[Means of purification of cephalexin with a view to therapeutic use]

Cephalexin (CEX) is the generic word of chemical compound 7-(D-alpha-aminophenylacetamido)-3-methyl-3-cephem-4-carboxylic acid, which is part of first generation oral cephalosporins group. It is use as cephalexin monohydrochloride monohydrate (CEX.HCl.H2O) syrup or tablets for oral administration. For obtaining a compound with great solubility and osmotic pressure, which is ideal for pharmaceutical forms with controlled dosage, it is necessary to achieve the crystalline form of Cephalexin monohydrochloride monohydrate. The therapeutic use Cephalexin has an output over 95 %, so it is necessary to purify CEX depending on it's isoelectric pH (pKa), which is 4.2. A good purification took place at greater or less values of pH, then the isoelectric pH value of CEX. The purification of CEX at greater values of pH then isoelectric point, took place with a greater output (75-76%), and the obtaining Cephalexin is much pure (97-98%).