Allergic reactions to local anesthetic mepivacaine in dental procedures: a case report

Pain control is an essential component of all dental procedures. Local anesthesia is unavoidable and compelling and is regarded as a safe, invasive procedure. However, local anesthetics (LAs) might have adverse effects, such as allergic reactions. Therefore, a deeper understanding of LA is required by dental clinicians for successful pain management and emergency control.

LAs are generally classified into two major types: esters and amides. Ester-type LAs, such as benzocaine, procaine, tetracaine, and amilocaine, are metabolized by plasma cholinesterase, whereas amide-type LAs, including lidocaine, mepivacaine, bupivacaine, and prilocaine, are broken down in the liver [1]. Most allergic reactions have been reported for ester-type LA. A known allergen is para-aminobenzoic acid (PABA), which is released after the hydrolysis of ester-type LAs by cholinesterases [2].

Mepivacaine is an amide-type LA that differs from lidocaine. It has a quick onset time (maxillary infiltration anesthesia: 2–3 min; inferior alveolar nerve block anesthesia: 5–8 min) and a moderate duration of action. When mepivacaine is administered in an acidic environment, such as during inflammation, the base form predominates and quickly passes through the nerve membrane, increasing the local anesthetic effect due to a higher pH than that of lidocaine. Also, mepivacaine is known as one of the less sensitizing anesthetics. Therefore, mepivacaine may be a useful LA [3]. Allergic reactions to amide-type LAs, including mepivacaine, are rare but do occasionally occur [4].

Herein, we report a case of an allergic reaction to mepivacaine in a 57-year-old woman who had a tooth extracted under local anesthesia and managed at Yonsei University Dental Hospital.

A 57-year-old woman with osteoporosis, rheumatoid arthritis, hepatitis B, and arrhythmia visited the Advanced General Dentistry Department of the Yonsei University Dental Hospital for tooth extraction. She had a history of lidocaine allergies. When she underwent knee resection surgery under local anesthesia 17 years prior, she was presented with a full-body rash and respiratory distress, raising suspicion that she could be allergic to lidocaine. Subsequently, allergies also appeared whenever she used lidocaine ointment on her skin or in her throat when she gargled with it.

At that time, tooth extraction at the Advanced General Dentistry Department used the administration of lidocaine, mepivacaine, and articaine under local anesthesia. Except for lidocaine, to which the patient is allergic, we considered applying one of the two LAs, mepivacaine or articaine.

Allergy testing in the Department of Allergy at Severance Hospital took several months owing to the large number of patients, and the situation was similar in other hospitals. However, there was no time to wait because of the severe inflammation and infection and the intolerable pain, which was not controlled by medication, the patient's tooth needed immediate extraction. In spite of the possibility of an allergic reaction, we decided that it would be more beneficial for the patient to relieve pain by having the tooth extracted rather than waiting for an allergy test.

We chose mepivacaine, which has a higher pH than lidocaine, which increases the effect of the drug on inflammation while reducing toxicity [3].

Therefore, 3.6 ml of mepivacaine (Scandonest 3%, Septogon, France; 54 mg in 1.8 ml) without a vasoconstrictor was injected into the buccal and lingual sides of the gingiva with needle aspiration before the extraction procedure. She developed continuous itching, diffuse erythema of the wrists and hands, dizziness, and pectoralgia during the tooth extraction procedure (Figs. 1 and 2). The moment she exhibited these symptoms, we checked her vital signs while she was resting inin the supine position (Blood pressure 159/89, SpO₂ 89, pulse rate 74). Forty minutes after the administration of local anesthesia, we hospitalized her in a daily care center and administered an intravenous injection of anti-histamine (Peniramin 4 mg) to alleviate her symptoms (Blood pressure 141/71, SpO₂ 95, pulse rate 72). One hour after local anesthesia, the patient gradually recovered to a normal state (Blood pressure 139/74, SpO₂ 100, pulse rate 70) (Figs. 3 and 4). Continuous monitoring of all vital signs was performed for an hour, and no signs of allergic reactions were noted. After confirming the patient’s vital signs were normal and no typical allergic symptoms existed, the patient was discharged. She was instructed to report any discomfort or allergy symptoms to the emergency department. The following day, her symptoms, such as dizziness and itching, disappeared, except for pectoralgia.

