Effect of Regular Use of High-dose Nebulized β2-Agonists on Resting Energy Expenditure, Weight, and Handgrip Strength in Patients With Chronic Airflow Limitation: COPD patients
Studies of nebulized salbutamol administered acutely in COPD patients have confirmed an acute rise in REE. The maximum increase appears at about 5 min following administration, and REE returns to baseline by 2 h. It has therefore been suggested that β2-agonists, even if they do not alter REE, could contribute to negative energy balance by increasing total 24-h energy expenditure. We found no supporting evidence for this hypothesis in that there was no change in weight, body composition, or HGS over time in either of our groups. There are no published data that we are aware of on the development of tolerance to the β2-induced elevation of REE in patients canadian health&care mall. The acute rise in REE appears to be much less marked in both COPD patients and age-matched control subjects than in younger control subjects, which highlights the problem of applying the findings of previous studies in healthy volunteers to the situation in patients with COPD.
Recently, there has been interest in the possible anabolic effects of β2-agonists. Clenbuterol, a long-acting β2-agonist, increases type Ha and lib muscle fibre size in rats. Martineau et al observed an increase in peripheral muscle strength and respiratory muscle strength in normal subjects given 8 mg of slow-release salbutamol orally for 3 weeks. Our study found no changes in weight, body composition, or HGS with regular nebulized β2-agonists. Again it is possible that there are important clinical differences in the route of administration. Another possibility is that the difference is due to duration of action of the β2-agonist drug. Choo et al reported that in rats the same anabolic effects as clenbuterol can be achieved by prolonged IV infusion of salbutamol. Whether long-term oral β2-agonists could cause this effect in patients is not known, although there was no evidence of weight gain or change in muscle bulk after a 2-week period of clenbuterol in a recent placebo-controlled trial in COPD patients.
Category: Airflow Limitation
Tags: chronic airflow limitation, resting energy expenditure