This study aims to answer the question: Does oxytocin increase the pain threshold on thermal heat pain in the presence of vibration on an area of skin exposed to a mild sunburn?

The goal of this clinical trial is to test whether intravenous oxytocin increases the analgesic effect of vibration on heat pain threshold of skin that has been exposed to Ultraviolet-B (UV-B) burn (mild sunburn). Researchers will compare oxytocin (a hormone that naturally occurs in the body) to a placebo (a look-alike substance that contains no drug) to see if oxytocin works to increase the pain threshold (the lowest intensity at which one begins to perceive or sense a stimulus as being painful).

Inclusion Criteria:

• Male or female > 18 and ≤55 years of age, Body Mass Index (BMI) <40
• Generally in good health as determined by the Principal Investigator based on prior medical history, and as assessed to be American Society of Anesthesiologists physical status 1, 2, or 3
• Fitzpatrick Scale rating I through III

Exclusion Criteria:

• History of skin cancer
• Dark enough skin complexion that would make it infeasible to determine the minimal erythematous dose of UV-B irradiation. Anyone Fitzpatrick Scale score >3 will be excluded
• Neuropathy, chronic pain (located in any body location that is being treated), diabetes mellitus, or taking benzodiazepines or pain medications on a daily basis
• Pregnancy or currently breast feeding
• Subjects with current or history of ventricular tachycardia, atrial fibrillation or prolonged QT interval
• Subjects with past or current history of hyponatremia or at risk for hyponatremia; anyone taking thiazide diuretics, loop diuretics, combination diuretics, lithium, carbamazepine, enalapril, Ramipril, celecoxib, temazepam, gliclazide, glimepiride, glibenclamide, glipizide, omeprazole, pantoprazole, desmopressin, SSRI's, MAOI, or the recreational drug ecstasy
• Subjects with a known latex allergy