Abstract:
:Warfarin, like all the 4-hydroxycoumarin compounds, has an asymmetric carbon atom. The clinically available warfarin preparations consist of a racemic mixture of equal amounts of 2 distinct S and R isomers, the former being 4-times more potent as anticoagulant and more susceptible to drug interaction. Warfarin is highly water soluble and rapidly absorbed from the stomach and the upper gastrointestinal tract; its plasma concentrations peak 60 to 90 minutes after oral administration. Warfarin binds to the enzyme vitamin K 2,3-epoxide reductase in liver microsomes, stopping the cycle of vitamin K and reducing gamma-carboxylation of the precursors of vitamin D-dependent pro- and anticoagulant factors. A variable fraction of the binding with the target enzyme, albeit small, can be reversed by competitive displacers, such as dithiol-reducing agent activity. Differences in dithiol-reducing activity have been suggested as a contributing factor to the wide interindividual differences in sensitivity to oral anticoagulants. The anticoagulant effect is caused by a small fraction of the drug, since most (97 to 99%) is protein bound (mainly to albumin) and ineffective. Drugs that can displace the albumin binding will increase the action of warfarin, even though this effect is counteracted by a more rapid elimination of the drug. The elimination half-life of warfarin varies greatly among individuals, ranging from 35 to 45 hours; the S isomer has, however, an average half-life shorter than the R isomer. The plasma levels of vitamin K-dependent proteins are determined by a dynamic equilibrium between their synthesis and half-life times. The delay before warfarin takes effect reflects the half-life of the clotting proteins; the levels of factor VII and protein C (with shorter half-lives) are reduced earlier, reaching steady inhibited levels in about 1 day, whereas factor II takes more than 10 days. Oral anticoagulant therapy (OAT) with warfarin or other coumarin derivatives is increasingly administered to patients for primary or secondary prevention of various arterial or venous thromboembolic diseases. If in some clinical conditions OAT is given indefinitely, in others--such as venous thromboembolism or after tissue heart valve replacement--anticoagulants are usually given only for the high risk period of thrombotic complication. A recent large prospective study performed by the Italian Federation of Anticoagulation Clinics showed that about 30% of the patients who began OAT for various clinical indications stopped treatment at different times, confirming that withdrawal from OAT is an occurrence that affects a large number of patients. The expression 'rebound phenomenon' was adopted to indicate a hypercoagulant condition occurring after warfarin withdrawal. A possible more frequent recurrence of thromboembolism after cessation of anticoagulation became a matter of controversy and many clinical studies, mostly observational and noncontrolled, reported on the issue with inconsistent results. Most authoritative commentators agreed that rebound phenomenon, though possible, was not clinically relevant and did not differ in frequency and intensity according to mode of withdrawal. Scientific interest in the topic waned until more sensitive methods for investigating blood hypercoagulability became available. In recent years, many studies (reviewed in the text) have investigated the levels of different markers of hypercoagulability [fibrinopeptide A, activated factor VII, prothrombin fragments F1+2, thrombin-antithrombin complexes, D-dimers (DD)], consistently finding an increase in their values after cessation of anticoagulation. Changes in the levels of markers of activated blood coagulation were prospectively investigated by our group in 32 patients with venous thromboembolism who were randomly withdrawn abruptly or gradually from warfarin treatment. Our results indicate that interruption of anticoagulant treatment frequently elicits low grade acti
journal_name
Clin Pharmacokinetjournal_title
Clinical pharmacokineticsauthors
Palareti G,Legnani Cdoi
10.2165/00003088-199630040-00003subject
Has Abstractpub_date
1996-04-01 00:00:00pages
300-13issue
4eissn
0312-5963issn
1179-1926journal_volume
30pub_type
杂志文章,评审abstract:OBJECTIVE:A prospective pharmacokinetic study was performed in Caucasian patients from an intensive care unit with respiratory support to evaluate the influence of this circumstance on the pharmacokinetic behaviour of levofloxacin. PATIENTS AND METHODS:A standard dosage regimen of 500 mg/day was administered to nine C...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-200544060-00004
更新日期:2005-01-01 00:00:00
abstract::Ertugliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), is approved in the US, EU, and other regions for the treatment of adults with type 2 diabetes mellitus (T2DM). This review summarizes the ertugliflozin pharmacokinetic (PK) and pharmacodynamic data obtained during phase I clinical developm...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.1007/s40262-020-00875-1
更新日期:2020-08-01 00:00:00
abstract::Antipyrine pharmacokinetics were studied in 6 healthy women before and 2, 8 and 12 weeks after administering the injectable progestagen (progestin), norethisterone (norethindrone) enanthate 200mg intramuscularly. Additionally, antipyrine kinetics in 5 women who had previously used the injectable contraceptive for 8 to...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-198611020-00007
更新日期:1986-03-01 00:00:00
abstract::Cisapride, a prokinetic agent, has been used for the treatment of a number of gastrointestinal disorders, particularly gastro-oesophageal reflux disease in adults and children. Since 1993, 341 cases of ventricular arrhythmias, including 80 deaths, have been reported to the US Food and Drug Administration. Marketing of...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-200039010-00004
更新日期:2000-07-01 00:00:00
abstract::This article reviews the information available to assist pharmacokineticists in the prediction of metabolic drug interactions. Significant advances in this area have been made in the last decade, permitting the identification in early drug development of dominant cytochrome P450 (CYP) isoform(s) metabolising a particu...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-199732030-00004
更新日期:1997-03-01 00:00:00
abstract::Aminoglycosides are important antibacterial agents for the treatment of serious infection. Evidence suggests that high peak plasma concentrations must be achieved early in the course of treatment if these agents are to be effective, but prolonged high concentrations may cause ototoxicity and nephrotoxicity. Peak plasm...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-199427010-00004
更新日期:1994-07-01 00:00:00
abstract::Peak expiratory flow rate, adverse effects and serum theophylline concentration were measured during treatment of episodes of severe airways obstruction. 174 patients were randomised to target theophylline concentrations of 10 mg/L or 20 mg/L. The recovery of peak flow rate towards normal values was explicable in term...
