Spectrophotometric determination of enrofloxacin and pefloxacin through ion-pair complex formation

Two simple, quick and sensitive spectrophotometric methods are described for the determination of enrofloxacin and Pefloxacin. The methods are based on the reaction of these drugs with bromophenol blue (BPB) and methyl orange (MO) in buffered aqueous solution at pH 2.3-2.5 in case of bromophenol blue and at pH 3.6 with MO to give highly coloured complex species, extractable with chloroform. The coloured products are quantitated spectrophotometrically at 420 and 424 nm for BPB and MO, respectively. Optimisation of the different experimental conditions is described. Beer's law is obeyed in the concentration ranges 2-12 and 2-18 microg ml(-1) with BPB and in the ranges 1-12 and 4-40 microg ml(-1)with MO for enrofloxacin and pefloxacin, respectively. The proposed methods are applied for determination of Enroxil oral solution, Peflacine tablets and Peflacine ampoules with mean percentage accuracies 99.5+/-0.99, 99.39+/-1.05 and 100.02+/-0.895, respectively, with BPB and 100.30+/-0.89, 100.25+/-0.98 and 100.20+/-0.72, respectively, with MO.     

Spectrophotometric determination of some fluoroquinolone antibacterials by binary complex formation with xanthene dyes

Two simple, rapid and sensitive spectrophotometric methods for the determination of levofloxacin, norfloxacin and ciprofloxacin have been performed in pure form, pharmaceutical tablets and spiked human urine. Both methods are based on the formation of a binary complex between the drugs and one of the two xanthene dyes, eosin Y or merbromin in aqueous buffered medium. Under the optimum conditions, the binary complexes showed absorption maxima at 547 nm for eosin Y and 545 nm for merbromin. Using eosin Y, the calibration graph was linear over the range 2-8 microg ml(-1) for the three drugs with mean percentage recoveries 99.935 +/- 0.648, 99.973 +/- 0.678 and 100.011 +/- 0.606 for levofloxacin, norfloxacin and ciprofloxacin, respectively. While in case of merbromin, the concentration range was 2-15 microg ml(-1) with mean percentage recoveries 99.960 +/- 0.491, 100.017 +/- 0.510 and 99.980 +/- 0.506 for the three drugs, respectively. The proposed methods were successfully applied to determine these drugs in their tablet formulations and spiked human urine and the results compared favorably to that of reference methods. The suggested methods have the advantage of being applicable for the determination of the three drugs without prior extraction. They are recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical techniques are of great importance.     

Fluorescence spectroscopy determination of fluoroquinolones by charge-transfer reaction

The charge-transfer (CT) reaction between chloranilic acid (CL) as a pi-electron acceptor and lomefloxacin (LOM), fleroxacin (FLX), ciprofloxacin (CPFX), norfloxacin (NOR) as electron donor have been studied by fluorimetry. The CT complexes have stable purple color in acetone solution and the fluorescence intensity of the CT complexes was enhanced in 4-14 fold higher than that of the four fluoroquinolones (FQS) itself, therefore a new spectrofluorimetric method with simple, rapid, accurate, high sensitivity and good selectivity for determination of the four FQS has been developed. The method was applied for determination of drugs (LOM, FLX, CPFX and NOR) in tablets with mean percentage accuracies 99.80+/-1.12, 99.93+/-0.92, 99.23+/-1.36 and 99.87+/-0.81, respectively.     

