A Study to Determine the Safety & Efficacy of ZPL-5212372 in Healthy Subjects and in Subjects With Atopic Dermatitis

Inclusion Criteria: * Healthy males or females, aged between 18 and 55 years, inclusive (healthy is defined as no clinically relevant abnormalities identified by a detailed medical history, full physical examination, including blood pressure and pulse rate measurement, 12-lead ECG and clinical laboratory tests). or Males and females aged 18-65 years inclusive with physician documented history or diagnosis of atopic dermatitis for at least 6 months prior to screening. AD should be diagnosed by the Eichenfield revised criteria of Hanifin and Rajka. For Atopic Dermatitis Patients: Eczema Area and Severity Index (EASI) of ≥9 and \<48 at Screening and an EASI of ≥12 and \<48 at Day 1. An Investigator's Global Assessment (IGA) score ≥ 3 at both Screening and Day 1. Atopic dermatitis affecting between ≥10 to \<40% BSA at Screening and ≥10% to \<50% BSA on Day 1. All Subjects: Evidence of a personally signed and dated informed consent form, indicating that the subject has been informed of all pertinent aspects of the study. Exclusion Criteria: For Healthy Subjects * Evidence or history of clinically significant haematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing). * Have tattoos covering areas of skin to be dosed with study ointment. * Subjects who are hirsute in areas of skin to be dosed with study ointment. * Subjects who have received treatment with an investigational drug within 3 months prior to screening. For Atopic Dermatitis Patients: * AD of such severity (EASI \>48) that the subject could not comply with the demands of the study and/or the subject is not a suitable candidate for a placebo-controlled study. * Have concomitant skin disease or infection (e.g. acne, impetigo) or presence of skin comorbidities in the study area to be dosed that may interfere with study assessments. * Have received phototherapy (e.g. UVA, UVB or PUVA therapy), or systemic therapy (e.g. immunosuppressants \[such as cyclosporine, azathioprine, methotrexate\], cytostatics) known or suspected to have an effect on AD, within 4 weeks of the start of the study. All other biologics should not have been used within 3 months of the start of study. * Have received systemic corticosteroids (e.g. oral, intravenous, intraarticular, rectal) within 4 weeks of the start of the study. Subjects on a stable maintenance dose (over the preceding 3 months) of inhaled or intranasal CS may participate. * Patients treated with oral antihistamines or topical calcineurin inhibitors or topical steroids within 7 days of starting study; intranasal antihistamines for the treatment of allergic rhinitis are acceptable.