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Medical Pharmacology Chapter 15: Local Anesthetics
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Purpose of local anesthetic combination preparations:
Prolonged duration (bupivacaine (Marcaine)) and decreased time to onset (chloroprocaine (Nesacaine))
Concerns:
Chloroprocaine (Nesacaine) in the epidural space may lead to possibly reduced subsequent epidural space bupivacaine (Marcaine) analgesia efficacy during labor
Mechanism
Chloroprocaine (Nesacaine) reduces pH which decreases the amount of nonionized (active) bupivacaine (Marcaine)
Tachyphylaxis to the mixture (possibly secondary to local acidosis caused by low pH of the chloroprocaine (Nesacaine) solution)
Suggestion: increased chloroprocaine (Nesacaine) solution pH just before use may enhance chloroprocaine (Nesacaine)-mepivacaine (Carbocaine) combination efficacy
Toxicity
is additive for local anesthetic combinations.
Stoelting, R.K., "Local Anesthetics", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, pp 158-181.
