That’s assuming the FDA cooperates and approves the idea. An agency advisory panel will meet on Dec. 13 and take up the notion for the third time since 2000. At issue is whether consumers can monitor LDL and HDL levels, contraindications with other drugs, and liver enzymes.

Glaxo, however, is optimistic, as today’s agreement with Merck suggests. Interestingly, the move comes not long after some Glaxo investors were calling for the drugmaker to shed its OTC biz and focus more intently on prescription meds.

Under the deal, Glaxo will have exclusive US rights to sell an OTC version of Mevacor in return for undisclosed milestone and royalty payments to Merck. “This reinforces the commitment Glaxo has to this particular part of the business,” Mike Ward, an analyst at Nomura Code Securities, tells Reuters. “The over-the-counter usage of products that are switching from prescription to non-prescription use is a good area to be in. A lot of health authorities would like to switch more products, so that the costs fall on the patients.”

The deal marks the second time of late that Glaxo has bought OTC rights to a prescription med developed by another drugmaker. Earlier this year, Glaxo launched Alli, an OTC version of Roche’s Xenical diet pill. So far, the drugmaker says sales are fattening.

The deal is also the second in less than a week for Glaxo, which has been hit hard by the controversy over its Avandia diabetes pill, which was linked to a 43 percent increase in heart attack risks and now carries a stern FDA warning. Last week, Glaxo agreed to pay $1.65 billion for Reliant Pharmaceuticals, which sells a heart med.

Mevacor lost patent protection in the United States in 2001 and Merck has been trying to secure OTC status for the product for years, initially in conjunction with Johnson & Johnson. Proposals to make it available without prescription were, however, rejected by an FDA panel in 2000 and again in 2005, prompting J&J to hand the product rights back to Merck, Reuters reminds us.

Merck is seeking approval of OTC Mevacor 20 milligrams taken once daily. The proposed use is for women age 55 and older and men age 45 and older with moderately raised cholesterol and one or more heart risk factors. Nomura’s Ward believes Mevacor has a better chance of winning a green light this time, but is likely to cause considerable debate by regulators. Allowing Mevacor to be sold OTC would be a major shift, since OTC meds generally treat short-term conditions with easily recognizable symptoms such as a headache; high cholesterol can be detected only with a blood test.

The final outcome will determine the size of payments from Glaxo to Merck.