Treatment of pain in fibromyalgia patients with testosterone gel: Pharmacokinetics and clinical response.

To test our hypothesis that testosterone deficiency plays an important role in chronic pain, a Phase I/II pilot study was initiated with 12 fibromyalgia patients to verify that a daily dose for 28days with transdermal testosterone gel would 1) significantly and safely increase mean serum testosterone concentrations from low baseline levels to mid/high-normal levels, and 2) effectively treat the pain and fatigue symptoms of fibromyalgia. Pharmacokinetic data confirmed that serum free testosterone concentrations were raised significantly above baseline levels, by assessment of maximum hormone concentration (Cmax) and area under the curve (AUC) parameters: free testosterone Cmax was significantly raised from a mean of 2.64pg/mL to 3.