I get it and I'm right there with you. Investing in drug companies off the U.S. exchanges is too much trouble.

Sure, the addition of Genentech to Roche and the diversity of Bayer make them interesting investment candidates, but it's not enough to overcome the extra effort required to invest in foreign markets or the relative illiquidity of over-the-counter ADRs -- especially when there are so many good investment choices available on the Nasdaq and NYSE.

But, unfortunately, that doesn't mean you get to just completely ignore drugmakers not trading in the U.S. They still have drugs in their pipelines that can affect the companies you are invested in. Here are a couple to keep an eye on:

The MS Oral
Current multiple sclerosis drugs -- Pfizer's (NYSE:PFE) and EMD Sorono's Rebif, Teva Pharmaceuticals' (NASDAQ:TEVA) Copaxone, and Tysabri from Elan and Biogen Idec (NASDAQ:BIIB), for instance -- are injected or infused. An oral drug that works as well as the current offerings could grab considerable market share because few people enjoy being poked with needles.

Earlier this year, German Merck KGaA -- not to be confused with American Merck (NYSE:MRK) -- reported positive phase 3 clinical trial results for its oral multiple sclerosis drug. The efficacy of Merck KGaA's cladribine isn't really in question, but issues over cancer arising in a few patients in the clinical trial will make an approval more complicated, although probably not impossible.

Merck KGaA submitted a marketing application for the EU this month and plans to file with the Food and Drug Administration in the next few months, so investors in companies with competing multiple sclerosis drugs won't have to wait too long to find out if the oral competition is real or just talk.

Me too, less often
Much has been made of the GLP-1 drug race between Eli Lilly (NYSE:LLY) and Amylin Pharmaceuticals' Byetta and Novo Nordisk's Victoza. Already-approved Byetta is taken twice daily; Victoza, which is taken once daily, could be approved soon, since its PDUFA date was months ago; but Lilly and Amylin have responded with a once-weekly version of Byetta that recently went under review by the FDA.

Waiting in the wings are Roche and Ipsen with a once-weekly GLP-1 drug of their own called taspoglutide. The drug looked good in phase 2 trials and the results of the phase 3 trial are expected next year. That'll put it a year or more behind once-weekly Byetta, but if taspoglutide's efficacy trumps Byetta's, then the late showing shouldn't hamper sales.

Remember we're not complete enemies
Rather than hurt drugmakers, one product Bayer is testing might actually help sales. The company is developing a marker for Alzheimer's disease, called Florbetaben, which looked good in a phase 2 trial. It was able to detect changes in the brains of 80% of patients suspected of having Alzheimer's disease, which is consistent with what you see in studies where researchers look at the brains after patients die.

Being able to diagnose patients earlier could lead to earlier use of Alzheimer's disease drugs from Pfizer, Novartis (NYSE:NVS), and others. The marker could even help a drug like bapineuzumab -- being developed by Wyeth, Johnson & Johnson (NYSE:JNJ), and Elan -- get on the market. Bapineuzumab is designed to remove beta-amyloid plaques in the brain, which is what Bayer's drug detects. Using Bayer's Florbetaben, bapineuzumab's developers could admit only patients who have the plaques into their clinical trials, and thus could benefit the most from the drug.

Final thoughts
Just because a drugmaker doesn't have easily traded shares here in the states doesn't mean stateside investors can ignore them. Both upside and downside can come from those "other" companies, affecting the results at our familiar companies ... and their shareholders. In other words, the pharma and biotech space is wider than you might think. Ignore it at your peril.

More international Foolishness:

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Novartis and Novo Nordisk are Motley Fool Global Gains selections. Investing internationally doesn't have to be scary and it can certainly be profitable. Click here to grab a 30-day trial subscription to the newsletter where you'll see all of our current picks for a global economy.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Elan is a Rule Breakers pick. Pfizer is an Inside Value selection and J&J is an Income Investor recommendation. The Fool has a disclosure policy.