[Antagonist for calcium-sensing receptor. JTT-305/MK-5442].

Calcium-sensing receptor (CaSR) is a G protein-coupled receptor which was identified as a molecule that medicates the suppression of parathyroid hormone (PTH) secretion by extracellular Ca. Calcilytics are chemicals that enhance PTH secretion by antagonizing CaSR. JTT-305/MK-5442 is one of calcilytics made in Japan and is considered to be used as a bone anabolic agent through its stimulatory effect on PTH secretion. It is reported that JTT-305/MK-5442 increased lumbar bone mineral density by a placebo-controlled trial. However, further studies with more subjects are necessary to establish the clinical utility of JTT-305/MK-5442.