TABLE 3.

Inhibitory effect of ritonavir and nelfinavir, combined with sulfadiazine or pyrimethamine

Drug and concn (μg/ml)	OD (103) at indicated drug concn (μg/ml)a
	Ritonavir					Nelfinavir
	0	1	2	5	25	0	0.5	2	5	10
Sulfadiazine
0	633 ± 43	611 ± 50	596 ± 49	472 ± 38	33 ± 16	762 ± 128	810 ± 87	767 ± 73	423 ± 133	80 ± 113
0.02	632 ± 34	631 ± 88	632 ± 63	463 ± 43	29 ± 12	695 ± 62	754 ± 109	690 ± 64	454 ± 106	15 ± 11
0.2	421 ± 77	455 ± 99	555 ± 39	383 ± 63	14 ± 13§	264 ± 69	370 ± 84	526 ± 109	556 ± 95	14 ± 12§
2	14 ± 11	52 ± 25	31 ± 17	64 ± 75	6 ± 6§	14 ± 12	31 ± 23	38 ± 29	57 ± 30	24 ± 16
Pyrimethamine
0	705 ± 58	766 ± 107	756 ± 105	628 ± 47	32 ± 29	821 ± 77	855 ± 65	842 ± 67	578 ± 190	15 ± 17
0.01	672 ± 128	830 ± 115	854 ± 128	614 ± 43	24 ± 17	764 ± 69	819 ± 32	808 ± 65	625 ± 106	9 ± 7
0.05	595 ± 69	543 ± 120	607 ± 55	500 ± 45	15 ± 17§	603 ± 48	565 ± 80	560 ± 50	583 ± 97	10 ± 8
0.25	120 ± 35	83 ± 50	105 ± 32	75 ± 44	17 ± 16§	11 ± 9	25 ± 14	16 ± 15	29 ± 23	11 ± 8

^aEach value represents the results from 8 to 12 replicate wells from 2 or 3 replicate plates. P values were calculated for the interaction effect. §, additive but not synergistic effect (P > 0.05).