Every year, the promise of safer and more effective drugs coming to market gives an aging population hope. According to the Phrma organization's website, roughly $49 billion was spent on researching some 2,900 compounds last year alone. The truly amazing part is that we've only touched the tip of the iceberg on what diseases are left to be researched and/or cured. We still have a long way to go with regards to cancer research, and many rare diseases still have largely unmet needs.

Each week for a total of five weeks, I'm going to look at an upcoming drug that has every indication of being not only a revenue blockbuster, but a true life changer. Keep in mind that none of the five drug hopefuls I'll be highlighting are approved by the Food and Drug Administration, so there are plenty of obstacles left to be encountered, including safety data, which could still stand in the way of an ultimate approval.

 In the previous two parts of this five part series I've highlighted two game-changing drugs:

This week, I want to take a closer look at osteoporosis drug hopeful odanacatib, being developed by Merck (MRK 0.37%).

As the world's population ages, the need for drugs catered to our older population -- especially bone care and protection treatments -- are going to be vital. At the moment, there are quite a few bone-strengthening medications already on the market including Fosamax, which is made by Merck; Actonel, which is made by Warner-Chilcott (NASDAQ: WCRX); Reclast by Novartis (NVS -1.64%) -- which is also set to go off patent in 2013 -- and Boniva, made jointly by GlaxoSmithKline (GSK 0.49%) and Roche (RHHBY 0.77%). 

According to American Bone Health, many of these treatments successfully reduce bone fracturing by approximately 35%. However, long-term use of this classification of osteoporosis drugs, known as bisphosphonates, has been linked to potentially unpleasant side effects. In addition to causing normal side effects of muscle and stomach pain, long-term use of bisphosphonates has been linked to fracturing of the upper-thigh bone and rare cases of osteonecrosis where a section of the jawbone dies after removal of a tooth.

Although I probably should have warned you not to eat before reading the current list of side effects caused by bisphosphonates, the good news is that Merck's new osteoporosis drug, which is set to hit the market in 2013, could change all that.

Late-stage trials of odanacatib were stopped early by outside monitors who noted that the experimental drug was incredibly effective in reducing fracturing in trials. Most Wall Street pundits predict that odanacatib will match or beat the current bisphosphonates success rate of reducing fractures by 40%. Furthermore, odanacatib has a considerably better safety profile than existing bisphosphonates, exhibiting minimal side effects. In the words of the outside monitors, "robust efficacy and a favorable benefit-risk profile" are what allowed them to recommend stopping the study early. 

According to a Reuters article, Leerink Swann analyst Seamus Fernandez believes that odanacatib could have peak sales of as much as $3 billion. Furthermore, I'm not sure whether that takes into account other possible indications for odanacatib that may arise down the road.

Ultimately, it looks like it will come down to a battle between Amgen's (AMGN 0.22%) Prolia for osteoporosis in post-menopausal women and Xgeva, which prevents fractures in patients suffering from bone metastases, versus odanacatib -- and I fully expect all three to succeed. All three drugs are hitting the market right as their bisphosphonate peers are set to lose many of their patents, which will give this safe and effective trio some running room.

Odanacatib alone may not be enough to replace the loss of Merck's asthma treatment Singular to the patent cliff, but it'll -- without question -- be a drug that changes the lives of an aging population for the better.

Be sure to check back next week when I unveil the fourth pipeline drug capable of changing your life for the better.