Quinidine and haloperidol as modifiers of CYP3A4 activity: multisite kinetic model approach.
Article Details
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Galetin A, Clarke SE, Houston JB
Quinidine and haloperidol as modifiers of CYP3A4 activity: multisite kinetic model approach.
Drug Metab Dispos. 2002 Dec;30(12):1512-22.
- PubMed ID
- 12433827 [ View in PubMed]
- Abstract
The selection of appropriate substrates for investigating the potential inhibition of CYP3A4 is critical as the magnitude of effect is often substrate-dependent, and a weak correlation is often observed among different CYP3A4 substrates. This feature has been attributed to the existence of multiple binding sites and, therefore, relatively complex in vitro data modeling is required to avoid erroneous evaluation and to allow prediction of drug-drug interactions. This study, performed in lymphoblast-expressed CYP3A4 with oxidoreductase, provides a systematic comparison of the effects of quinidine (QUI) and haloperidol (HAL) as modifiers of CYP3A4 activity using a selection of CYP3A4 substrates: testosterone (TST), midazolam (MDZ), nifedipine (NIF), felodipine (FEL), and simvastatin (SV). The effect of QUI and HAL on CYP3A4-mediated pathways was substrate-dependent, ranging from potent inhibition of NIF (K(i) = 0.25 and 5.3 micro M for HAL and QUI, respectively), weak inhibition (TST), minimal effect (HAL on MDZ/SV) to QUI activation of FEL and SV metabolism. Inhibition of TST metabolite formation occurred but its autoactivation properties were maintained, indicating binding of a QUI/HAL molecule to a distinct effector site. Various multisite kinetic models have been applied to elucidate the mechanism of the drug-drug interactions observed. Kinetic models with two substrate-binding sites have been found to be appropriate to a number of interactions, provided the substrates show hyperbolic (MDZ, FEL, and SV) or substrate inhibition kinetic properties (NIF). In contrast, a three-site model approach is required for TST, a substrate showing positive cooperativity in its binding to CYP3A4.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Felodipine Cytochrome P450 3A4 Protein Humans UnknownSubstrateDetails Haloperidol Cytochrome P450 3A4 Protein Humans UnknownSubstrateInhibitorDetails Midazolam Cytochrome P450 3A4 Protein Humans UnknownSubstrateInhibitorDetails Nifedipine Cytochrome P450 3A4 Protein Humans UnknownSubstrateInhibitorInducerDetails Quinidine Cytochrome P450 3A4 Protein Humans UnknownSubstrateInhibitorDetails Simvastatin Cytochrome P450 3A4 Protein Humans UnknownSubstrateDetails - Drug Interactions
Drugs Interaction Integrate drug-drug
interactions in your softwareQuinidineErythromycin The risk or severity of QTc prolongation can be increased when Erythromycin is combined with Quinidine. QuinineErythromycin The risk or severity of QTc prolongation can be increased when Erythromycin is combined with Quinine.