Variation in the Biological Availability of Digoxin

Shaw, T. R. D.; Howard, M. R.; Hamer, John

doi:10.1016/s0140-6736(72)92908-x

Cited by 99 publications

(10 citation statements)

References 10 publications

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“…Several reports have recently considered the variation in biological availability of different digoxin preparations (Lindenbaum et al, 1971;Shaw et al, 1972) and even between batches of digoxin from the same drug company (Van Oudtshoorn, 1972). Initially we attempted to identify the digoxin preparation in each individual, but as many of the patients were elderly, lived alone, and could not even specify the pharmacist from whom the tablets were obtained we found comprehensive information impossible to obtain.…”

Section: Discussionmentioning

confidence: 99%

Do patients take digoxin?

Johnston¹,

Kelly²,

McDevitt³

1978

Heart

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Plasma digoxin concentrations on admission to hospital have been compared with levels on day 8 in a group of 50 patients who were maintained on their preadmission digoxin doses for 7 days. In the absence of a change in renal function, 18 patients (36%) had higher levels on day 8 and were considered to be non-compliant: a further 7 patients (14%) had lower levels on day 8 suggesting that before admission they had been taking more than their prescribed digoxin dose. Fifty per cent were, therefore, taking their digoxin improperly. In addition, an incorrect dose of digoxin may have been prescribed in 14 patients (28%) with plasma digoxin concentrations either below 0-8 ng/ml (1.02 nmol/l) or above 2-0 ng/ml (2 56 nmol/l) on day 8. Long-term compliance was assessed by comparing day 8 'steady state' digoxin levels with those obtained at outpatient follow-up. Thirty of the originalgroup were studied at 4 weeks when 27per cent were considered non-compliant, and 20 at 3 months when 30 per cent were non-compliant. These results have serious implications both for drug prescribing andfor the treatment of disease, and suggest that a problem of communication exists between doctors and their patients.In a previous study of patients already taking digoxin when admitted to hospital as emergencies (Carruthers et al., 1974), it was found that only 42 per cent had plasma digoxin concentrations within the normal therapeutic range of 08 to 2-0 ng/ml (1-02-2*56 nmol/l) (Whiting et al., 1973); 33 per cent had levels below 08 ng/ml (1P02 nmol/l) and were presumably under-treated and 25 per cent had levels greater than 2-0 ng/ml (2-56 nmol/l) and may have been potentially at risk from digoxin toxicity (Chamberlain et al., 1970;Whiting et al., 1973). Factors responsible for the wide scatter of digoxin concentrations were not identified. A further group of patients have now been studied in which serial inpatient and outpatient plasma digoxin concentrations were used to investigate non-compliance as a possible explanation of the fact that so many levels lie outside the 'therapeutic range'. Patients and methodsConsecutive patients admitted as emergencies to a general medical ward in the Belfast City Hospital and receiving maintenance digoxin treatment before admission were studied. For each patient, a careful history relating to digoxin treatment was taken with particular reference to the dose, the

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Section: Discussionmentioning

confidence: 99%

Do patients take digoxin?

Johnston¹,

Kelly²,

McDevitt³

1978

Heart

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“…Since then, the pharmacokinetics and bioavailability of different preparations has been adequately described, (5)(6)(7)(8)(9)(10)(11). The need for a kit which is precise and accurate throughout the whole range of digoxin levels found in the blood has been highlighted by several authors (12)(13)(14)(15), who have described the differing response to digoxin in different clinical situations, where toxic symptoms may occur at very much lower concentrations than those normally encountered.…”

Section: Discussionmentioning

confidence: 99%

A Test of Six Commercial 125 I-Labelled Digoxin Radioimmunoassay Kits

Wood¹

1977

Clinical Chemistry and Laboratory Medicine

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The Clinical Assays kit was used as the "reference" kit against which the other 5 kits were compared, as this kit had been in routine use for 15 months. These kits showed good correlation with the reference kit (p < 0.001). Kits -D were tested to see if the high circulating steroids in the second half of a clinically normal pregnancy influenced kit performance. In these kits no "digoxin" level above 0.38 nmol · liter" 1 was recorded, despite the high cortisol In another 49 hospitalised patients undergoing regular digoxin therapy, the greatest discrepancy between these 4 kits in measuring digoxin in a single serum was 1.15 nmol · liter" 1 .In the kits employing antibody-coated tubes, modification of procedure often led to improved sensitivity and therefore to better precision in the lower concentration range. Untersuchungen von sechs kommerziellen I2s j-markierten Digoxin-KitsZusammenfassung: Es wurden folgende kommerziell erhältlichen

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“…3). In some individual cases the older Lanoxin had produced higher levels than other brands (Shaw, Howard and Hamer, 1972). The mean levels found with the group of 'other brands' is influenced both by the bio-availability of individual brands and by the frequency with which each brand was used.…”

Section: Introductionmentioning

confidence: 88%

The digoxin affair

Shaw

1974

Postgraduate Medical Journal

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Summary The cardiac glycosides are potentially dangerous medicines and consistent preparations are necessary. However, presently used tablets of digoxin differ markedly in the fraction of the dose which is absorbed. Measurement of plasma digoxin levels by radioimmunoassay show that absorption from the Lanoxin brand has varied considerably in recent years due to changes in manufacturing technique. Other brands marketed in the U.K. form a wide range of bio-availability. Hazards to the patient are not entirely avoided by brand name prescribing and it is suggested that new pharmacopoeial standards are needed.

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Variation in the Biological Availability of Digoxin

Cited by 99 publications

References 10 publications

Do patients take digoxin?

Do patients take digoxin?

A Test of Six Commercial 125 I-Labelled Digoxin Radioimmunoassay Kits

The digoxin affair

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