Wednesday, February 4, 2015

Ipratropium (or tiotropium)

A patient with chronic obstructive pulmonary disease (COPD, eg, emphysema , chronic bronchitis ) i s receiving an orally inhaled muscarinic receptor-blocking drug to maintain bronchodilation. 

What drug belongs to that class ?

a . Albuterol
b. Diphenhydra mi ne
c. Ipratropium (or tiotropium)
d. Piloca rpi ne
e. Vecuronium

The answer is c.  Ipra tropium, a quaternary (and so poorly absorbed) a nicotimuscarinic
drug, i s FDA-a pproved for use as aninhaled bronchodilator for COPD. Its action involves blocka de/a ntagoni s m of ACh-medi a ted bronchocons tri cti on, a nd i t i s often us ed a djuncti vel y wi th a l buterol or other β2 agonist bronchodilators . A related drug is tiotropium.

Al buterol (a ) i s a n i nha l ed bronchodi l a tor for a s thma or COPD, but i t works , of cours e, a s a β2-a drenergi c a goni s t. Di phenhydra mi ne (b) ha s bronchodi l a tor a cti vi ty (by bl ocki ng both hi s ta mi ne H1 a nd mus ca ri ni c receptors ), but i t i s not gi ven by i nha l a ti on; moreover, for a mbul a tory pa ti ents wi th a s thma the mucus -thi ckeni ng effects of mus ca ri ni c receptor bl ocka de ca n do more ha rm tha n good. Vecuroni um (e) i s a cura re-l i ke s kel eta l neuromus cul a r bl ocker (competi ti ve a nta goni s t of ACh a t NM receptors ) a nd i s us ed ma i nl y for ca us i ng i ntenti ona l s kel eta l mus cl e pa ra l ys i s duri ng s urgry to s uppres s s ponta neous venti l a ti on i n s ome ICU pa ti ents on a venti l a tor. Pi l oca rpi ne (d) i s a mus ca ri ni c a goni s t, us ed
ma i nl y for ca us i ng mi os i s (cons tri cti ng the pupi l [s ] of the eye[s ]) i n s ome pa ti ents wi th a ngl e-cl os ure gl a ucoma . Pi l oca rpi ne wi l l ca us e bronchocons tri cti on—a n effect tha t ma y be ha rmful , i f not fa ta l , for pa ti ents wi th COPD or a s thma .


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