How Bisphosphonates Work
To understand how bisphosphonates work, it helps to know a bit about normal bone activity.
Normal bone activity
Your bones are made of living tissue, and are constantly changing. In healthy bones, specialised bone cells constantly break down and replace bone tissue.
These specialised bone cells are:
osteoclasts – which break down old bone
osteoblasts – which build new bone
This process is called bone remodelling. There is a very good balance between the rates of bone breakdown and growth, which keeps bones strong and healthy.
What bisphosphonates do
Bisphosphonates target the areas of higher bone turnover. The osteoclast cells absorb the bisphosphonate drug, which slows down their activity and reduces bone breakdown.
There are several different types of bisphosphonates, and they each work slightly differently. Doctors are still learning more about the exact ways in which bisphosphonates work.
We know that bisphosphonates can:
interfere with the formation of osteoclasts
make osteoclasts self destruct or die early
change the signalling between osteoclasts and osteoblasts
form a barrier between the bone and the osteoclast
Researchers have found that bisphosphonates can prevent or slow down the development of myeloma and secondary bone cancers in some people.
Cancer cells seem to be attracted to an environment where bones are being broken down. Researchers hope that stopping this process could slow cancer growth and help people live longer, as well as reduce bone damage.
General side effects of bisphosphonates
Bisphosphonates don’t usually cause too many side effects. They tend to be mild if you do have them. Everyone reacts differently to drugs and you may have one or more side effects.
Fever and flu-like symptoms
These are more common when you have the bisphosphonate as a drip (infusion). Symptoms usually last for a few hours and taking paracetamol can help.
Low levels of calcium in your blood (hypocalcaemia)
You will have blood tests to check the levels of calcium and other minerals such as potassium and magnesium.
Bone and joint pain
You can control this with a mild painkiller such as paracetamol.
Changes in bowel movements
Constipation or diarrhoea usually lasts only for a few days – it is important to drink plenty of fluids (6 to 8 glasses a day).
Tiredness and low energy levels
These may occur with some types of bisphosphonates but are usually mild.
This is usually mild and gets better after a few days, but your doctor or nurse can prescribe anti sickness tablets if it continues or is severe.
Changes to your kidneys
You’ll have regular blood tests to check how well your kidneys are working.
Irritation of the food pipe (oesophagus)
This can be a side effect of taking bisphosphonate tablets. Tell your doctor if you already have problems with your food pipe (oesophagus) or if you develop new symptoms such as pain or difficulty swallowing.
Let your doctor know if you have heartburn.
This is a rare side effect that might happen if you take bisphosphonates for over a year. You should have a dental check up before you start treatment. Always tell your dentist that you’re having bisphosphonate therapy or tell your doctor if you need dental treatment.