Phthalazinone modulators of h1 receptors and/or ltc4 receptors

A pharmaceutical composition comprising a pharmaceutically acceptable carrier together with a compound of structural Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1-R24 are independently selected from the group consisting of hydrogen and deuterium;
• and
• at least one of R1-R24 is deuterium.

A method of treatment of a H1 receptor-mediated disorder or LTC4-mediated disorder comprising the administration, to a patient in need thereof, of a therapeutically effective amount of a compound of structural Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1-R24 are independently selected from the group consisting of hydrogen and deuterium;
• and
• at least one of R1-R24 is deuterium.

A compound for the use as a medicament, having structural Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1-R24 are independently selected from the group consisting of hydrogen and deuterium;
• and
• at least one of R1-R24 is deuterium.

A compound for use in the manufacture of a medicament for the prevention or treatment of a disorder ameliorated by modulating H1 receptor activity or modulating LTC4 production, wherein said compound has structural Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• R1-R24 are independently selected from the group consisting of hydrogen and deuterium;
• and
• at least one of R1-R24 is deuterium.