Penicilloic Acid Research Articles

Determination of mezlocillin and its penicilloate and penilloate by high-performance liquid chromatography and stability of mezlocillin at different temperatures.

A method is described for the determination of mezlocillin and its metabolites penicilloic acid and penilloic acid in biological fluids by high-performance liquid chromatography. The stability of mezlocillin in serum and buffer was studied at different temperatures (4, -20, -70, and -196 degrees C) over a period of 6 months. Mezlocillin remained stable at -70 and -196 degrees C, whereas degradation was observed at -20 and 4 degrees C in serum and buffer.

Epileptogenic action of penicillin derivatives: structure-activity relationship

In the hippocampal slice preparation, perfusion with benzyl penicillin evokes multiple population spikes and spontaneous discharges. Doses of 0.25 to 2 mM of the drug produced this effect within 20–40 min. Cleavage products and analogues of benzyl penicillin, penicilloic acid, 6-aminopenicillanic add, cephalexin, thioproline and penicillamine, were devoid of such action. It is concluded that the structural requirements for epileptogenic action of penicillin include not only the β-lactam ring and side chain substitution on C-6, but also the thiazolidine ring.

Effect of clavulanic acid on inactivated amoxicillin excretion in urinary tract infection.

Oral amoxicillin was taken with and without clavulanic acid by normal subjects and by patients with chronic complicated urinary tract infection to examine the in vitro protective effect of clavulanic acid on amoxicillin degradation. When amoxicillin alone was taken, urinary excretion of the penicilloic acid of amoxicillin in bacteria-positive patients was higher than that in bacteria-negative patients and in normal subjects. There was no comparable change in urinary penicilloic acid excretion in the presence of clavulanic acid. There were significant in vitro protective effects of clavulanic acid on beta-lactamases in the urine.

Spectrophotometric Assay of Penicillins by Reaction with 1,2,4-Triazole and Mercury(II) Chloride

A simple and rapid spectrophotometric method for the determination of penicillins has been developed. The method is based on the measurement of ultraviolet absorbance at 323–346 nm of reaction products with 1–2 M 1,2,4-triazole and 1 × 10-3 M mercury(ll) chloride in solution (pH 9.0) for 10 min at 60°C. The method, which permits detection of concentrations of penicillins down to 0.1 μg/ml, is accurate and precise. The assay of amino-penicillins was interfered with the coexistence of the corresponding penicilloic acids, while the method is specific to other intact penicillins without interference of the corresponding penicilloic acids.

A coupled enzyme assay for isopenicillin N synthetase

The development of a coupled enzyme assay for the determination of isopenicillin N synthetase activity in purified extracts from Cephalosporium acremonium was described. Isopenicillin N formed from its precursor, δ-( l-α-aminoadipyl)- l-cysteinyl- d-valine (ACV), by the synthetase was hydrolyzed by β-lactamase I to the corresponding penicilloic acid. Automatic titration of the acid with standard sodium hydroxide delivered by a pH-stat gave a continuous plot of product formed vs time. This assay has been used in kinetic studies and to determine the effects of pH, ionic strength, and temperature on the enzyme's activity.

High-performance liquid chromatographic assay of carbenicillin, ticarcillin and sulbenicillin in serum and urine using pre-column reaction with 1,2,4-triazole and mercury(II) chloride.

A high-performance liquid chromatographic method has been developed for the assays of carbenicillin (CBPC), ticarcillin (TIPC) and sulbenicillin (SBPC) in serum and urine. These penicillins were reacted with 2 M 1,2,4-triazole and 10–3M mercury(II) chloride in solution (pH 9.0) at 60 °C for 10 min. The resulting products were separated on a C18 column using a mobile phase containing tetrabutylammonium bromide and sodium thiosulphate, and were detected at between 327 and 331 nm. The method has been applied to the assays of these penicillins in serum and urine samples, which were ultra-filtered with a YMT membrane, or filtered with an acrylate copolymer membrane. The procedure permits the accurate determination of penicillin concentrations in serum down to 0.05 µg ml–1 for SBPC and 0.1 µg ml–1 for CBPC and TIPC, and is specific to intact penicillins without interference from corresponding penicilloic acids.

Determination of penicillin V in fermentation samples by flow injection analysis

Penicillin V in fermentation broths is determined, with linear response over the range 100–1000 U ml −1, by enzymatic hydrolysis to penicilloic acid and subsequent formation of a molybdenum blue. The Auto-Analyzer and flow-injection procedures are compared.

The crystal structure of beta-lactamase from Staphylococcus aureus at 0.5 nm resolution.

The preparation, crystallization and low-resolution structure determination of beta-lactamase (EC 3.5.2.6, 'penicillinase') from Staphylococcus aureus is described. The enzyme crystallizes in space group I222 with 1 molecule per asymmetric unit and cell dimensions a = 5.45(1), b = 9.39(1) and c = 13.87(2) nm. The structure was determined at 0.5 nm resolution by using phases calculated from (NH4)2Pt(CN)4 and KAu(CN)2 derivatives. The mean figure of merit mean value of m, for the 1106 reflexions used was 0.70. Difference Fourier syntheses for data collected from crystals soaked in platinum D-methionine and in 6-(4-hydroxy-3,5-di-iodobenzamido)penicilloic acid revealed the likely position of the active site of the enzyme.

