Cytochrome p450 enzymes

Author:Prof. Dr. med. Peter Altmeyer

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Last updated on: 25.12.2020

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Synonym(s)

CYP; CYP enzymes; Cytochrome P450; cytochrome P450 mixed oxigenase; cytochrome P450 monooxigenase; P450 monooxygenase

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DefinitionThis section has been translated automatically.

Enzymfamilie (siehe unten Enzyme ), die im endoplasmatischen Retikulum von Zellen lokalisiert ist und eine zentrale Rolle bei der Entgiftung von Arzneimitteln oder Fremdstoffen im Allgemeinen spielt. Alle Enzyme tragen eine eisenhaltige Hämgruppe und katalysieren Oxidationsprozesse auf fettlöslichen Substraten unter NADPH- und Sauerstoffverbrauch (chemisch gehört die Cytochrom P450-Enzymfamilie zu den Oxy-Reduktasen oder ihrer Untergruppe von Monooxygenasen, siehe unten; s.a. Enzyme ).

General informationThis section has been translated automatically.

Cytochrome P450 enzymes can transfer (oxidize) an oxygen atom to the substrate (e.g. a drug) by forming hydroxyl groups and are therefore classified as hydroxylases or referred to as monooxygenase or mixed oxygenase (phase 1 reaction). In a phase 2 reaction, side groups are coupled to this group (e.g. conjugation with glucuronic acid: glucuronidation, sulfation , acetylation), which makes the substance water-soluble and thus suitable for the kidneys. In addition, drug-active metabolites can be formed from inactive substances (prodrugs) by transformation.

Main localization is the endoplasmic reticulum of the liver, but they are also found in skin, genitals, intestine, pancreas, brain, lung, kidney, adrenal gland.

5 of these enzymes (CYP3A4, CYP2D6, CYP2C19, CYP2C9, CYP1A2) metabolize the majority of liver-derived drugs. Drugs metabolized by the same cytochrome may interfere with each other. It depends on the kinetics of this process how fast metabolization occurs (fast and slow metabolizers).

Several drugs can lead to enzyme induction. Other drugs (e.g. phenobarbital), including phytopharmaceuticals such as St. John's wort inhibit Cyp3A4. This causes its substrates to be degraded at a slower rate (prolonging efficacy). CYP2D6 is involved in the metabolism of about every 4th drug (e.g. antiarrhythmics, antidepressants, neuroleptics, antitussives and antiemetics).

Polymorphisms (see pharmacogenetics below) in the coding genes can also lead to significantly altered pharmacokinetics (slowing/acceleration of elimination) of certain drugs, with corresponding consequences (see also under codeine).

Note(s)This section has been translated automatically.

The designation P450 is derived from pigment (acronym: "P") and the absorption spectrum (Soret band) in the CO differentiation spectrum at 450 nm.

LiteratureThis section has been translated automatically.

  1. Beubler E (2003) Pharmacology of cyclooxygenase 2 inhibition. Vienna Med Weekly 153: 95-99
  2. Hippius M et al (2003) Adverse drug reaction monitoring in Jena. Relevance of polymorphic drug metabolizing enzymes for inducing adverse drug reactions. Exp Toxicol Pathol 54: 417-421
  3. Kessova I et al (2003) CYP2E1: biochemistry, toxicology, regulation and function in ethanol-induced liver injury. Curr Mol Med 3: 509-518
  4. Masri M et al (2003) Cyclosporine blood level monitoring. Cross-reactivity of anti-cyclosporine A monoclonal with its sulphate metabolite: an in vitro study. Mol Immunol 39: 1059-1060
  5. Papp-Jambor C et al (2002) Cytochrome P450 enzymes and their role in drug interactions. Anaesthetist 51: 2-15
  6. Tracy TS (2003) Atypical enzyme kinetics: their effect on in vitro-in vivo pharmacokinetic predictions and drug interactions. Curr Drug Metab 4: 341-346

TablesThis section has been translated automatically.

Isoenzyme

Substrate group

Active substance

Inducers

Inhibitors

CYP1A2

TCA

Amitriptyline

omeprazole, smoking

cimetidine, amiodarone, ticlopidine, ciprofloxacin, fluvoxamine

Clomipramine

Imipramine

SSRI

Fluvoxamine

Neuroleptics

Haloperidol, Clozapine

NSAID

Paracetamol

Other

theophylline, caffeine, ropivacaine

CYP3A4

Opiates

Fentanyl

Cimetidine, macrolides (e.g., erythromycin, clarithromycin), antifungals (e.g., ketoconazole, itraconazole, fluconazole), Ca antagonists (verapamil, diltiazem), SSRIs (fluvoxamine, fluoxetine), HIV protease inhibitors, grapefruit juice

Alfentanil

Sufatenil

Pethidine

Codeine

Dextromorphan

Benzodiazepines

Midazolam

Barbiturates (phenobarbital, thiopental)

Alprazolam

Diazepam

Dipotassium clorazepate

Triazolam

Local anesthetics

Lidocaine

Ropivacaine

Antiarrhythmics

Amiodarone

Antiepileptic drugs

Carbamazepine

Phenytoin

Propafenone

Quinidine

Ca antagonists

Verapamil

Glucocorticoids

Diltiazem

Nifedipine

Nisoldipine

Nitrendipine

Felodipine

Amlodipine

Antiepileptic drugs

Carbamazepine

Rifampicin

Phenytoin

Macrolides

Erythromycin

Clarythromycin

TCA

Amitriptyline

Imipramine

H1 blockers

Astemizole

Terfenadine

5-HT3 antagonists

Ondansentrone

Tropisetron

Granisetron

CSE inhibitors

Lovastatin

Simvastatin

Atorvastatin

HIV protease inhibitors

Indinavir

Nelfinavir

Ritonavir

Saquinavir

Other

Paracetamol

Ciclosporin A

CYP2C9

TCA

Amitriptyline

phenobarbital, rifampicin

cimetidine, amiodarone, fluconazole, fluvoxamine, paroxetine, sertalin, proton pump blockers (omeprazole, lansoprazole)

NSAID

Diclofenac

Ibuprofen

Naproxen

Piroxicam

Celecoxib

AT-II receptor antagonists

Losartan

Ibesartan

Antidiabetics

Tolbutamide

Glipizide

Coumarin derivatives

Warfarin

Phenprocoumon

Other

Phenytoin

CYP2C19

TCA

Amitriptyline

Phenobarbital, Rifampicin

cimetidine, ticlopidine, fluvoxamine, paroxetine, sertalin, proton pump blockers (omeprazole, lansoprozole)

Clomipramine

Imipramine

Proton pump blockers

Omeprazole

Lansoprazole

Other

Diazepam

Phenytoin

Propanolol

CYP2D6

Opioids

Tramadol

Pregnancy

Cimetidine, antiarrhythmics (amiodaromn, quinidine), SSRIs (fluoxetine, paroxetine), methadone

Codeine

dextromethorphan

Beta blockers

Carvedilol

Metoprolol

Timolol

Antiarrhythmics

Propafenone

Flecainide

Mexiletine

Ajmaline

TCA

Amitriptyline

Clomipramine

Imipramine

Desipramine

SSRI

Fluvoxamine

Fluoxetine

Paroxetine

Citalopram

Neuroleptics

Haloperidol

Droperidol

Risperidone

Thiorisdazine

5-HT3 antagonists

Ondansentrone

Tropisetron

CYP2E1

Inhalational anesthetics

Halothane

ethanol, isoniazid

Disulfiram

Enflurane

Isoflurane

Sevoflurane

NSAID

Paracetamol

Authors

Last updated on: 25.12.2020