How many times have you given your patient IM ceftriaxone for that presumed gonococcal infection? ... still counting?
Many of us learned (or at least thought we learned) that ceftriaxone has to be administered IM to get the ‘depot’ effect.
Myth busted: There is no depot effect. IV and IM ceftriaxone have very similar pharmacokinetic profiles. Let me prove it to you, straight from the FDA-approved ceftriaxone package insert.
Time after dose administration (hrs) and Average plasma concentration (mcg/mL)
| Dose/route | 0.5 hr | 1 hr | 2 hr | 4 hr | 6 hr | 8 hr | 12 hr | 16 hr | 24 hr |
| 0.5 g IV | 82 | 59 | 48 | 37 | 29 | 23 | 15 | 10 | 5 |
| 0.5 g IM | 22 | 33 | 38 | 35 | 30 | 26 | 16 | unknown | 5 |
- The plasma concentrations are almost identical after IM and IV administration through 24 hours.
- The volume of distribution is the same for both parenteral routes, too. This means that its penetration into the “affected area” is similar.
- For further proof, the CDC Guidelines recommend IV or IM ceftriaxone interchangeably for most gonococcal infections in infants and children.
Trick of the Trade:
If the patient already has an IV line, give IV ceftriaxone instead of IM .
While most of the time patients with STD (or STI, if you prefer) complaints don’t have an IV line established, occasionally they do. My hospital stocks 1 gm and 2 gm premixed IV bags of ceftriaxone, so we just give 1 gm IV in these rare cases. But 250mg IV should be just fine.
Of course, the other way to avoid the painful injection is to mix the ceftriaxone with lidocaine... or avoid contracting gonorrhea altogether.
References:
Product Information: ROCEPHIN(R) IV, IM injection, ceftriaxone sodium IV, IM injection. Genentech USA, Inc. (per Manufacturer), South San Francisco, CA, 2010.
Workowski KA, Berman S; Centers for Disease Control and Prevention (CDC). Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep 2010;59(RR-12):1-110. [
