The present invention addresses the problem of providing a medicinal composition and, in particular, a compound suitable for treating nocturia. Under the expectation that nocturnal urinary frequency could be reduced via an antidiuretic action, said antidiuretic action being induced by inhibiting placental leucine aminopeptidase (P-LAP) that is an AVP-metabolic enzyme at night and thus maintaining and/or increasing endogenous AVP concentration, extensive studies were made on compounds capable of inhibiting P-LAP. As a result, it was discovered that a (2R)-3-amino-2-[(4-substituted pyridin-2-yl)methyl]-2-hydroxypropanoic acid derivative has an excellent P-LAP inhibiting effect. By testing the antidiuretic action using drinking water-loaded rats, furthermore, it was discovered that the aforesaid compound has an effect of suppressing urine production due to an increase in endogenous AVP concentration based on the inhibition of P-LAP. Thus, the present invention provides a compound that is likely usable as a therapeutic agent for nocturia based on a mechanism of inhibiting P-LAP.La presente invención aborda el problema de proveer una composición medicinal y en particular, un compuesto adecuado para tratar nicturia. Bajo la expectativa de que la frecuencia urinaria nocturna podría reducirse vía una acción antidiurética, siendo inducida dicha acción antidiurética al inhibir la aminopeptidasa de leucina placentaria (P-LAP), que es la enzima metabólica de AVP en la noche y así mantener y/o incrementar la concentración de AVP endógena, se hicieron extensos estudios sobre compuestos capaces de inhibir P-LAP. Como un resultado, se descubrió que un derivado de ácido (2R)-3-amino-2-{[4-(piridina sustituida)-2-il]metil}-2-hidroxipropanoico tiene un excelente efecto inhibidor de P-LAP. Al probar la acción antiduiurética que usa ratas cargadas con agua para beber, adicionalmente, se descubrió que el compuesto antes mencionado tiene un efecto para suprimir la producción de orina debi
