Osteoporosis and Anticonvulsants

by Alana Greca, BSN, RN
TNA Patient Representative

Even though Regi Cook, Tampa Support Group Leader, knew she was at high risk for developing osteoporosis, she thought she could avoid her mother’s fate by doing all the right things.

Last year she found out that her preventive measures were not enough. Regi and her doctor were astounded when her bone density test showed osteoporosis after a normal test only two years earlier. Regi did not realize that anticonvulsant drugs (AEDs) are one of the secondary causes of osteoporosis. Her abnormal results were the effect of Tegretol, which she had taken for the last 8 years, and which doubled her chance of osteoporosis.

The primary risk factors for osteoporosis are: heredity (for both men and women); low body weight; lack of sunlight; female, white; low estrogen levels; high intake of alcohol, caffeine, and cigarettes; dietary considerations, especially calcium; and sedentary life style.

The older anticonvulsant drugs, such as Dilantin, Phenobarbital, and Tegretol, have been identified as causing osteoporosis since the 1960s, because they interfere with the metabolism of vitamin D. For many years, the newer AEDs, which worked through different actions, were thought to be safe. However, a study released in 2003 by Lorraine Fitzpatrick illustrated that these medications are also causing bone loss—just by different actions. Based on World Health Organization standards for measurement of the femoral neck BMD, this study, whose participants were epileptics and had taken anticonvulsants an average of 25 years, showed the changes in the table below:
The conclusion of Fitzpatrick’s study was that “all patients taking AEDs are at an increased risk for bone loss; therefore, their BMD should be monitored.” Recent studies have also found that taking two or more anticonvulsants together may further escalate the occurrence of osteoporosis.

Bone density testing can be conducted on the finger, wrist, or heel, with machines which utilize ultrasound or x-ray. This is the less expensive method, but perhaps not accurate, since bone mass may vary in different areas. The most accurate BMD testing is a dual energy x-ray absorptionetry (DXA), which uses the hip or spine, and involves only lying on a padded table, while an arm sweeps above the body. Spinal density can be measured by a quantitative CT scan (QCT). Your results are compared to:
a. A person at peak bone density
(T score)
b. A person of similar background
- age, sex, race (Z score)

Medical prevention and treatment of osteoporosis are interrelated with controlling the risk factors. Exercise is an impor-tant factor. Recommendations in the past have called for exercise to be vigorous and weight bearing in order to be useful, but a recent Harvard Nurses Health Study report revealed that moderate walking was effective. This same health study also showed that:
• Surprisingly, dietary calcium did not make a significant impact on bone mass, and that supplements have questionable influence. The National Academy of Sciences still suggests a daily intake through either source of 1,000 mg for ages 19-50 and 1,200 mg for those over 50.

• Vitamin D protected against hip fracture, even when calcium did not. There was a 40% less chance of fracture if over 500IU was taken daily.

• Vitamin K also gave a 30% decrease in the risk of hip fracture with at least 100 mcg per day. (There is 70 mcg in one cup of lettuce, and 300mcg in a cup of broccoli.)

Stopping the anticonvulsant drugs is not an option for most facial pain patients, so we need to do all that we can to compensate for their effects on our bones. Make life style changes. Talk to your health care professional about bone density testing, calcium and vitamin D supplements, and if necessary, bone-sparing medications such as Fosamax or Actonel.

Regi had another bone density test a few weeks ago. Her hip measurements remained the same, but she had a further decrease in her spinal density, despite the fact that she has been taking weekly doses of Actonel for the past year. Regi continues taking Actonel, adding Forteo, a stronger injectable drug, hoping it will stop the progression of her new disorder - osteoporosis.

Updated 4-13-05