Opening of the thiazolidine ring of penicillin derivatives

Penicilloic acid derivatives undergo two types of reversible thiazolidine ring opening reactions; in aqueous alkaline solution methyl benzylpenicilloate ring opens to give an enamine intermediate by a base-catalysed elimination process involving C-6-H whereas benzylpenicilloic acid epimerises at C-5 by unimolecular ring opening to form an intermediate iminium ion.

Simultaneous release of penicilloic acid and phenylacetyl glycine by penicillin-binding proteins 5 and 6 of Escherichia coli.

Penicillin-binding proteins (PBPs) 5 and 6 of Escherichia coli released the bound penicilloyl moiety at an intermediate rate relative to, e.g., Staphylococcus aureus PBPs 4 (rapid) and 1 or 2 (slow). Each of these E. coli PBPs released the bound penicilloyl moiety as both penicilloic acid (hydrolysis) and phenylacetyl glycine (scission of the C-5--C-6 bond followed by hydrolysis).

Specific High-Performance Liquid Chromatographic Determinatioin of Ampicillin in Bulks, Injectables, Capsules, and Oral Suspensions by Reverse-Phase Ion-Pair Chromatography

Abstract A rapid, specific, stability-indicating high-performance liquid chromatographic (HPLC) method has been developed for the assay of Ampicillin in Ampicillin Trihydrate bulk, capsules and oral suspensions and Sodium Ampicillin bulk and injectables. The assay is specific for Ampicillin in the presence of possible contaminants; Penicillin V, Phenylglycine, and 6-Aminopenicillanic Acid (6-APA); the degradation product, Penicilloic Acid of Ampicillin; and all excipients present in the formulations assayed. Ampicillin, Ampicillin formulations, and formulation excipient blends were force-degraded to further demonstrate specificity. The assay is precise, accurate, linear over the range 50% to 125% of expected Ampicillin sample level, and stability-indicating toward the described thermal, acid, base, aqueous, and light degradations. The procedure employs an ion-pairing eluent with UV detection at 254 nm. Ampicillin Trihydrate and Sodium Ampicillin bulk are stable in assay diluent for six hours allowing the ...

Determination of water in penicillins using fast Karl Fischer reagents and electronic end-point optimization

When using conventional Karl Fischer reagents for titration of water in penicillins, decomposition products (i.e. penicilloic acid) are shown to be partly cotitrated. Water in ampicillin, bacampicillin, carboxybenzylpenicillin and cloxacillin was titrated with slow and fast reagents and the differences in the results obtained were compared with the content of penicilloic acid determined mercurimetrically. A simple electronic control unit has been developed to optimize the speed of titration.

Determination of degradation products and impurities of amoxicillin capsules using ternary gradient elution high-performance liquid chromatography

A specific high-performance liquid chromatography method has been developed for the determination of amoxicilin penicilloic acids (PA), p-hydroxyphenyl-glycine ( p-HPG), 6-aminopenicillanic acid (6-APA) and unidentified materials in amoxicillin capsules. The accuracy of the measurement was demonstrated by the standard addition technique on actual capsule samples. Within-day and between-day precision studies gave coefficients of variation of 3.15 and 1.70% for PA, 4.75 and 3.81% for p-HPG, and 5.59 and 32.23% for 6-APA, respectively. Typical calibration and expanded linearity of response curves for these components show no curvature over the range of interest. The detection limits for PA, p-HPG and 6-APA are 0.7, 0.2 and 0.6 μg/ml of sample extract and are considered adequate for the intended use of the method. These levels corespond to 0.35, 0.10, 0.30 mg per 500-mg Amoxil® capsule, respectively.

Positive and negative ion fast atom bombardment mass spectra of some penicilloic acids.

The technique of fast atom bombardment mass spectrometry has been shown to be capable of producing molecular weight and useful fragmentation information from a selection of penicilloic acids. In addition, the technique has been shown to give similar information on alkali metal salts of penicilloic acids.

Physiologically Based Pharmacokinetic Model for β-Lactam Antibiotics I: Tissue Distribution and Elimanation Rates

