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February 16

How sensitive is nebulizable budesonide to heat, light and oxidation relative to nebulizable salbuterol?

As EMTs, we are told to safeguard our albuterol sulfate (salbuterol) from high temperatures (like a poorly air-conditioned ambulance front cabin on a hot summer day), light and other stressors. I can see why, as my basic organic chem training tells me the ortho/para dialkylphenol ring in salbuterol is electron-rich and the hydroxymethylene group is a fairly decent general acid/base catalyst (sort of like the 2-OH group in RNA?). Thus the clarity, color and consistency of our nebulizable albuterol supplies must be constantly monitored as it can go bad prior to its relatively short expiration date if stored improperly.

The steroidal nature of over the counter nebulized budesonide seems less susceptible to oxidation but I notice there is a conjugated dienone functionality with a possibly activated / vulnerable neighboring C-H bond. How sensitive is budenoside to heat, light and oxidation relative to salbuterol? Yanping Nora Soong (talk) 03:25, 16 February 2020 (UTC)[reply]

Perhaps this article (PMID 23925057) answers the question. I can only see the abstract, which does not identify the specific drugs studied, but the lead author's LinkedIn page suggests they were albuterol, cromolyn, budesonide, and ipratropium. --Lambiam 06:42, 16 February 2020 (UTC)[reply]

PMID:28719374 talks about the stability of budesonide (same journal as Lambiam's ref, I too can only see the abstracts). PMID:28652557 discusses the oxygen- and pH-sensitivity of salbutamol. In addition to your thought about reactivity of the electron-rich benzene ring, that ref of mine also notes that salbutamol is stereochemically unstable at low pH. That probably means it can lose the OH form a benzylic carbocation, leading to additional decomposition pathways. DMacks (talk) 07:50, 16 February 2020 (UTC)[reply]