Reduction in Pain Intensity Following IV or Oral Pain-relieving Products

A Randomized, Placebo-Controlled, Double-Blind, Two-Part, Cross-over Study in Healthy Adult Male Subjects to Compare the Reduction in Pain Intensity After Single-Dose Administration of Intravenous or Oral Acetaminophen and Intravenous Morphine by Using UVB Burn and Intradermal Capsaicin Experimental Pain Models

The purpose of this study is to evaluate two experimental pain models to see if they would be useful for comparing different products for reduction in pain intensity.

The models evaluated were the ultraviolet-B (UVB) burn and intradermal capsaicin experimental pain models. Medications compared were a single dose each, of intravenous (IV) acetaminophen, oral acetaminophen, placebo, and IV morphine.

Inclusion Criteria

1. Must have a health status of "healthy" assessed by the investigator and defined as no clinically significant deviation from normal medical history, physical examination, vital signs, and clinical laboratory determinations.
2. Must be male, Caucasian, between 18 and 55 years of age (inclusive) at the time of the screening.
3. Must have a body mass index (BMI) ≥ 19.0 and ≤ 30.0 kg/m2 with a minimum weight of 110 pounds (50 kg) at screening.

Exclusion Criteria

1. A positive test result for human immunodeficiency virus (HIV), hepatitis B (surface antigen), or hepatitis C virus antibody at Screening.
2. A history of any drug allergy, hypersensitivity, or intolerance to acetaminophen, morphine, or capsaicin or to any of the excipients in the IV or oral formulations used.
3. A positive test result for drugs of abuse, alcohol, or cotinine.
4. Fitzpatrick Skin Type V or VI (based on a Skin Type score of greater than 30.
5. A history of conditions which might be specifically contraindicated or require caution to be used during the administration of any drug in the study.
6. Any other medical, psychiatric and/or social reason for exclusion as determined by the investigator.