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Verapamil Increases the Toxicity of Local Anesthetics
Author(s) -
Tollman Richard D.,
Rosenblatt Richard M.,
Weaver Joel M.,
Wang Yanlin
Publication year - 1988
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1988.tb03150.x
Subject(s) - verapamil , lidocaine , medicine , anesthesia , local anesthetic , calcium channel blocker , toxicity , anesthetic , pharmacology , bupivacaine , calcium , drug , drug interaction , calcium channel
The calcium channel blocker verapamil has, in addition to its other properties, been shown to be a local anesthetic. Its concurrent use in a patient undergoing regional anesthesia may, therefore, increase the potential risk for local anesthetic toxicity. To evaluate this possibility, the effect of verapamil on the median lethal dose (LD 50 ) of lidocaine and bupivacaine in mice was determined. Immediate pretreatment with verapamil increased the mortality of mice given the LD 50 dose of lidocaine to 74%, and in mice given the LD 50 doses of bupivacaine, to 82%. In animals pretreated with verapamil and calcium chloride, the mortality associated with the administration of LD 50 doses of lidocaine and bupivacaine decreased to 43% and 48%, respectively, thus returning the mortality rate back to the LD 50 of the local anesthetics when administered alone, It seems that the combined administration of local anesthetic and verapamil results in a significant drug interaction: the resulting blockade of sodium and calcium channels apparently impairs membrane function to a greater degree than with either drug alone. Additional investigation is warranted, and caution should be exercised in giving verapamil to patients during regional anesthesia. Should an adverse drug interaction ensue, the administration of calcium may be beneficial.