[Effect of NPS R-467 on PTH secretion of cultured parathyroid cells from secondary hyperparathyroidism patients]

To observe the effect of NPS R-467, a calcimimetic, on PTH secretion of cultured parathyroid cells from severe secondary hyperparathyroidism (SHPT) patient.

The parathyroid tissue from a severe SHPT patient (iPTH: 2000 pg/ml) who had underwent parathyroidectomy was cultured in medium containing 1.05 mmol/L Ca and 0.8 mmo/L Mg. After 90 minutes' culture, NPS R-467 or NPS S-467, as negative control, with the final concentrations of 25, 50, and 100 nmol/L was added. The supernatant of medium was aspirated after 15, 30, and 60 minutes and iPTH therein was measured by radioimmunoassay.

There was no difference between the PTH concentrations in NPS R-467 group and NPS S-467 15 minutes after the reagents were added (1.8 ng/10(5) cells). In the NPS S-467 group, the PTH secretion was elevated along with the culture time, at 60 minutes up to 2.3 ng/10(5) cells. The PTH concentration of NPS R-467 was 80% of that of control group 30 minutes later and 60% of that in control group 60 minutes later. No difference was found among the effects of NPS R-467 at different concentrations.

The calcimimetic NPS R-467 significantly suppresses the PTH secretion, even in severe uremic hyperparathyroidism patient. It is an effective medicine for hyperparathyroidism.