Table 1

Influence of quinidine on metabolism of meloxicam, testosterone, and nifedipine by human liver microsomes and recombinant human CYPs

	Substrate	Substrate Concentration	Activator	Activator Concentration	Control
		μM		μM	%
Microsomes	Meloxicam	10			100
Microsomes	Meloxicam	10	Quinidine	10	140
Microsomes	Meloxicam	10	Quinidine	100	280
CYP 2C9	Meloxicam	10			100
CYP 2C9	Meloxicam	10	Quinidine	10	110
CYP 2C9	Meloxicam	10	Quinidine	100	60
CYP 3A4	Meloxicam	10			100
CYP 3A4	Meloxicam	10	Quinidine	10	160
CYP 3A4	Meloxicam	10	Quinidine	100	510
CYP 3A4	Testosterone	50			100
CYP 3A4	Testosterone	50	Quinidine	10	120
CYP 3A4	Testosterone	50	Quinidine	100	60
CYP 3A4	Nifedipine	200			100
CYP 3A4	Nifedipine	200	Quinidine	10	30
CYP 3A4	Nifedipine	200	Quinidine	100	10

Values were corrected for basic activity (0.14 pmol/min/mg protein) of control microsomes not expressing CYP 3A4 or CYP 2C9 (mean of duplicate to triplicate experiments).