ceftriaxone + lidocaine

Ceftriaxone + lidocaine is a combination used for intramuscular (IM) injection, where the antibiotic ceftriaxone is reconstituted with a solution of 1% lidocaine hydrochloride. Ceftriaxone is a third-generation cephalosporin antibacterial that acts by inhibiting bacterial cell wall synthesis through binding to penicillin-binding proteins, leading to cell lysis and death. Lidocaine is a local anesthetic that blocks voltage-gated sodium channels in neuronal membranes, preventing nerve impulse conduction and thereby reducing pain at the injection site. The addition of lidocaine significantly decreases the pain associated with IM administration of ceftriaxone without affecting its antibacterial efficacy. This combination is indicated for severe bacterial infections such as meningitis, pneumonia, typhoid fever, shigellosis, leptospirosis, relapsing fevers, pyelonephritis, neurosyphilis; and for sexually transmitted infections like gonorrhea. The mixture must only be administered intramuscularly—never intravenously—due to safety concerns related to systemic absorption of lidocaine.