喹诺酮药物荷移反应的研究

目的：研究分光光度法测定吡哌酸、氟哌酸和乳酸环丙氟哌酸的含量,方法：基于在水溶液中药物与２,４二硝基酚生成荷移络合物。结果：表现摩尔吸光系数ε＝１３４×１０４～４２０×１０４Ｌ·ｍｏｌ－１·ｃｍ－１,络合物组成均为１∶１,络合物的最大吸收波长λｍａｘ＝３９７４～４０４０ｎｍ,相对标准偏差为１４３％～３６５％。结论：应用本方法测定吡哌酸、氟哌酸和乳酸环丙氟哌酸药物制剂含量可得到满意的结果。     

Simultaneous determination of terbinafine HCL and triamcinolone acetonide by UV derivative spectrophotometry and spectrodensitometry

A binary mixture of terbinafine hydrochloride and triamcinolone acetonide was determined by three different methods. The first one concerned with determination of both drugs using first derivative (D(1)) spectrophotometric technique at 297 and 274 nm over concentration ranges of 5-30 and 4-24 microg ml(-1), with mean percentage accuracies 99.90+/-0.67 and 100.25+/-0.49, respectively. The second method depends on ratio-spectra 1st derivative (RSD(1)) spectrophotometry at 298 and 248 nm over the same concentration ranges with mean percentage accuracies 100.22+/-0.51 and 99.93+/-0.56, respectively. The spectrodensitometric analysis provides a rapid and precise method for the separation and quantitation of both terbinafine hydrochloride and triamcinolone acetonide. The method depends on the quantitative densitometric evaluation of thin layer chromatogram of terbinafine hydrochloride and triamcinolone acetonide at 283 and 238 nm over concentration ranges of 5-25 and 2.5-22.5 microg spot(-1), with mean percentage accuracies 100.66+/-0.51 and 100.27+/-0.73, respectively. The suggested procedures were checked using laboratory prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The three methods retained their accuracy and precision when applying the standard addition technique. The results obtained by applying the proposed methods were statistically analysed and compared with those obtained by a reported method.     

Simple, rapid determination of enrofloxacin and ciprofloxacin in bovine milk and plasma by high-performance liquid chromatography with fluorescence detection

A rapid and simple procedure for determination of enrofloxacin and ciprofloxacin in bovine milk and plasma is described. Protein precipitation from both milk and plasma samples was achieved by addition of acetonitrile and phosphoric acid. Acetonitrile was removed with methylene chloride, leaving enrofloxacin and ciprofloxacin in the acidic aqueous extract. The aqueous extract was analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection. The limit of quantitation (LOQ) for enrofloxacin and ciprofloxacin in milk was found to be 2ng/ml. LOQ for enrofloxacin and ciprofloxacin in plasma was found to be 1ng/ml. Linear calibration curves were obtained with correlation coefficient (r(2)) >/=0.99. Analysis of quality control (QC) samples gave results within +/-10% of the nominal values. Inter-assay precision for the analysis of milk QC samples were in the ranges: 4.63-12.49% (for enrofloxacin) and 4.67-9.86% (for ciprofloxacin). Inter-assay precision for the analysis of plasma QC samples were in the ranges: 6.60-17.31% (for enrofloxacin) and 6.14-13.87% (for ciprofloxacin). Intra-assay precision for the analysis of milk QC samples were in the following ranges: 3.65-7.21% (for enrofloxacin) and 1.58-14.28% (for ciprofloxacin). Intra-assay precision for the analysis of plasma QC samples were in the following ranges: 2.17-16.95% (for enrofloxacin) and 3.31-16.31% (for ciprofloxacin). The effectiveness of protein precipitants other than phosphoric acid was investigated. The method described has been applied to a study of the pharmacokinetics of enrofloxacin and ciprofloxacin in lactating dairy cows and beef steers.     

Spectrophotometric determination of pefloxacin in pharmaceutical preparations

It has been established that the antibiotic pefloxacin (Abaktal) methane-sulphonate reacts with Fe(III) at pH 1.00–8.00 to form a water-soluble complex with maximum absorbance at 360 nm. The composition of the complex, determined spectrophotometrically by the application of Job's, molar-ratio and Bent—French's methods, was pefloxacin: Fe(III) = 1:1 (pH = 2.50; λ = 360 nm; μ = 0.1 M). The relative stability constant, obtained by the methods of Sommer and Asmus was 10^5.02 (pH = 2.50; λ = 360 nm; μ = 0.1 M). The molar absorptivity of the complex at 360 nm was found to be 4.8 × 10³ l mol⁻¹ cm⁻¹, Beer's law was followed for pefloxacin concentrations of 2.15–85.88 μg ml⁻¹. The lower sensitivity limit of the method was 2.15 μg ml⁻¹. The relative standard deviation (n = 10) was 0.57–1.07%. The method can be applied to the rapid and simple determination of pefloxacin in aqueous solutions and tablets.     

