4-AminoPyridine (4-AP) is an experimental drugs that may reduce symptoms in some people with MS, particularly those who are more sensitive to Heat.
4-AP blocks Potassium channels and improves conduction of electrical impulses through Nerves whose protective Myelin sheath has been damaged or destroyed by MS.
Studies Show Drugs Helps Some People
4-AP is still being tested in clinical trials. Early clinical trials of 4-AP, given either intravenously or orally, showed that the drug provided temporary improvement in symptoms such as Weakness, Imbalance, and Decreased Vision in small numbers of MS Patients.
In a somewhat larger study, involving 68 MS patients over a three-month period, 27% reported improvement in symptoms while they were taking 4AP, compared to only 2% (1 patient) who reported improvement while taking a placebo, an inactive substance used as a control in testing new drugs.
In addition, 10 patients on 4-AP significantly improved their ratings on a Neurologic Function scale called the Expanded Disability Status Scale, or EDSS, while none of the patients taking a placebo improved their EDSS rating.
Patients with more Neurologic Impairment and those More Sensitive to Heat were more likely to be helped by 4-AP.
Although this study was double-blind controlled (neither the patients nor the investigators knew who was taking 4-AP or who was taking the placebo), 41 patients correctly guessed they had received 4-AP rather than the placebo.
Side Effects Can Be Troublesome
Side effects in this trial included Dizziness, Numbness and Tingling, and Instability while walking. Less common side effect included Nausea, Vomiting, and Abdominal Pain. Some of these side effect, however, also occurred among patients taking the placebo.
Serious side effects of 4-AP treatment have only been reported in a few patients and generally occurred at high doses. These included generalized Convulsion, Confusion, and one case of Liver Inflammation (Chemical Hepatis).
Large-scale controlled trials, using a slow-release formulation of 4-AP, which may improve its effectiveness and reduce side effects, are now in progress.
Related Compound Not as Effective
One clinical trial showed that 3, 4-DAP was less effective than 4-AP and produced more side effects, such as Nausea and Abdominal Pain.