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Stereochemistry of tissue distribution of racemic propranolol in the dog
Author(s) -
Walle U. Kristina,
Thibodeaux Harold,
Privitera Philip J.,
Walle Thomas
Publication year - 1989
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.530010303
Subject(s) - propranolol , chemistry , stereoselectivity , enantiomer , cerebrospinal fluid , adipose tissue , endocrinology , pharmacokinetics , medicine , in vivo , distribution (mathematics) , metabolism , pharmacology , biochemistry , stereochemistry , biology , mathematical analysis , microbiology and biotechnology , mathematics , catalysis
Only limited information is available on the stereochemistry of the in vivo distribution of β‐receptor‐blocking drugs. In this study we determined the levels of the propranolol enantiomers in plasma, cerebrospinal fluid (CSF) and central nervous system (CNS), and peripheral tissues in the dog following an intravenous dose of a deuterium‐labeled pseudoracemate. The appearance of the propranolol enantiomers in the CSF was rapid and nonstereoselective, with maximum concentrations reached at 15 min after dosing. The levels of the enantiomers in both CSF and plasma then declined in a parallel biphasic fashion, with a terminal t 1/2 of about 125 min. Except for an early high CSF/plasma concentration ratio of 0.35, the CSF propranolol levels corresponded to the unbound concentration in plasma, CSF/plasma 0.20. All areas of the brain showed a similar uptake of propranolol, with a tissue concentration exceeding that in plasma about 10‐fold during the terminal phase of elimination. The uptake of propranolol by peripheral tissues varied widely, ranging from a 50‐fold accumulation by the lungs compared to plasma to no accumulation by adipose tissue. However, as for the CSF, there was no evidence of stereoselective uptake of propranolol by any CNS or peripheral tissue except for the liver. A significantly higher level of (+)‐ vs. (–)‐propranolol in liver tissue presumably was a reflection of stereoselective hepatic metabolism of (–)‐propranolol by this tissue. The slight stereoselectivity in plasma binding of propranolol known to exist in the dog had no significant influence on tissue or CSF distribution.