荷移分光光度法测定乳酸环丙沙星乳膏的含量

目的：建立乳酸环丙沙星乳膏的含量测定方法。方法：利用乳酸环丙沙星与2.4-二硝基酸产生反应，可形成电荷转移络合物，以分光光度法测定。结果：荷移反应后，乳酸环丙沙星最大吸收波长为398nm，在此波长处基质无干扰，吸收度与浓度间呈良好的线性关系，平均回收率为98.6%,RSD=0.8%(n=4)。结论：用荷移分光光度法可排除基质干扰，准确测定乳酸环丙沙星乳膏的含量。     

Pharmacokinetics of fluoroquinolones in uncompensated cirrhosis: the significance of penetration in the ascitic fluid.

In order to study the penetration of routinely used fluoroquinolones in the ascitic fluid of patients with uncompensated cirrhosis the following doses were given. Three patients received three consecutive iv doses of 200 mg of ciprofloxacin, six patients, three consecutive iv doses of 300 mg of ciprofloxacin, seven others, three consecutive iv doses of 400 mg of pefloxacin and six, three consecutive iv doses of 400 mg of ofloxacin. Drug levels in serum and the ascitic fluid were monitored at regular time intervals. Peak levels of the 200 mg dose of ciprofloxacin, of the 300 mg dose of ciprofloxacin, of pefloxacin and of ofloxacin in serum were 2.11,2.45,9.21 and 8.86 microg/ml, respectively and in the ascitic fluid 0.67, 0.45, 6.09 and 5.83 microg/ml, respectively T(1/2) was 3.19+/-0.73, 3.55+/-1.68, 15.60+/-12.40 and 9.45+/-3.14 h, respectively with AUC of 3.62+/-4.02, 7.39+/-4.70, 137.85+/-63.96 and 119.8+/-16.83 mg/l h. Urinary excretion of ciprofloxacin and of ofloxacin was similar to healthy individuals but pefloxacin showed a mean urinary excretion of 30.11%. It is concluded that pefloxacin and ofloxacin at the administered iv doses result in serum and ascitic fluid levels above the MICs of the common pathogens causing spontaneous bacterial peritonitis and that they should be administered to cirrhotic patients in dosing regimens similar to those in patients with normal hepatic function. The use of ciprofloxacin requires further studies to define the appropriate dose.     

The qualitative and quantitative determination of quinolones of first and second generation by capillary electrophoresis

Capillary electrophoresis (CE) was applied to the study of 10 quinolones of first and second generation--nalidixic acid, oxolinic acid, pipemidic acid, cinoxacin, norfloxacin, ciprofloxacin, ofloxacin, pefloxacin, fleroxacin, and flumequine. Separation was performed on a fused silica capillary (75 microm-60 cm) using a phosphate buffer (pH 7.0, 125 mM). Detection was at 214 nm. Only norfloxacin and ciprofloxacin cannot be separated in this way. Because of the specificity of the method, the identification of the individual quinolones by their migration time was possible. The same system has been applied for the quantitative determination of quinolones in tablets and capsules. Excipients do not adversely affect the results. Some parameters (linearity, precision, accuracy) were validated. Especially the possibility of simultaneous quantification and identification of the active ingredient in the finished product is very attractive.     

