Prescribing 4-aminopyridine for Multiple Sclerosis

4-aminopyridine (4-AP) is indicated for symptomatic treatment in patient with a decreased walking capacity due to multiple sclerosis. A potassium channel blocker, 4-AP, is considered a muscle strengthener. The Food and Drug Administration (FDA) approved of the compounding on 4-AP in 2010 along with a commercially available form, dalfampridine (Ampyra), which is an extended-release form. In clinical trials, a significantly greater proportion of patients improved walking speed (feet per second) when taking 10mg twice a day compared to placebo (34.8% vs. 8.3% in one clinical trial). Doses greater than 20mg per day were associated with an increased incidence of seizure activity.

Prescribing 4-AP should carefully be done because increased doses correlate with increased risk of seizures and other toxicities. Every patient will respond to 4-AP differently, some patients may experience side effects at doses lower than 20mg daily. This is where compounding of 4-AP helps patients get the right dose that is safe and effective. Commercially available dalfampridine is only available in 10mg capsules, while 4-AP can be compounded as low as 5mg capsules. Starting with lower doses can help monitor tolerance in patients and assist in helping them get to a dose that will improve their walking capacity with minimal risk of toxicity.


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