Fampridine-PR (prolonged released 4-aminopyridine) is not effective in patients with inflammatory demyelination of the peripheral nervous system.

Fampridine-PR is a voltage-gated potassium channel inhibitor potentially improving nerve conduction in demyelinated axons. Based on its established clinical efficacy in patients with demyelination in the central nervous system, we assessed if fampridine-PR is also effective in patients with inflammatory demyelination of the peripheral nerve. In this small open-label study, 10 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) were treated with fampridine-PR 10 mg BID for 28 days and assessed clinically as well as by nerve conduction studies. In this study, Fampridine-PR failed to improve CIDP based on clinical measures and nerve conduction studies. Our findings suggest that Fampridine-PR appears to be ineffective in demyelinating polyneuropathies. These observations may indicate a more complex mode of action beyond improving action potential conduction in demyelinated axons.