The electron flow in cytochrome C oxidase can be blocked by
Inhibitors of Electron transport chain (Respiratory chain)

Complex I :- Barbiturates (amobarbital), piercidin A, rotenone, chlorpromazine, guanithidine.
Complex II Carboxin, TTFA, malonate.
Complex HI Dimercaprol, BAL, actinomycin A, Naphthyloquinone.
Complex IV (cytochrome c oxidase) :- Carbon monoxide (CO), cyanide (CN),H2S, azide (N3-)
Rotenone
Antimycin-A
Cyanide
Actinomycin