Typically, a clinical history consistent with a delayed cutaneous reaction to a local anesthetic, combined with a positive patch test result, is sufficient to diagnose a local anesthetic allergy. Patch testing is a means of diagnosing hypersensitivity reactions by controlled exposure of a small area of skin to the suspected allergen (Fonacier, 2015). The patient should not have applied topical glucocorticoids to the tested skin for at least one week, and should not have taken systemic glucocorticoids for at least one to two weeks prior to testing. Some local anesthetics may contain sulfites (bisulfite or metabisulfite) as stabilizers or preservatives when a vasoconstrictor is added. A few case reports have described local reactions attributed to sulfite sensitivity in patients (Dooms-Goossens, de Alam, Degreef, & Kochuyt, 1989; Henderson, 2011; Schwartz & Sher, 1985). One case described a woman who developed severe edema of the face and neck after receiving a local anesthetic for dentistry, with a positive patch test to both metabisulfite and the local anesthetic (Dooms-Goossens et al., 1989). Patients with suspected allergic reactions to local anesthetics should be evaluated because most patients can tolerate other local anesthetic agents (Grzanka, Wasilewska, Śliwczyńska, & Misiołek, 2016). Case reports show evidence of cross-reactivity among the group of amide-type local anesthetics – bupivacaine, lidocaine, and mepivacaine – and a lack of cross-reactivity between the ester-type and amide-type groups of local anesthetics (Calderon et al., 2013; Cuesta-Herranz et al., 1997; Warrington & McPhillips, 1997; Bina, Hersh, Hilario, Alvarez, & McLaughlin, 2018). This evidence should be considered when choosing other local anesthetics to test as possible treatment alternatives. It is often recommended that the clinician choose one or more alternatives from the other local anesthetic group as an alternative agent for patch testing. Skin testing and challenge is typically reserved for patients with a history of symptoms that could have been either nonallergic (such as syncope or hypotension) or a true IgE-mediated allergic reaction (Table 11). Skin testing and challenge are performed to determine what alternative local anesthetics the patient may tolerate. Conclusion The development of local anesthetics has been of great importance in the history of dental practice. These agents have improved overall patient satisfaction with oral health care by reducing intraoperative pain, postoperative pain, and anxiety, and by improving the overall comfort of the oral healthcare team as well. The slightly varying clinical characteristics of these highly effective agents, which are based on their structures, lead to different pharmacokinetic and pharmacodynamic profiles. Dentists should avoid relying on a single local anesthetic for all of their patients. They should try all of the commercially available local anesthetics and carefully consider the pharmacologic Resources Helpful websites and literature to enhance further learning: ● http://www.globalrph.com/local-anesthetics.htm This website covers the general pharmacology of individual local anesthetics, and includes calculators for dosing and drug interaction information. ● http://www.colgate.com/en/us/oc/oral-health/ procedures/ anesthesia/article/local-anesthesia There are a number of modules available in this vendor- sponsored website to include both patient and practitioner resources as they relate to local anesthesia. ● http://multimedia.3m.com/mws/media/597398O/loc- compendium-brochure-ebu.pdf?fn=LOC_Comp_Brochure_ EBU.pdf This compendium provides a scientific overview of both material handling and technologies for the interested reader. Aspects such as neuronal structures, chemistry, and pharmacology of local anesthetics and of vasoconstrictors
If the local anesthetic associated with the reaction is known to be an ester, a potential alternative local anesthetic from the amide group is tested or, if the culprit drug is an amide, an alternative amide-type local anesthetic should be tested (Schatz, 1992). If the local anesthetic associated with the reaction is unknown, lidocaine should be chosen, since it is commonly available and since there are cases of tolerance of lidocaine even in patients who reported previous reactions to lidocaine (Barer & McAllen, 1982). Local anesthetics without vasoconstrictors should be used for skin testing because the vasoconstrictor may mask a positive test (Ravindranathan, 1975). Finally, for patients with a documented amide local anesthesia allergy in whom ester local anesthesia is also contraindicated, diphenhydramine with epinephrine may be a safe and somewhat effective alternative. Limiting injection volumes to less than 5 mL of 1% diphenhydramine with 1:100,000 epinephrine may limit facial swelling and drowsiness (Bina, Hersh, Hilario, Alvarez, & McLaughlin, 2018). Table 11: Skin Testing Protocol for Patients with a Possible Local Anesthetic Allergy Step Route Volume (mL) Dilution* 1 Puncture -- Undiluted 2 Intradermal 0.02 cc 1:100 Patch (epicutaneous) testing is performed initially, with appropriate positive (histamine) and negative (diluent) controls. Results are assessed at 20 minutes. A positive result consists of a wheal 3 mm greater than the ne injecting 0.02 mL of a 1:100 dilution of the local anesthetic in question. * The concentration of the local anesthetic (usually 1 to 2 percent) to be used for the procedure. Note . Adapted from “Local and General Anesthetics Immediate Hypersensitivity Reactions,” by G. W. Volcheck and G. W. Mertes, 2014, Allergy Clinics of North America, 34(3), pp. 525-546. properties of each and learn how to take advantage of those properties in various clinical situations. For example, in the presence of an infection, it may be best to consider using mepivacaine because of its low pKa value. Another clinical example involves using articaine, with its ability to diffuse into bone, in cases of difficulty in achieving profound anesthesia with mandibular blocks. Matching the right drug at the right dose for the right patient and the right procedure is more of the art than the science of dentistry. However, when employed properly, even in some of the highest risk patient populations (e.g., cardiac, pregnant, or breast-feeding patients), these agents are not only inherently safe, but provide for overall safer dentistry. are highlighted, along with dental anesthetic techniques and clinical aspects such as posology/dosage, adverse effects, and precautions concerning use. ● www.SafeFetus.com SafeFetus.com is a website set up for pregnant mothers and their physicians and pharmacists in order to protect the baby, whether during pregnancy or during lactation, from any harmful effects of medication (whether prescribed or over- the-counter). The site also provides information on maternal exposures, whether to physical agents, infectious agents, or diseases, and ways they may affect the unborn child. The site is maintained by a fully qualified team of physicians and pharmacists who work continually to update the information, adding new drugs that are emerging in the markets, with the aim of producing a fully comprehensive worldwide database. All information is presented in an unbiased manner and is extracted from well-documented and respectable sources.
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