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I would consider that significant enough to counsel patients about before prescribing though. Having said that, it's a bit of a throwaway comment because I dont know if that tachycardia is physiologically significant during maximal exercise
It's on the patient information leaflet, but it has never been explicitly drawn to my attention by any physician. AFAIK, it's rarely troublesome with inhaled salbutamol, the increase in resting HR if it exists at all is typically of the order of 20bpm. If your exercise induced tachycardia is adding 100bpm or more to your resting HR, any effect of salbutamol is likely to be buried in the noise.
gbj_tester
Fair enough. I think this is an issue of semantics. Based on my anectodal evidence of patients I have prescribed it for (admittedly hospital inpatients and not men cycling up spanish mountains), ~10% sounds about right, and that's the number GSK quote too. I would consider that significant enough to counsel patients about before prescribing though. Having said that, it's a bit of a throwaway comment because I dont know if that tachycardia is physiologically significant during maximal exercise
I am not a specialist respiratory physician but it's my understanding that patients with poorly controlled asthma (of which, exercise-induced asthma is a usually a sign of) tend to respond to a combination of the other drugs available (of which there are several beyond inhaled steroids and salmeterol), eventually escalating to oral steroids (or an excuse to get some triamcinolone) . I find it somewhat difficult to believe that Froome's asthma is severe enough to warrant any of this as this population of patient are more likely to be seen in ICU or the mortuary than in the red jersey.
It's also now thought that asthma in elite athletes mighht be a different pathology to asthma in the general population, so the optimum management strategies might be different. But there's evidence to suggest that long term salbutamol use induces tolerance and reduces its effectiveness in exercise induced asthma, so simply increasing his dose is probably not best practice.
Having said all that, I do take your point re pharmocokineticsI'm sure we'll be seeing "The effects of altitude and dehydration on salbutamol pharmocokinetics in elite cyclists: a single case report" Brailsford et al. 2017, soon enough...