Spectrophotometric determination of gliclazide in pharmaceuticals and biological fluids through ternary complex formation with eosin and palladium (II)

A simple and sensitive spectrophotometric method has been developed for the determination of gliclazide (GLZ) in pharmaceutical formulations and biological fluids. The proposed method is based upon the formation of a ternary complex between palladium (II), eosin and GLZ in the presence of methyl cellulose as a surfactant and acetate buffer of pH 4.5. The ternary complex showed an absorption maximum at 550 nm. The solution of ternary complex obeyed Beer's law over the concentration range of 0.5-4 microg ml(-1) with minimum detectability (S/N = 2) of 0.05 microg ml(-1) (1.545 x 10(-7) M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official or reference spectrophotometric method. The proposed method was further applied to spiked human urine and plasma, the percentage recoveries were 97.84 +/- 0.72 and 97.43 +/- 0.83, respectively, (n = 4). A proposal of the reaction pathway was presented.     

High performance liquid chromatographic determinations of khellin, phenobarbitone and dipyrone combination in tablets

High performance liquid chromatographic methods for the individual determination of khellin, phenobarbitone and dipyrone in tablets are presented. The methods specify a reverse phase column: methanol + water (68 + 32) as mobile phase at a flow rate of 0.7 ml/min with detection at 254 nm for khellin, visgnagin and dipyrone; water + ammonia + methanol (94.5 + 0.5 + 5) as a mobile phase at a flow rate of 0.7 ml/min with detection at 240 nm for phenobarbitone. At sensitivity of 0.01 AUFS, linearity ranges were found to be 0.5-4 micrograms/ml for khellin, 2.5-12.5 micrograms/ml for dipyrone and 1-7 micrograms/ml for phenobarbitone and with relative standard deviations less than 2%. The mean percentage recoveries +/- SD of khellin, dipyrone and phenobarbitone added to tablets were found to be 101.0 +/- 0.65, 100.0 +/- 0.74 and 99.9 +/- 0.74, respectively. The system can detect 2% w/w visnagin in khellin.     

A stability-indicating LC method for the simultaneous determination of ramipril and hydrochlorothiazide in dosage forms

A simple, rapid and sensitive HPLC method has been developed for the simultaneous determination of ramipril and hydrochlorothiazide in their dosage forms. Acetonitrile: sodium perchlorate solution (0.1 M) adjusted to pH 2.5+/-0.2 with phosphoric acid (46:54 v/v), was used as the mobile phase, at a flow rate of 1.5 ml/min. A supelcosil LC-8 column (5 microm), 15 cm x 4.6 mm i.d. was utilized as stationary phase. Detection was affected spectrophotometrically at 210 nm. Clobazam was used as an internal standard. The method was also applied for the determination of ramipril in the presence of its degradation products. Linearity ranges for ramipril and hydrochlorothiazide were 4.5-45 and 0.6-14 microg/ml, respectively. Minimum detection limits (S/N = 2) obtained were 180 and 23 ng/ml for ramipril and hydrochlorothiazide, respectively. The proposed method was further applied to the analysis of tablets containing the two drugs, the percentage recoveries +/- S.D. (n = 5) were 100.45%+/-0.63 and 99.55%+/-0.78 for ramipril and hydrochlorothiazide, respectively.     

Determination of the antibiotic drug pefloxacin in bulk form,tablets and human serum using square wave cathodic adsorptive stripping voltammetry

A simple, rapid, reliable and fully validated square wave cathodic adsorptive stripping voltammetric procedure has been developed for the determination of the antibiotic pefloxacin drug in bulk form, tablets and human serum, based on its electrochemical reduction at a hanging mercury drop electrode. The Britton–Robinson buffer of pH 7.0 was found to be reasonable as a supporting electrolyte for assay of the drug. Pefloxacin drug, at the optimized conditions, showed a single 2-electron well-defined peak at −1.07 V (versus Ag/AgCl/KCl_s) using an accumulation potential of −0.40 V. This peak may be attributed to the reduction of the C=O group. A mean recovery of 99.54%±0.23 and a detection limit of 1.65×10⁻¹⁰ M pefloxacin were achieved. After being validated, the proposed procedure was successfully applied for the determination of the drug in tablets and human serum with mean recoveries of 99.57±0.48 and 98.55±0.78%, respectively. A detection limit of 4.50×10⁻¹⁰ M was achieved for the determination of the drug in human serum. Results of the proposed procedure were comparable with those obtained by reported methods.     

