dosages up to 2 grams per day. The rest is excreted in the bile as unchanged drug which is ultimately excreted in feces as inactive compounds from hepatic and gut flora metabolism. Elimination: The average elimination half-life in healthy adults is 5.8–8.7 (mean 6.5) hours, with some reviews estimated half-life up to 10 hours. In people with renal impairment, the average elimination half-life increases to 11.4–15.7 hours. Chemistry Ceftriaxone is commercially available as a white to yellowish-orange crystalline powder for reconstitution. Reconstituted ceftriaxone injection solutions are light yellow- to amber-colored depending on how long the solution had been reconstituted, the concentration of ceftriaxone in the solution, and the diluent used. To reduce pain with intramuscular injections, ceftriaxone may be reconstituted with lidocaine. The syn-configuration of the methoxyoxime moiety confers resistance to beta-lactamase enzymes produced by many Gram-negative bacteria. The stability of this configuration results in increased activity of ceftriaxone against otherwise resistant Gram-negative bacteria. In place of the easily hydrolyzed acetyl group of cefotaxime, ceftriaxone has a metabolically stable thiotriazinedione moiety. Research Ceftriaxone has also been investigated for efficacy in preventing relapse to cocaine addiction. Ceftriaxone seems to increase excitatory amino acid transporter-2 pump expression and activity in the central nervous system, so has a potential to reduce glutamatergic toxicity. Ceftriaxone has been shown to have neuroprotective properties in a number of neurological disorders, including spinal muscular atrophy and amyotrophic lateral sclerosis (ALS). Despite earlier negative results in the 1990s, a large clinical trial was undertaken in 2006 to test ceftriaxone in ALS patients, but was stopped early after it became clear that the results would not meet the predetermined criteria for efficacy. References External links Acetaldehyde dehydrogenase inhibitors Cephalosporin antibiotics Hoffmann-La Roche brands Thiazoles Triazines World Health Organization essential medicines Wikipedia medicine articles ready to translate