Effects on cytochrome

Yang CS, Brady JF, Hong JY Dietary effects on cytochromes P450, xenobiotic metabolism, and toxicity. FASEB J 1992 6 737. 

Fenofibrate appears to be complementary with certain statins in the treatment of familial combined hyperlipoproteinemia and other conditions involving elevations of both LDL and VLDL. The combination of fenofibrate with rosuvastatin is particularly effective. Some other statins may interact unfavorably owing to effects on cytochrome P450 metabolism. 

Acetone, methyl ethyl ketone (2-butanone) and methyl isobutyl ketone (4-methyl-pentan-2-one) (6.8 mmol/kg bw for 3 days) increased the hepatotoxicity of carbon tetrachloride to Sprague-Dawley rats (Raymond Plaa, 1995a) this enhancement of toxicity was coincident with increased microsomal aniline hydroxylase activity (Raymond Plaa, 1995b). In addition to the effect on cytochrome P450, acetone, but not the other ketones, increased basal canalicular membrane fluidity, as measured by fluorescence polarization of 1,6-diphenyl-1,3,5 -hexatriene or 1 - [4-(trimethylammoniumphenyl)-6-phenyl] -1,3,5 -hexa-triene (Raymond Plaa, 1996). 

St. John s wart, rifampin, efavirenz, nevirapine and amprenavir will lower plasma concentrations of lopinavir due to their effect on cytochrome P-450 enzyme CYP3A4. Lopinavir increases plasma concentrations of ergot derivatives, triazolam, midazolam, and propafenone and should not be given together. 

Tegaserod has no known effects on cytochrome P450 enzymes and no known drug interactions. Unlike cisapride, tegaserod does not inhibit cardiac repolarization and does not prolong the QT interval. 

Walseth F, Toftgard R, Nilsen OG. 1982. Phthalate esters. I Effects on cytochrome P-450 mediated metabolism in rat liver and lung, serum enzymatic activities and serum protein levels. Arch Toxicol 50 1-10. 

Of all the SSRIs citalopram has the least inhibitory effect on cytochrome P450 enzymes and has not been associated with clinically significant interactions with other CNS drugs. 

An important consideration in the use of all HIV-1 protease inhibitors, but of ritonavir in particular, is their potential for drug interactions through their effects on cytochrome P450 isozymes. The various interactions of ritonavir with other antiretroviral drugs have been reviewed (139). Ritonavir, which inhibits CYP2D6, the principal pathway by which MDMA is metabolized, can also produce clinically relevant interactions with recreational drugs (140). 

The acute toxicity of HCN and cyanide is a consequence of the affinity of these substances for various heavy metals, such as iron or copper, by forming cyano complexes. The effect on cytochromes, which results in an efficient inhibition of respiration, is most important. In addition, numerous other metabolic processes are affected (for a review, see Solomonson, 1981). The lefhal dose of cyanide for humans is considered to be about 1 mg per kg... 

As with other HIV-1 protease inhibitors, saquinavir may be associated with drug interactions as a result of the effect of saquinavir on the hepatic cytochrome P450 oxidase system. Although compared with other HIV protease inhibitors, saquinavir has less of an inhibitory effect on cytochrome P450 isozymes clinically relevant interactions can nevertheless occur. Drug interactions with saquinavir have been reviewed (3). 

Elskus, A.A. and J.J. Stegeman. Further consideration of phenobarbital effects on cytochrome P-450 activity in the killifish, Fundulus heteroclitus. Comp. Biochem. Physiol. 92C 223-230, 1989. 

Crop. ProL Confi -Pests Dis. 1977, 593 R. G. Harris et al, ibid. 1979, 53. Efficacy against cereal powdery mildew D. M. Weigh ton et al, ibid. 1977, 25. Protective effect against blotch in winter wheat and barley R. G. Harris, G. Barnes, ibid. 1981, 267. Effect on cytochrome P-450 and sterol biosynthesis in Japanese quail J.-L. Riviere et al, Pestic. Sci. 15, 317 (1984). Review A. de Seint-Blanquat, J. My, Def. Veg. 37, 121 (1983). 

The separation of methionine into methanethiol and hydrogen sulfide by microbes was shown in patients with alcoholic liver cirrhosis to cause liver encephalopathy (McClain et al. 1980). Methanethiol reduced oxygen consumption in the liver and in brain mitochondria, inhibited the Na/K-ATPase of the brain, and had a deleterious effect on cytochrome c oxidase (Waller 1977, Vahlkamp et al. 1979, Quaforth et al. 1976). 

Middle-age alterations in the sexually dimorphic plasma growth hormone profiles Involvement of growth hormone-releasing factor and effects on cytochrome p450 expression. Drug Melab. Dispos. 30, 141-147. 

Kharasch, E.D., D.C. Hankins, C. Jubert, R.E. Thummel, and J.K. Taraday (1999). Lack of singledose disulfiram effects on cytochrome P-450 2C9, 2C19,2D6, and 3A4 activities Evidence for specificity toward P-450 2E1. Drug Metab. Dispos. 27, 717-723. 

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