Osteoporosis drugs: Which one is right for you?

Reviewed by Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing

There’s no one-size-fits-all answer when it comes to osteoporosis. Understanding your options begins with knowing what’s available.

Throughout our lives, our bones undergo constant renovation. In a process called bone turnover, cells called osteoclasts break down and remove old bone, and then cells called osteoblasts lay down new bone. After menopause, the rate of bone removal speeds up, and bone formation doesn’t always keep pace. The net result can be bone loss and ultimately the weakened, brittle bones of osteoporosis.

Even if you’ve been diagnosed with osteoporosis, a fracture isn’t inevitable. Many drugs available today can slow the rate of bone loss—and can rebuild bone strength.

Your doctor will determine whether you have osteoporosis by measuring your bone density—usually at the hip and spine—using dual energy x-ray absorptiometry (DEXA). The result, expressed as a number called a T-score, compares your bone density with that of a healthy 30-year-old woman.

The doctor will likely recommend medicine if you have

• a T-score of –2.5 or lower—the definition of osteoporosis
• a history of hip or vertebral (spinal) fracture caused by a fall while standing (in contrast to a fall from a height)
• a T-score between –1.0 and –2.5 (called osteopenia) and a high risk of hip or osteoporosis-related fracture in the next 10 years according to a fracture risk calculator.

Osteoporosis treatment: Where to start

To slow bone breakdown, many doctors first turn to one particular class of drugs. If someone has a very low T-score, doctors typically start with the bisphosphonates. Nitrogen-containing bisphosphonates work by inhibiting farnesyl pyrophosphate synthase, which is important in promoting attachment of the osteoclast to the bone. As a result, the osteoclast detaches from the bone surface, thus inhibiting bone resorption.

There are several bisphosphonates to choose from, such as:

• pills, such as alendronate (Fosamax), ibandronate (Boniva), or risedronate (Actonel, Atelvia), taken daily, weekly, or monthly
• injections of ibandronate (Boniva), given once every three months
• intravenous infusion of zoledronic acid (Reclast), given once a year.

Your doctor will also consider where your bone loss is centered. Alendronate, risedronate, and ibandronate have all been shown effective for reducing spine fractures. For women with a history of hip or non-spinal fractures, alendronate and risedronate may be better options than ibandronate.

If you have gastrointestinal problems like reflux, or if you can’t sit or stand upright for the full 30 to 60 minutes required after taking an oral bisphosphonate, then your doctor may put you on an injection or infusion of these drugs, which works about as well as the oral versions.

You might have read about risks associated with bisphosphonate drugs—particularly fractures of the thighbone (femur) and osteonecrosis (bone death) in the jaw. Though these concerns are real, they are more common in people taking intravenous bisphosphonates to treat cancer that has spread to the bones, or in women who are on long-term, high-dose bisphosphonates.

Doctors acknowledge that the risk of these side effects also increases with long-term use of bisphosphonates, so most women take these drugs for about five years. The good news is that the bone-protective benefits continue even after you stop taking bisphosphonates.

Other drug options

For postmenopausal women who aren’t starting with a bisphosphonate, or those who’ve already been on one for five years, here are a few other options.

Raloxifene (Evista), a selective estrogen receptor modulator (SERM), is perhaps best known for its role in breast cancer prevention and treatment, but it serves double duty in treating osteoporosis, too. It works by binding with estrogen receptors around the body to produce estrogen-like effects, one of which is to decrease bone turnover. For people with osteoporosis of the spine, raloxifene reduces the risk of vertebral fractures. The main side effects are hot flashes, muscle pain, and an increased risk of blood clots in the leg (deep-vein thrombosis).

Teriparatide (Forteo)and abaloparatide (Tymlos) are synthetic versions of parathyroid hormone that increases bone density and strength. Abaloparatide, a PTHrP, is a selective parathyroid hormone receptor type 1 (PTH1R) agonist. As an agonist, anabolic activity on PTH1R on osteoblasts stimulates the Gs-protein–mediated cyclic adenosine monophosphate (cAMP) pathway, which activates phospholipase C (PLC) and phosphokinase A (PKA) to increase osteoblast activity. Abaloparatide shifts the balance of bone remodeling to favor bone formation by osteoblasts with a minimal increase in osteoclast bone resorption. This leads to increases in the formation of bone at periosteal, trabecular, and endocortical surfaces. These drugs can reduce the risk of fractures significantly in the spine and other bones. They are a reasonable option for someone with very low bone density and vertebral fractures. Doctors usually limit  this particular treatment to two years and then switch patients to a bisphosphonate to maintain bone density. Women on teriparatide or abaloparatide need to give themselves a daily injection.

Denosumab (Prolia) is a monoclonal antibody given as a twice-yearly injection. It prevents bone-dissolving osteoclast cells from forming. Denosumab may be an option if a woman cannot tolerate bisphosphonates. Once started, women usually stay on this therapy indefinitely because if stopped bone resorption will accelerate.

Romosozumab (Evenity) is another monoclonal typically reserved for women with severe osteoporosis, usually considered after a woman has had a fragility fracture. It acts by blocking sclerostin, a protein that inhibits bone formation. The medication is injected once a month using two separate prefilled syringes for a full dose. Romosozumab should only be taken for one year, because its bone-making activity wanes after 12 months.

What is abaloparatide?

Its brand name is Eladynos (Tymlos in the US). It’s an osteoporosis drug treatment that strengthens bones and makes them less likely to break, administered via a small daily injection which you give yourself, just under the skin, for 18 months. You would usually be prescribed another type of osteoporosis medication to follow on from this after the 18 months.

Who is it for?

It’s recommended by NICE for those with a ‘very high risk’ of fracture. This means those who have ‘many risk factors for fracture’. It will be offered to you mainly if you have had spinal fractures or continue to have broken bones despite taking another drug treatment.

Can men have abaloparatide?

Abaloparatide is currently licensed for post-menopausal women. There isn’t much research yet on its use for men, although it’s likely to be effective. It isn’t yet licensed or approved for men or pre-menopausal women.

Is it better at strengthening bones than other osteoporosis drug treatments?

Abaloparatide is one of the three drugs now available that has an anabolic effect. The other drugs are teriparatide and romosozumab. Anabolic means they stimulate the cells that build bone, so they may be the best drugs for those with the highest risk of fracture. This is called a ‘very high fracture risk’. Most osteoporosis drugs, like bisphosphonates, work by slowing down the cells that break down bone. These drugs work well for most people. 

How does abaloparatide compare to teriparatide?

The two drugs are very similar and are likely to have the same benefits for bones, as well as similar possible side effects. You can read more about teriparatide here.

How can I find out if abaloparatide is right for me?

There’s no urgency, but you can discuss this with your doctor or other health care professional if you think that you may need a treatment, or when your current drug treatment is reviewed. Your doctor or health care professional will discuss your fracture risk and help decide what treatment will suit you best.