Cefamandole nafate

Antibiotic therapies to eradicate medical device-associated infections often fail because of the ability of sessile bacteria, encased in their exopolysaccharide matrix, to be more drug resistant than planktonic organisms. In the last two decades, several strategies to prevent microbial adhesion and biofilm formation on the surfaces of medical devices, based mainly on the use of antiadhesive, antiseptic, and antibiotic coatings on polymer surfaces, have been developed. More recent alternative approaches are based on molecules able to interfere with quorum-sensing phenomena or to dissolve biofilms. Interestingly, a newly purified beta-N-acetylglucosaminidase, dispersin B, produced by the gram-negative periodontal pathogen Actinobacillus actinomycetemcomitans, is able to dissolve mature biofilms produced by Staphylococcus epidermidis as well as some other bacterial species. Therefore, in this study, we developed new polymeric matrices able to bind dispersin B either alone or in combination with an antibiotic molecule, cefamandole nafate (CEF).

The European Pharmacopoeia (Ph.Eur.) monograph for Cefamandole Nafate (CFN) and the revised monograph prescribe the identification of the antibiotic in solid state by infrared (IR) absorption spectrophotometry using potassium bromide (KBr) disc technique. But, this technique may cause unwanted solid-solid transformations in the crystalline structure of the beta-lactam antibiotic CFN. The latter is a drug with proven polymorphism/pseudopolymorphism. In this context we have examined the suitability of the two techniques (KBr disc and Nujol mull) for IR spectral analyses to identify the antibiotic CFN in solid state. The results of our examinations show that KBr disc technique alters the crystalline state of CFN during the preparation of its KBr disc samples by the tribomechanical treatments (grinding and compression pressure). On the contrary, the Nujol mull technique does not cause such transformations and it is estimated as a better, more suitable technique to be employed for identification of CFN.

The influence of temperature and relative humidity (RH) on the stability of cefamandole (CM) nafate sodium in the solid phase was investigated. Changes in the concentration of cefemandole nafate sodium were recorded using HPLC with UV detection. The method was validated for the following parameters: selectivity, linearity, precision, limit of detection and sensitivity. It showed good linearity (r=0.9996) in the range 0.4 x 10(-4)-5.6 x 10(-4) g ml(-1) using a LiChrospher RP-18 column and as mobile phase acetonitryle-triethylamine (10% v/v, adjusted to pH 2.5 with phosphoric acid (84%) and diluted with water) (35:65). The degradation of CM occurring at 0% RH of the ambient air and at air humidity RH>50% is a first-order reaction relative to substrate concentration. The first-order rate constants (k) were determined for CM degradation in dry air at 373, 383, 388 and 393 K, at air humidity RH=76.4% at 323, 333, 343 and 353 K, and at 353 K at air humidity RH>50%.