Spectrophotometric determination of acyclovir in some pharmaceutical formulations

A simple and reliable spectrophotometric method has been developed for the determination of acyclovir in pharmaceutical formulations. The method is based on its oxidative coupling reaction with 3-methylbenzothiazolin-2-one hydrazone (MBTH) in the presence of FeCl3 as an oxidant to produce deep-green colored species measurable at 616 nm. The absorbance-concentration plot is linear over the range 20-200 microg ml(-1) with minimum detectability of 1.06 microg ml(-1) (4.71 x 10(-6) M). The molar absorptivity was 9.41 x 10(2) l mol(-1) cm(-1) with correlation coefficient (n = 7) of 0.9998. The different experimental parameters affecting the development and stability of the color were studied carefully and optimized. The proposed method was applied successfully to the determination of acyclovir in its dosage forms. The percentage recoveries +/-SD (n = 9) were 98.63 +/- 0.34, 99.61 +/- 0.58, 99.35 +/- 0.58 and 99.72 +/- 0.86 for tablets, ophthalmic ointment and cream, respectively. A proposal of the reaction pathway was presented.     

Use of 7-fluoro-4-nitrobenzo-2-oxo-1,3-diazole (NBD-F) for the determination of ramipril in tablets and spiked human plasma.

Ramipril, as a secondary amine compound, reacts with 7-fluoro-4-nitrobenzo-2-oxo-1,3-diazole (NBD-F) producing the corresponding fluorescent NBD-ramipril. According to this fact, spectrophotometric and fluorimetric methods for the determination of ramipril were developed. The effect of these parameters on the reaction product were carefully studied to optimize reaction conditions. The relationship between the absorbance at 465 nm and the concentration was found to be linear over the range 1-10 microg/ml. Moreover, the fluorescence intensity was also found to be directly proportional at the concentration over the range of 20-100 ng/ml at 530 nm after excitation at 465 nm. The proposed procedure was successfully applied to the determination of ramipril in both tablet dosage form and in plasma. Spectrophotometric determination of ramipril tablets yielded a percentage recovery of 98.66+/-0.38, while the percentage recovery of spectrofluorimetric determination of ramipril in spiked human plasma was 99.08+/-1.11%. The results obtained are in good agreement with those obtained by the reference method. No interference could be observed from the co-administered drug (hydrochlorothiazines).     

First derivative ratio spectrophotometric,HPTLC-densitometric,and HPLC determination of nicergoline in presence of its hydrolysis-induced degradation product

Three methods are presented for the determination of Nicergoline in presence of its hydrolysis-induced degradation product. The first method was based on measurement of the first derivative of ratio spectra amplitude of Nicergoline at 291 nm. The second method was based on separation of Nicergoline from its degradation product followed by densitometric measurement of the spots at 287 nm. The separation was carried out on HPTLC silica gel F(254) plates, using methanol-ethyl acetate-glacial acetic acid (5:7:3, v/v/v) as mobile phase. The third method was based on high performance liquid chromatographic (HPLC) separation and determination of Nicergoline from its degradation product on a reversed phase, nucloesil C(18) column using a mobile phase of methanol-water-glacial acetic acid (80:20:0.1, v/v/v) with UV detection at 280 nm. Chlorpromazine hydrochloride was used as internal standard. Laboratory prepared mixtures containing different percentages of the degradation product were analysed by the proposed methods and satisfactory results were obtained. These methods have been successfully applied to the analysis of Nicergoline in Sermion tablets. The validities of these methods were ascertained by applying standard addition technique, the mean percentage recovery +/- R.S.D.% was found to be 99.47 +/- 0.752, 100.01 +/- 0.940, 99.75 +/- 0.740 for the first derivative of ratio spectra method, the HPTLC method and the HPLC method, respectively. The proposed methods were statistically compared with the manufacturer's HPLC method of analysis of Nicergoline and no significant difference was found with respect to both precision and accuracy. They have the advantage of being stability indicating. Therefore, they can be used for routine analysis of the drug in quality control laboratories.     

