Novartis (NYSE: NVS) currently has the oral multiple sclerosis drug market all to itself. Gilenya is the only drug that's taken orally to treat the progression of the disease. All the other drugs have to be injected or infused.

Technically, Acorda Therapeutics' (Nasdaq: ACOR) Ampyra also doesn't require needles, but it's designed to treat one of the symptoms of multiple sclerosis -- the inability to walk – and it doesn't treat the progression of the disease.

Unfortunately for Novartis, it looks like Gilenya's competition-free period will vanish in the not-too-distant future.

The most advanced is Merck KGaA's Movectro, but it may not be the next on the market. The German company pulled its EU application after it was clear regulators there would rebuff the drug. The Food and Drug Administration followed suit, turning down the drug last month.

In the pipeline
Last week, Biogen Idec (Nasdaq: BIIB) shared some details from its phase 3 trial of its oral multiple sclerosis drug, BG-12. The biotech had already said the trial passed, but the level of efficacy was quite impressive. BG-12 cut the annualized relapse rate by 53% and reduced disability progression by 38%.

Teva Pharmaceutical (Nasdaq: TEVA) also has an oral multiple sclerosis drug that's read out a phase 3 clinical trial, but on the surface, the data don't look as good. Laquinimod cut the annualized relapse rate by 23% in its most recently released data and reduced disability progression by 36%.

Adding to the mix, sanofi-aventis (NYSE: SNY) also has an oral multiple sclerosis drug, teriflunomide. In a phase 3 trial, the drug cut the annualized relapse rate by 31% and the disability progression by 30%.

The only way to know for sure which drug is better is for one of the companies to run a head-to-head clinical trial, but the data certainly seem to favor BG-12 with the substantial decrease in the annualized relapse rate.

Big competition
The fight investors should be keeping their eye on is between oral drugs and those that need to be injected or infused. There's an awful lot of revenue at stake among the current needle-requiring drugs.

Teva's Copaxone is a $3.3 billion drug and Biogen's Avonex wasn't that far behind at $2.5 billion last year. Pfizer (NYSE: PFE) and Merck KGaA have Rebif, and there's also Bayer's Betaseron.

My guess is that Tysabri, sold by Biogen and Elan (NYSE: ELN), will be safe from immediate competition. Because of potential side effects -- a potentially deadly brain infection -- Tysabri is primarily used as a secondary treatment. The oral medications are likely to be used as a first-line treatment for needle-phobic patients.

What's an investor to do?
The only pure play on multiple sclerosis is Acorda. Biogen and Elan are close, with multiple sclerosis drugs making up a majority of their options. If you're going to invest in the rest, you'll need to like their additional offerings as well.

At the moment, Biogen seems to be the best bet for driving sales forward. Coming to market after Gilenya won't be so bad; Novartis will have done the leg work, prepping doctors for the next-generation of multiple sclerosis drugs. BG-12 will likely cannibalize sales of Biogen's Avonex, but there's plenty of additional patients to steal from competing injectable drugs as well.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.