Cephalosporin

Ceftriaxone

An injected third-generation cephalosporin for meningitis, gonorrhea, severe pneumonia, typhoid and other serious infections.

Drug card

Class: Cephalosporin
How it works: Binding penicillin-binding proteins so the bacterial wall is never cross-linked
Used for: Bacterial meningitis
Gonorrhea
Severe and hospital-acquired pneumonia
Typhoid (enteric fever)
Known for: Gallbladder sludge (pseudo-gallstones)
Its name: cef- means a cephalosporin

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Mechanism of action

How does ceftriaxone work?

Ceftriaxone is a third-generation cephalosporin with strong Gram-negative activity, including Neisseria gonorrhoeae, N. meningitidis, H. influenzae and many Enterobacterales, while keeping activity against streptococci. It resists many beta-lactamases, enters inflamed meninges, and is cleared through both bile and urine.

Like other cephalosporins: Cephalosporins are beta-lactams first derived from Acremonium (Cephalosporium) fungi. Like penicillins, they bind and inactivate penicillin-binding proteins, so peptidoglycan is not cross-linked and the bacterial cell wall weakens and lyses. They withstand many beta-lactamases; from first to third generation, Gram-negative activity rises and Gram-positive activity falls.

Uses

What is ceftriaxone used for?

Bacterial meningitis
Gonorrhea
Severe and hospital-acquired pneumonia
Typhoid (enteric fever)
Complicated intra-abdominal infections
Severe kidney infection (pyelonephritis)

Side effects

Side effects of ceftriaxone

Gallbladder sludge (pseudo-gallstones)Known for
Diarrhea
Rash
Allergic reactions, including anaphylaxisSerious
Kidney stones and post-renal kidney failureSerious
Immune hemolytic anemia, sometimes fatalSerious
Encephalopathy and seizures, mainly in kidney failureSerious
C. difficile colitisSerious
Prolonged prothrombin time and bleedingSerious
Pancreatitis linked to biliary sludgeSerious
Raised liver enzymes
Pain where it is injected

Known for marks what an exam expects you to know it for.

Watch for

Cautions and what sets it apart

Never give it with calcium-containing IV fluids to newborns, or mix the two in one line: ceftriaxone-calcium precipitates have killed neonates.
Avoid in premature or jaundiced newborns: it displaces bilirubin from albumin and can cause kernicterus.
Keep patients well hydrated, and stop it if gallbladder or kidney stone symptoms appear.
Warfarin: the bleeding risk rises, so clotting is checked during and after treatment.

Good to know: It does not cover Chlamydia trachomatis, so chlamydia treatment is added when needed; CDC no longer pairs it with azithromycin for gonorrhea.

Remember it

A way to remember it

Climb the generations, gain the Gram-negatives: from first to third generation, Gram-negative reach grows while Gram-positive reach shrinks.

First-generation cefalexin suits streptococcal and staphylococcal skin infections. Second-generation cefuroxime adds beta-lactamase-producing H. influenzae. Third-generation ceftriaxone and cefixime reach gonococci, E. coli and Klebsiella, and cefixime misses most staphylococci.

Written for biofideX

Its name

cef- means cephalosporin
Cefalexin, cefuroxime, ceftriaxone and cefixime share it. Older US names keep the spelling ceph- (cephalexin).
Every drug name stem

Its class

Cephalosporins

Other cephalosporins with a card:

Easily mixed up with penicillins and carbapenems.

All about cephalosporins

Sources

Checked against

Written for biofideX in plain words, after checking these references:

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.

Practice it

Antibiotics: the cell wall

Ceftriaxone is one of 12 drugs practiced together here: their classes, how they work, what they treat and what they're known for.

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