PURPOSE: A soluble drug delivery system is provided to prevent early drug release and to directly apply to a lesion. CONSTITUTION: A novel drug delivery system which enables sustained release contains 0.01-30 weight% of drug with positive charge and 0.01-30 weight% of multivalent cation. The drug with positive charge is selected from Teicoplanin dexamethasone disodium phosphate cefalotin sodium colistimethate sodium and Tolmetin sodium. The multivalent cation is selected from Mg^2+ Ca^2+ Sr^2+ B...

Cefalotin is methoxylated in position 7α desacetylated and then carbamoylated in position 3 to provide acid cefoxitin without any isolation of intermediate products. The acid cefoxitin is then transformed into the sodium salt by means of ion exchange resin.

Cefalotin is methoxylated in position 7± desacetylated and then carbamoylated in position 3 to provide acid cefoxitin without any isolation of intermediate products. The acid cefoxitin is then transformed into the sodium salt by means of ion exchange resin.

Cefalotin is methoxylated in position 7α desacetylated and then carbamoylated in position 3 to provide acid cefoxitin without any isolation of intermediate products. The acid cefoxitin is then transformed into the sodium salt by means of ion exchange resin.

Cefalotin is methoxylated in position 7? desacetylated and then carbamoylated in position 3 to provide acid cefoxitin without any isolation of intermediate products. The acid cefoxitin is then transformed into the sodium salt by means of ion exchange resin.

Cefalotin is methoxylated in position 7alpha, desacetylated and then carbamoylated in position 3, to provide acid cefoxitin without any isolation of intermediate products. The acid cefoxitin is then transformed into the sodium salt by means of ion exchange resin.