The disposition characteristics of β-lactam antibiotics in rats were investigated, and a physiologically based pharmacokinetic model capable of predicting the tissue distribution and elimination kinetics of these drugs was developed. Protein-binding parameters in rat serum were determined by equilibrium dialysis. Linear binding was found for penicillin G, methicillin, dicloxacillin, and ampicillin; however, nonlinear binding was observed for penicillin V and cefazolin. After intravenous bolus dosing, cefazolin was recovered almost completely in urine and bile, while for the penicillins, penicilloic acid was found to be the major metabolite. Biliary excretion of cefazolin followed Michae-lis–Menten kinetics, and no significant inhibition of urinary secretion was observed after probenecid administration. The renal clearance of unbound drug was 0.82ml/min with a reabsorption ratio (R) of 0.22. Tubular secretion was inhibited for the penicillins by probenecid plasma concentrations of 50 μg/ml, resulting in an R-value of 0.32. Erythrocyte uptake, serum protein binding, and tissue-to-plasma partition coefficient (Kp) were measured. Theoretical Kp values were calculated and found to be in good agreement with the Kp values for three of the antibiotics. Plasma and tissue concentrations (lung, heart, muscle, skin, gut, bone, liver, and kidney) were measured as a function of time at various doses for inulin and cefazolin in rats after an intravenous bolus dose, and were found to be in reasonable agreement with concentrations predicted by the model. These correlations demonstrate that the proposed model can accurately describe the plasma and tissue contributions of inulin and cefazolin in the rat and suggest that this model could have utility in predicting drug distribution in humans.

High-performance liquid chromatographic determination and moment analysis of urinary excretion of flucloxacillin and its metabolites in man

Pharmacokinetic evaluation of flucloxacillin in man has been achieved through detailed investigation of urinary excretions of unchanged flucloxacillin and 3 metabolites (penicilloic acid, 5-hydroxymethyl derivative, and penicilloic acid of the 5-hydroxymethyl derivative). The last metabolite was newly found from human urine. The time courses for excretion of unchanged flucloxacillin and the metabolites were measured by HPLC analysis of urine excreted after oral administration of flucloxacillin capsules to 5 human subjects. The values for cumulative excretion amount at infinite time (X u ∞) and mean residence time (MRT) for each species were estimated by moment analysis of excretion rate vs time curves. The results indicate that the average values of excretion ratio (X u ∞/D, D = 500 mg) and MRT are, respectively, 64.8% and 2.30 h for unchanged flucloxacillin, 3.8% and 4.51 h for penicilloic acid, 10.5% and 2.72 h for 5-hydroxymethyl derivative, and 1.0% and 4.04 h for penicilloic acid of the 5-hydroxymethyl derivative. The metabolic pathways of flucloxacillin are depicted, and the transfer ratio at each elimination step and the MRT value intrinsic to each metabolite were evaluated from the results of mom its.

Structure re-assignment of a metabolite of ampicillin and amoxycillin and epimerization of their penicilloic acids.

Products formed in-vitro from ampicillin and amoxycillin penicilloates have been examined by high-performance liquid chromatography, ultraviolet and nuclear magnetic resonance spectroscopy and thiol group determination and were found to be the 5S epimers of the penicilloic acids. This is in contrast to a published claim that the corresponding penamaldic acids were formed by the treatment used.

Cathodic stripping voltammetric determination of trace amounts of penicillins

The cathodic stripping voltammetric behaviour of four penicillins is described. After conversion to the corresponding penicilloic acid by alkaline hydrolysis, accumulation is performed at a hanging mercury drop eletrode at -0.10 V vs. SCE in a pH 4.6 buffer containing excess of copper(II). During the accumulation, the penicilloic acid is further degraded and a copper complex of penicillamine is formed. This complex is subsequently reduced at about -0.4 V in the stripping step. After accumulation for 1 min. or 10 min, 1 × 10 -9 or 2 × 10 -10_ M penicillin, respectively, may be detected. Cathodic stripping voltammetry conducted in absence of copper(II), at pH 4.6 or 9.2, yields a stripping peak corresponding to the reduction of a mercury complex of penicillamine. At pH 9.2, an additional peak, regarded as the reduction of a penamaldic acid complex with mercury is obtained. This complex degrades with time which makes its stripping peak less valuable for the determination of traces. The mercury complex peak disappears in presence of copper(II). The anoidc stripping voltammetric behaviour in presence of copper(II) is also reported. Two anodic film stripping peaks are obtained, at + 0.08 and + 0.13 V.

Formation of penicillin polymers and determination of molecular weight

The impurities in penicillins such as proteins and polymers have been investigated’ -j and the chemical aspects of penicillins have been studied4 -7. Penicillins form polymers by cleavage of the /J-lactam in aqueous solutions at room temperature, and these polymers are considered to be one of the causes of penicillin allergya1’. For the study of penicillin polymer formation, Sephadex G-25 chromatography has been widely used. We, however, found strong adsorption of a few penicillins to the gel and the peaks of penicilloic acids formed by cleavage of the p-laa Sephadex LH-60 was used and a chromatographic system was designed for molecular weight determinations. This paper describes the formation of polymers of ampicillin, amoxicillin, piperacillin and PL-385 (Fig. l), and the determination of the molecular weights of the polymers by using Sephadex LH-60.

Study on the rate of epimerization of amoxicillin β-penicilloic acid to its α-form in aqueous solutions using high-performance liquid chromatography

Using automated high-performance liquid chromatography, a preliminary study on the rate of conversion of β-penicilloic acid to its α-form in aqueous solutions, using amoxicillin penicilloic acid as an example is described. An octadecyl-silica column eluted with 0.05 M potassium phosphate buffer solution (pH 5.9) with detection at 228 nm was used for this study. The conversion rate was found to follow pseudo first-order kinetics.