ABSTRACT
One titrimetric and two spectrophotometric methods have been described for the determination of ofloxacin (OFX) in bulk drug and in tablets, employing N-Bromosuccinimide as an analytical reagent. The proposed methods involve the addition of a known excess of NBS to OFX in acid medium, followed by determination of unreacted NBS. In titrimetry, the unreacted NBS is determined iodometrically, and in spectrophotometry, unreacted NBS is determined by reacting with a fixed amount of either indigo carmine (Method A) or metanil yellow (Method B). In all the methods, the amount of NBS reacted corresponds to the amount of OFX. Titrimetry allows the determination of 1-8 mg of OFX and the calculations are based on a 1:5 (OFX:NBS) reaction stoichiometry. In spectrophotometry, Beer's law is obeyed in the concentration ranges 0.5-5.0 µg/mL for method A and 0.3-3.0 µg/mL for method B. The molar absorptivities are calculated to be 5.53x10(4) and 9.24x10(4) L/mol/cm for method A and method B, respectively. The methods developed were applied to the assay of OFX in tablets, and results compared statistically with those of a reference method. The accuracy and reliability of the methods were further ascertained by performing recovery tests via the standard-addition method.
Descrevem-se métodos, um titulométrico e dois espectrofotométricos, para a determinação de ofloxacino (OFX) na matéria-prima e em comprimidos, empregando a N-bromossuccinimida (NBS) como reagente analítico. Os métodos propostos envolvem a adição de excesso conhecido de NBS ao OFX, em meio ácido, seguida de determinação do NBS que não reagiu. Na titulometria, o NBS que não reagiu é determinado iodometricamente e na espectrofotometria, o NBS que não reagiu é determinado pela reação com quantidade fixa de índigo carmim (Método A) ou amarelo de metanila (Método B). Em todos os métodos, a quantidade de NBS que reagiu corresponde à quantidade de OFX. A titulometria permite a determinação de 1-8 mg de OFX e os cálculos se baseiam na estequiometria de reação de 1:5 (OFX:NBS). Na espectrofotometria, a Lei de Beer é obedecida nas faixas de concentração de 0,5-5,0 µg/mL, para o método A, e de 0,3-3,0 µg/mL, para o método B, respectivamente. Os métodos desenvolvidos foram aplicados para o teste de OFX em comprimidos e os resultados foram comparados estatisticamente com aqueles do método de referência. A precisão e a confiabilidade dos métodos foram, posteriormente, verificadas por meio dos testes de recuperação via método de adição de padrão.
Subject(s)
Bromosuccinimide/diagnosis , Spectrophotometry/methods , Ofloxacin/diagnosis , Titrimetry/methods , Analytic Sample Preparation Methods , Anti-Bacterial Agents/diagnosis , Chemistry, Pharmaceutical/methodsABSTRACT
Abstract:Perinatal infection significantly contributes to neonatal morbidity and mortality. There are no reliable rapid diagnostic tests. Drug resistance is increasing in organisms acquired in hospital. There are little data on the indications for antibiotic use and the prevalent organisms in lower resource settings; and none in regional hospitals in South Africa. We conducted a retrospective cohort study of risk factors; indications for and drugs used at Worcester Provincial Hospital Neonatal Unit. A systematic sample of every alternate neonate listed in the admissions register from 1 July 2005 to 30 June 2006 was taken. Charts for all cases were reviewed. Early antibiotic use was defined as therapy within 72 hours of life. One hundred and ninetyfive infants where included; 144 (74) had 194 antibiotic events. Antibiotic events occurred at a rate of 99 events per 100 neonates. Prematurity was common (83 of admissions) and; in conjunction with prolonged rupture of membranes; was the major driver of early antibiotic use. Ceftriaxone use within 72 hours of birth was significantly associated with subsequent antibiotic events; compared with penicillin alone or in combination with an aminoglycoside (p 0.04). Longer duration of treatment for early events was associated with subsequent empiric need for antibiotics (p 0.02). Prematurity is the major driver for antibiotic use at this unit. Antibiotics are prescribed appropriately but earlier discontinuation; which may be complicated by the inability to confirm/refute infection; should be practised. Alternatives to third generation cephalosporins should be available to treat hospital infection at secondary level
Subject(s)
Anti-Bacterial Agents/diagnosis , Infant , Infant Mortality , Infant, Newborn , Morbidity , Risk FactorsABSTRACT
Our objective was to improve the media and the antibiotic supplements in order to increase the detection rate of Helicobacter pylori from gastric biopsy specimens. For the primary isolation of H. pylori taken from gastric biopsies, we compared the efficacy of two media: Columbia blood agar (CBA, Difco); brain heart infusion agar (BHIA, Difco); and two antibiotic supplement sets--a commercial antibiotic supplement (SR147, Oxoid) and an in-house antibiotic supplement (IHS). Gastric biopsies obtained from 210 patients were diagnosed by culture, rapid urease test (RUT) and histology. The true positive criteria were defined as a culture or both urease and histology tests being positive. The H. pylori infection rate was 44.3% (93/ 210). To compare the two media, a total of 106 gastric biopsies were plated on CBA or BHIA with 7% human blood, containing the antibiotic supplement SR147 and incubated under microaerophilic conditions. Of the 106 samples, 48 (45.3%) case of H. pylori infection, compared to the true positive criteria. The isolation rate using a combination of the two media was 83% (40/48). Of the 40 samples, 36 (90%) and 35 (87.5%) were positive on CBA and BHIA, respectively. To compare the two antibiotic supplement sets, a total of 104 gastric biopsies were plated on CBA, containing the commercial antibiotic supplement SR147 (5 mg/l trimethoprim, 10 mg/l vancomycin, 5 mg/l amphotericin B and 5 mg/l cefsulodin) or containing IHS (5 mg/l trimethoprim, 10 mg/l vancomycin, 2 mg/l amphotericin B and 2,500 U/l polymyxin B). Of the 104 samples, 45 (43.2%) case of H. pylori infection were found compared to the true positive criteria. The isolation rate using a combination of the two selective supplement sets was 82% (37/45). Of the 37 samples, 35 (95%) and 34 (92%) were positive with SR147 and IHS, respectively. Our study indicates that the combination of the two media and two antibiotic supplements is useful for maximum recovery of H. pylori isolated from gastric biopsies. CBA, and the commercial antibiotic supplement SR147 provided higher detection rates for H. pylori than BHIA, and IHS but the differences were not statistically significant.