SPL Set ID: dec3a1ef-1e85-4236-804b-e7a343d3a58f

Cephalexin, USP is a semisynthetic cephalosporin antibiotic intended for oral administration. It is 7- (D-α-Amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate. Cephalexin has the molecular formula C 16 H 17 N 3 O 4 S • H 2 O and the molecular weight is 365.41. Cephalexin has the following structural formula: The nucleus of cephalexin is related to that of other cephalosporin antibiotics. The compound is a zwitterion; i.e., the molecule contains both a basic and an acidic group. The isoelectric point of cephalexin in water is approximately 4.5 to 5. The crystalline form of cephalexin which is available is a monohydrate. It is a white crystalline solid having a bitter taste. Solubility in water is low at room temperature; 1 or 2 mg/mL may be dissolved readily, but higher concentrations are obtained with increasing difficulty. The cephalosporins differ from penicillins in the structure of the bicyclic ring system. Cephalexin has a D -phenylglycyl group as substituent at the 7-amino position and an unsubstituted methyl group at the 3-position. Each capsule contains cephalexin USP equivalent to 250 mg or 500 mg of anhydrous cephalexin. The capsules also contain the following inactive ingredients D&C Yellow 10, FD&C Blue 1, FD&C Green 3, FD&C Yellow 6, ferric oxide black, gelatin, magnesium stearate, microcrystalline cellulose, potassium hydroxide, propylene glycol, shellac and titanium dioxide. Molecular Structure