Rukhsana Sohail Chughtai.
Beta Blockers Revisited.
Mother & Child Jan ;13(3):78-82.

Haemodynamic effects of Propranolol, Timolol, Atenolol and Labetalol were studied in Mongrel & dogs. The animals were anaesthetized with Pentobarbitone sodium given in doses of 35mg/kg intravenously. the parameters used for study were changes in the mean arterial blood pressure and changes in the resting heart rate. Four test groups, each comprising of six animals, were treated with the four beta blockers. The dose employed was 2.5mg/kg given intravenously. The mean of the hypotensive effect of each beta blockers in six different animals was calculated. It was found that Labetalol produced the maximum hypotensive effect, followed by Propranolol. Fall in the blood pressure produced by Timolol and Atenolol was less as compared to the other two agents.The anaesthetized dogs were also used to study the slowing of the heart rate by the same four agents. Six different animals were used for each drug. ECG recording was taken at short intervals, after intravenous injection of the beta blocking agents in a dose of 2.5mg/kg day weight. Bradycardia produced by Propranolol and Labetalol was about 13%, whereas Timolol and Atenolol slowed the heart rate by 10%.The results of the study suggest that beta blockers can be employed an effective therapy for for controlling blood pressure.

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