NORWICH-EATON’s DIDRONEL NDA WILL BE FILED "VERY SHORTLY"
NORWICH-EATON's DIDRONEL NDA WILL BE FILED "VERY SHORTLY" for the treatment of postmenopausal osteoporosis, the company said. A study appearing in the July 12 issue of the New England Journal of Medicine and authored by Nelson Watts, MD, Emory University School of Medicine et. al, shows that intermittent cyclical therapy with Didronel (etidronate) resulted in significant increases in the bone mineral density of the spine and reductions in vertebral-fracture rates. The study was funded by Norwich-Eaton parent Procter & Gamble. The NDA for the osteoporosis prevention indication will include data from Watts' two-year study in a total of 429 women as well as data from an earlier 66-patient study that appeared in the May 3 New England Journal. Norwich-Eaton has sponsored at least one other similar study, which was presented at a 1987 international conference on osteoporosis in Denmark, that could support the FDA submission. The Watts study was a multicenter, placebo-controlled, double-blind trial of 429 women with one to four vertebral compression fractures plus radiographic evidence of osteopenia. The study has been extended beyond two years to see whether the positive results can be maintained in the absence of more serious side effects. The Watts trial subjects were randomized at seven centers to one of four treatment groups. Each patient was administered Didronel in a cyclical therapy during which they took the drug for 14 days out of every three months. Subjects received 1 g of phosphate or placebo twice daily for three days and 400 mg Didronel (etidronate) or placebo daily for the next 14 days, followed by 500 mg calcium daily for the next 74 days. The cycle was repeated eight times during the course of the two-year period. The investigators found that patients in the two groups receiving etidronate had significant increases in their mean spinal bone density, 4.2% and 5.2%, respectively, after 24 months. In addition, the rate of new vertebral fractures was 50% lower in the etidronate-treated patients compared to those not receiving the drug -- 29.5 fractures per 1,000 patient years versus 62.9 in the placebo group. The researchers noted that the beneficial effects of the drug were greatest in women who had the lowest spinal bone mineral densities at the beginning of the study. The study found that the increase in spinal density did not occur as a result of losses in bone mass of the hip or wrist; nor did it improve the bone mass of the wrist or hip. "The failure of the hip and wrist to mirror the improvement in bone mass noted in the spine was not unexpected," the researchers noted, adding that "varying responses at skeletal sites with different proportions of trabuncular and cortical bone" have shown that results are not uniform. The addition of phosphate provided no apparent benefit, and no major side effects were reported; some women, however, did experience nausea and diarrhea. A preliminary comparative study, published in 1988 in the Journal of Endocrinology and Metabolism, found that treatment with etidronate did not prevent axial bone loss in osteoporotic women; however, Watts et al, note that etidronate is poorly absorbed and must be taken on an empty stomach. In the 1988 trial, the subjects were concurrently taking calcium, which blocks absorption of etidronate. Didronel has been available in the U.S. since 1987 for treating symptomatic Paget's disease, a rare condition characterized by abnormal and accelerated metabolism in one or more bones. Initial administration of the drug is for three or six months. Side effects in Paget's patients include increased or recurrent bone pain. High doses of the drug may lead to reduced calcium deposition in bones or osteomalacia in women deficient in Vitamin D. It is also indicated for the prevention and treatment of heterotopic ossification following total hip replacement or spinal cord injury, also a rare condition. There are an estimated 1.3 mil. spinal fractures annually in the U.S. resulting from osteoporosis. The bone-weakening disease is estimated to affect from one-third to one-half of American women over age 50. Currently approved therapies for osteoporosis include estrogen replacement to prevent bone loss and injectable calcitonin with calcium to replace bone mass.
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