New anabolic agent may revamp osteoporsis Tx. (Teriparatide Awaits FDA Approval).

HONOLULU -- The anticipated Food and Drug Administration approval of an anabolic agent, teriparatide, for the treatment of osteoporosis offers an intriguing opportunity to begin combining drugs or using them sequentially for enhanced effect, a number of speakers suggested at an international symposium sponsored by the National Osteoporosis Foundation.

Teriparatide, to be marketed by Eli Lilly & Co. as Forteo, is synthetic human parathyroid hormone 1-34 (PTH). Its mechanisms of action differ considerably from those of currently available antiresorptive agents, said Dr. Robert Neer, director of the osteoporosis center at Massachusetts General Hospital in Boston.

He reviewed his own and others' data about the bone-building potential of PTH, which reduces new vertebral fractures by 65% and nonvertebral fractures by more than 50% as it restructures the microarchitecture of the bone itself.

"Despite these impressive effects, bone mineral density is seldom restored to youthful levels. Fragility fractures, although reduced, are not eliminated," he said.

Combination therapy, therefore, might make sense to heighten results.

"PTH, like [insulin-like growth factor I] and growth hormone, increases bone resorption as well as bone formation. Therefore, combining PTH with an antiresorptive agent might possibly have a greater beneficial effect on bone mass and strength" than either agent alone, Dr. Neer said.

Three relatively small studies have explored the use of PTH in combination with hormone replacement therapy with mixed results. The first two found significant increases in spine and hip bone mineral density (BMD) with PTH, but no appreciably enhanced effect of adding HRT to the ...