The US company will pay the money to Dong Wha Pharmaceutical, a South Korean firm which has patented the use of thiazolylphenoxyalkoxybenzamidine derivatives as osteoporosis treatments.
The move is part of P&G's wider aim of becoming the leader in bone health, according to its president of global health care, Tom Finn.
He said: "[We hope to do this by] developing a range of therapy options that will bring relief to the many patients suffering from musculoskeletal diseases.
"The potential of this new class of compounds as a novel treatment for osteoporosis is very impressive and a perfect fit as we look to broaden our portfolio."
This new agreement includes Dong Wha's drug DW-1350 plus a family of back up compounds, which it claims prevent bone resorption and promote bone formation. DW-1350 is currently in Phase I clinical trials. Although the company has not disclosed how DW-1350 achieves this - i.e. what its target is - the aforementioned patent indicates it is a thiazolylphenoxyalkoxybenzamidine derivative.
These compounds block the receptor for leukotriene B4 (LTB4), which is produced by white blood cells to allow them to cross the endothelial lining of blood vessels and enter tissue. It is known to promote bone resorption, and also promote platelet aggregation, immune response, and vasoreactivity.
As well as Dong Wha's research on this target for osteoporosis, others, such as DeCode, are investigating it as a possible preventative treatment for heart attacks. Leutotriene's in general have long been investigated by drug developers and other receptors have been targeted when designing compounds to treat asthma.
The first to be marketed in the US was AstraZeneca's Accolate (zafirlukast) around 10 years ago, but now others have also been approved, including Merck & Co's Singulair (Montelukast). Ironically, these drugs proved popular in this indication as other therapeutic options such as steroids, are known to cause osteoporosis.
As part of the deal, Dong Wha will retain rights for specific countries in Asia, with P&G gaining access to the rest of the world. The move is also a significant boost for Dong Wa and was described by its CEO, Mr Kil-Joon Yoon as a "a major milestone in our process for becoming a global pharmaceutical company."
As part of the patent application, Dong Wha tested DW-1350 and the follow-up compound DW-1352 (listed as 4-(5-[4-(5-isopropyl-2-methyl-thiazol-4-yl)phenoxy]pentoxy)benzamidine) to see if they prevented osteoclast differentiation in vitro using mice bone marrow cells. For comparison, it also tested two other known LTB4 receptor blockers: its own HS-1141 and Novartis' CGS-25019C.
The inhibition ranged from 17.7 to 92.7 per cent for DW-1352. According to Dong Wha, both of the compounds tested were more active than the known LTB4 receptor antagonists. The effect of two compounds on bone resorption was also measured in vitro with the percentage inhibition rated at 90 per cent, again for DW-1352.