journal_title:Clinical pharmacokinetics
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.2165/00003088-199325060-00008
更新日期:1993-12-01 00:00:00
abstract::The critically ill patient occupies an increasing amount of time and bed space in modern hospital practice, and also commands increasing expenditure. Drug therapy in these patients has, in the past, been based on data derived from healthy volunteers, fit anaesthetised patients undergoing minor operative procedures, or...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-198814060-00003
更新日期:1988-06-01 00:00:00
abstract:BACKGROUND AND OBJECTIVES:This analysis used a population pharmacokinetic approach to identify covariates that influence plasma exposure of liraglutide 3.0 mg, a glucagon-like peptide-1 (GLP-1) receptor agonist approved for weight management in overweight and obese individuals. METHODS:Samples for pharmacokinetic anal...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,随机对照试验
doi:10.1007/s40262-016-0410-7
更新日期:2016-11-01 00:00:00
abstract:OBJECTIVE:The aim of this study was to characterize the relationship between morphine plasma concentration and repeated time to postoperative remedication events in children undergoing cardiac surgery. METHODS:Data from our previously published study of morphine pharmacokinetics were utilized in this pharmacodynamic s...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.1007/s40262-016-0398-z
更新日期:2016-10-01 00:00:00
abstract::The pharmacokinetics of grepafloxacin in healthy male subjects following single oral administration of doses ranging from 200 to 1200 mg, and following repeated oral administration of 400 and 800 mg doses are reported. Plasma levels of grepafloxacin reached a peak within 2 hours (on average) following drug administrat...
journal_title:Clinical pharmacokinetics
pub_type: 临床试验,杂志文章
doi:10.2165/00003088-199700331-00003
更新日期:1997-01-01 00:00:00
abstract::With the use of combination chemotherapy as well as a wide range of symptomatic therapies (e.g. analgesics and antiemetics) for the treatment of patients with cancer, the field of oncology practises polypharmacy to an extreme degree. The risk for a drug interaction under these conditions is high, and the pharmacologic...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-198611030-00004
更新日期:1986-05-01 00:00:00
abstract:BACKGROUND:Enzyme replacement therapy (ERT) is currently the standard treatment for patients with Gaucher disease type I (GD1), but the pharmacokinetics have hardly been studied. This study aimed to quantify in vivo enzyme activity in peripheral leukocytes from patients receiving long-term treatment with imiglucerase o...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.1007/s40262-016-0387-2
更新日期:2016-09-01 00:00:00
abstract::Renewed interest in vancomycin over the past decade has led to an abundance of data concerning the pharmacokinetics of vancomycin, and its dosage selection and concentration-response relationships. No definitive data exist that correlate vancomycin serum concentrations with clinical outcomes. However, inconsistencies ...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-199528040-00005
更新日期:1995-04-01 00:00:00
abstract::The effects of anaesthesia and surgery on the pharmacokinetics of ketobemidone were studied in 12 patients. Plasma ketobemidone concentrations were assayed with a mass-fragmentographic method. The peroperative Vd(area) was 5.9 +/- 2.6L/kg and the terminal half-life was 3.9 +/- 1.7 h. In the postoperative period Vd(are...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-198207030-00005
更新日期:1982-05-01 00:00:00
abstract::Following administration of equivalent oral doses (30mg) of either prednisone or prednisolone to 5 patients with chronic active liver disease who had failed to respond to therapy, 5 patients with chronic active liver disease in remission induced by prednisone, and 7 healthy volunteers, corticosteroid concentrations we...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-198207050-00005
更新日期:1982-09-01 00:00:00
abstract::Interleukins and tumour necrosis factor (TNF) are a complex group of proteins and glycoproteins able to exert pleiotropic effects with respect to a number of different target cells. In physiological conditions, they are induced and released in basal amounts only in restricted microenvironments where they have paracrin...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-199121040-00004
更新日期:1991-10-01 00:00:00
abstract::Voriconazole is both a substrate and a potent inhibitor of cytochrome P450 (CYP) 3A. It has a high bioavailability and non-linear pharmacokinetics. We investigated the pharmacokinetics and metabolism of 50 mg and 400 mg doses of intravenous and oral voriconazole in 14 healthy volunteers. Concurrently, we determined sy...
