Some investors are happy campers after this week's market action. Quite a few health-care stocks blew the doors off. Here are three of the companies that made the most humongous moves.

Double in a day and then some
Acadia Pharmaceuticals
(NASDAQ:ACAD) managed to do in one week what it takes most companies years to accomplish: increase share prices by 137%. Actually, it took Acadia just one day to do it.

The company's shares went into orbit after announcing its phase 3 study results for pimavanserin in the treatment of Parkinson's disease psychosis. As you might expect, those results were quite positive. The clinical trial found that pimavanserin was highly effective in reducing symptoms including hallucinations and delusions associated with Parkinson's disease psychosis.

Other antipsychotic drugs used as off-label treatments for the disease have serious drawbacks, including loss of motor control. The phase 3 study found that pimavanserin did not result in worsened motor control.

Acadia now appears to be well positioned to move forward with seeking FDA approval. If it gets the nod from the FDA, Dr. Jeffrey Cummings with the Cleveland Clinic Lou Ruvo Center for Brain Health thinks pimavanserin has "the potential to transform the treatment landscape" for patients with Parkinson's disease psychosis.

A steady beat
Cadence Pharmaceuticals
(UNKNOWN:CADX.DL) didn't do too bad, either. Shares jumped 21% this week.

The stock has been on a nice run since mid-November. An announcement that Cadence settled litigation with Perrigo (NYSE:PRGO) might have helped. Perrigo filed an ANDA to market a generic version of Cadence's Ofirmex injection, but Cadence sued to prevent the generic maker from moving ahead with its plans. Under the agreement reached in the settlement, Perrigo gains dibs on marketing an authorized version of the drug beginning possibly in 2020.

These so-called "pay for delay" arrangements regarding generic versions of brand drugs are controversial. Many are opposed to the deals because they could make generics available later than they otherwise would. Supporters say the arrangements work best for all parties involved. Cadence shareholders might tend to agree with the latter view after this week's gains.

Amicus brief
Last, but not least (well, actually, it is least for this week), is Amicus Therapeutics (NASDAQ:FOLD). Shares climbed more than 17% during the week.

Like Cadence, Amicus stock has steadily moved upward since mid-November. And similar to Acadia, Amicus has phase 3 clinical trials under way that could cause shares to go up much more. The company is partnering with GlaxoSmithKline (NYSE:GSK) on two phase 3 studies related to treatment of Fabry disease.

The market seems to be anticipating positive results from the phase 3 trials. It also could be factoring in the possibility that GlaxoSmithKline will acquire Amicus. Glaxo already holds a 20% stake in the company. 

Best of the best
It's a tough choice as to which of this week's three humongous performers are the best. My hunch, though, is to go with Amicus. The stock could see tremendous movement if the phase 3 Fabry disease studies turn out well. Of course, there's considerable risk with Amicus. For that matter, there's plenty of risk with the other two stocks also.


Keith Speights has no positions in the stocks mentioned above. The Motley Fool owns shares of GlaxoSmithKline. Motley Fool newsletter services recommend GlaxoSmithKline. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.