Pfizer's Eucrisa has been cleared by the US Food and Drug Administration as a treatment for mild to moderate atopic dermatitis in patients two years of age and older.

Atopic dermatitis is the most common type of eczema caused by a combination of genetic, immune and environmental factors, which causes red, scaly and crusted bumps on the skin that are extremely itchy.

Eucrisa (crisaborole), a topical ointment used twice daily, is a phosphodiesterase 4 (PDE-4) inhibitor, but the FDA notes that its specific mechanism of action in atopic dermatitis is not known.

Pfizer picked up the drug via its acquisition of Silicon Valley biotech Anacor for around $5.2 billion back in June.

According to the drug giant, Eucrisa could achieve or exceed peak sales of more than $2 billion, given its performance in Phase III trials and sizeable target market; up to 25 million people in the US are thought to suffer from the condition.