Question

Given equal-volume infiltrations for local anesthesia, which of the following would be associated with a higher risk for inducing cardiac arrhythmias?

A. 0.5% racemic bupivacaine
B. 0.5% R(+) bupivacaine
C. 0.5% S(.) bupivacaine
D. 0.5% levo-bupivacaine
E. 0.5% ropivacaine

Answer 1

Among the options provided, 0.5% racemic bupivacaine would be associated with the highest risk for inducing cardiac arrhythmias because it contains the R(+) enantiomer, which is more cardiotoxic than the S(-) enantiomer or levo-bupivacaine, and ropivacaine.

Step-by-step explanation:

When comparing equal-volume infiltrations for local anesthesia and their associated risks for inducing cardiac arrhythmias, the agents in question are various forms of bupivacaine and ropivacaine. Bupivacaine is known for its potential to cause cardiotoxicity, which includes the risk of arrhythmias. Among the options given, 0.5% racemic bupivacaine (option A) would be associated with the highest risk for inducing cardiac arrhythmias. Racemic bupivacaine is a mixture of two enantiomers, R(+) and S(-), and it is the R(+) enantiomer that is more cardiotoxic. Therefore, preparations that contain only the S(-) enantiomer (option C) or the levo-enantiomer (option D), such as levo-bupivacaine which is another name for S(-) bupivacaine, or that contain ropivacaine (option E), which is structurally similar to bupivacaine but less cardiotoxic, would have a lower risk of causing cardiac arrhythmias compared to racemic bupivacaine.