Reduction of morning stiffness and improvement in physical function in fibromyalgia syndrome patients treated sublingually with low doses of human interferon-α

One hundred and twelve fibromyalgia syndrome (FMS) patients were randomized into one of four demographically similar groups (n = 28/group). Sequential primary FMS patient volunteers were to receive daily sublingual placebo or interferon-α (IFN-α) at 15, 50, or 150 IU. After a screening evaluation, analgesic or sedative hypnotic medications were withdrawn. Two weeks later, daily IFN-α or placebo was initiated with follow-up evaluations at 2-week intervals ending with week 6. One primary, three secondary, and seven tertiary variables were assessed. Study outcome was based on improvement in the tender point index (TPI). The TPI did not improve with any IFN-α dose. However, significant improvement was seen in morning stiffness and in physical function with the 50 IU IFN-α (p < 0.01). None of the other outcome means changed significantly and no adverse events were attributable to IFN-α therapy.