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Blood levels of practolol after oral and parenteral administration and their relationship to exercise heart rate
Author(s) -
Carruthers S. George,
Kelly John G.,
McDevitt Denis G.,
Shanks Robin G.
Publication year - 1974
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1974155497
Subject(s) - practolol , liter , heart rate , medicine , anesthesia , blockade , oral administration , blood pressure , propranolol , receptor
Blood levels of practolol after oral and parenteral administration were determined in normal subjects, and the effects of each dose on the heart rate induced by strenuous exercise were measured. Oral practolol was rapidly absorbed and produced peak blood levels in 1 to 3 hours. Between 2 and 7 hours blood levels varied little more than twofold either within or between subjects. The half‐life of practolol in blood was 10 to 11 hours. Practolol100 mg was the minimum dose to produce near maximum blockade at 2 hours; maintenance of this effect for 24 hours reqUired 400 mg. Near maximum blockade was produced as long as a blood practolol level of 1.0 to 1.4 µg per milliliter was maintained. There was a correlation between the logarithm of the blood practolollevel and the percentage reduction of exercise heart rate. Practolol 40 mg and 80 mg intravenously initially achieved near maximum blockade associated with blood practolol levels above 1.0 p.g per milliliter. The effects and blood levels fluctuated during the first 7 hours. Intramuscular doses up to 40 mg failed to produce near maximum blockade; higher doses were precluded by pain at the injection site.