Elevated International Normalized Ratio associated with concurrent use of ophthalmic erythromycin and warfarin

2010 ◽  
Vol 67 (1) ◽  
pp. 38-41 ◽  
Author(s):  
Debra L. Parker ◽  
Teresa Kay Hoffmann ◽  
Mary Ann Tucker ◽  
Gregory P. Gerschutz ◽  
Patrick M. Malone
Keyword(s):  
International Normalized Ratio ◽  
Concurrent Use

scholarly journals Resveratrol stereoselectively affected (±)warfarin pharmacokinetics and enhanced the anticoagulation effect

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tse-Yin Huang ◽  
Chung-Ping Yu ◽  
Yow-Wen Hsieh ◽  
Shiuan-Pey Lin ◽  
Yu-Chi Hou
Keyword(s):  
Breast Cancer ◽  
Breast Cancer Resistance Protein ◽  
Systemic Exposure ◽  
International Normalized Ratio ◽  
Therapeutic Window ◽  
Cancer Resistance ◽  
Parallel Design ◽  
Concurrent Use ◽  
Resistance Protein ◽  
Conjugated Metabolites

Abstract Resveratrol (RVT) has various beneficial bioactivities and popularly used as a dietary supplement. RVT showed inhibitions on CYP1A2/2C9/3A4, breast cancer resistance protein (BCRP), and some conjugated metabolites of RVT also inhibited BCRP. (±)Warfarin, an anticoagulant for cardiovascular disease but with narrow therapeutic window, were substrates of CYP1A2/3A4(R-form), 2C9(S-form) and BCRP. We hypothesized that the concurrent use of RVT might affect the metabolism and excretion of warfarin. This study investigated the effect of RVT on the pharmacokinetics and anticoagulation effect of (±)warfarin. Rats were orally given (±)warfarin (0.2 mg/kg) without and with RVT (100 mg/kg) in a parallel design. The results showed that RVT significantly increased the AUC0−t of S-warfarin and international normalized ratio. Mechanism studies showed that both RVT and its serum metabolites (RSM) inhibited BCRP-mediated efflux of R- and S-warfarin. Moreover, RSM activated CYP1A2/3A4, but inhibited CYP2C9. In conclusion, concomitant intake of RVT increased the systemic exposure of warfarin and enhanced the anticoagulation effect mainly via inhibitions on BCRP and CYP2C9.

A Review of Warfarin Dosing With Concurrent Acetaminophen Therapy

2013 ◽  
Vol 26 (5) ◽  
pp. 518-521 ◽  
Author(s):  
G. Michelle Pinson ◽  
Jennifer W. Beall ◽  
Jeffrey A. Kyle
Keyword(s):  
Drug Interaction ◽  
Drug Interactions ◽  
Warfarin Therapy ◽  
International Normalized Ratio ◽  
Over The Counter ◽  
Pain Medications ◽  
Concurrent Use ◽  
Prevention And Treatment ◽  
Drug Drug Interaction ◽  
Warfarin Dosing

Warfarin is frequently used for the prevention and treatment of thromboembolism, yet it is associated with numerous drug interactions. Regarding over-the-counter pain medications, the preferred analgesic for those patients who are taking warfarin is acetaminophen. There are, however, reports of elevation in the international normalized ratio (INR) in those patients taking concurrent warfarin and acetaminophen. For those practitioners who manage warfarin therapy, there is little guidance regarding management of the drug–drug interaction between warfarin and acetaminophen. This review seeks to evaluate the drug interaction between warfarin and acetaminophen and provides recommendations for concurrent use of these drugs.

scholarly journals Warfarin control in Hong Kong clinical practice

2019 ◽  
Author(s):  
Amy SM Lam ◽  
Isis MH Lee ◽  
Ka Shing Mak ◽  
Bryan PY Yan ◽  
Vivian WY Lee
Keyword(s):  
Hong Kong ◽  
Clinical Outcomes ◽  
Therapeutic Range ◽  
Warfarin Therapy ◽  
Prosthetic Heart Valve ◽  
International Normalized Ratio ◽  
Clinical Complications ◽  
Concurrent Use ◽  
The Status ◽  
One Year

