Pimecrolimus

Pimecrolimus is a topical calcineurin inhibitor used to treat inflammatory skin conditions, most notably atopic dermatitis (eczema). It is formulated as a 1% cream and is approved for patients aged 2 years and older with mild-to-moderate disease or when corticosteroids are undesirable or ineffective. It may also be used off-label for other inflammatory dermatoses in some settings.

Mechanism of action: Pimecrolimus binds to the intracellular protein macrophilin-12 to form a complex that inhibits calcineurin. This prevents activation of T cells and transcription of interleukin-2 and other cytokines, reducing skin inflammation without the vasoconstrictive effects of corticosteroids. The preparation is non-steroidal and designed to be used on areas where steroid exposure is a concern.

Indications and administration: The cream is applied in a thin layer to affected areas twice daily until symptoms improve, with continued use as needed to prevent flares. It should be avoided on broken skin, mucous membranes, and around the eyes; hands should be washed after applying. It is typically used as part of a broader eczema management plan, including moisturizers and trigger avoidance.

Pharmacokinetics and safety: Systemic absorption from intact skin is limited, but absorption can increase with extensive or broken skin. Metabolism is hepatic and excretion occurs mainly via the urine and feces. Common local adverse effects include burning or warmth at the application site and irritation. Systemic adverse effects are uncommon due to limited absorption. Notably, topical calcineurin inhibitors carry regulatory warnings about potential cancer risk, and use should be balanced against benefits, with avoidance of use in active infections.

See also: tacrolimus, another topical calcineurin inhibitor.