Calcium Carbonate

How it works

It provides elemental calcium to support bone mineralisation and, in the gut, binds dietary phosphate to reduce its absorption in renal disease.

Prescribing in practice

• Avoid in hypercalcaemia and severe hypercalciuria, and use with caution where there is a risk of milk-alkali syndrome or renal stones.
• It reduces the absorption of several drugs, including some antibiotics, levothyroxine and bisphosphonates, so doses should be separated.
• As a phosphate binder it is taken with food, whereas as a supplement absorption is best with food and adequate vitamin D.

Monitoring

Monitor serum calcium (and phosphate when used as a binder) particularly in renal impairment.

Counselling the patient

• Separate this medicine in time from thyroid medication, certain antibiotics and bisphosphonates.
• Take with food when used to lower phosphate.
• Report symptoms such as nausea, constipation or confusion that could suggest high calcium.

Evidence & guidelines

Calcium with vitamin D supplementation is recommended by NICE within osteoporosis management for at-risk patients.