Neomycins concentrations

Pregnalatto and Sabino200 incorporated glycerine into the ninhydrin solution and reported an improved sensitivity and reproducibility enabling neomycin concentrations as low as 4 yg/ml to be determined. An automated ninhydrin assay has been described by Kaptionak, Biernacka and Pazdera O based on a modified Moore and Stein methodl l. 

Dutcher et al 54 used 40% sulphuric acid to produce an acid concentration of 37% in the solution for hydrolysis and obtained maximum formation of furfural after 1 hrs reflux. Morgan et al 59 however, used 70% sulphuric acid to produce a 25% acid concentration in the hydrolysis solution and obtained maximum formation of furfural after one hour. Ivashkivl O has evaluated the use of both hydrochloric and sulphuric acids and found up to four times more furfural to be produced by sulphuric acid, the yield being extremely sensitive to the concentration of acid employed. Continuing further work with sulphuric acid, the formation of furfural as a function of neomycin concentration was examined and the conclusion reached that better yields of furfural are obtained at low concentrations of the antibiotic. Heyesl has shown a constant amount of furfural to be produced on hydrolysis with 27-28% sulphuric acid, refluxing for 1 hour. This makes it unnecessary to accurately... 

Brammer and Hemson employed an electrophoretic procedure to separate neomycin from blood-proteins before determining the neomycin concentration colorimetrically. 

Very high specificity toward neomycin B was observed with respect to other very similar antibiotics. Application of the method to the analysis of real samples was also demonstrated by testing neomycin spiked whole milk with a recovery of 102% and 109%, respectively, for two different neomycin concentrations. 

Pharmaceutical. Ion-exchange resins are useful in both the production of pharmaceuticals (qv) and the oral adrninistration of medicine (32). Antibiotics (qv), such as streptomycin [57-92-17, neomycin [1404-04-2] (33), and cephalosporin C [61-24-5] (34), which are produced by fermentation, are recovered, concentrated, and purified by adsorption on ion-exchange resins, or polymeric adsorbents. Impurities are removed from other types of pharmaceutical products in a similar manner. Resins serve as catalysts in the manufacture of intermediate chemicals. 

Co-administration of ofloxacin and chitosan in eyedrops increased the bioavailabUity of the antibiotic [290]. Trimethyl chitosan was more effective because of its solubility (plain chitosan precipitates at the pH of the tear fluid). On the other hand, N-carboxymethyl chitosan did not enhance the corneal permeability nevertheless it mediated zero-order ofloxacin absorption, leading to a time-constant effective antibiotic concentration [291]. Also W,0-carboxymethyl chitosan is suitable as an excipient in ophthalmic formulations to improve the retention and the bioavailability of drugs such as pilocarpine, timolol maleate, neomycin sulfate, and ephedrine. Most of the drugs are sensitive to pH, and the composition should have an acidic pH, to enhance stability of the drug. The delivery should be made through an anion exchange resin that adjusts the pH at around 7 [292]. Chitosan solutions do not lend themselves to thermal sterilization. A chitosan suspension, however. 

DiPiro JT, Patrais JM, Townsend RJ, Bowden TA Jr, Hooks VH 3rd, Smith RB, Spiro TE Oral neomycin sulfate and erythromycin base before colon surgery A comparison of serum and tissue concentrations. Pharmacotherapy 1985 5 91-94. 

Neomycins B and C have been shown to differ in their specific rotation values, neomycin B having a specific rotation of + 80° and neomycin C a specific rotation of + 120° 1 7. Brooks et al -2 made this fact the basis for a number of methods to determine the B C content of commercial neomycin. The specific rotation of the test solution is determined at 25°C and total neomycin determined either titrimetrically or spectro-photometrically. By substitution of these values in a suitable equation the concentration of neomycins B and C are calculated. In a second method the same authors determined the specific rotation of the test-solution at temperatures of 25° and 75°C. The change in the value of specific rotation on increasing the temperature from 25°to 75°C can then be used to calculate the amounts of neomycin B and C in the sample. 

The neomycin molecule does not exhibit fluorescence but following suitable de-rivatisation two spectrofluorimetric determinations have been described. Maeda et al l reported the complexation of simple hexosamines with pyridoxal and zinc ions to result in a fluorescent derivative. Applying this procedure to neomycin, Simpsonl32 demonstrated a linear response over the concentration range 0-50 yg/ml of neomycin sulphate. 

The reaction of neomycin with fluorescamine to form a fluorescent complex has been reported by Kusnir Barna The fluorescence intensity varies with both the pH of the solution (optimum pH range 7.5-9.5) and the amount of fluorescamine added. This procedure may be used to determine neomycin at very low levels, the minimum concentration determinable being 45 ng/ml. 

