Valeant Pharmaceuticals (NYSE:VRX) is trying to buy Allergan (NYSE:AGN) for $47.5 billion with the help of billionaire William Ackman, which, with his investment fund, bought almost 10% of Allergan to get a foot in the door.

Last week, he had a presentation with Valeant CEO Michael Pearson where Ackman presented an interesting slide with a laundry list of reasons not to invest in drugmakers.

In the video below, senior biotech specialist Brian Orelli and health-care analyst David Williamson go through the list, discounting many of Ackman's points. For instance he cites patent cliffs as a problem, but investors know that they're coming; everyone could value Pfizer (NYSE:PFE) properly knowing when generic copies of Lipitor would launch, impacting Pfizer's revenue.

Ackman also complains about pricing pressure, but Gilead Sciences (NASDAQ:GILD) has been able to launch its hepapatitis C drug, Sovaldi, at $1,000 per pill and despite a decrease in prescriptions Merck's (NYSE:MRK) diabetes drug franchise, Januvia, U.S. revenue increased year over year in the first quarter thanks to a price increase.

While Brian and Max might not agree with Ackman's general take on the sector, they're more content with his positive view of specialty pharma -- companies that sell smaller drugs that they often acquire rather than develop internally -- and offer up some specialty pharma companies that investors should keep an eye on.

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Brian Orelli has no position in any stocks mentioned. David Williamson owns shares of Merck and Pfizer. The Motley Fool recommends and owns shares of Gilead Sciences and Valeant Pharmaceuticals. 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.