The present invention addresses the problem of providing a pharmaceutical composition, particularly a compound suitable for the treatment of nocturia. Extensive and intensive studies have been made on compounds capable of inhibiting placental leucineaminopeptidase (P-LAP), in the anticipation that an antidiuretic activity associated with the maintenance of or increase in an endogenous AVP concentration can be exerted by inhibiting P-LAP, which is a metabolic enzyme for AVP, in the nighttime and the urination frequency in the nighttime can be decreased through the antidiuretic activity. As a result, it is found that a (2R)-3-amino-2-(bicyclic pyridylmethyl)-2-hydroxypropanoic acid derivative has a good P-LAP inhibition activity, and it is also found that, in an antidiuretic test using a drinking water-fed rat, the compound has a urine production inhibition activity associated with the increase in an endogenous AVP concentration which is resulted from the P-LAP inhibition by the compound. Thus, the present invention provides a compound which is expected to be used as a therapeutic agent for nocturia and of which the mechanism of action against nocturia is through the inhibition of P-LAP.
