A new oral medication to treat patients in the early stages of multiple sclerosis has shown considerable promise in two clinical trials, researchers announced on Wednesday.

The medication is on track to become just the third oral drug available to M.S. patients, and potentially the safest and most effective, experts said. The second oral drug, called Aubagio, was approved just last week.

M.S. was virtually untreatable only two decades ago, but today nine “disease modifying” drugs are available for early-stage patients; a half-dozen more are in the late stages of development. Most patients in the early stage of the disease, a form called relapsing-remitting M.S., take drugs by injection.

The two new studies, published online in The New England Journal of Medicine, found that the drug BG-12, developed by Biogen Idec, reduced relapse rates in patients with relapsing M.S. by about 50 percent. The drug also significantly reduced the frequency of new brain lesions often associated with these attacks, and slowed the progression of disease compared with a placebo.