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Dear All,
There is a question regarding omeprasole pharmacokinetics in rabbits
and a problem that I am facing.
Can anyone explain the following observation:
After administration of per os capsulae of omepazole (Losec,"Astra"; ca.
9 mg/kg) in rabbits, plasma concentrations of the drug are not detected
during 8 hours of observation.
After each blood sampling, heparinized plasms was collecteed and 25 mcl
1N Na2CO3 were added to each sample. Plasma was stored at - 20 oC until
assay.
The method of detectrion of drug is validated. Limit of detection is
10 ng/ml.
Is there any interspecies difference in omeprazole pharmacokinetic?
Thank you very much in advance for all the answers.
Igor Miroshnichenko, Ph.D.
Pharmacokinetic Lab.
Mental Health Research Center Russian Academy of Medical Science
E-mail:
valg111.-at-.online.ru
http://www.igormir.newmail.ru/
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Dear Dr. Miroshnichenko:
Are you administering the capsules without any prior dissolution or
disintegration? Omeprazole capsules are pH sensitive to release at a pH of
about 7. Omeprazole is labile in gastric acid and is inactivated. This may
explain your lack of omeprazole absorption.
Michael E. Burton, Pharm.D.
Associate Professor
Department of Pharmacy: Clinical and Administrative Sciences
The University of Oklahoma Health Science Center
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Dear Dr. Miroshnichenko
Further to the previous email, it could be possible that the enteric
coated beads are not opening in the rabbits GI system due to
different pH conditions.
One suggestion might be to disperse the capsules in a sodium
bicarbonate solution and administer the solution. This normally
protects against degradation, and is used clinically in humans who
cannot swallow the capsules.
Cheers
Carl Kirkpatrick
Chief Drug Information Pharmacist
Department of Clinical Pharmacology
Christchurch Hospital
PO Box 4710
CHRISTCHURCH
NEW ZEALAND
Ph: 00 64 3 3640 901
fax: 00 64 3 3640 902
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Omeprazole PK you should include as many time points as possible between 0-4
hrs as OMP is a short half life drug and it quickly disappear from the
circulation.
Hope this helps.
Prasad NV Tata
Prasad NV Tata, M.Pharm., Ph.D.
Mallinckrodt, Inc.
P.O. Box 5840
675 McDonnell Blvd.
St. Louis, MO 63134
Tel: (314) 654-5325
Fax: (314) 654-9325
E-mail: prasad.tata.aaa.mkg.com
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