Pfizer has made the next selection in its long-running shopping spree: the drugmaker announced today that it would pay $3.6 billion for Tennessee-based King Pharmaceuticals.

The announcement comes almost a year after Pfizer shelled out $68 billion for Wyeth. In fact, Pfizer has done 30 deals over the past five years (Businessweek) as it attempts to bolster revenues in the face of looming generic competition. Generic forms of Lipitor, Pfizer’s cholesterol medication that brought in over $6 billion in US sales last year, are due to enter the market in 2011.

The acquisition will give Pfizer access to King’s pain medications and animal health business, two therapeutic areas that Pfizer has said it wants to emphasize in the future. King Pharmaceuticals is perhaps best known for developing reformulations of existing pain medications, such as longer-acting forms of morphine and oxycodone.

Pfizer is offering to pay King $14.25 per share, which amounts to a 40% premium over Monday’s closing price.