It's been a dizzying (and likely nauseating) few months for shareholders in Questcor Pharmaceuticals (NASDAQ: QCOR). The stock shot up by 45% for the year by early July. Then shares plunged nearly 40% from that point by the first week of August.  

Just when despair ruled the day, Questcor rebounded. Shares rose 47%. But, alas, investors' joy didn't last long. Since mid-September, the stock has collapsed by around 60%. 

No one could blame investors from throwing in the towel after such a wild ride. However, the possibility for long-term profits with Questcor still exists. Here are three key things to watch beyond all of the hype associated with this volatile stock. 

1. Payer poker
The most recent stock collapse stemmed from a bulletin issued by Aetna (AET). The large insurer stated that Questcor's H.P. Acthar gel was medically necessary (and, therefore, reimbursable) only for infantile spasms, a rare disorder making up a small fraction of total Acthar prescriptions. The primary use for the gel -- and biggest money-maker for Questcor -- is in treating multiple sclerosis.

Even though Aetna accounts for only 5% of Acthar paid prescriptions, massive selling of Questcor shares kicked into gear. Fears mounted that other insurers would follow Aetna's lead.

It certainly is possible that major payers could decide not to cover Acthar. But none has taken any negative action so far. On the contrary, UnitedHealth Group (UNH -1.03%) recently announced minor changes to its policies for Acthar reimbursement that could allay concerns that the insurer will limit coverage for multiple sclerosis.

The cards in this game of payer poker seem to be generally in favor of Questcor at this point.

2. Litigation lottery
Another flurry of bad news for Questcor came from the announcement by the U.S. Attorney's Office for the Eastern District of Pennsylvania that it was investigating the company's promotional practices. A flood of other lawsuits poured in after the announcement.

These investigations and related lawsuits can prove to be quite costly. Pfizer (PFE 0.23%), for example, paid a record $2.3 billion in 2009 to settle litigation based on allegations about its promotional practices. Amgen (AMGN 0.60%) settled for $780 million last year over alleged sales and marketing violations.

These examples are exceptions, though. Some investigations don't result in any finding of wrongdoing or need for settlement. Others are settled but for relatively insignificant amounts.

For its part, Questcor maintains that it has "meritorious defenses" to the allegations. However, the company acknowledges that it can't determine the likelihood of a positive or negative outcome or possible losses, if any.

The bottom line on this front is that it's just too early to know what will happen. It is also difficult to predict how long it might take for the dark cloud hanging over Questcor associated with the investigation and lawsuits to go away.

3. Revenue roulette
Questcor recently released preliminary September results for paid prescriptions of Acthar. At first blush, these numbers don't look too good. 

Paid prescriptions for use of the gel in multiple sclerosis fell from 508 in August to between 400 and 410 in September. Nephrotic syndrome prescriptions decreased from 119 in August to between 105 and 110 in September.

Do these drop-offs mean that the Aetna decision and other bad news could be taking a toll? Not really. 

The key point to note with the preliminary numbers is that August had 23 business days but September only had 19. When we look at prescriptions per business day, September was a better month than August for nephrotic syndrome and only slightly lower for multiple sclerosis.

So far, the revenue continues to roll in. 

The gamble
I used gambling references for all of the key things to watch because Questcor remains a gamble at this point.

Risks are easy to find. The prospect of further payer restrictions on Acthar reimbursement and/or costly litigation settlements make for a compelling case on why to avoid this stock like the plague.

On the other hand, if the other big payers stay the course and the U.S. Attorney's investigation doesn't pan out, Questcor could make intrepid risk-takers a lot of money. 

For those who really want to play this high-risk/high-reward game, perhaps the best approach is to use options -- as long as you know what you're doing. Either buy Questcor calls instead of the stock or buy the stock along with a protective put. 

Most investors, though, should stay away for now. There just isn't enough evidence to know whether or not the dizzying ride will keep going.