Table 4

Inhibition of human liver microsomal CYP1A2 phenacetin O-deethylation and CYP2D6 bufuralol 1′-hydroxylation by antiparasitic drugs

CYP Compound	K_i	Type of Inhibition	PlasmaC_max	Inhibitory Potency	Predicted % Inhibition {[I]/([I] ⁺K_i)} × 100
	μM		μM	[I]/K_i
CYP1A2
Artemisinin	0.43	Competitive	1.38	3.20	76
Niclosamide	2.70	Mixed	Negligible	—^4-a	Negligible
Thiabendazole	1.54	Mixed	89	57.80	98
Primaquine	0.22	Competitive	0.44	2.0	67
Dihydroartemisinin	3.67	Competitive	2.50	0.68	41
CYP2D6
Quinine	15.51	Competitive^4-b	15.41	0.99	50
Chloroquine	12.68	Competitive^4-c	0.39	0.031	3
Amodiaquine	2.1	Competitive	74	35.24	97
Desethylamodiaquine	4.13	Mixed	444	107.51	99
Proguanil	6.76	Mixed	0.76	0.11	10
Cycloguanil	5.97	Competitive	0.21	0.04	3

↵4-a —, cannot calcualte [I]/K_i since [I] is negligible.
↵4-b Quinine is a competitive inhibitor of 2D6 activity (Kobayashi et al., 1989).
↵4-c Chloroquine competitively inhibits 2D6 activity (Masimirembwa et al., 1995).