Didronel (etidronate) is another bisphosphonate. It is FDA-approved for Paget's disease, high calcium levels related to cancer, and rare bone conditions related to hip replacement surgery, but not for osteoporosis. Outside of the United States, Didronel is used for osteoporosis. It works a little differently from other bisphosphonates in that it kills off the osteoclasts (the cells that break down bone). Nonetheless, Didronel has been very effective in reducing osteoporosis-related fractures, particularly spinal ones, and safety has been established for 7 years or more use in postmenopausal women. Additionally, like other bisphos-phonates, some protective effects of Didronel on bone density have been shown to persist even after stopping the medication. Didronel is not FDA-approved for treatment or prevention of osteoporosis in the United States.
Although Paget's disease is also a bone disease, it is totally unrelated to osteoporosis. One person can have both conditions. Paget's disease causes large, deformed bones because of an excessive breakdown and formation of bone. The most common presenting symptom is bone pain located where the bone is closest to a joint. Paget's disease can often be mistaken for arthritis because it is usually diagnosed in people who are over 40 years of age. However, x-rays of bones in individuals with Paget's disease show a characteristic pattern and fractures occur frequently. Blood levels of alkaline phosphatase are usually elevated in people with Paget's disease. If the skull bone is affected, hearing loss can result.
Causes large, deformed bones due to the excessive breakdown and formation of bone. Although totally unrelated to osteoporosis, it can occur with osteoporosis in the same bones.
The treatment of choice for Paget's is a bisphosphonate. Bisphosphonates Actonel, Fosamax, and Didronel are FDA-approved for the treatment of Paget's. Unlike the longer dosing regimens of other bisphosphonates, Didronel is generally prescribed for only two weeks to three months at a time depending on the dosage, with a rest period off the medication lasting at least three months. This regimen is usually repeated for about two years. Didronel is taken on an empty stomach without eating or drinking for two hours after taking it. Didronel should still be prescribed with caution in those with upper intestinal disorders. The most common side effects include nausea, diarrhea, and flatulence. Medications that cause stomach upset, such as non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, naproxen, or aspirin, can increase the risk for ulcer or heartburn. Table 11 has information on Didronel.
Table 11 Didronel (etidronate)
(Generic Name) Most Common
[Manufacturer] Side Effects and
How Supplied Clinical Uses Contraindications Adverse Reactions
Didronel (etidronate) [Procter and Gamble]
200 and 400 mg tablets
Also given as an IV injection after hip replacement surgery
Hypercalcemia related to cancer
Bone healing problems associated with hip replacement surgery and spinal cord injuries
Allergy or sensitivity to etidronate
Severe kidney disease Inability to remain upright for 2 hours
GI upset (pain, nausea, acid reflux)
Bone pain and tenderness
Skin rash Other adverse reactions (i.e., seizures, difficulty breathing, and fever have also been reported in IV use)
Although it is a bisphosphonate, it works by causing toxins to destroy some of the bone-breakdown cells (osteoclasts)
Taken with plain water on an empty stomach with no food or drink for 2 hours
Originally intended for the treatment of Paget's disease
After taking Didronel, wait 2 hours before taking calcium and Vitamin D
Can cause decreased levels of calcium in the blood
Prescribed in cycles of daily treatment of 400 mg daily for 2 weeks out of every 3 months for 2 years
Not quite as effective as other bisphosphonates for increasing BMD
In very rare cases could increase the risk for osteonecrosis of the jaw following dental surgery
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