Fosamax

How does it work?

Fosamax tablets contain the active ingredient alendronic acid (as sodium alendronate), which is a type of medicine called a bisphosphonate. (NB. Alendronic acid tablets are also available without a brand name, ie as the generic medicine.) Bisphosphonates are medicines that prevent the breakdown of bone.

Bone is not a static structure. It is continually shaped, reformed and rebuilt by cells called osteoblasts and osteoclasts. These cells continously deposit and remove calcium and phophorous, stored in a protein network that makes up the structure of the bone. Old bone is broken down by the osteoclasts and new bone is formed by the osteoblasts.

In women at the menopause, blood levels of the female hormone oestrogen start to decrease. This results in an increase in bone breakdown by the osteoclasts, which can lead to a loss of bone density. Bone loss is particularly rapid for the first ten years after the menopause and it may lead to the development of osteoporosis - a condition in which the bones become weak and brittle and break (fracture) more easily.

Osteoporosis can also occur in men and as a result of long-term treatment with corticosteroid medicines such as prednisolone. Other risk factors include smoking, a family history of osteoporosis, early menopause and thin body build.

Alendronic acid is used both to prevent bone loss in people who are at risk of developing osteoporosis, and to prevent fractures in people who already have osteoporosis. The medicine works by binding very tightly to the bone and preventing the calcium being removed by the osteoclasts. This stops the osteoclasts from breaking down the bone, which helps to keep the bones strong and less likely to break.

As this medicine slows bone turnover and so prevents calcium being rebsorbed from the bones into the blood, it can cause the amount of calcium in your blood to fall too low. If your dietary intake of calcium and vitamin D is low, your doctor may ask you to take supplements to prevent this.

What is it used for?

Prevention and treatment of osteoporosis in women who have passed the menopause

Treatment of osteoporosis in men

Prevention and treatment of osteoporosis caused by long-term treatment with corticosteroids such as prednisolone.

Warning!

It is very important that the instructions for taking these tablets are followed completely. This is because when alendronic acid is taken by mouth it can cause irritation and ulceration of the foodpipe (oesophagus). Following the instructions below minimises this risk. If you are unclear about anything ask your pharmacist for advice.

Your tablet should be taken in the morning at least 30 minutes before the first food, drink or medicine of the day. The tablet should be swallowed whole with a glass of plain water (at least 200ml, not mineral water) while you are sitting or standing in an upright position. Do not chew or suck the tablet. You should not lie down for at least 30 minutes after taking the tablet. You should not eat or drink anything other than plain water for at least 30 minutes after taking the tablet. This is because food and some drinks (including mineral water) can interfere with the absorption of the medicine from the gut and hence make it less effective.

You should not take any other medicine by mouth at the same time as this tablet, or for at least 30 minutes after taking the tablet. See the end of this factsheet for more details.

If you experience any signs of irritation to your foodpipe during treatment with this medicine, for example new or worsening problems with swallowing, pain on swallowing, pain behind your breastbone, or heartburn, you should stop taking these tablets and inform your doctor.

Your doctor may want you to have regular blood tests to monitor the level of calcium in your blood while you are taking this medicine.

The class of medicines that alendronic acid belongs to (bisphosphonates) has been associated with a rare condition called osteonecrosis of the jaw. The majority of cases of this condition have been in cancer patients treated with bisphosphonates by injection into a vein and many of these patients were also having treatment with chemotherapy or corticosteroids. However, the condition has also been seen in people taking bisphosphonates by mouth. The risk may be increased by poor oral hygiene, dental problems, teeth extractions and oral surgery. For this reason, your doctor may want you to have a dental examination and, if necessary, appropriate preventive dentistry, before you start treatment with this medicine. Discuss this with your doctor. It is important to look after your mouth and teeth as much as possible while you are receiving this medicine. Invasive dental procedures such as tooth extraction or surgery should be avoided if possible. If you need to see a dentist during treatment, make sure they know you are receiving this medicine.

Use with caution in

Decreased kidney function

Active disorders of the upper part of the digestive system, such as difficulty swallowing, disorders affecting the foodpipe (eg reflux disease), ulcers, inflammation of the lining of the stomach (gastritis), inflammation of the small intestine (duodenitis)

People who have had major disorders of the upper part of the digestive system in the last year, eg peptic ulcer, bleeding from the stomach or intestines, or surgery on the stomach or intestines

Disorders of the parathyroid gland (gland that produces hormones responsible for regulating calcium metabolism)

Vitamin D deficiency.

Not to be used in

Children

Abnormalities of the food pipe (oesophagus)

Conditions causing delayed passage of food through the foodpipe (oesophagus), eg narrowing or obstruction of the foodpipe

People who cannot stand or sit upright for at least 30 minutes

Low levels of calcium in the blood (hypocalcaemia)

Pregnancy

Breastfeeding

Rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption (Fosamax tablets contain lactose).

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

This medicine has not been studied in pregnant women, hence its safety has not been established. It should not be used during pregnancy.

It is not known if this medicine passes into breast milk. It should not be used by breastfeeding mothers.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Disturbances of the gut such as diarrhoea, constipation, nausea, vomiting or abdominal pain

Indigestion (dyspepsia)

Excess gas in the stomach and intestines (flatulence)

Bloating

Difficulty or pain when swallowing (dysphagia)

Acid regurgitation

Ulceration of the food pipe (oesophagus)

Headache

Pain in joints, muscles or bones (musculoskeletal pain)

Inflammation of the food pipe (oesophagitis)

Skin reactions such as rash or itching

Flushing of the skin due to widening of the small blood vessels (erythema)

Inflammation of the stomach (gastritis)

Low blood calcium level (hypocalcaemia)

Ulceration, bleeding or perforation of the stomach or intestines

Dark colored, tarry stools, due to the presence of blood altered by the intestinal juices (melaena)

Inflammation of the front parts of the eye (uveitis)

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

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