MQX-503 Applied to the Hand Versus Nitroglycerin Ointment Applied to the Chest: A Pharmacokinetic Comparison

Inclusion Criteria: * 18 to 50 years of age * Subjects who do not take any prescription medication or who can safely discontinue use prior to visit 1. * Negative pregnancy test for fertile women and agree to use effective contaception throughout the study. Exclusion Criteria: * Subjects who can not safely discontinue current prescription medications. * Subjects who have a known allergy to nitroglycerin or common topical formulation ingredients. * Subjects with an unstable medical problem. * Subjects who, within the past three months, have had either a myocardial infarction, uncontrolled congestive heart failure, unstable angina, uncontrolled hypotension, or uncontrolled hypertension. * Subjects who participated in a study of any investigational drug or device within four weeks prior to Visit 1. * Subjects who have screening laboratory values which are outside the normal range and which are considered to be clinically significant to the investigator. * Subjects who have had major abdominal, thoracic, or vascular surgery within six months of Visit 1. * Subjects with non-epithelialized skin lesions or interfering skin conditions at time of screening in the area where either study medication is to be applied. * Pregnant or nursing women. * Women of childbearing potential who are unable or unwilling to comply with the contraceptive requirements during the study period.