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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...
jzk-
Having said that, I do take your point re pharmocokinetics. I'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.
Hopefully it'll be published alongside their study into the blood values of altitude natives and the biological passport.
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It's also now thought that asthma in elite athletes mighht be a different pathology to asthma in the general population
As we go down the track of individualised medicine, we'll probably stop talking about asthma and start discussing asthmas. The range of triggers, the interactions between them and the variation in individuals from one day or decade to the next all point to asthma being a symptom of a suite of pathologies.
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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.
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there's evidence to suggest that long term salbutamol use induces tolerance and reduces its effectiveness in exercise induced asthma
From two quite different studies with a total of 18 subjects using salbutamol monotherapy. It's evidence of a kind, but not that strong and not a very large effect. Before coming to conclusions, I'd want to see the effect of combination therapy (steroid+β2-agonist) which is the standard regime, and I'd want to see whether tolerance was permanent or transitory. As I said earlier, we're moving towards individualised medicine, and asthma therapy is one of the easy ones to individualise because we can do (and I have done) simple cheap spirometry tests to compare different regimes. For all that we know, Froome might have spent the whole of every training camp for the last decade carefully testing different regimes in order to optimise his pulmonary function.
andyp
gbj_tester
[citation needed]
Any numbers to go with that assertion? Prevalence and severity of tachycardia for inhaled salbutamol in the usual 2×100μg every 3-6 hours regime? The best I could find was a blanket <10%, which covers a multitude of sins. Since the reported number was only 3% for tablets (typically 4mg) and AFAIK systemic side effects are both more common with oral administration and dose dependent, I'd be a bit surprised if your "regularly" had the meaning understood by laymen.