Can Ertapenem IM Be Given with Lidocaine?
Yes, ertapenem can and should be administered intramuscularly with 1% lidocaine hydrochloride (without epinephrine) as the reconstitution diluent. This is the FDA-approved and recommended method for IM administration of ertapenem 1.
Preparation and Administration
For IM administration, ertapenem must be reconstituted with 1% lidocaine HCl injection (without epinephrine):
Adults: Reconstitute 1 g vial with 3.2 mL of 1% lidocaine HCl injection, shake thoroughly to form solution (resulting concentration approximately 280 mg/mL), and administer by deep IM injection into a large muscle mass such as the gluteal muscles or lateral thigh 1
Pediatric patients (3 months to 12 years): Reconstitute 1 g vial with 3.2 mL of 1% lidocaine HCl injection, then withdraw volume equal to 15 mg/kg body weight (not to exceed 1 g/day) and administer by deep IM injection 1
Timing: The reconstituted IM solution must be used within 1 hour after preparation 1
Important Safety Considerations
Contraindication: Due to the use of lidocaine as the diluent, ertapenem administered intramuscularly is contraindicated in patients with known hypersensitivity to local anesthetics of the amide type 1. Always screen for lidocaine allergy before IM administration.
Clinical Evidence: The combination has been extensively studied and demonstrates excellent tolerability. In a prospective, randomized, double-blind study comparing IM ertapenem (reconstituted in lidocaine) versus IM ceftriaxone, only 1.1% of ertapenem patients experienced moderate-to-severe injection site symptoms compared to 10% in the ceftriaxone group 2. The most common local symptoms were tenderness and pain, which were generally mild 2.
Clinical Efficacy
The IM formulation with lidocaine achieves approximately 90% bioavailability compared to IV administration, with peak plasma concentrations reached in approximately 2.3 hours 1, 3. This pharmacokinetic profile supports once-daily dosing and has demonstrated clinical equivalence to IV administration in multiple studies 2, 4, 5.
Do not use lidocaine with epinephrine for reconstitution, as the FDA labeling specifically requires lidocaine without epinephrine 1.