4‐Aminopyridine improves clinical signs in multiple sclerosis

Abstract

Twelve temperature‐sensitive male patients with multiple sclerosis and 5 normal men were monitored before, during, and after the intravenous injection of 7 to 35 mg of 4‐aminopyridine (4‐AP) in 1‐to 5‐mg doses, every 10 to 60 minutes. Static quantitative perimetry, flicker‐fusion frequency, visual acuity, and videotaped neurological examinations were performed. Ten of the 12 patients showed mild to marked improvement. Vision improved in 7 patients, oculomotor function in 5, and motor function (power, coordination, gait) in 5. Improvements developed gradually within minutes of drug injection at doses as low as 2 mg, and gradually reversed around 2 to 4 hours after the peak drug effect. No effects were observed in 5 patients given saline injections. No serious side effects occurred in either the normal subjects or the patients receiving 4‐AP. It is concluded that 4‐AP lessens multiple neurological deficits in multiple sclerosis and, furthermore, that the K⁺ channel is functional in demyelinated central nervous system axons in humans. The improvements with 4‐AP are substantial enough to be of transient therapeutic benefit in selected patients.