journal_title:Clinical pharmacokinetics
pub_type: 临床试验,杂志文章
doi:10.1007/s40262-016-0416-1
更新日期:2016-12-01 00:00:00
abstract::Pancuronium is frequently used in coronary artery surgery, but its pharmacokinetics in these patients are still unknown. It is possible that dopamine, administered to prevent renal impairment induced by the surgery, might promote the elimination of pancuronium. Therefore, the pharmacokinetics of a bolus dose of pancur...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-199019060-00005
更新日期:1990-12-01 00:00:00
abstract:BACKGROUND AND OBJECTIVE:A simple approach is proposed to predict drug clearance in children when no paediatric data are available for drugs metabolised by cytochromes. METHODS:The maturation functions of cytochrome activity and binding proteins in plasma were combined with several measures of body size to describe dr...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.1007/s40262-017-0596-3
更新日期:2018-07-01 00:00:00
abstract:: ...
journal_title:Clinical pharmacokinetics
pub_type: 评论,信件
doi:10.1007/s40262-018-0665-2
更新日期:2018-07-01 00:00:00
abstract::The pharmacokinetics and antihypertensive effects of felodipine, a new dihydropyridine calcium channel blocker, were studied in elderly hypertensive patients, 67 to 79 years of age and in young healthy subjects, 20 to 34 years of age following oral administration of 5 mg twice daily to steady-state. A single intraveno...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-198814060-00004
更新日期:1988-06-01 00:00:00
abstract:BACKGROUND AND OBJECTIVE:Tegafur is an oral fluorouracil prodrug used in the treatment of colorectal cancer. The aim of this phase II, crossover, bioequivalence study was to compare the pharmacokinetics (primary objective) and tolerability (secondary objective) of tegafur-uracil (UFT) given as three daily doses (tid, r...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,随机对照试验
doi:10.2165/00003088-200746110-00003
更新日期:2007-01-01 00:00:00
abstract::The pharmacokinetics of oral morphine sulphate as controlled release tablets ('MS-Contin') and solution were compared at steady-state. Plasma morphine concentrations were determined over 24 hours following the last dose of each drug when given in a randomised, crossover fashion to healthy subjects. Radioimmunoassay wa...
journal_title:Clinical pharmacokinetics
pub_type: 临床试验,杂志文章,随机对照试验
doi:10.2165/00003088-198611060-00006
更新日期:1986-11-01 00:00:00
abstract::The alignment of drug metabolism and pharmacokinetic departments with drug discovery has not produced a radical improvement in the pharmacokinetic properties of new chemical entities. The reason for this is complex, reflecting in part the difficulty of combining potency, selectivity, water solubility, metabolic stabil...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-200241130-00001
更新日期:2002-01-01 00:00:00
abstract::The pharmacokinetics of dothiepin were evaluated in 9 depressed patients following a single oral dose of 75 mg. Blood and plasma concentrations of dothiepin and 2 major metabolites, northiaden and dothiepin S-oxide, were measured by gas chromatography/mass fragmentography. The mean (+/-SD) peak plasma concentrations o...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-198308020-00004
更新日期:1983-03-01 00:00:00
abstract:BACKGROUND AND OBJECTIVE:Escitalopram is one of the most commonly prescribed selective serotonin reuptake inhibitors (SSRIs). It is thought to act by blocking the serotonin transporter (SERT). However, its dose-SERT occupancy relationship is not well known, so it is not clear what level of SERT blockade is achieved by ...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.1007/s40262-016-0444-x
更新日期:2017-04-01 00:00:00
abstract::There are many pathological changes in patients with cystic fibrosis (CF) which can lead to alterations in drug disposition. Although, in patients with CF, the extent of drug absorption varies widely and the rate of absorption is slower, bioavailability is not altered. Plasma protein binding for the majority of drugs ...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-199835040-00004
更新日期:1998-10-01 00:00:00
abstract::The half-life of a drug, which expresses a change in concentration in units of time, is perhaps the most easily understood pharmacokinetic parameter and provides a succinct description of many concentration-time profiles. The calculation of a half-life implies a linear, first-order, time-invariant process. No drug per...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章
doi:10.2165/00003088-200140040-00001
更新日期:2001-01-01 00:00:00
abstract::Protein binding of antibacterials in plasma and tissues has long been considered a component of their pharmacokinetic parameters, playing a potential role in distribution, excretion and therapeutic effectiveness. Since the beginning of the 'antibacterial era', this factor has been extensively analysed for all antibact...
journal_title:Clinical pharmacokinetics
pub_type: 杂志文章,评审
doi:10.2165/00003088-200241100-00004
更新日期:2002-01-01 00:00:00