**2.5 Ceftriaxone-associated biliary pseudolithiasis**

Ceftriaxone, is a third-generation cephalosporin, and is commonly used as broad-spectrum antibiotic in children. Gall stones or biliary sludge has been reported as a complication of ceftriaxone treatment since long [25]. The incidence of ceftriaxone induced pseudolithiasis is variable from 15–45%, depending on dose, duration and predisposing host factors [26–30]. Since biliary lithiasis is reversible and disappears on discontinuation of drug it has been termed pseudolithiasis [31]. Ceftriaxone is 40% excreted via bile, as an anion it concentrates in bile easily and readily forms an insoluble salt with calcium [calcium-ceftriaxone] that precipitates in gallbladder [32]. The predisposing risk factors for ceftriaxone induced biliary lithiasis are, high dose (>2 g or >200 mg/kg/day), long-term treatment, hypercalcemia, renal failure, and gallbladder stasis [33]. The mechanism of ceftriaxone induced lithiasis is explained in **Figure 1**. Most cases of ceftriaxone induced pseudolithiasis are asymptomatic and detected on sonography. If cholelithiasis is symptomatic, discontinuation of drug is to be done but in incidentally detected asymptomatic cases of there is no need to stop drug. Usually these sludge/stones appear after one week of therapy and disappear after two weeks of discontinuation of therapy, however the time duration may vary with patient [34, 35].
