Lysine salt of cephalexin - effect when administered parenterally as well as orally

摘要

Antibiotic compsn. contains the lysine salt of cephalexin (7-(D-alpha-amino-alpha-phenylacetamido)-3-methyl-3-cephem-4-carb- oxylic acid) of formula (I) which is water soluble and may be administered by intramuscular or intravenous injection as well as orally. Cephalexin is insoluble in water and is well absorbed when administered orally. It is used to treat infections, especially those of the respiratory and urinary tracts, and is used prophylactically for post-operative infections. When the sodium or potassium salt is administered by injection it causes local pain and is poorly absorbed. This poor absorption has led to the use of other antibiotics, e.g cephaloridine for the initial parenteral treatment of acute infections followed later by the oral administration of cephalexin. This use of two different antibiotics, is inconvenient and antagonism occurs between them. The use of (I) which is well absorbed parenterally as well as orally overcomes these problems. The recommended intramuscular doses of (I) are 2-4g per day for adults, adn 30-50 mg/kg/day (rising to 100 mg/kg/day for serious infections) for children. (I) is a yellowish-white powder, m. pt 168-174 degrees C which dissolves in water to give a clear, yellow solution and is insoluble in ether and other non-polar solvents. (I) has LD50 in rats of 6g/kg s. c or i. p and in guinea pigs, 3-6g/kg s. c and 3g/kg i.p.