Vitamin K Deficiency in the Elderly

Hazell, Kenneth; Baloch, Komal

doi:10.1159/000245257

Cited by 25 publications

(4 citation statements)

References 3 publications

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“…12 This link with warfarin sensitivity may be multifactorial, including poor nutritional status and hence a relative vitamin K deficiency, and may also be a reflection of a relative inability of the liver to produce sufficient clotting factors. 13,14 Warfarin is highly protein bound, primarily to albumin. The effect of an increased unbound fraction on loading dose requirements is unknown.…”

Section: Discussionmentioning

confidence: 99%

Assessment of an Age-Adjusted Warfarin Initiation Protocol

et al. 2003

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Section: Discussionmentioning

confidence: 99%

Assessment of an Age-Adjusted Warfarin Initiation Protocol

et al. 2003

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“…There are a number of possible explanations for this age-dependent difference in susceptibility to warfarin. With advancing years changes may occur in lean body mass (Forbes & Reina, 1970), in sensitivity to vitamin K or warfarin (Hazel & Baloch, 1970), in serum proteins and in renal function. Alternatively, as occurs with the metabolism of antipyrine and phenylbutazone (O'Malley, Crooks, Duke & Stevenson, 1971), the rate of inactivation of warfarin may decrease in the elderly.…”

Section: Discussionmentioning

confidence: 99%

Determinants of anticoagulant control in patients receiving warfarin.

O’Malley¹,

Stevenson²,

Ward³

et al. 1977

Brit J Clinical Pharma

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1A hospital-based drug information system has been used to assess the time for which patients treated with warfarin were outside the range of Thrombotest values 5-10% and 5-15% and to examine possible contributory factors in situations where anticoagulation fell outside these ranges. 2 Anticoagulant control varied with the age of the patient and with concomitant drug therapy but not with patient sex or indication for anticoagulation. 3 Most patients were 'under-anticoagulated' at some stage but patients over 70 years spent significantly longer in the 5-10% range than those in the age range 30-59 years and Thrombotest values of less than 5% were found predominantly in the older group. 4 Patients given drugs known to interact with warfarin spent least time in the defined Thrombotest ranges. Those on drugs known to potentiate warfarin effect had significantly lower Thrombotest values than the other patients studied.

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“…Several reasons for the connection between age and dose have been proposed: Changes in the lean body mass (Forbes & Reina, 1970), changed sensitivity to vitamin K or warfarin (Hasel & Baloch, 1970), the rate of inactivation of warfarin being possibly decreased with age (O'Malley et al, 1977, Husted & Andreasen, 1977 lower albumin values in the aged, a change of the affinity of the receptor site and an increased degradation rate of coagulation factors (Husted & Andreasen, 1977). Shepherd, Hewick, Moreland & Stevenson (1977) showed that vitamin K dependent clotting factors were more effectively inhibited by warfarin in the elderly.…”

Section: Resultsmentioning

confidence: 99%

Comparison of a new microcrystalline dicoumarol preparation with warfarin under routine treatment conditions.

Lockner¹,

Paul²

1979

Brit J Clinical Pharma

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1 To determine whether two different oral anticoagulants show difference under routine clinical conditions, 71 patients were randomized to treatment with Apekumarol, a microcrystalline dicoumarol preparation, and 72 patients to treatment with warfarin. 2 During the inpatient phase of treatment both drug groups remained for about 94% of their treatment time within prothrombin value limits of 5‐25% (Simplastin A). No statistically significant difference was found between the drugs. 3 While under outpatient care, both drug groups remained for about 80% of their treatment time within prothrombin value limits of 5‐25%. No statistically significant difference was found between the drugs. 4 The intensity of control and number of prothrombin‐ determinations did not differ significantly between the groups. 5 Variations in the daily dose did not differ significantly between the groups. 6 The mean daily dose could not be correlated to mean body weight. 7 The mean daily dose decreased with age for the male patients taking warfarin, not for the female patients. There was no such decrease for either male or female patients taking Apekumarol. An additional 137 patients who at the time of the trial were under routine treatment with warfarin were also studied with regard to mean daily dose, age and sex. In this additional group the mean daily dose could be correlated with age in both males and females. 8 No difference between Apekumarol and warfarin could be demonstrated when tested under routine clinical conditions according to the design of the present study. Sensitivity for warfarin, but not for Apekumarol, seems to increase with age, this sensitivity has been demonstrated in both sexes.

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Vitamin K Deficiency in the Elderly

Cited by 25 publications

References 3 publications

Assessment of an Age-Adjusted Warfarin Initiation Protocol

Assessment of an Age-Adjusted Warfarin Initiation Protocol

Determinants of anticoagulant control in patients receiving warfarin.

Comparison of a new microcrystalline dicoumarol preparation with warfarin under routine treatment conditions.

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