Asthma, ICS, MDI, Corticosteroid, Pulmonology How many buffs of corticosteroid inhaler are needed to induce systemic side effect in asthmatic patient?
It depends on the age. In prepubertal children it doesn't take much to have a small impact on growth. In adults, it is hard to show a systemic effect until you get to a pretty high dose. About 20% of adults getting fluticasone 220mcg/puff 4 puffs twice a day will have an effect on bone mineralization. There are some differences depending on the particular steroid but few studies aimed at identifying side effects at high doses. Because the dose response curve is relatively flat for most inhaled steroids, it doesn't make sense to push the dose until you see systemic effects because that will be higher than the maximum effective dose.
I agree.
Age, dose and time of usage are important. Usually low dose of ICCS (see GINA) are not associated with systemic side effects.
There is no simple answer to your question. At any age, it depends on the corticosteroid and other factors, such as the inhalation device used and the method of inhalation.
As far as systemic penetration is concerned, a useful concept is the L:T ratio, where L represents the local or lung availability of an inhaled drug and T is the total systemic availability. Another way of describing the L:T ratio is the concept of “pulmonary targeting". Drug properties that improve pulmonary targeting include slow absorption from the lungs, low oral systemic availability, and rapid systemic clearance. There is some evidence that the order for the main inhaled drugs is budesonide = beclomethasone dipropionate > triamcinolone acetonide = flunisolide. However, it is important to go beyond pharmacokinetics and to consider the actual adverse reactions that have been described; there have been many studies of those.
You also have about 5x12ml per MDI puff of HFA134a (Norflurane) propellant which is an intermediate potency anaestheic inhalational agent, and will bronchodilate (as do all hydrofluorocarbon agents eg halothane), and help steroid delivery. Steroid MDIs have 13% ethanol per puff too, which makes you cough. A strict religious sect in Saudi Arabia proscribes all alcohol in medication, but is allowed for medical reasons in all others. HFA134a is 1,1,1,2 tetrafluroethane, few have made the connection, least of all the toxicology studies which consider it inert.
Dear Collegeau!
What do you mean on"systemic side effect". I think one thing is the cortisol suppression and other things are the Cushing-syndrome, the osteoporosis or diabetes. Sorry:The article is in Hungarian language, but you can use the references. Best regards
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