Which local anesthetic has the highest lipid solubility and slowest onset?

Which local anesthetic has the highest lipid solubility and slowest onset?

• A. Articaine
• B. Prilocaine
• C. Mepivicaine
• D. Bupivicaine

Answer: (D)

Lipid solubility strongly influences potency, duration, and how quickly a local anesthetic starts working. The more lipophilic a drug is, the more potently it binds to nerve membranes and the longer it remains active, because it partitions into fatty tissues and proteins. However, this same lipophilicity can slow the rate at which the drug initially penetrates the nerve membrane to reach the sodium channels, leading to a slower onset. Bupivacaine stands out as the most lipophilic among the options, and it also has a long duration of action. Its high lipid solubility means it stays in the tissue and nerve longer, but the diffusion into the nerve membrane occurs more slowly, resulting in the slowest onset compared with the others.

Lipid solubility strongly influences potency, duration, and how quickly a local anesthetic starts working. The more lipophilic a drug is, the more potently it binds to nerve membranes and the longer it remains active, because it partitions into fatty tissues and proteins. However, this same lipophilicity can slow the rate at which the drug initially penetrates the nerve membrane to reach the sodium channels, leading to a slower onset.

Bupivacaine stands out as the most lipophilic among the options, and it also has a long duration of action. Its high lipid solubility means it stays in the tissue and nerve longer, but the diffusion into the nerve membrane occurs more slowly, resulting in the slowest onset compared with the others.