Holding shares of companies with large debt loads and no signs of imminent profitability should scare investors more than any ghoul or ghost could. Biopharmaceutical Elan (NYSE:ELN) looks like just such a company, and despite many investors' hopes, it's looking more like a Halloween trick than a treat.

Elan currently has several marketed products for treating infectious diseases, and it also derives some revenue from its manufacturing facilities. But it is best known for the multiple sclerosis treatment Tysabri, and only Tysabri has the potential to bring in meaningful sales growth for Elan.

Speaking of sales, Elan brought in $394 million in revenues for the first nine months of this year, up 13% over the same period last year. At first, this sounds like quite a Halloween treat, until one looks down to the $241 million net loss that accompanied these revenues.

Elan investors are optimistic in part because they hope that Tysabri will become a blockbuster drug. But the drug has a very restrictive label for its use, and in its first quarter on the market, the drug produced only $8.1 million in global net sales.

The most frightening thing about Elan is not just the slow uptake of Tysabri sales or its unprofitability, but rather the bones in the closet of the company's balance sheet. Nearly $870 million in debt is coming due in 2008, and $1.15 billion is due in 2011. Elan does have nearly $1 billion in cash, but this cash pile is dwindling -- down nearly $100 million for the year -- because of the company's continued losses.

Just to get an idea of the hole Elan has dug for itself, it's going to take nearly a billion dollars in Tysabri sales, assuming 80% gross margins, just to get the company above breakeven earnings. And that doesn't even include being able to make the upcoming debt payments. (Remember that Elan splits Tysabri revenues and costs with partner Biogen Idec (NASDAQ:IDEC)).

Elan does have one promising compound in its pipeline, AAB-101, which is just finishing a phase 2 trial in treating Alzheimer's disease. But the drug is a gamble at best, considering the lack of solid clinical trial results to date and the difficulty of developing effective drugs for this disease. Elan also has another Alzheimer's drug, AAC-001, in phase 1 trials. This Alzheimer's research is in collaboration with pharmaceutical giant Wyeth (NYSE:WYE).

Of course, if Tysabri starts to gain traction and sales grow at a faster rate, then Elan may turn out to be a bag of yummy Halloween candy corn, rather than the rotten egg it could become if it doesn't get its debt under control. Unless that happens, just like the toilet paper that I'll put in my neighbor's tree, Elan is one Halloween trick that investors shouldn't look forward to.

Biogen Idec is a Motley Fool Stock Advisor recommendation. Sign up for Tom and David Gardner's market-beating newsletter service today, and we'll send you a free report on the Fool's top two picks and the Street's dirtiest secret.

Fool contributor Brian Lawler loves Halloween candy corn and does not own shares of any company mentioned in this article.

The Motley Ghoul's Tricks or Treats represents the opinions of each Fool only and should in no way be taken as the opinion of either The Motley Fool, Inc. or any company in question, or as representative of anyone or anything other than that specific Fool's thoughts. So do your homework, and review The Motley Fool's disclosure policy.