Ceftriaxone

Overview
Ceftriaxone (INN) (IPA: ) is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram positive and Gram negative bacteria. In most cases, it is considered to be equivalent to cefotaxime in terms of safety and efficacy. Ceftriaxone sodium is marketed by Hoffman-La Roche under the trade name Rocephin.

Clinical use
Ceftriaxone is often used (in combination, but not direct, with macrolide and/or aminoglycoside antibiotics) for the treatment of community-acquired pneumonia. It is also a choice drug for treatment of bacterial meningitis. In pediatrics, it is commonly used in febrile infants between 4 and 8 weeks of age who are admitted to the hospital to exclude sepsis. It has also been used in the treatment of Lyme disease and gonorrhea.

The usual starting dose is 1 gram IV daily although dosage may be adjusted for body mass in younger patients. Doses range from 1–2 grams IV or IM every 12–24 hours, depending on the type and severity or the infection, up to 4 grams daily. For gonorrhoea the usual adult dose is a single intramuscular injection of 125 mg. Patients treated for gonorrhoea are usually also treated for chlamydia, often with azithromycin. The injection is unusually painful and therefore administered with lidocaine as a local anesthetic. However, individuals who are allergic to lidocaine can expect approximately 1 hour of pain, similar to being forcefully kicked or punched in the site of injection (usually the buttocks). It is not a stinging or burning pain, and it is very intense for about 20 minutes, diminishing over 60 to 180 minutes. Residual discomfort can last 24 hours.

Ceftriaxone is contraindicated in patients with known hypersensitivity to cephalosporins, penicillins and/or carbapenems.

Long term use of ceftriaxone through intravenous route can cause overgrowth of organisms on the surface of the tongue. Monitoring tongue and oral cavity is recommended.

Warnings
FDA notified healthcare professionals of an update to a previous alert that addresses the interaction of ceftriaxone with calcium-containing products, based on previously reported fatal cases in neonates.

At the request of FDA, the manufacturer of ceftriaxone (Roche) conducted two in vitro studies to assess the potential for precipitation of ceftriaxone-calcium when ceftriaxone and calcium-containing products are mixed in vials and in infusion lines.

These two in vitro studies were conducted in neonatal and adult plasma to assess the potential for precipitation of ceftriaxone-calcium using varying ceftriaxone and calcium concentrations, including concentrations in excess of those achieved in vivo.

Based on the results from these studies, FDA now recommends that ceftriaxone and calcium-containing products may be used concomitantly in patients >28 days of age, using the precautionary recommendations noted because the risk of precipitation is low in this population.

FDA had previously recommended, but no longer recommends, that in all age groups ceftriaxone and calcium-containing products should not be administered within 48 hours of one another.

Chemistry
Ceftriaxone is a yellowish-orange crystalline powder which is readily-soluble in water, sparingly soluble in methanol and very slightly soluble in ethanol. The pH of a 1% aqueous solution is approximately 6.7.

The syn-configuration of the methoxyimino moiety confers stability to β-lactamase enzymes produced by many Gram-negative bacteria. Such stability to β-lactamases increases the activity of ceftriaxone against otherwise resistant Gram-negative bacteria. In place of the easily hydrolysed acetyl group of cefotaxime, ceftriaxone has a metabolically-stable thiotriazinedione moiety.