The use of bioautography for the quantitation of chromatograms has been described by many workers. Emilianowicz-Czerska and Herman228 separated neamine from neomycins B and C then quantitatively determined total neomycin B and C by bioautography with B.iubtZZZi. A linear response for concentrations between 0.25 and lOyg of neomycin was obtained. With a similar technique but using a mathematical analysis of the bioauto-... 

OV-1 on Gas Chrom Q as longer columns required a higher temperature to chromatograph neomycin and consequently had a reduced column life. A concentration of 3% OV-1 was preferred, as 2% or less resulted in increased column adsorption of neomycin. After a further study of the procedure Margosis and Tsuji238 recommended a number of improvements to optimise the analysis of neomycin by G.L.C. The improvements to the assay included the modification of the injection port to prevent sample decomposition by contact of injected material with... 

Various organisms have been used to assay neomycin turbidimetrically. These are summarised in Table 17 with the working concentration for the antibiotic as reported by the respective authors. 

The concentration of neomycin in urine has been determined with a fluorimetric method 15. Interfering amines were separated by chromatography on SE Sephadex C-25 before reacting the isolated neomycin with fluorescamine. 

Fig. 12 Time evolution (at pH 7.0 and 310 K) of neomycin-B (1, /e/f), derivative 2 (mzd-dle) and derivative 3 (right) at 100 jxM concentration in the presence of ATP or AcCoA (100 JiM), after addition of 0.2 jiM ANT(40 (lower part)y AAC(2 ) (middle) or APH(3 ) (upper part) followed by 1-D NMR. 1-Ad and 3-Ad stand for the adenylated derivatives 1 and 3, respectively. 1-Ac stands for the acetylated derivative 1. 1-P, 2-P and 3-P stand for the phosphorylated derivatives 1, 2 and 3, respectively...

CD and UV melting profiles in the presence of the ligands were carried ont to confirm the presence of a DNA-RNA hybrid duplex in the presence of the ligands. The addition of 2.2 tiM of neomycin and ethidium bromide results in a increase of 12°C, whereas the addition of 6 resnlts in a increase of 20°C. Increased concentration of 6 caused a gradual increase in the hybrid melting temperature. As the concentration of NM was increased from 0 p.M to 3 p.M, the melting temperature of the hybrid increases from 48.9°C to 70.1°C, a 21.2°C increase overall. 

The aminoglycosides include streptomycin, gentamicin, tobramycin, netilmicin, kanamycin, amikacin, sisomicin, neomycin, paromomycin and others. Those are bactericidal antibiotics. This bactericidal activity is concentration dependent in contrast to the... 

Some antibiotics are also used in horticulture to control contamination of micropropagation, plant tissue culture, and in controlling bacterial diseases of fruit trees (Levy, 1992 FaUdner, 1998). Commonly used in horticulture are cephalosporins, neomycin, novobiocin, polymyxin, and sulfaguanidine. More than 20 tons of streptomycin and tetracycline are used by the horticulture industry in the United States per annum. Substantial amounts of antibiotics are also used in aquaculture, whereby they are either directly added to the water (therapy) or as part of the feed, resulting in high concentrations in the water and adjoining sediments. An examination of the levels of use of various PPCPs for various purposes is outline next. 

Usual irrigation dosage Continuous Bladder Irrigation 1 ml urogenital concentrate (contains 200,000 units polymyxin B, 57 mg neomycin) added to 1,000 ml 0.9% NaCl. Give each 1,000 ml >24 hr for up to 10 days (may increase to 2,000 ml/day when urine output >2 L/day). 

Gramicidin is available only for topical use, in combination with other antibiotics such as neomycin, polymyxin, bacitracin, and nystatin. Systemic toxicity limits this drug to topical use. The incidence of sensitization following topical application is exceedingly low in therapeutic concentrations. 

Topical application of neomycin rarely results in detectable serum concentrations. However, in the case of gentamicin,... 

A 62-year-old man treated with continuous mediastinal irrigation with a 1 10 solution of povidone-iodine developed seizures on the fifth day of drainage (14). After the seizure, his serum iodine concentration was raised (120 pg/ml). Renal insufficiency developed at the same time. The electroencephalogram showed no evidence of epileptic activity or other abnormalities. The povidone-iodine irrigation was replaced by continuous irrigation with a solution of neomycin and polymyxin B. Renal function improved and the creatinine concentration returned to normal 3 days after the seizure. 

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