Table 2.

Distribution of estimated peak concentrations (C _2 hr) for isoniazid and rifampin.

Drug	Diabetics (early TDM)	Nondiabetic slow responders (standard TDM)	P value
Rifampin  (expected range 8–24 μg/mL)	N = 20	N = 14
Mean C 2 hr   μg/mL ± SD	6.6 ± 4.3	8.2 ± 6.2	P = 0.40
Below expected range (%N)	12 (60)	4 (41)	P = 0.31
Isoniazid (daily)  (expected range 3–6 μg/mL)	N = 17	N = 8
Mean C 2 hr   μg/mL ± SD	2.1 ± 1.5	3.1 ± 1.1	P = 0.11
Below expected range (%N)	11 (65)	5 (63)	P = 0.92
Isoniazid (intermittent)  (expected range 9–18 μg/mL)	N = 4	N = 6
Mean C 2 hr   μg/mL ± SD	6.0 ± 3.0	11.3 ± 2.5	P = 0.03
Below expected range (%N)	3 (75)	1 (17)	P = 0.19

TDM: therapeutic drug monitoring (see Figure 1).