Amoxicillin, oxidation

Reaction of these antibiotics with chlorine mostly generated chlorinated and OH-substituted by-products [86, 87]. Unlike fluroquinolones, whose quinolone ring is left mostly intact, disinfection with CIO2 may diminish the antibiotic capacity of tetracyclines because it leads to cleavage of the tetracyclines ring system [86,88]. On the other hand, oxidation of p-lactam antibiotics such as penicillin, amoxicillin, and cefadroxil with CIO2 leads to the formation of hydroquinone and a wide range of substituted phenols [89]. 

Bactericidal effects have been reported for two (3-lactams amoxicillin and its combination with clavulanic acid. They showed in vitro effects on the oxidative... 

Recently, prodrugs have been constmcted in which amoxicillin (antibacterial agent) and clavulanic acid or cephalosporin 1-oxide (/3-lactamase inhibitors) are covalently linked. All these compounds show better antibacterial activity than Augmentin , comparable anti-/3-lactamase activity, and better solubility properties <2002BMC3489>. 

Two iodine based methods have been published for amoxicillin and other penicillins which claim an exact stoicheiometry so that a reference standard is not required. In one [62] the penicilloic acid was reacted with potassium iodate at pH 5 and the liberated iodine titrated. A sample blank could be carried out as in the conventional iodometric method. In the other [63], the penicillin in 10% HC1 was reacted with iodoxybenzoate, potassium iodide added and the released iodine titrated. The same group had previously claimed exact stoicheiometry for a method in which amoxicillin in 10% HC1 was titrated with dibromodimethylhydantoin [64]. Both these methods were based on oxidation of products of penicillin degradation in the strong acid conditions. No information was provided about possible interference by potential impurities and the conditions are such that inclusion of a sample blank seems to be impossible. 

Amoxicillin has been quantified in drug substance or formulated product by polarography of a pH 6.2 solution [138], an acid hydrolysis product [139] or a bromine oxidation product [140],... 

Flow injection methods in which amoxicillin was hydrolysed by immobilised (1-lactamase, the penicilloic acid reacted with iodine and the blue starch - iodine colour measured [141], and in which the red colour produced by oxidative condensation with l-nitroso-2-naphthol in the presence of ceric ions was measured [142], have been reported. They are capable of 30 and 40 samples per hour respectively. 

Mascher, H. Kikuta, C. Determination of amoxicillin in plasma by high-performance liquid chromatography with fluorescence detection after on-line oxidation. J.Chromatogr., 1990, 506, 417-421... 

Acetic acid Acetylsalicylic acid Alpha-Tocopherol Aluminum Hydroxide Aluminum Potassium Sulfate Aluminum Oxide Ammonium Hydroxide Ammonium Nitrate Ammonium Sulfate Amoxicillin Amyl Acetate Amyl Nitrite Ascorbic Acid Benzoic Acid Boric Acid Butyl Acetate Butylated Hydroxyanisole and Butylated Hydro-xytoluene Caffeine... 

In complexes with antibiotics [amoxicillin, ampicillin, methiciUin, penicilUnG, cephalexin and ciprofloxacin (Figure 12.16, a-c)], polymeric compounds may be originated by direct reaction between dialkyltin(IV) chlorides and antibiotic sodium salt, or by direct reaction between trialkyltin(IV) hydroxides and free antibiotic acid. Other combinations (diorganotin oxide/free acid ligand triorganotin(IV) chloride/antibiotic salt) produce monomeric species. 

The determination of amoxicilline, ciprofloxacin, and piroxicam in bulk and pharmaceutical preparations has been performed by combining the oxidation character of Fe(III) with the chelation property of Fe(II), affording highly colored complexes. The reagent solutions are (1) a mixture of 1,10-phenanthroline and iron(III) ammonium sulfate in hydrochloride medium and (2) 2,2 -bipyridyl and iron(III) ammonium sulfate in hydrochloride medium. The resulting Fe(II) concentration, proportional to the amount of drug present, is monitored by the measurement of absorbances of tris(o-phenanthro-line) iron(U) or tris (bipyridyl) iron(II) complexes at 510 and 522 nm, respectively. 

Figure 3 (a) Cold contact observation results (i) the cociystal grew from clavulanate crystal to amoxicillin solution in NaOH> (ii) amoxicillin melted at 194°C, clavulanate oxidized at 203°C> while the cocrystal oxidized least, (b) DSC data of amoxicillin trihydiate (top), potassium clavulanate (middle), and the physical mixture 1 1 (bottom). The exothermic peak of I 1 mixture shows that amoxicillin and clavulanate overlay and become 1 peak at 202°C which indicates a solid solution interaction. 

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