A model which predicts maintenance warfarin dosage requirements from the response to a single dose [letter]

Peterson, Gregory; McLean, Susannah; Jupe, D. M. L.; Griffith, Richard; Roberts, Jason A.

doi:10.1111/j.1365-2125.1985.tb05055.x

Cited by 5 publications

(6 citation statements)

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“…We have previously described a model, developed from retrospectively collected data, for predicting individual MD requirements 24 h after the administration of a single dose of warfarin (Peterson et al, 1985). This Also excluded were seven patients whose factor VII activity fell by less than 30% during the 24 h period after the initial warfarin dose, since we had shown previously, using computer simulations, that the model may be less precise in that region (Peterson et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…This Also excluded were seven patients whose factor VII activity fell by less than 30% during the 24 h period after the initial warfarin dose, since we had shown previously, using computer simulations, that the model may be less precise in that region (Peterson et al, 1985). Patients with other possible complicating factors (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…We have previously described a model, developed from retrospectively collected data, for predicting individual MD requirements 24 h after the administration of a single dose of warfarin (Peterson et al, 1985). This model was developed from the relationship between the initial anticoagulant response, measured as the 24 h percentage fall in plasma clotting factor VII activity, and the maintenance prothrombin ratio (PR) response per MD.…”

Section: Introductionmentioning

confidence: 99%

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Warfarin dosage requirements: prospective clinical trial of a method for prediction from the response to a single dose.

Jupe

Peterson

Coleman

et al. 1988

Brit J Clinical Pharma

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We have previously described a model for predicting individual daily maintenance dosage (MD) requirements of warfarin 24 h after the administration of a single dose. This model relies on measurement of the initial anticoagulant response as the 24 h percentage fall in plasma clotting factor VII activity. It permits prediction of the individual MD given the size of the initial dose, a baseline and desired maintenance value of the prothrombin ratio, and a baseline and 24 h plasma level of factor VII activity. We now present the results of a prospective clinical trial of the method. Data from 65 patients were suitable for analysis. The mean daily MD of warfarin was 4.0 mg (range 1-10 mg). There was a moderately strong linear relationship between predicted and actual MDs of warfarin (r = 0.66, P < 0.001). Actual vs predicted MDs in individual patients were not significantly different. The mean difference was 0.39 mg. The results of this prospective trial suggest that our model predicts warfarin MD requirements with reasonable accuracy. Nevertheless, the accuracy of the model is not sufficient to replace careful clinical and haematological monitoring of each patient commencing warfarin therapy.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…We have previously described a model, developed from retrospectively collected data, for predicting individual MD requirements 24 h after the administration of a single dose of warfarin (Peterson et al, 1985). This model was developed from the relationship between the initial anticoagulant response, measured as the 24 h percentage fall in plasma clotting factor VII activity, and the maintenance prothrombin ratio (PR) response per MD.…”

Section: Introductionmentioning

confidence: 99%

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Warfarin dosage requirements: prospective clinical trial of a method for prediction from the response to a single dose.

Jupe

Peterson

Coleman

et al. 1988

Brit J Clinical Pharma

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“…The simplest techniques involve graphical or computerized descriptions of relationships between responses following initial loading doses and those of subsequent maintenance doses. (Routledge et al, 1977;Sawyer, 1979;Lammle et al, 1981;Sharma et al, 1982;Carter et al, 1983;1987;Peterson et al, 1985;Jupe et al, 1988).…”

Section: Chapter VI Individualizing Warfarin Administrationmentioning

confidence: 99%

“…Individual factor mesurements were implemented by Peterson et al, 1985 andJupe et al, 1988 (Factor VII, measured by a clotting test) in the prediction of warfarin maintenance dose and Aiach et al, 1982, who suggest the use of Factor X, measured by a chromogenic method, as a better predictor than Factor VII or PT during the initiation of acenocoumarol treatment. Whether based on extrapolation from initial effects to maintenance dose or on iterative methods these techniques have not improved significantly on empirical therapy (Carter et al, 1987;Weiss et al, 1986;Holford, 1986).…”

Section: Chapter VI Individualizing Warfarin Administrationmentioning

confidence: 99%

Warfarin: Phamacokinetic and Pharmacodynamic Studies

Ριτσιου¹

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it never was a single person's achievement. In the formation of the present work various people contributed, each at a different level.My supervisor, Professor Malcolm Rowland, has been a source of inspiration with his enthousiasm about the work and his insight. Dr. Leon Aarons has patiently clarified obscure aspects of data analysis, put things into prospective and relieved a lot of tension with his stoic sense of humour. Eva Nilsson, apart from assisting in part of the experimental work, has been a valuable companion in the exploration of ideas. Diane Matthew proof read the final text and knew when to provide support and advice. George Fleming put up with panic attacks and made possible the optimal use of instrumentation. The personel in MEDEVAL, especialy Frank Mullins, assisted in various experimental and analytical matters.My brother, Stelios, and my friend, Victoria, stayed with me through long working hours and sustained my morale, with their caring and love.

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Standardised initial warfarin treatment: evaluation of initial treatment response and maintenance dose prediction by randomised trial, and risk factors for an excessive warfarin response

Doecke

Cosh

Gallus

1991

Australian and New Zealand Journal of Medicine

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We report a comparison of warfarin treatment outcomes in 172 inpatients in two general hospitals randomly assigned to commence warfarin therapy by one of two methods; the first where warfarin dosage was determined using a flexible dose induction protocol, and the other where dosage was prescribed empirically by resident medical staff. The mean INR for each treatment day, the mean time to reach a therapeutic level of INR, the mean maintenance dose and the mean time to reach maintenance dose were not significantly different between the protocol and empirical treatment groups. Although the mean observations of warfarin effect were similar between the two groups, there were more patients with excessive warfarin effect (INR greater than 4.0) during empirical treatment. In addition, age and identified complicating factors such as interfering drugs, heart failure or alcohol abuse were significant predictors of excessive warfarin effect, regardless of treatment group. The protocol dose administered on day 4 of treatment, which has been used as a determinant of maintenance dose, predicted maintenance dose to within 1 mg in 57/83 patients (69%, 95% confidence interval: 59-79%). We conclude that as a method for safely and effectively initiating warfarin therapy, this protocol at least matches the empirical prescribing skills of medical staff in a teaching hospital.

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A model which predicts maintenance warfarin dosage requirements from the response to a single dose [letter]

Cited by 5 publications

References 4 publications

Warfarin dosage requirements: prospective clinical trial of a method for prediction from the response to a single dose.

Warfarin dosage requirements: prospective clinical trial of a method for prediction from the response to a single dose.

Warfarin: Phamacokinetic and Pharmacodynamic Studies

Standardised initial warfarin treatment: evaluation of initial treatment response and maintenance dose prediction by randomised trial, and risk factors for an excessive warfarin response

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