PharmPK Discussion - Omeprazole interactions

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On 2 Mar 2001 at 14:15:58, =?iso-8859-1?Q?=22Jes=FAs_Fr=EDas_Iniesta=22?= (jesus.frias.-a-.uam.es) sent the message


The following message was posted to: PharmPK

Dear colleagues,

I will greatly appreciate if someone could give me information related with
Omeprazol drug interaction with warfarin and diazepam. We are looking for
references related with omeprazole 40mg dose.

Thank you--

J. Frias-Iniesta
Farmacologia Clinica.
Departamento de Farmacologia y Terapeutica.
Facultad de Medicina. Univ. Autonoma de Madrid.
Fax 91 397 53 74
email jesus.frias.-at-.uam.es

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On 2 Mar 2001 at 14:18:30, =?iso-8859-1?Q?=22Jes=FAs_Fr=EDas_Iniesta=22?= (jesus.frias.-at-.uam.es) sent the message


The following message was posted to: PharmPK

Dear colleagues,

I will greatly appreciate if someone could give me information related with
Omeprazol drug interaction with warfarin and diazepam. We are looking for
references related with omeprazole 40mg dose.

Thank you--

J. Frias-Iniesta
Farmacologia Clinica.
Departamento de Farmacologia y Terapeutica.
Facultad de Medicina. Univ. Autonoma de Madrid.
Fax 91 397 53 74
email jesus.frias.-a-.uam.es

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On 3 Mar 2001 at 11:38:29, Dr Federico Pea (federico.pea.at.med.uniud.it) sent the message


Dear Dr. Frias-Iniesta,
                                       omeprazole is metabolized mainly by
CYP2C19 and to a lesser extent by CYP3A4 . It has the potential to inhibit
metabolism of CYP2C19 substrated, but not or only minimally that of CYP3A4
ones. Therefore, diazepam clearance is expected to be impaired during
cotreament, since diazepam is metabolized by CYP3A4 and by CYP2C19. On the
other hand, no or minor interaction was found when omeprazole was
coadministered with warfarin, R-warfarin being metabolized mainly by CYP1A2 and
CYP3A4, and S-warfarin by CYP2C9.

References

    * Unge P, Svedberg LE, Nordgren A, Blom H, Andersson T, Lagerstrom PO,
      Idstrom JP
      A study of the interaction of omeprazole and warfarin in anticoagulated
      patients.
      Br J Clin Pharmacol 1992 Dec;34(6):509-12
    * Andersson T, Andren K, Cederberg C, Edvardsson G, Heggelund A, Lundborg P
      Effect of omeprazole and cimetidine on plasma diazepam levels.
      Eur J Clin Pharmacol 1990;39(1):51-4
    * Sutfin T, Balmer K, Bostrom H, Eriksson S, Hoglund P, Paulsen O.
      Stereoselective interaction of omeprazole with warfarin in healthy men.
      Ther Drug Monit. 1989;11(2):176-84.
      Andersson T
    * Pharmacokinetics, metabolism and interactions of acid pump inhibitors.
      Focus on omeprazole,
      lansoprazole and pantoprazole.
      Clin Pharmacokinet. 1996 Jul;31(1):9-28
    * Unge P, Andersson T.
      Drug interactions with proton pump inhibitors.
      Drug Saf. 1997 Mar;16(3):171-9.
    *  Negro RD.
      Pharmacokinetic drug interactions with anti-ulcer drugs.
      Clin Pharmacokinet. 1998 Aug;35(2):135-50.

Hoping this may help
Yours sincerely
--
Dr. Federico Pea, MD
Clinical Pharmacologist
Institute of Clinical Pharmacology & Toxicology
Medical School
University of Udine
P.le SM Misericordia, 3
33100 Udine
Italy
email: federico.pea.-a-.med.uniud.it
URL:http://www.uniud.it/ifct/welcome.html
Phone & Fax: +39 0432 559833

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