Abstract Objectives: Time-in-therapeutic range (TTR) assesses safety and effectiveness of warfarin therapy using international normalized ratio (INR). This study aimed to investigate the status of TTR in Hong Kong and patients’ economic and clinical outcomes. Predictors of poor warfarin control and patient’s knowledge in warfarin therapy were assessed. Methods: A five-month observational study was conducted in Prince of Wales Hospital in Hong Kong. The TTRs calculated using Caucasian and Japanese therapeutic range were examined among patients on warfarin for at least one year. Patients’ knowledge was assessed using the Oral Anticoagulation Knowledge (OAK) test. Results: A total of 259 patients were included in this study, with 174 of them completed the OAK test. Using Caucasian therapeutic range, calculated mean TTR was 40.2 ± 17.1%, compared that of 49.1 ± 16.1% with Japanese therapeutic range (P<0.001). Mean TTR in patients with atrial fibrillation was higher than those with prosthetic heart valve (p<0.001). Predictability of TTR on clinical outcomes and economic outcomes was comparable between Caucasian and Japanese therapeutic range. Patients with ideal TTR had fewer clinical complications and lower warfarin-related healthcare costs. Patients with younger age, concurrent use of aspirin, frusemide, famotidine, pantoprazole and simvastatin were associated with poorer TTR. Mean score of OAK test was 54.1%. Only 24 patients (13.8%) achieved the satisfactory overall score of ≥75% in the test. Conclusion: Warfarin use in Hong Kong patients was poorly controlled regardless of indication. Patients’ knowledge towards warfarin use was suboptimal. More education to patients on warfarin use is warranted.

Plasmatic hemostasis at very high altitude — a thrombelas-tometric approach

2021 ◽  
Vol 17 (4) ◽  
pp. 1-5
Author(s):  
Micaela Tobler ◽  
Christos T. Nakas ◽  
Matthias P. Hilty ◽  
Andreas Huber ◽  
Tobias Merz ◽  
...  
Keyword(s):  
High Altitude ◽  
Blood Coagulation ◽  
Hypobaric Hypoxia ◽  
Prospective Observational Study ◽  
Activated Protein C ◽  
International Normalized Ratio ◽  
Global Evaluation ◽  
Fibrinogen Concentration ◽  
Concurrent Use ◽  
Very High

Introduction: Changes in blood coagulation during exposure to high altitude are not well understood and studies of activation and consumption of specific coagula-tion factors in hypoxic humans have yielded conflicting results. In this study we used thrombelastometry (TEM) which allows a global evaluation of clot formation and lysis process to study blood coagulation profiles in volunteers exposed to pro-longed hypobaric hypoxia at extreme altitudes. Material and methods: We conducted a prospective, observational study in 39 healthy volunteers during a research expedition up to an altitude of 7050 m. Plasma based thrombelastometric measurements and standard coagulation parameters were performed at different altitudes. Results: TEM measurements showed an increase in clotting time (CT) and maxi-mum clot firmness (MCF) at high altitudes, paralleled by an increase in international normalized ratio (INR) and activated partial thromboplastin time (aPTT). Fibrinogen concentration increased until 6022 m. D-Dimer and Thrombin-Antithrombin complex (TAT) increased with time exposed to severe hypoxia. For both measurements highest levels were found at 4844 m after acclimatization; in contrast, lower values were observed again at 7050m in the group of summiteers. Activated protein C resistance (APC-R) was slightly lowered at all altitudes. Conclusion: Our results suggest that activation of the coagulation and fibrinolytic system occurs with increasing hypobaric hypoxia with concurrent use of coagula-tion factors indicating the occurrence of a consumption-coagulopathy phenotype.

