Disclosed are methods and compositions which may be used in human cytochrome P450 (CYP450) enzyme phenotyping. The methods and compositions typically utilize substrate for CYP3A5 comprising eplerenone which may be administered orally to a subject. Subsequently, metabolites of eplereone may be detected in the subject's saliva as well as any non- metabolized eplerenone to calculate a metabolic ratio for CYP3A5 enzyme in order to generate a phenytopic CYP3A5 enzyme profile for the subject.

Disclosed are methods and compositions which may be used in human cytochrome P450 (CYP450) enzyme phenotyping. The methods and compositions typically utilize substrate for CYP3A5 comprising eplerenone which may be administered orally to a subject. Subsequently, metabolites of eplereone may be detected in the subject's saliva as well as any non- metabolized eplerenone to calculate a metabolic ratio for CYP3A5 enzyme in order to generate a phenytopic CYP3A5 enzyme profile for the subject.

Methods of characterizing the time-based hepatotoxicity of a test compound are provided. In some embodiments the provided methods allow prediction of the hepatotoxic potential of a test compound in a way that is improved relative to that achievable with prior art methods. In some embodiments the methods may be used to quantify the relationship between measurements or estimates of toxicity made at different, successive points in time, to provide highly meaningful tool to assess the likely in vivo hepatotoxicity of test compounds in vivo.

Chemiluminescent compositions, methods, assays and kits for oxidative enzymes are described. Further disclosed are dioxetane compounds of the form: ##STR00001##
where R can independently be any branched alkyl or cycloalkyl group which provides stabilization for the dioxetane or where both R groups together form a cycloalkyl or polycycloalkyl moiety spiro bound to the dioxetane ring, wherein each R group or the spiro bound moiety can be unsubstituted or substituted with one or more electron-withdrawing groups or electron donating groups, or groups providing preferential oxidative isozyme substrate recognition, and wherein R.sub.1 is an aryl group, or an alkyl group of 1-20 carbon atoms, which can be optionally substituted with 1 or more halogen atoms, and wherein T is an aryl or heteroaryl ring capable of emitting light upon enzyme activated decomposition of the dioxetane I. Kits, methods and assays are also disclosed that comprise the dioxetane compounds.

Chemiluminescent compositions, methods, assays and kits for oxidative enzymes are described. Further disclosed are dioxetane compounds of the form:

##STR00001##

where R can independently be any branched alkyl or cycloalkyl group which provides stabilization for the dioxetane or where both R groups together form a cycloalkyl or polycycloalkyl moiety spiro bound to the dioxetane ring, wherein each R group or the spiro bound moiety can be unsubstituted or substituted with one or more electron-withdrawing groups or electron donating groups, or groups providing preferential oxidative isozyme substrate recognition, and wherein R.sub.1 is an aryl group, or an alkyl group of 1-20 carbon atoms, which can be optionally substituted with 1 or more halogen atoms, and wherein T is an aryl or heteroaryl ring capable of emitting light upon enzyme activated decomposition of the dioxetane I.

Kits, methods and assays are also disclosed that comprise the dioxetane compounds.