A Safety and Pharmacokinetics Study of IDP-118 Lotion in Pediatric Participants With Plaque Psoriasis

Inclusion Criteria: * Is 4 to 16 years 11 months of age at time of informed consent/assent obtained. * Verbal and written informed consent/assent obtained from the participant and/or parent or legal guardian. * Has a clinical diagnosis of psoriasis at Screening and Baseline with an Investigator's Global Assessment (IGA) score of 3 or 4. The face, scalp, axillae, and intertriginous areas are to be excluded in this assessment, if psoriasis is present. * Has an area of plaque psoriasis appropriate for topical treatment that involves a BSA of at least 10% at Screening and Baseline. The face, scalp, axillae, and intertriginous areas are to be excluded in this calculation. * Is willing and able to avoid prolonged exposure of the treatment area to ultraviolet radiation (natural and artificial) for the duration of the study. * Is in good general adrenal health, as determined by a 30-minute postcosyntropin stimulation serum cortisol level that is \>18 μg/dL at the Screening visit. * Females of childbearing potential and females who are pre-menses (9 years and older) must be willing to practice effective contraception for the duration of the study. Exclusion Criteria: * Has a history of adrenal disease. * Presents with any concurrent skin condition that could interfere with the evaluation of the treatment areas, as determined by the Investigator. * Is pregnant, nursing an infant, or planning a pregnancy during the study period. * Has received treatment with any investigational drug or device within 60 days or 5 drug half-lives (whichever is longer) prior to baseline or is concurrently participating in another clinical study with an investigational drug or device. * Received treatment with a topical antipsoriatic drug product other than corticosteroids within 14 days prior to the Baseline visit and/or treatment containing corticosteroids within 28 days prior to the screening HPA axis stimulation test. * Has a history of hypersensitivity or allergic reaction to any of the study drug constituents. * Is considered by the Investigator, for any other reason, to be an unsuitable candidate for the study.