If you or someone you know is being treated for osteoporosis using one of Actonel, Boniva, or Fosamax, then you/they are receiving bisphosphonate therapy.
We're used to thinking of bones as being static objects once we reach adulthood, but they are of course really collections of living (and dying) cells that must be constantly maintained over time. The body produces two types of specialized cells that are responsible for this maintenance. Osteoclasts "digest" what they think are old, ineffective bone cells, and osteoblasts create their replacements. In patients with osteoporosis or multiple myeloma, the osteoclasts outrun the osteoblasts for a variety of reasons, resulting in gradual bone loss. The bisphosphonates inhibit the osteoclasts' activities, either by interfering with their creation, or by interfering with their attachment to the bones' surfaces.
The bisphosphonates used to treat multiple myeloma, either Aredia or Zometa, are much more powerful and dangerous (in terms of possible side effects) than those used to treat osteoporosis. They are delivered monthly, via an IV drip, oral versions being unavailable. This Friday, I will get my first monthly dose of Aredia via an IV drip lasting approximately two hours.