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Ann Rheum Dis. 2007 Jun;66(6):821-4. Epub 2007 Feb 26.

Very low blood hydroxychloroquine concentration as an objective marker of poor adherence to treatment of systemic lupus erythematosus.

Author information

1
AP-HP, Service de Médecine Interne, Centre de Référence National pour le Lupus Systémique et le Syndrome des Antiphospholipides, CHU Pitié-Salpêtrière, 47-83 Boulevard de l'Hôpital, 75651 Paris Cedex 13, France. nathalie.costedoat@psl.aphp.fr

Abstract

BACKGROUND:

Poor adherence to treatment is difficult to diagnose accurately. Hydroxychloroquine (HCQ) has a long elimination half-life and its concentration in whole blood can be measured easily.

OBJECTIVE:

To evaluate the utility of a very low blood HCQ concentration as a marker of poor compliance in patients with systemic lupus erythematosus (SLE).

METHODS:

HCQ concentrations were determined on a blinded basis in 203 unselected patients with SLE. At the end of the study, the patients were informed of the results and retrospectively interviewed about their adherence to treatment.

RESULTS:

14 (7%) patients said that they had stopped taking HCQ (n = 8) or had taken it no more than once or twice a week (n = 6). Their mean (SD) HCQ concentration was 26 (46) ng/ml. range (0-129 ng/ml) By contrast, the other patients had a mean HCQ concentration of 1079 ng/ml range (205-2629 ng/ml). The principal barriers to adherence were related to HCQ treatment characteristics. Adherence subsequently improved in 10 of the 12 patients whose blood HCQ concentrations were remeasured.

CONCLUSIONS:

Very low whole-blood HCQ concentrations are an objective marker of prolonged poor compliance in patients with SLE. Regular drug assays might help doctors in detect non-compliance and serve as a basis for counselling and supporting these patients.

PMID:
17324970
PMCID:
PMC1954674
DOI:
10.1136/ard.2006.067835
[Indexed for MEDLINE]
Free PMC Article

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