Fig. 1
Diffuse erythema and mild swelling on the left wrist and hand

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Fig. 2
Diffuse erythema on the right wrist and hand wearing a pulse oximeter

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Fig. 3
Alleviated erythema on the left wrist and hand after intravenous injection of anti-histamine.

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Fig. 4
Alleviated erythema on the right wrist and hand after intravenous injection of anti-histamine.

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She was referred to the Department of Allergy due to an imminent implant surgery. Through a challenge test, the allergist confirmed that articaine is suitable for dental surgeries. She underwent provocation testing with subcutaneous injections of 0.01, 0.1, 0.5, and 1.0 ml of diluted articane solution. Articaine is recommended for her as a safe alternative to local anesthesia prior to future dental surgeries.

Allergic reactions to local anesthetics are rare and account for 1% of all dental treatments, including oral and maxillofacial surgeries [5]. Because of their low molecular weight, it is assumed that hapten-carrier complexes cause allergic reactions rather than the local anesthetics themselves [6]. Allergic reactions, or hypersensitivity reactions, are classified into 4 categories: immediate (types I, II, and III) or delayed (type IV) [7]. Most types of allergic reactions detected by clinicians are type I. Type I is related to allergen-specific IgE bound to particular high-affinity receptors on mast cells and basophils. If an allergen cross-links to these receptors, mediators (e.g., histamine) are released, which can cause angioedema, urticaria, and/or anaphylaxis [8]. Symptoms and signs of the allergic reaction can appear in the respiratory system (wheezing, coughing, dyspnea, and laryngeal edema), cardiovascular system (tachycardia, palpitations, hypotension, unconsciousness, and cardiac arrest), skin (pruritus, urticaria, and erythema), and gastrointestinal tract (nausea, vomiting, muscle spasm, and incontinence) [4].

The severity of allergic reactions determines the treatment. Mild allergic reactions can be managed with oral and intramuscular antihistamine agents, such as diphenhydramine. However, if patients are in critical conditions, immediate treatments should be provided, including intramuscular or subcutaneous epinephrine 0.3–0.5 mg injection, basic life support, and transfer to the emergency room in general hospitals [9]. The case we reported was relatively mild, the patient’s vital signs were within the normal range, and the patient’s symptoms could be rescued with an injection of intravenous antihistamine (4 mg).

Mepivacaine is similar to lidocaine in terms of low toxicity and intermediate duration of action [10]. The cross-reactivity among amide-type LAs was almost comparable between lidocaine and mepivacaine. Lidocaine and mepivacaine should not be used as substitutes in patients with allergy to either substance because of possible cross-allergenicity [11]. No cross-allerginicity to articaine was observed in either study. Articaine differs from other amide-type LAs containing a phenyl-methylated ring in that it has a thiophene ring. Based on this fact, articaine may be the best option; however, a challenge test is still recommended [12]. Articaine may exhibit infrequent cross-allergenicity with other amide-type LAs, including delayed-type reactions [13, 14].

Consistent with previously published studies, in this case report, the patient was allergic to lidocaine and mepivacaine, and articaine is advisable for future local anesthesia based on the articaine challenge test, which produced a negative result.

In conclusion, clinicians should consider the patients’ history related to allergic reactions, such as the name of the medicine, how to administer the medicine, symptoms, alternative medicine used, and medical and dental histories, such as systemic diseases and abnormal reactions during dental treatment, in order to prepare for a serious allergic reaction to LAs or any drug. Allergy tests in the Department of Allergy and Clinical Immunology may help select safe LAs or medicines to avoid adverse effects. Furthermore, if a patient has allergic reactions to either lidocaine or mepivacaine, clinicians should consider using alternative LAs, such as articaine, instead of either of the above. Whenever dental clinicians anesthetize patients for routine treatment, awareness of the adverse effects of LA, especially allergic reactions, is an indispensable part of LA use.