Multi-Center Study of Thromboplastin Calibration Precision – Influence of Reagent Species, Composition, and International Sensitivity Index (ISI)

1993 ◽  
Vol 69 (01) ◽  
pp. 035-040 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Oral Anticoagulants ◽  
International Normalized Ratio ◽  
The Other ◽  
World Health ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Bovine Plasma ◽  
Significant Difference ◽  
The Mean ◽  
International Sensitivity Index

SummaryFour thromboplastin reagents were tested by 18 laboratories in Europe, North-America, and Australasia, according to a detailed protocol. One thromboplastin was the International Reference Preparation for ox brain thromboplastin combined with adsorbed bovine plasma (coded OBT/79), and the second was a certified reference material for rabbit brain thromboplastin, plain (coded CRM 149R). The other two thromboplastin reagents were another rabbit plain brain thromboplastin (RP) with a lower ISI than CRM 149R and a rabbit brain thromboplastin combined with adsorbed bovine plasma (RC). Calibration of the latter two reagents was performed according to methods recommended by the World Health Organization (W. H. O.).The purpose of this study was to answer the following questions: 1) Is the calibration of the RC reagent more precise against the bovine/combined (OBT/79) than against the rabbit/plain reagent (CRM 149R)? 2) Is the precision of calibration influenced by the magnitude of the International Sensitivity Index (ISI)?The lowest inter-laboratory variation of ISI was observed in the calibration of the rabbit/plain reagent (RP) against the other rabbit/plain reagent (CRM 149R) (CV 1.6%). The highest interlaboratory variation was obtained in the calibration of rabbit/plain (RP) against bovine/combined (OBT/79) (CV 5.1%). In the calibration of the rabbit/combined (RC) reagent, there was no difference in precision between OBT/79 (CV 4.3%) and CRM 149R (CV 4.2%). Furthermore, there was no significant difference in the precision of the ISI of RC obtained with CRM 149R (ISI = 1.343) and the rabbit/plain (RP) reagent with ISI = 1.14. In conclusion, the calibration of RC could be performed with similar precision with either OBT/79 or CRM 149R, or RP.The mean ISI values calculated with OBT/79 and CRM 149R were practically identical, indicating that there is no bias in the ISI of these reference preparations and that these reference preparations have been stable since their original calibration studies in 1979 and 1987, respectively.International Normalized Ratio (INR) equivalents were calculated for a lyophilized control plasma derived from patients treated with oral anticoagulants. There were small but significant differences in the mean INR equivalents between the bovine and rabbit thromboplastins. There were no differences in the interlaboratory variation of the INR equivalents, when the four thromboplastins were compared.

Relationship Between Total Prothrombin, Native Prothrombin and the International Normalized Ratio (INR)

1992 ◽  
Vol 68 (02) ◽  
pp. 160-164 ◽  
Author(s):  
P J Braun ◽  
K M Szewczyk
Keyword(s):  
Anticoagulant Therapy ◽  
Oral Anticoagulant ◽  
Inverse Relationship ◽  
Low Dose ◽  
Oral Anticoagulant Therapy ◽  
International Normalized Ratio ◽  
Antigen Assay ◽  
Dose Oral ◽  
Anticoagulated Patients ◽  
Sensitive Method

SummaryPlasma levels of total prothrombin and fully-carboxylated (native) prothrombin were compared with results of prothrombin time (PT) assays for patients undergoing oral anticoagulant therapy. Mean concentrations of total and native prothrombin in non-anticoagulated patients were 119 ± 13 µg/ml and 118 ± 22 µg/ml, respectively. In anticoagulated patients, INR values ranged as high as 9, and levels of total prothrombin and native prothrombin decreased with increasing INR to minimum values of 40 µg/ml and 5 µg/ml, respectively. Des-carboxy-prothrombin increased with INR, to a maximum of 60 µg/ml. The strongest correlation was observed between native prothrombin and the reciprocal of the INR (1/INR) (r = 0.89, slope = 122 µg/ml, n = 200). These results indicated that native prothrombin varied over a wider range and was more closely related to INR values than either total or des-carboxy-prothrombin. Levels of native prothrombin were decreased 2-fold from normal levels at INR = 2, indicating that the native prothrombin antigen assay may be a sensitive method for monitoring low-dose oral anticoagulant therapy. The inverse relationship between concentration of native prothrombin and INR may help in identification of appropriate therapeutic ranges for oral anticoagulant therapy.

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