A prospective study of the effects of prolonged timolol therapy on alpha- and beta-adrenoceptor and angiotensin II receptor mediated responses in normal subjects.

What Was Tested

This randomized controlled trial looks at Timolol and Phenylephrine.

Long-term treatment with beta 1-selective adrenergic antagonists gives rise to cross-sensitisation of cardiac beta 2-adrenoceptor responses, with no corresponding alteration in beta 1-adrenoceptor responses.

The researchers performed a prospective randomised double-blind placebo-controlled cross-over study of the effects of nonselective beta-blockade with timolol on alpha-adrenergic and angiotensin II receptor mediated responses in normal subjects.

The researchers also wished to study the time course of beta 1- and beta 2-adrenergic responses after withdrawal of timolol.

Who Took Part

By PubMed's age tags, the people studied were adults, men only.

Following cessation of treatment with timolol or placebo, beta 1- and beta 2-adrenoceptor mediated responses were assessed by measuring the heart rate responses to treadmill exercise and intravenous salbutamol infusion respectively.

Half each of the subjects underwent this 2 days and 3 days respectively, after the end of treatment.

How the Study Was Run

In design terms this was a randomized, double-blind, placebo-controlled and crossover study.

The participants were allocated by chance, so the Timolol group and the comparison group should start out alike.

Blinding on both sides kept the participants and researchers unaware of who received Timolol.

Some participants received a placebo instead of Timolol, giving a reference point.

In the crossover set-up each of the participants took both Timolol and the comparison in turn, acting as their own control.

What Was Measured

Topics PubMed links to this paper include Adrenergic alpha-Agonists, Adrenergic beta-Agonists, Adrenergic beta-Antagonists, Albuterol, Blood Pressure, Exercise and Heart Rate.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Timolol and Phenylephrine.

Results are reported in around 9 sentences of the abstract; we leave them to the paper itself rather than summarise them.

The publication is from 1997 (British journal of clinical pharmacology), a journal based in England.

More context: all human trials.