CEPHALEXIN - cephalexin powder, for suspension
Karalex Pharma LLC
To reduce the development of drug-resistant bacteria and maintain the effectiveness of Cephalexin for Oral Suspension and other antibacterial drugs, Cephalexin for Oral Suspension should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
DESCRIPTION
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 C16 H17 N3 O4 S�H2 O and the molecular weight is 365.41.
Cephalexin has the following structural formula:
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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.
Cephalexin for Oral Suspension, USP is a white to off white granular powder with characteristic flavor, and gives orange colored viscous suspension after reconstitution with water.
After mixing, each 5 mL of Cephalexin for Oral Suspension, USP will contain cephalexin monohydrate equivalent to 125 mg or 250 mg of anhydrous cephalexin. The suspensions also contains the following inactive ingredients: colloidal silicon dioxide, FD&C Yellow No.6, tutti-frutti flavor, orange flavor, sodium lauryl sulphate, sucrose and xanthan gum.
CLINICAL PHARMACOLOGY
Human Pharmacology
Cephalexin is acid stable and may be given without regard to meals. It is rapidly absorbed after oral administration. Following doses of 250 mg, 500 mg, and 1 g, average peak serum levels of approximately 9, 18, and 32 mcg/mL respectively were obtained at 1 hour. Measurable levels were present 6 hours after administration. Cephalexin is excreted in the urine by glomerular filtration and tubular secretion. Studies showed that over 90% of the drug was excreted unchanged in the urine within 8 hours. During this period, peak urine concentrations following the 250-mg, 500-mg, and 1-g doses were approximately 1000, 2200, and 5000 mcg/mL respectively.
