Merck put Fosamax (alendronate sodium) and its $3 billion in total 2007 sales inits rear-view mirror yesterday, following the lapse of patent protection on theosteoporosis drug.

Merck forecast that 2008 sales will decline by at least halfthat, followed by more attrition later, according to a report. Fosamaxis part of about $20 billion worth of drugs expected to lose patent protectionthis year, according to IMS Health stats cited in the report.

This month alone, upcoming patent losses will includeGlaxoSmithKline asthma meds Advair ($6 billion in total sales) andSerevent ($500 million in total sales), according to BusinessWeek.

Hoping to stem some of its own losses, Merck quicklylaunched an authorized generic version of Fosamax (alendronate) through WatsonPharmaceuticals. Under terms of the agreement with Watson, Merck willmanufacture and supply the alendronate tablets to Watson, which willmarket, sell and distribute the pills in the US. Merck will get a cut of USsales. Further details were not disclosed.

Also yesterday, Teva Pharmaceuticals and Barr Labs becamethe first two generics companies to receive FDA approval to make and sellalendronate.