Patent ID: 7741321

Claim:
A kit for use in measuring the activity of CFTR in a biological sample in vitro or in vivo, comprising: (i) a compound of formula (I): or a pharmaceutically acceptable salt thereof, wherein: Each R 1 is an optionally substituted C 1-6 aliphatic, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted C 3-10 cycloaliphatic, an optionally substituted 3 to 10 membered heterocycloaliphatic, carboxy, amido, amino, halo, or hydroxy, provided that at least one R 1 is an optionally substituted cycloaliphatic, an optionally substituted heterocycloaliphatic, an optionally substituted aryl, or an optionally substituted heteroaryl attached to the 5- or 6- position of the pyridyl ring; Each R 2 is hydrogen, an optionally substituted C 1-6 aliphatic, an optionally substituted C 3-6 cycloaliphatic, an optionally substituted phenyl, or an optionally substituted heteroaryl; Each R 3 and R′ 3 together with the carbon atom to which they are attached form an optionally substituted C 3-7 cycloaliphatic or an optionally substituted heterocycloaliphatic; Each R 4 is an optionally substituted aryl or an optionally substituted heteroaryl; and Each n is 1,2,3 or 4; and (ii) instructions for: a) contacting the compound with the biological sample; and b) measuring activity of said CFTR.