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 28 days 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 2.64 pg/mL to 3.91 pg/mL (p < 0.05), and 24 hour free testosterone AUC was significantly raised from a mean of 35.0 pg-hr/mL to 53.89 pg-hr/mL. Assessment of the typical symptoms of fibromyalgia by patient questionnaire and tender point exam demonstrated significant change in: decreased muscle pain, stiffness, and fatigue, and increased libido during study treatment. These results are consistent with the hypothesized ability of testosterone to relieve the symptoms of fibromyalgia. Symptoms not tightly related to fibromyalgia were not improved.