An Open-Label, Two-Cohort, Pharmacokinetic Study in a Maximal Use Setting for Patients With Actinic Keratosis on the Upper Extremities or the Face

Inclusion Criteria: * Provided written Informed Consent. * Patient is willing and able to comply with study protocol, visit schedule, and other study-related instructions/procedures, including in-clinic stay as required. * Patient is a male or non-pregnant female 18 to 85 years of age (inclusive) at Screening. * Patient has either 4 or more AK lesions on the upper extremities; or 6 or more AK lesions on the face. Lesions must be within an area of 25 cm2. * Patient is in good general health and free of any disease state or physical condition. * Patient has veins suitable for repeat blood draws. * Patient is willing to abstain from sunbathing, solarium use, exposure to artificial tanning devices. * Patient is willing to follow a consistent skin care routine without significant change. * Patient is willing to stop using all topical products within the Treatment Area(s) starting from 8 hours prior to initiation of treatment. * Patients who are women of childbearing potential must agree to use a highly effective method of contraception during the study. * Patients who are male with female partners of childbearing potential must use a barrier method of contraception (e.g., condom) if not surgically sterile. * Females of childbearing potential must have a negative serum pregnancy test at Screening and a negative urine pregnancy test before initiation of treatment at Baseline. Exclusion Criteria: * Patient is pregnant, lactating, or is planning to become pregnant during the study. * Patient has severe AK lesions within the Treatment Area. * Patient has untreated skin cancers or lesions suspicious for skin cancer within the Treatment Area. * Patient has an active herpes simplex infection OR a history of ≥2 outbreaks within past 12 months in the Treatment Area. * Patient has significant skin abnormality involving the Treatment Area * Patient has a history of skin sensitivity to light. * Patient has known hypersensitivity to one or more components of the IP. * Patient has a history of lead poisoning or a history of significant exposure to lead. * Patient smokes more than 10 cigarettes/day. * Patient has a suppressed immune system. * Patient has a coagulation defects. * Patient has a Body Mass Index (BMI) \> 32.0 kg/m2. * Patient has donate blood recently. * Patient is positive for HIV, Hepatitis B and/or Hepatitis C. * Patient has history of alcohol or drug abuse during the past year prior. * Patient has a positive urine screen for drugs of abuse. * Patient has abnormal labs at Screening. * Patient had a major surgery within 30 days or plans to have surgery during the study. * Patient has any condition which would make it unsafe for the patient to participate in this research study or interferes with assessment/interpretation of study outcomes. * Patient received any topical or systemic therapies on the Treatment Area within a certain amount of time. * Patient is currently enrolled in an investigational drug, investigational biologic, or investigational device study. * Patient has received an investigational drug, investigational biologic, or investigational device treatment within 30 days or 5 half-lives of the experimental agent, whichever is longer, prior to initiation of treatment at Baseline.