Didrocal or Didronel (Etidronate) is a biphosphonate medicine used to prevent and treat thinning of the bones (called osteoporosis), a condition called Paget’s disesase, and other diseases where loss of bone mass is a concern.

Biphosphonates are a class of medicines that all work in a similar way to help the bones.

Taking Didrocal

Didrocal is available as an oral tablet that is taken in 90-day cycles. For the first 14 days, 400 mg of Didrocal is taken each day. For the remaining 76 days, a 500 mg calcium tablet is taken.

To minimize side-effects and ensure the best response, we recommend that patients take Actonel as follows:

First Thing in the Morning

Didrocal should be taken first thing in the morning. Patients should not lie down after taking this medicine.

On an Empty Stomach

Didrocal should be taken on an empty stomach. Patients should wait at least 1 hour before taking any other medication, or eating or drinking anything other than clean water (no coffee, juice, or tea).

With Water

It is recommended that patients drink a full glass of water while taking their tablet.

To help build the bones, patients should take calcium and vitamin D supplements while taking Actonel. A doctor can tell you the right amount of calcium and vitamin D to take.

Important Tests and Risks

Bone Mineral Density (BMD) Test

Doctors monitor the response of patients taking Didrocal with a Bone Mineral Density test, usually once every 1 to 3 years.

Pain in the Jaw

Biphosphonate medicines like Didrocal have been associated with a very rare problem with the jaw called osteonecrosis. This problem is sometimes seen after dental work.

People taking Didrocal should let their doctor know if they develop sudden pain in the jaw.

Alcohol Consumption

Alcohol is known to increase fracture risk by decreasing bone mineral density and promoting osteoperosis.

Patients who are prescribed Didrocal should stop drinking alcohol, or at least reduce the amount of alcohol that they drink.


How Didrocal Works

The body features an ongoing process called bone remodeling where bones are constantly broken down (bone resorption) and rebuilt.

Bones are broken down by a type of cell called osteoclasts and are built back up by a type of cell called osteoblasts.

In patients with osteoporosis and Paget’s disease, too much bone is being broken down too quickly.

All bisphosphonate medications, including Didrocal, bind to the surface of bones and slow down the bone resorption process. It works because it is toxic to the osteoclasts that break down bone.

When Didrocal slows down the resorption process, it gives the body more time to build up and strengthen the bones.

Didrocal, unlike other bisphosphonates, can also prevent bone calcification. This is the process where bones accumulate calcium. This effect is usually not desired in patients who have osteoporosis, but it may be desirable in treating other medical conditions.


Side Effects

Patients should talk to their doctor if they are concerned about any side effects.

The most common side effect of Didrocal is stomach upset, pain, bloating, and nausea. To minimize side effects, it is best to take Didrocal as prescribed: in the morning before any food or drink other than water. It is best to wait at least one hour after taking Didrocal before taking any other medication or eating or drinking anything else but water.

  • Nausea & diarrhea – The most common side effect of Didrocal is stomach upset, pain, bloating, and nausea. Didrocal can irritate the lining of the stomach, esophagus, or intestine. This is rare. It can result in stomach pain or trouble swallowing.
  • Headache & dizziness – Didrocal can rarely cause a headache
  • Muscle & bone pain – Didrocal can rarely cause bone, muscle, or joint pain.

Didrocal should not be taken during pregnancy or breastfeeding. Patients who become pregnant should stop taking the medicine and contact their doctor.

Who Should NOT Take Didrocal

Patients who should NOT be taking Didrocal include:

  • Patients who are allergic to Didrocal or any ingredient in this medicine
  • Patients who are allergic to other biphosphonate medications
  • Patients that are pregnant or breast-feeding

Anyone who becomes pregnant while taking Didrocal should notify their doctor immediately.

When to Call a Doctor

Patients should call their doctor if they feel sick and want to stop, or they you are concerned about any side effects.

Other reasons to call a doctor while taking Didrocal include:

  • Stomach pain or trouble swallowing
  • Pregnant or Planning Pregnancy
  • New severe pain in the jaw
  • Upcoming surgery


Watch Dr. Andy Thompson, a Canadian rheumatologist, introduce Didrocal in this short video: