Is Meropenem (Meropenem) safe in patients with penicillin (PCN) allergy?

From the Guidelines

Meropenem can generally be used safely in patients with penicillin allergies, but caution is warranted depending on the severity of the previous allergic reaction. For patients with mild penicillin allergies (such as rash), meropenem is typically safe to administer. However, for patients with severe penicillin allergies involving anaphylaxis or other life-threatening reactions, there is approximately a 1% cross-reactivity risk with carbapenems like meropenem 1. In these cases, careful clinical judgment is needed, and if meropenem is deemed necessary, consider administering the first dose under close observation or potentially performing skin testing beforehand. The structural difference between carbapenems and penicillins explains the low cross-reactivity - while both contain a beta-lactam ring, carbapenems have a different side chain configuration that often prevents recognition by the same antibodies that react to penicillins.

Some key points to consider when using meropenem in patients with penicillin allergies include:

• The severity of the previous allergic reaction: patients with severe reactions may require closer monitoring or alternative treatments
• The use of skin testing: this can help identify patients who are at low risk of cross-reactivity with meropenem
• The importance of documenting the patient's penicillin allergy in their medical record: this can help guide future antibiotic decisions
• The need for careful clinical judgment: meropenem should only be used in patients with severe penicillin allergies when the benefits outweigh the risks. According to 1, every effort should be made to avoid administering penicillin to penicillin-allergic patients, unless the anaphylactic sensitivity has been removed by acute desensitization.

Standard adult dosing for meropenem is typically 500 mg to 1 gram IV every 8 hours, with adjustments needed for renal impairment. Always document the nature of the patient's penicillin allergy in their medical record to guide future antibiotic decisions.

From the FDA Drug Label

5 WARNINGS AND PRECAUTIONS

1. 1 Hypersensitivity Reactions Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving therapy with β-lactams. These reactions are more likely to occur in individuals with a history of sensitivity to multiple allergens There have been reports of individuals with a history of penicillin hypersensitivity who have experienced severe hypersensitivity reactions when treated with another β-lactam.

Meropenem is not completely safe in patients with a penicillin allergy, as there is a risk of cross-reactivity between β-lactam antibiotics.

• Hypersensitivity reactions can occur in patients with a history of penicillin allergy.
• It is essential to inquire about previous hypersensitivity reactions to penicillins, cephalosporins, and other β-lactams before initiating therapy with meropenem.
• If an allergic reaction occurs, the drug should be discontinued immediately 2.

From the Research

Meropenem Safety in Patients with Penicillin Allergy

• Meropenem is a widely prescribed beta-lactam antibiotic for hospitalized patients, and its safety in patients with a reported history of penicillin allergy has been evaluated in several studies 3, 4, 5, 6.
• A retrospective analysis of 182 inpatients labeled with a penicillin allergy who received meropenem after an allergy assessment found that 96.4% of the diagnostic workups were tolerated, with only two patients experiencing a non-severe cutaneous reaction 3.
• Another study prospectively monitored 110 patients treated with meropenem who reported penicillin allergic reactions and found that all patients tolerated prolonged meropenem therapy safely without any allergic reactions 4.
• A review of penicillin allergy evaluation and management noted that the rate of IgE-mediated penicillin allergies is decreasing, and cross-reactivity between penicillin and cephalosporin drugs occurs in about 2% of cases 7.
• A retrospective study comparing the clinical safety of administering carbapenems, including meropenem, in patients with a history of penicillin allergy found that the incidence of hypersensitivity reactions was not statistically significant between patients with and without penicillin allergy 5.
• A retrospective review of electronic medical records of adults with a self-reported allergy to penicillin who received meropenem found that the incidence of allergic reactions was low, with 5% of patients experiencing an allergic reaction 6.

Key Findings

• Meropenem can be safely administered to patients with a reported history of penicillin allergy, with a low incidence of allergic reactions 3, 4, 6.
• The risk of cross-reactivity between penicillin and meropenem is low, and meropenem can be considered for use in patients with a self-reported nontype I penicillin allergy 4, 5, 6.
• Patients with a concomitant "sulfa" allergy or multiple drug allergies may be more likely to experience an allergic reaction to meropenem 6.