RELATIONSHIP OF AGE, WEIGHT AND BODY SURFACE AREA TO WARFARIN MAINTENANCE DOSE REQUIREMENTS
| Autor: | Duane M. Kirking, Tracy A. Hutchison, Ira A. Cohen, M. E. Shue |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Male
Body Surface Area Population Physiology Pharmacology Pharmacokinetics Humans Medicine Pharmacology (medical) education Aged Body surface area Volume of distribution education.field_of_study business.industry Maintenance dose Body Weight Age Factors Warfarin Middle Aged Pharmacodynamics Prothrombin Time Lean body mass Female business medicine.drug |
| Zdroj: | Journal of Clinical Pharmacy and Therapeutics. 10:101-105 |
| ISSN: | 0269-4727 |
| Popis: | Multiple factors have been shown to influence the pharmacokinetics, pharmacodynamics and, hence, dosage requirements of the oral anticoagulant, warfarin (1-3). The relationship between patient age in the adult population and warfarin maintenance dose is controversial. Several studies (4-6) have found a significant inverse correlation between age and dose, and it has been reported (5) that the elderly, when compared to a population of relatively younger adults, are more sensitive to the pharmacologic effects of the drug at any given dose. Subsequently, two other research groups (7,8), however, failed to conrim a significant age-dose relationship. A recent study by Dobrzanski et al. (9) found both an inverse correlation between age and warfarin maintenance dose (r= -0.39; P< 0.01) and a positive correlation between patient total body weight and warfarin dosage requirements (r = 0.39; P < 0.01). Although the authors acknowledged that additional variables affect warfarin dose, they suggested that patient age and weight may be a useful guide in choosing initial warfarin maintenance doses. It is presently uncommon in clinical practice for warfarin dose to be calculated on the basis of weight (i.e. mg/kg), and the only other study in the literature which reported the relationship between weight and dose (6) failed to find a significant correlation between those parameters. If a relationship between patient weight and warfarin dose exists, the correlation may be greater if lean body weight (i.e., the lesser of either total body weight minus excess weight due to obesity or, in the case of a lean individual, actual body weight) were utilized instead of total body weight. Such a finding would be expected since warfarin has a low volume of distribution consistent with its high affinity for serum proteins. It partitions poorly into adipose tissue and, therefore, the apparent volume of distribution should not increase linearly with total body weight in the case of an obese patient (1). For the same reasons, a relatively strong correlation between lean body weight-derived body surface area (BSA) and dosage requirements should be found. The objectives of our study were, therefore, to attempt to verify the findings of Dobrzanski and coworkers, and to determine if measures of lean body weight and BSA will enhance the predictive value of the potential correlation between body weight and warfarin maintenance dose. |
| Databáze: | OpenAIRE |
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