Relationship between lipophilicity and brain extraction of C-11-labeled radiopharmaceuticals. [Baboons]
The brain extraction of fifteen C-11-labeled compounds during a single capillary transit was studied in adult baboons by external detection of these tracers after injection into the internal carotid artery. The log P/sub oct/ (partition coefficient for octanol/water) values of these compounds range from -0.7 to greater than 4.0. A parabolic relationship was found between the log P/sub oct/value of the C-11-labeled compounds and the fraction of the radiopharmaceutical entering the brain. Compounds with log P/sub oct/ values between 0.9 and 2.5 were found to pass freely across the blood-brain barrier at a cerebral blood flow of 100 ml-min/sup -1/-hg/sup -1/. An apparently decreased extraction of very lipophilic compounds was shown to be related to binding of the tracer to blood components and macromolecules (red blood cells, albumin, etc.). These data suggest that a radiopharmaceutical designed to measure blood flow should have a log P/sub oct/ value of between 0.9 and 2.5.
- Research Organization:
- Wahington Univ. School of Medicine, St. Louis
- OSTI ID:
- 5327261
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 24:11
- Country of Publication:
- United States
- Language:
- English
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38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
BLOOD-BRAIN BARRIER
BLOOD FLOW
BRAIN
POSITRON COMPUTED TOMOGRAPHY
RADIOPHARMACEUTICALS
CHEMICAL PREPARATION
RETENTION
APES
CARBON 11
LIPIDS
MYELIN
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CARBON ISOTOPES
CENTRAL NERVOUS SYSTEM
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DRUGS
EMISSION COMPUTED TOMOGRAPHY
EVEN-ODD NUCLEI
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIPOPROTEINS
MAMMALS
MINUTES LIVING RADIOISOTOPES
NERVOUS SYSTEM
NUCLEI
ORGANIC COMPOUNDS
ORGANS
PRIMATES
PROTEINS
RADIOISOTOPES
SYNTHESIS
TOMOGRAPHY
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics
400702 - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials