Atopic dermatitis (AD) is a chronic inflammatory skin disease estimated to occur in 10% to 20% of the adult population. The disease is characterized by itching (also called pruritus), skin dryness and skin lesions whose features include redness, oozing with crusting, scratches or abrasions, and areas of the skin that become thickened and hardened. The scratching behavior associated with the itching is believed to worsen the AD lesions by causing mechanical damage to the skin allowing the penetration of bacteria which triggers inflammatory responses, leading to further worsening of the itching and inflammation of the skin.

A substance called Interleukin (IL-31) has been shown to play a role in the itching and inflammation seen in pruritic skin disorders like atopic dermatitis. Nemolizumab, a monoclonal antibody, inhibits the activity of IL-31. Medications that can inhibit the effect of IL-31 may have the potential to improve the symptoms of AD. In previous studies, a reduction in itching and lesion size after treatment with nemolizumab was observed in patients with AD after 8 weeks of treatment.

Some inflammatory diseases like atopic dermatitis can affect the way the body metabolizes certain medications. When patients with AD are treated with an agent that has an anti-inflammatory effect like nemolizumab, this too can affect the metabolism of some medications. This is due to the combined effects of the disease itself and the treatment (this is called disease-drug interaction).

Evaluation of these disease-drug interactions is very important. Patients with AD frequently take other medications in addition to the medications they take to treat their AD. To avoid potential problems, it is important to know if disease-drug interactions exist and if adjustments to the doses of medications are needed when taken together. The existence of these disease-drug interactions is evaluated in clinical studies like the proposed one in patients with AD.

The study includes 3 important elements: an investigational medication (nemolizumab), some commonly used medications (substrates), and a specific disease state. In this study, the disease state is AD. Since an active disease state is a key element, this study will be conducted in patients with active moderate-to-severe AD as they have significant inflammation and are candidates for systemic therapy, as per guidelines. These patients have the greatest potential for cytokine effects on CYP450 activity.