Adverse Reactions to Local Anesthetics

Following the first description of allergy to a local anesthetic over 90 years ago, there was initially a steady stream of reports of reactions to the drugs consisting mainly of erythema or edema. With the introduction of the amide local anesthetics, the number of hypersensitivity reactions tapered off significantly, indicating that ester compounds were less well tolerated. Even today, however, reports of adverse reactions to local anesthetics occasionally appear, but the nature of the reactions cannot always be described 

7 Drugs and Other Agents Used in Anesthesia and Surgery 

Apart from the presence of epinephrine, local anesthetics may evoke sympathetic effects that include palpitations, light-headedness, syncope, or tachycardia. Local anesthetics are heavily used in dental procedures and many reports of adverse reactions following their administration anate 

The rarity of immediate reactions to local anesthetics is further emphasized in results obtained in two large studies of a total of 354 patients with a history of reacting to the drugs. No evidence for an IgE-mediated reaction was found in one of the studies involving 157 patients while three patients, two with an immediate reaction and one with a delayed response, were seen in the review of the other 197 patients. No IgE antibodies were detected in the two immediate reactors. 

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Adrian J Etiology and management of adverse reactions to local anesthetics. Int Anesthesiol Clin 1972 10 127-151. 

GaU H, Kaufmann R. Kalveram CM Adverse reactions to local anesthetics analysis of 197 cases. J Allergy CUn Immunol 1996 97 933-937. 

Wasserfallen JB. Frei PC Long-term evaluation of 39 usefulness of skin and incremental challenge tests in patients with history of adverse reaction to local anesthetics. Allergy 1995 50 162-165. 

Troise C, Voltolini S. Minale P. Modena P. Negrini 40 AC Management of patients at risk for adverse reactions to local anesthetics analysis of 386 cases. J Investig Allergol Clin Immunol 1998 8 172-175. 41... 

Berkum Y. Ben-Zvi A. Levy Y. Galili D. Shalit M Evaluation of adverse reactions to local anesthetics experience with 236 patients. Ann Allergy Asthma Immunol 2003 91 342-345. 42... 

Nervous system Pain on injection is a very common adverse reaction to local anesthetics when used for infiltration. A review of the efficacy of bicarbonate in reducing pain on intradermal injection of local anesthetic agents showed a significant advantage of the buffered solution [43 ]. When bicarbonate was added to the local anesthetic pain scores on a visual analogue scale were reduced by 12% (95% Cl = 6.7, 17). 

Breit S, Rueff F, PrzybiUa B Deep impact contact allergy after subcutaneous injection of local anesthetics. Contact Dermatitis 2001 45 296-297. Orasch CE, Helbling A, Zanni MP, Yawalkar N. Hari Y Pichler WJ T-cell reaction to local anaesthetics relationship to angioedema and urticaria after subcutaneous application-patch testing and LTT in patients with adverse reaction to local anaesthetics. Clin Exp Allergy 1999 29 1549-1554. 

These results confirm that real allergic reactions to local anesthetics are rare. Nevertheless, in each case of an adverse reaction, careful review of the history and testing of immediate and late allergic reactions, not only to local anesthetics, but also to latex and preservatives, should be mandatory. 

Systemic hypersensitivity reactions are not a frequent problem in local anesthesia. Systemic toxicity or allergy to additives (hyaluronidase, bisulfate, parabens) has sometimes been mistakenly classified as hypersensitivity to local anesthetics (SEDA-17,135) (29). WeU-documented case reports are very few, relating particularly to the older aminoesters this appears to be because these agents have the highly antigenic para-aminobenzoic acid as a metabolite (SEDA-13, 98). The incidence of true allergy is actually very low, probably less than 1% of all the adverse effects attributable to these substances (SEDA-20, 123). 

Hypersensitivity to local anesthetics appears to be related to both chemical structure and the method of administration. Allergic reactions occur most frequently with csler-ba.sed local anesthetic agents (benzoic acid derivatives). Adverse effects include allergic dermatitis, asthmatic attack, or. in extreme cases, death due to anaphylactic shock. Individuals suffering a hypersensitive reaction from one local anesthetic agent are often sensitive to compounds with a. similar structure. For example, patients semsilive to procaine arc often also sensitive to amethocaine... 

Nervous system A 22-year-old woman developed paresthesia, a metallic taste, and hot flushes within 20 minutes of administration of intravenous spiramycin for toxoplasmosis during labor [80" ]. The adverse reactions were initially attributed to local anesthetic toxicity associated with epidural analgesia however, epidural catheter aspiration was negative, suggesting that the catheter was not placed intravenously and the temporal relation to spiramycin administration suggested that the drug was the more probable cause. 

Yamamoto F, Hamburger RN Administration of 27 local anesthetics to patients with a history of prior adverse reaction. J Allergy Clin Immunol 1978 61 339-345. 28... 

Benzonatate (Tessalon) is related to the local anesthetic tetracaine. It anesthetizes the stretch receptors in the lungs, thereby reducing coughing. Adverse reactions include hypersensitivity, sedation, dizziness, and nausea. 

Mepivacaine hydrochloride (Carbocaine) is longer acting than lidocaine and has a more rapid onset of action (3-5 minutes). Topical application is not effective. It has been widely used in obstetrics, but its use has declined recently because of the early transient neurobehavioral effects it produces. Adverse reactions associated with mepivacaine are generally similar to those produced by other local anesthetics. It can be used with epinephrine or levonordefrin (dental use only). 

Local anesthetics typically contain a hydrophilic tertiary amine group linked to a lipophilic ester or amide. The most commonly used local anesthetics are either amides or esters, as shown in Table 1. The aminoester anesthetics cause adverse reactions more commonly than local anesthetics in the amide group. The esters are typically metabolized by de-esterification by esterases, such as pseudocholinesterase in the plasma or esterases in the liver. Metabolism occurs rapidly, and so these agents have short durations of action after they reach the systemic circulation. The amides are mainly metabolized in the... 

UNDESIRED EEEECTS OF LOCAL ANESTHETICS In addition to blocking conduction in nerve axons in the peripheral nervous system, local anesthetics interfere with the function of all organs in which conduction or transmission of impulses occurs. Thus, they have important effects on the CNS, autonomic ganglia, neuromuscular junctions, and all forms of muscle. The danger of such adverse reactions is proportional to the concentration of local anesthetic achieved in the circulation. In general, in local anesthetics with chiral centers, the -enantiomer is less toxic than the R-enantiomer. 

This product is also applied to the skin with an occlusive clear dressing. It is effective without the covering, but as the cream warms, it will drip off the desired location. After a 30 min application, analgesia is comparable to that achieved with a 60 min appUcation of EMLA. The local anesthetic effect lasts for 60 min after a typical 30 min application. LMX-4 appUcation should be limited to 100 cm in children weighing < 10 kg or between 10 kg and 20 kg for each use. There are limited data in children under 2 years of age, but adverse reaction in small infants has generally not been reported. 

Various potentially significant adverse reactions may occur due to hypersensitivity to any of the components (local anesthetics, bone cement and plastics). 

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