荷移分光光度法测定加替沙星片中主药的含量

目的：建立测定加替沙星片含量的方法。方法：通过加替沙星与茜素络合指示剂间发生的电荷转移反应,采用紫外-可见分光光度法测定其含量,并与该制剂现行标准测定方法（高效液相色谱法）测定结果进行比较。结果：加替沙星与茜素络合指示剂在乙醇与水混合介质中发生荷移反应,产物最大吸收波长为533nm,表观摩尔吸光系数为2.31×103L·mol-1·cm-1,荷移络合物的组成比为1：1,方法重现性试验中RSD为0.98%（n=6）;加替沙星检测浓度线性范围为10～90mg·L-1（r=0.9996）,平均回收率为99.9%,RSD=1.02%。2种方法测定样品含量结果一致。结论：建立的方法操作简便、快速,灵敏度高,结果准确。     

Use of mixed anhydrides for the determination of terfenadine in dosage forms and spiked human plasma

Terfenadine reacts with mixed anhydrides (malonic and acetic anhydrides) producing a yellow-coloured product with intense fluorescence. Based on this fact, a spectrophotometric method was developed for the determination of terfenadine in dosage forms. The relation between the absorbance at 395 nm and the concentration is rectilinear over the range 0.5-5 microg ml(-1) (molar absorptivity is 1.405 x 10(5) l mol(-1) cm (-1)). The reaction product was also measured spectrofluorimetrically at 435 nm after excitation at 395 nm. The fluorescence intensity was directly proportional to the concentration over the range 0.5-4 ng ml(-1) with minimum detectability (S/N = 2) of 0.07 microg ml(-1) (approximately 1.5 x 10(-10) M). The different parameters affecting the development and stability of the reaction product were carefully studied and incorporated into the procedure. The proposed spectrophotometric method was successfully applied to the determination of terfenadine in tablets and suspensions; the percentage recoveries were 99.83 +/- 0.75 and 99.65 +/- 0.83, respectively. The proposed spectrofluorimetric method was applied to the determination of terfenadine in spiked human plasma. The percentage recovery was 99.35 +/- 2.19. The method is highly sensitive and specific. No interference was noticed from co-formulated drugs, such as pseudoephedrine and ibuprofen.     

Kinetics of 4-fluoroquinolones permeation into saliva.

Following a single oral administration of ciprofloxacin, norfloxacin, pefloxacin and ofloxacin preparations to healthy volunteers simultaneously collected, saliva and plasma 4-fluoroquinolone concentrations were assayed by HPLC. Pharmacokinetic properties were determined by ordinary least squares fitting of the two compartment pharmacokinetic model to the experimental data. A good correlation between plasma and saliva data has been demonstrated. The saliva to venous plasma drug concentration ratio S/P appeared to be time-dependent in the case of norfloxacin and pefloxacin. It was demonstrated that S/P is a function of the quotient of the rate of absorption and venous plasma drug concentration. The calculated S/P ratios with the influence of absorption eliminated, (S/P)(corr) are: ciprofloxacin 0.53+/-0.02, norfloxacin 0.34+/-0.04, ofloxacin 0. 43+/-0.02 and pefloxacin 0.39+/-0.02 (mean+/-S.E.). These values are apparently independent of log D thus making it impossible to predict S/P on the basis of partition principles. The corresponding (S/P)(dif) ratios were calculated on the basis of the assumption that an equilibrium is established across the blood-saliva barrier, which is permeable only for nonionized and nonprotein bound drug fraction. Comparing (S/P)(corr) with the calculated (S/P)(dif) ratios it is evident that 4-fluoroquinolone permeation in saliva cannot be described by passive diffusion based on pH-partition theory.