxis ◽  
Time Curve ◽  
Team Members ◽  
First Order ◽  
Concentration Time ◽  
Study Team ◽  
Auc Estimation

Abstract Background Current guidelines endorse area under the concentration-time curve (AUC)-based monitoring over trough-only monitoring for systemic vancomycin. Vancomycin AUC can be estimated using either Bayesian modeling software or first-order pharmacokinetic (PK) calculations. The objective of this pilot study was to evaluate and compare the efficiency and feasibility of these two approaches for calculating the estimated vancomycin AUC. Methods A single-center crossover study was conducted in four medical/surgical units at Brigham and Women’s Hospital over a 3-month time period. All adult patients who received vancomycin were included. Patients were excluded if they were receiving vancomycin for surgical prophylaxis, were on hemodialysis, if vancomycin was being dosed by level, or if vancomycin levels were never drawn. The primary endpoint was the amount of time study team members spent calculating the estimated AUC and determining regimen adjustments with Bayesian modeling compared to first-order PK calculations. Secondary endpoints included the number of vancomycin levels drawn and the percent of those drawn that were usable for AUC calculations. Results One hundred twenty-four patients received vancomycin during the study, of whom 47 met inclusion criteria. The most likely reasons for exclusion were receiving vancomycin for surgical prophylaxis (n=40) or never having vancomycin levels drawn (n=32). The median time taken to assess levels in the Bayesian arm was 9.3 minutes [interquartile range (IQR) 7.8-12.4] versus 6.8 minutes (IQR 4.8-8.0) in the 2-level PK arm (p=0.004). However, if Bayesian software is integrated into the electronic health record (EHR), the median time to assess levels was 3.8 minutes (IQR 2.3-6.8, p=0.019). In the Bayesian arm, 30 of 34 vancomycin levels (88.2%) were usable for AUC calculations, compared to 28 of 58 (48.3%) in the 2-level PK arm. Conclusion With EHR integration, the use of Bayesian software to calculate the AUC was more efficient than first-order PK calculations. Additionally, vancomycin levels were more likely to be usable in the Bayesian arm, thereby avoiding delays in estimating the vancomycin AUC. Disclosures All Authors: No reported disclosures

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