Use of Lidocaine with IM Ceftriaxone During Pregnancy
Lidocaine can safely be used as a diluent for intramuscular ceftriaxone administration in pregnant women, as there are no contraindications to this practice in pregnancy.
Evidence for Safety
The FDA drug label for ceftriaxone specifically addresses lidocaine use, stating that when lidocaine solution is used as a solvent with ceftriaxone for intramuscular injection, the only restriction is to exclude all contraindications to lidocaine itself 1. The FDA drug label for lidocaine indicates it is a Pregnancy Category B medication, meaning reproduction studies in animals have revealed no evidence of harm to the fetus 2.
Clinical guidelines support this practice:
- The 1993 CDC STD Treatment Guidelines specifically mention that "some health-care providers believe that the discomfort of the injection may be reduced by using 1% lidocaine solution as a diluent" for ceftriaxone injections 3.
- Antimicrobial Agents and Chemotherapy published research showing that "when lidocaine was used for reconstitution of ceftriaxone, the intramuscular route was well tolerated by all patients" 4.
Ceftriaxone in Pregnancy
Ceftriaxone is the recommended treatment for gonorrhea in pregnancy:
- The CDC recommends ceftriaxone for gonococcal infections in pregnant women 3.
- For children and pregnant patients with gonococcal conjunctivitis, the American Academy of Ophthalmology recommends ceftriaxone 25-50 mg/kg body weight intravenous or IM as a single dose (not to exceed 250 mg IM) 3.
- A prospective study of 252 pregnant women with gonorrhea found ceftriaxone 250 mg IM to be 95% effective with no increased incidence of congenital malformations 5.
Practical Administration Guidelines
When administering IM ceftriaxone with lidocaine in pregnant women:
Dosing: Use standard ceftriaxone dosing (typically 250-500 mg IM as a single dose for gonorrhea)
Lidocaine preparation: Use 1% lidocaine without epinephrine as the diluent
Administration technique:
- Reconstitute ceftriaxone powder with the appropriate amount of 1% lidocaine
- Administer in a large muscle mass (gluteal or vastus lateralis)
- Use proper IM injection technique to minimize discomfort
Precautions:
- Ensure the patient has no history of lidocaine allergy
- Follow standard precautions for IM injections in pregnancy
- Monitor for any adverse reactions
Important Considerations
While lidocaine is Pregnancy Category B, it does cross the placenta 2. However, at the small amounts used for IM injection diluent, systemic effects are minimal.
For patients with known lidocaine allergy, use sterile water or normal saline as alternative diluents.
When treating gonorrhea in pregnancy, remember that co-infection with chlamydia is common (40% in one study 5), so appropriate treatment for chlamydia should be considered.
For pregnant women with chlamydial infection, azithromycin 1 g orally in a single dose or amoxicillin 500 mg orally three times a day for 7 days is recommended 3. Doxycycline is contraindicated in pregnancy.
The practice of using lidocaine as a diluent for IM ceftriaxone is well-established and can significantly reduce injection pain, improving patient comfort and compliance with this important treatment during pregnancy.