Question

Rank the following LAs in order of Protein binding, from most PB to least:

a) bupivacaine
b) tetracaine
c) mepivacaine
d) levo-bupivacaine
e) ropivacaine
f) lidocaine
g) prilocaine
h) chloroprocaine
i) procaine
Most PB to least:
a) d, e, b, a, f, c, g, h, i
b) e, d, a, b, f, c, g, h, i
c) a, b, d, e, f, c, g, h, i
d) h, i, c, g, f, a, b, d, e

Answer 1

Local anesthetics differ in protein binding ability, influencing their duration and toxicity. Bupivacaine has the highest protein binding followed by tetracaine, levo-bupivacaine, ropivacaine, lidocaine, mepivacaine, prilocaine, chloroprocaine, and procaine in decreasing order.

Step-by-step explanation:

The ranking of local anesthetics (LAs) by their protein binding ability is significant as it influences their duration of action, toxicity, and efficacy. Protein binding refers to the capacity of drugs to bind to plasma proteins such as albumin. This binding generally correlates with the lipophilicity of the drug; more lipophilic drugs tend to have higher protein binding and a longer duration of action.

Among the choices provided, bupivacaine is known to exhibit high protein binding, which prolongs its analgesic effects. Tetracaine also shows relatively high protein binding. Levo-bupivacaine, the S-enantiomer of bupivacaine, tends to have less systemic toxicity while maintaining significant protein binding. Similarly, ropivacaine is less lipophilic compared to bupivacaine, resulting in less protein binding and toxicity. Lidocaine and mepivacaine have intermediate binding, while prilocaine and chloroprocaine have lower protein binding. Procaine has the least protein binding among the choices provided.

Therefore, the correct order from most protein binding to least is: a) bupivacaine, b) tetracaine, c) levo-bupivacaine, d) ropivacaine, e) lidocaine, f) mepivacaine, g) prilocaine, h) chloroprocaine, i) procaine. Option c) reflects this correct order.