Let's end the week with some good news. Sure, there were some stocks in the health-care sector that really stank over the last few days. However, a few proved to be big winners. Let's take a look at three stocks with humongous gains for the week (or at least more humongous than most others).

Fat and happy
Our first big mover in the health-care world this week is Vivus (NASDAQ:VVUS). Shares started the week off on a good note, and continued to climb throughout the week, ending up more than 24%.

A deal with Express Scripts (NASDAQ:ESRX) served as the primary catalyst for the huge jump. The large pharmacy benefits manager will distribute Vivus' weight-loss pill Qsymia under the arrangement.

Vivus is gearing up to do battle with Arena Pharmaceuticals (NASDAQ:ARNA). Opinions differ over which company is more likely to prevail. Judging solely by year-to-date stock performance, Arena has received more pocketbook votes from investors. Shares are up nearly three times more than Vivus at this point.

Not anemic at all
Affymax (NASDAQOTH:AFFY), maker of anemia drug Omontys, benefited from an upgrade by Lazard earlier this week. We're not talking about a run-of-the-mill upgrade here. Lazard upped its price target for Affymax from $20 per share to $28 per share. The analyst upgrade turbocharged Affymax shares. The stock shot up over 19% during the week. It's not like they needed a huge boost. Affymax surged more than 400% in the last year.

Rival Amgen (NASDAQ:AMGN) won't take too kindly to Affymax's ascendance. Its anemia drug Epogen made over $2 billion in fiscal 2011. We'll see how great a challenge Affymax's Omontys mounts over the next few quarters.

Can I vie a bowel?
Last on this week's humongous health-care list is NPS Pharmaceuticals (UNKNOWN:NPSP.DL). The stock meandered throughout much of the week, but skyrocketed 19% on Friday

The company officially meets with the FDA on Oct. 16 about Gattex, its drug that's targeted for treatment of patients with short bowel syndrome. However, FDA staff announced in advance of that meeting they they supported NPS's risk-management plan for the drug. That news fired up investors.

Fellow Fool Brian Orelli sees a small risk that the FDA might challenge the relatively small patient size in the phase 3 trial for Gattex, but notes that more data forthcoming from an open-label study should alleviate concerns.

Taking off
Health-care stocks like these tend to take off more spectacularly than stocks in many other industries. Of course, they also are prone to crash with equal fanfare.

If we look mainly at potential market size, Vivus stands out as the potential biggest winner over the long run. Obesity runs rampant, especially in the U.S.

Those are the humongous winners in health care for this week. Take off for the weekend, relax, and hit the ground running on Monday, when the fun begins again.  

Keith Speights has no positions in the stocks mentioned above. The Motley Fool owns shares of Express Scripts. Motley Fool newsletter services recommend Express Scripts. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.