Beta adrenergic blocking properties of D and DL propranolol in man
The beta adrenergic blocking activity of D and DL propranolol was compared in healthy male subjects.
On intra-arterial administration, DL propranolol was more than 25 times as potent as D propranolol in antagonizing the forearm blood flow response to intra-arterial isoprenaline.
On intravenous administration DL propranolol was about 100 times as potent as D propanolol in antagonising the heart rate, forearm blood flow and diastolic blood pressure response to intravenous isoprenaline.
Intra-arterial D and DL propranolol also antagonised the forearm blood flow response to intra-arterial acetylcholine. It is suggested that the acetylcholine antagonism of the two forms of propranolol is related to their actions as local anaesthetics and separate from their actions as beta adrenergic receptor antagonists.
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