Use of osmotic minipumps for delivery of parathyroid hormone

To determine if osmotic minipumps can be used for the local delivery of parathyroid hormone (PTH), we examined the bone resorbing activity of PTH in minipumps, either removed and assayed in bone organ cultures or released over rat calvaria. Biological activity of PTH was maintained for up to 6 days when the hormone solution contained serum and the minipumps and tubing were siliconized and flushed with diluent prior to use. Addition of cysteine did not enhance activity.