There are investment opportunities in every sector, but biotechs launching new drugs offer a unique investment opportunity to take advantage of hyper-growth as sales increase dramatically. Quarter-over-quarter growth of 50% to 100% isn't unheard of at the beginning of drug launches.

Here are a few investment opportunities from companies that have recently launched drugs.

An orphan investment opportunity
Aegerion Pharmaceuticals (NASDAQ: AEGR) sold just $1.2 million worth of Juxtapid, its treatment for a rare genetic disease called homozygous familial hypercholesterolemia, or HoFH, which causes extremely high cholesterol levels.

While that's a pretty small number, it's only the first quarter the drug has been on the market. For the remaining three quarters of the year, Aegerion is looking for sales between $14 million and $24 million. And that only includes U.S. sales. The drug, which will be called Lojuxta in Europe, should be launched next year based on a stamp of approval from the European Committee for Medicinal Products for Human Use last month.

Finding patients is the biggest challenge; Aegerion believes there are about 3,000 patients in the U.S. with HoFH and another 3,000 in the EU. As of the first-quarter conference call, Aegerion had 75 patients on therapy, so there's considerable room to ramp up.

A fat investment opportunity
Two, in fact. Arena Pharmaceuticals (ARNA) and VIVUS (VVUS) have both recently launched obesity drugs.

For VIVUS and Eisai, Arena's marketing partner, the problem obviously isn't finding patients. They're everywhere. The opportunity is huge.

But the companies have to convince doctors that treating obesity with drugs is the right move after Fen-Phen and Abbott Labs' Meridia left doctors worried about side effects that might show up after a drug is on the market. It's going to take time getting them comfortable with prescribing the drugs to a large number of their patients.

And obesity drugs haven't typically been covered by insurance, so they've had an uphill battle with reimbursement as well.

Investment opportunity in expanding indications
Ariad Pharmaceuticals (NASDAQ: ARIA) gained FDA approval for its leukemia drug Iclusig at the end of last year and managed $6.4 million in sales in the first quarter. That's a pretty decent start, and the drug should be launched in Europe next month, accelerating sales further.

But the true potential for Iclusig is in expanding into the first-line indication, which requires investors to take a long-term approach to owning Ariad. The Epic trial, which pits Iclusig against Novartis' (NVS -0.55%) Gleevec in patients with newly diagnosed chronic myeloid leukemia, is expected to complete enrollment by the end of the year and read out the primary endpoint a year later. Gleevec -- to give some context on Iclusig's potential -- racked up $4.7 billion in sales last year.

Best investment opportunity?
Of the four companies, Aegerion looks like the best bet to me. I have no doubt that Ariad can get Iclusig to blockbuster status, but at a market cap of $3 billion, there are a lot of sales already priced in. Aegerion, by contrast, is only a $1.7 billion company. The potential market for Arena's and VIVUS's obesity drugs is probably the largest of the three, but they're also the most risky; it could take years for the companies to change the prescription habits of doctors and convince most insurers to cover the drugs.