Table 2

Kinetic parameter estimates for naproxen demethylation in the presence of dapsone

DapsoneKm1(S.E.)Vmax1 (S.E.)CLint (S.E.)
μM μM pmol/min/pmol P450 μl/min/pmol P450
0433  (252)11.7  (4.3)0.002  (0.002)
2233  (73.5)14.9  (2.4)0.003  (0.001)
5250  (92.4)21.8  (4.0)0.002  (0.002)
10163  (30.8)24.9  (2.0)0.002  (0.001)
5058.9  (18.0)27.4  (2.7)0.007  (0.002)
1002-a 67.4  (22.5)34.7  (3.8)0.002  (0.003)

Data were fit to a two-site biphasic model (eq. 2).

  • CLint, the linear portion of the biphasic curve ( Vmax2/ Km2).

  • 2-a  Also fit to Michaelis-Menten equation ( Km = 80.0 μM; Vmax = 37.0 pmol/min/pmol of P450).