Blood concentrations of pimecrolimus in adult patients with atopic dermatitis following intermittent administration of pimecrolimus cream 1% (Elidel) for up to 1 year.

Objectives: To determine blood concentrations of pimecrolimus after long-term intermittent administration of pimecrolimus cream 1% in adult patients with extensive atopic dermatitis (AD).
Methods: This was an open-label, multiple topical dose study in adults with moderate to severe AD and a total body surface area (TBSA) involvement of at least 20%. Pimecrolimus cream 1% was administered twice daily according to treatment need for up to 12 months to all lesions, including the neck and face. Blood samples were collected at regular time points and pimecrolimus concentrations were measured using a radioimmunoassay with a limit of quantitation (LoQ) of 0.5 ng/ml.
Results: Forty patients (19 females), aged from 19 to 59 years, with moderate to severe AD entered the study. Twenty patients completed 6 months and 13 completed 1 year in the study. The individual blood concentrations of pimecrolimus were consistently low and there was no sign of drug accumulation. In 900 of the 918 samples examined (98%), pimecrolimus concentrations remained below the LoQ. The maximum concentration observed throughout the entire study was 0.8 ng/ml.
Conclusion: Long-term intermittent treatment of adult patients with extensive AD with pimecrolimus cream 1% is associated with minimal systemic exposure and no evidence of drug accumulation.