This medication contains two different medications to be taken at different times: etidronate and calcium carbonate. Etidronate belongs to a family of medications known as bisphosphonates. Etidronate and calcium carbonate are used in combination to treat and prevent osteoporosis in postmenopausal women. It can also be used to prevent steroid-induced osteoporosis (osteoporosis caused by taking corticosteroids such as prednisone for long periods of time).

Etidronate increases the thickness of bone (bone mineral density) by slowing down the cells that usually break down bone (osteoclasts). This allows the cells that build bone (osteoblasts) to work more efficiently. By making bones stronger, etidronate can help to reduce the incidence of osteoporosis-related fractures. Calcium is one of the building blocks of bones and therefore helps to prevent bone loss.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

This medication is taken in 90-day cycles that are repeated. Each cycle consists of 14 white etidronate 400 mg tablets (to be taken once daily on an empty stomach with a full glass of water) and 76 blue calcium tablets (to be taken once daily for the following 76 days, with a full glass of water).

The white etidronate tablets should be taken at bedtime with a full glass of water on an empty stomach (at least 2 hours before or after eating). Food in the stomach, especially if it is high in calcium, may prevent etidronate from being properly absorbed into the body. Vitamins with minerals such as iron and calcium, laxatives containing magnesium, and antacids containing calcium or aluminum should not be taken within 2 hours before or after taking etidronate (the white tablets in the first 2 weeks of therapy).

Calcium carbonate can prevent other medications from being properly absorbed into the body, so it is best to take them at least 2 hours before taking other medications. For this reason, it is suggested that the blue calcium tablets be taken at bedtime with a full glass of water, on either an empty or full stomach. If you find the tablets difficult to swallow, you can crush or chew them.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor in a cyclical fashion. If you miss a dose of your medication, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and carry on with your regular dosing schedule. Do not take a double dose for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take etidronate - calcium carbonate if you:

• are allergic to etidronate disodium or any ingredients of the medication
• have osteomalacia (softening of the bones)

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• headache
• heartburn
• joint pain
• leg cramps
• nausea

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• bone fractures, especially of the thigh bone
• confusion
• pain or delayed healing and infection of gums, mouth or  jaw (usually after tooth extraction)
• eye pain, sensitivity to light, red or inflamed eyes, or decreased vision
• hair loss
• increased occurrence of infections
• prickling, tingling sensation
• signs of bleeding (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• worsening of asthma

Stop taking the medication and seek immediate medical attention if any of the following occur:

• pain and swelling of the tongue or esophagus (the tube connecting the mouth and stomach)
• skin reactions (rash, sores, blisters) involving mucous membranes
• symptoms of a severe allergic reaction (e.g., swelling of the hands, feet, ankles, face, lips, mouth, or throat; difficulty breathing or swallowing)
• symptoms or worsening of symptoms of a stomach or intestinal ulcer (e.g., nausea, vomiting, abdominal pain, loss of weight or appetite, black or bloody stools, or vomiting blood)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Atypical femur fracture: There is evidence that long term use of this class of medication may contribute to a type of rare fracture of the long bone in the thigh (femur).

If you experience new or unusual pain in the groin, hip, or thigh area, contact your doctor as soon as possible.

Calcium and vitamin D: Calcium and vitamin D are important contributors to bone growth and strength. It may be necessary to take additional calcium or vitamin D supplements to get the best effect from etidronate if you are not getting enough from your diet. Your doctor may test you for low calcium levels or vitamin D deficiency before you start taking etidronate.

Dental procedures: A dental examination and any necessary dental procedures should be considered before you start treatment with etidronate-calcium if you have one of the following risk factors: cancer; chemotherapy, radiotherapy of the head or neck, treatment with corticosteroids, or dental problems or dental infections. Etidronate, like other similar medications has been known to cause severe jaw problems associated with delayed healing and infection, especially in people with cancer or after tooth extractions. If you experience any pain in the jaw, teeth or gums, especially after having a tooth removed, contact your doctor immediately.

Gastrointestinal disorders: This medication can cause an increased frequency of bowel movements with diarrhea. This is more likely if you have a gastrointestinal disorder that makes you prone to diarrhea, such as colitis.

If you have colitis, irritable bowel syndrome or other disease that causes an increase in frequency of loose bowel movements, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: If you have kidney disease or decreased kidney function, your doctor should closely monitor your condition while you are taking etidronate - calcium carbonate, as this medication can cause changes in kidney function.

Pregnancy: This medication should not be used during pregnancy as it may cause harm to the developing fetus. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if etidronate passes into breast milk. It is not intended for use during breast-feeding. If you are a breast-feeding mother and are taking etidronate, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

There may be an interaction between the etidronate (first 14 days) portion of etidronate - calcium and any of the following:

• aminoglycoside antibiotics (e.g., gentamicin, tobramycin)
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide) taken within 2 hours of taking etidronate
• bevacizumab
• other bisphosphonates (e.g., alendronate, risedronate, zoledronate)calcium supplements taken within 2 hours of taking etidronate
• deferasirox
• iron supplements (e.g., ferrous gluconate, ferrous sulphate)
• lenalidomide
• magnesium-containing products (such as laxatives) taken within 2 hours of taking etidronate
• nonsteroidal anti-inflammatory medications (e.g., diclofenac, ibuprofen, ketoprofen, naproxen)
• pazopanib
• proton pump inhibitors (e.g., omeprazole, pantoprazole)
• regorafenib
• sorafenib
• vandetanib
• vitamins containing minerals such as calcium, iron, and magnesium taken within 2 hours of taking etidronate

Most other medications should be taken at least 1 hour before or 2 hours after taking the calcium tablet of etidronate - calcium.

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.