[carnold1965]

Hello everybody,

is it true that Lidocaine (as in the sprays used for bronchoscopy) does contain tertiary amines? I am a chemist, not a pharmacologist, and from the structural formula I can readily imagine that tertiary amines occur through decomposition. But is nothing done to stabilize the compound in the sprays? Why would anybody be using Lidocaine when this means getting a breath (or croak?) of tertiary amines?[xx(]

Any information on this?

With kind regards
Claudia

[pharmd06]

guten abend,
the pka of lidocaine is 7.9. so at the body's pH of 7.4 it should be inonized. it is prepared as the HCl salt.

with lidocaine in the bronch tubes, you have to think of everything as relative. the agent itself will be dispersed into the tissues of the upper respiratory tract. this causes numbness and the lidocaine is slowly absorbed (into the blood stream), then metabolized by the liver. some will even stick to the tube. i am not aware of lidocaine itself causing respiratory problems.

The amide in lidocaine (along with help from the bulky side chain) makes the compound relatively stable to esterases found in the tissues. this allows the numbness to have an effect until the drugs is absorbed and carried away from the site via blood.

lidocaine is metabolized via de-ethylation in the liver. CYP1A2 is the primary enzyme responsible for the metabolism of lidocaine via oxidative de-ethylation and 3-hydroxylation. the two metobolites are MONOETHYLGLYCINEXYLIDIDE (MEGX) AND GLYCINEXYLIDIDE (GX). from what i understand these are not toxic amines and would be excreted like any other nitrogenous waste.

http://encyclopedia.laborlawtalk.com...-Lidocaine.png