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Prediction of Drug Interactions With CYP2C9 Substrates

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00226538
Recruitment Status : Completed
First Posted : September 27, 2005
Last Update Posted : October 29, 2008
Information provided by:
Hadassah Medical Organization

Brief Summary:

CYP2C9, is one of the major drug metabolism enzymes accounting for about 20% of the hepatic cytochrome P450 content and being second only to CYP3A4.

The proposed study will explore different possible drug interactions with CYP2C9 substrates by evaluating the effect of prototype inducers and inhibitors on the phenotypic trait measurement. It is expected that the identification of drugs that might interact with CYP2C9 substrates will be used to rationalize future drug interaction studies designed to evaluate the actual magnitude of effect and its clinical implications. This approach should be particularly useful when applied to those CYP2C9 drugs characterized by a narrow therapeutic index (i.e. warfarin).

This study will consist of three study periods separated from each other by a two weeks washout period. In the course of the study the subjects will receive in a double blind, crossover fashion, rifampin 300 mg. twice daily, diclofenac 50 mg twice daily. and fluconazole 200 mg. twice daily, each for one week. All drugs will be administered as identical looking tablets that will be prepared at the pharmacy of the Hadassah University Hospital and their order of administration will be randomized.On the day prior to, on day 6 of and 7 days following each drug period, the activity of CYP2C9 will be evaluated by the administration of a single phenytoin 300 mg. dose. The subjects will be requested to collect their urine for 24 hours and a single blood sample will be obtained 12 hours post phenytoin intake.

Condition or disease Intervention/treatment Phase
Healthy Volunteers Drug: Phenytoin Drug: Rifampicin Drug: Diclophenac Drug: Fluconazole Not Applicable

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Study Type : Interventional  (Clinical Trial)
Enrollment : 16 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Official Title: Prediction of Potential Drug Interaction With CYP2C9 Substrate by Using Phenytoin Metabolic Ratio as a Marker of Its Activity in-Vivo.
Study Start Date : August 1999

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Drug Reactions

Primary Outcome Measures :
  1. Phenytoin metabolic ratio prior to and following exposure to fluconazole, diclophenac and rifampicin.

Information from the National Library of Medicine

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Ages Eligible for Study:   20 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Age range 20-50
  • Absence of significant disease states

Exclusion Criteria:

  • Known hypersensitivity to one of the drugs used in the study
  • Significant disease states
  • Regular use of drugs (including birth control pills)

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00226538

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Hadassah Medical Organization
Jerusalem, Israel
Sponsors and Collaborators
Hadassah Medical Organization
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Principal Investigator: Yoseph Caraco, MD Hadassah Medical Organization
Layout table for additonal information Identifier: NCT00226538    
Other Study ID Numbers: yc19555-HMO-CTIL
First Posted: September 27, 2005    Key Record Dates
Last Update Posted: October 29, 2008
Last Verified: October 2008
Additional relevant MeSH terms:
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Anti-Inflammatory Agents, Non-Steroidal
Analgesics, Non-Narcotic
Sensory System Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Anti-Inflammatory Agents
Antirheumatic Agents
Cyclooxygenase Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action
Antifungal Agents
Anti-Infective Agents
14-alpha Demethylase Inhibitors
Cytochrome P-450 Enzyme Inhibitors
Steroid Synthesis Inhibitors
Hormone Antagonists
Hormones, Hormone Substitutes, and Hormone Antagonists
Cytochrome P-450 CYP2C9 Inhibitors
Cytochrome P-450 CYP2C19 Inhibitors
Antibiotics, Antitubercular
Antitubercular Agents
Anti-Bacterial Agents
Leprostatic Agents
Nucleic Acid Synthesis Inhibitors
Cytochrome P-450 CYP2B6 Inducers