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11-03-2010 | Dermatology | Article

Drug-drug interactions common with methotrexate or cyclosporine for psoriasis


Free abstract

MedWire News: Researchers warn of the potential risk for drug-drug interactions in patients prescribed methotrexate or cyclosporine for psoriasis, and the substantial impact of these interactions on healthcare resources.

They report that over half of patients treated with methotrexate or cyclosporine (MTX/CYC) they observed were exposed to potential drug-drug interactions due to comedication with interacting drugs.

“Concomitant use of these drugs to control chronic conditions or comorbidities could alter or prolong the blood concentrations of MTX/CYC and enhance their toxicities, which can cause adverse effects and compromise the treatment efficacy,” say Jean-Hilaire Saurat, from Hôpital Cantonal in Geneva, Switzerland, and colleagues.

The team investigated the prevalence and outcomes of MTX/CYC polypharmacy using information from the Ingenix Impact National Managed Care Database (1999–2007), which includes the medical and pharmacy history of more than 60 million patients from 46 health plans across all regions of the USA.

Included in the study were 7955 psoriasis patients who were taking either MTX or CYC. Of these, 5483 were exposed to drugs that could potentially interact with MTX or CYC and 3372 were not.

The most commonly used drugs with potential to interact with both MTX and CYC in exposed patients were non-steroidal anti-inflammatory drugs (NSAIDs) and sulfonamide antibiotics.

As reported in the journal Dermatology, psoriasis patients in the exposed group, compared with the non-exposed group, had significantly greater risks for developing renal (odds ratios [OR]=2.58), gastrointestinal (OR=1.36), and pulmonary events (OR=1.20).

This increased risk for complications in turn significantly heightened the need for healthcare resources in psoriasis patients in the exposed group.

Indeed, during the 6-month study, the rates of inpatient and emergency department visits were 61% and 31% greater, respectively, for patients in the exposed group compared with the non-exposed group.

The exposed group also experienced significantly greater healthcare costs for all categories of medical services. During the study, the average total cost for pharmacy and medical services per patient was 59% greater for the exposed group compared with the non-exposed group. The adjusted incremental total costs for the exposed group were US$1722, reflecting a 28% increase on those for the non-exposed group.

Saurat and colleagues say: “Caution should be exercised when prescribing conventional systemic therapies to patients with psoriasis because of the likelihood and potential effects of interactions with concurrent medication use.

“Both the drug and the patient’s unique characteristics need to be considered when making treatment decisions to promote optimal outcomes, even if that means selecting more costly therapies.”

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Lucy Piper