Bioavailability and Pharmacokinetic Measures of H. Procumbens Extract

Inclusion Criteria:- adult (at least 18 years of age); * diagnosed with knee osteoarthritis (OA) ; * body mass index (BMI) of less than 40; * willing to use only the study product, and Tramadol or Tylenol as a rescue pain medication over the course of their participation in the study; * willing and able to monitor blood glucose levels if diabetic; * willing to abstain from caffeine-containing drinks and food before coming into a study visit; * able to read and understand English and have the cognitive capacity to give consent; * willing to abstain from use of the following during participation in the study: prescription and over-the-counter non-steroidal anti-inflammatory medications, (e.g., aspirin, ibuprofen, Advil, Motrin, Nuprin, Naproxen, etc.); any dietary supplements (St. John's Wort, etc.); and, grapefruit and/or products containing it. Exclusion Criteria:- cardiovascular disease, previous myocardial infarction, stent, coronary artery bypass graft (CABG), arrhythmia, high or low blood pressure; * recurrent stomach upset, or gastric or duodenal ulcers; * gallstones or gall bladder disease (cholelithiasis); * liver or kidney disease; * alcohol use of more than two drinks per day on a regular basis; * Coumadin or anti-platelet drug use; * at risk for respiratory depression, history of seizures, or taking drugs that reduce the seizure threshold or may increase the risk for development of serotonin syndrome; * pregnant or breast feeding, or intention to become pregnant during the study; * pronounced allergies, or known allergy to study product or corn starch (placebo); * have had an injection to treat OA within the past three months; * currently taking NSAIDs, unless they are willing to stop for a 1-week wash-out period; * currently on a selective serotonin reuptake inhibitor (SSRI) but are poorly stabilized, or have evidence of suicidal ideation and/or suicide attempts in the past year; and, * reported use during the 7 days prior to study drug administration of: prescription and over-the-counter medications (e.g., NSAIDs), and any dietary supplements; grapefruit and/or its products; and, St. John's Wort.