Analysis of protein-bound metabolites of furazolidone and furaltadone in pig liver by high-performance liquid chromatography and liquid chromatography-mass spectrometry

Studies undertaken using radiolabelled furazolidone have demonstrated the covalent binding of residues of the drug to cellular protein in vivo. A portion of these bound residues and those formed by furaltadone, a related nitrofuran drug, possess intact side-chains, 3-amino-2-oxazolidinone (AOZ) and 5-morpholino-methyl-3-amino-2-oxazolidinone (AMOZ), respectively. These side-chains have molecular characteristics in common with the parent compounds and may be released from liver tissue under mild acidic conditions. Derivatization with 2-nitrobenzaldehyde (NBA) serves to isolate the released side-chains and the derivatives NPAOZ and NPAMOZ are chromophoric, thereby permitting UV detection. This paper reports the introduction of an extract clean-up step to the existing procedure which eliminates or decreases interference from NBA in the HPLC-UV determination of NPAOZ. The modified procedure was also applied to the determination of AMOZ. The development of an LC-MS method for the quantitative and confirmatory determination of AOZ and AMOZ extracted and derivatized according to the same procedure as that for HPLC-UV is described. The methods were validated for AOZ and AMOZ in fortified (intra- and inter-assay studies) and incurred (inter-assay studies) pig liver samples. The limit of determination for fortified control liver samples was 5 ng AOZ g-1 and 10 ng AMOZ g-1 by HPLC-UV and 10 ng AOZ or AMOZ g-1 by LC-MS. In addition, a study to determine the ratio of released AOZ to the total bound residues present in incurred liver samples from pigs treated with furazolidone is described.

Determination of furazolidone in porcine tissue using thermospray liquid chromatography-mass spectrometry and a study of the pharmacokinetics and stability of its residues

A method is presented for the detection of the nitrofuran, furazolidone, in porcine tissue. Following methanol-buffer extraction of the tissue, liquid partitioning, and solid-phase clean-up, samples are analysed by using thermospray LC-MS monitoring the positive ion m/z 243 with filament-assisted ionization. The LOD is 1 microgram kg-1. The assay is used to investigate the depletion of furazolidone from tissue and sample stability post mortem. It is necessary to snap-freeze samples by immersion in liquid nitrogen immediately upon collection in order to improve the stability of residues in tissue.

Liquid chromatographic determination of furazolidone in swine serum and avian egg

A rapid, simple, and accurate method for determination of furazolidone (FZ) in swine serum and avian egg using liquid chromatography (LC) with a 358 nm ultraviolet-visible spectrophotometric detector is described. After liquid-liquid extraction of sample with ethyl acetate using Extrelut-3, the extract is evaporated, redissolved in 40% acetonitrile, and injected directly into the chromatograph. The antibiotic can be analyzed within 30 min. Within-day recoveries for swine serum and avian egg spiked with FZ at 1 ppm were 90.0 and 88.1%, respectively, with coefficients of variation of 3.52 and 3.88%, respectively. Between days recoveries for the 1 ppm samples were 87.2 and 87.0%, with coefficients of variation of 3.10 and 4.29%, respectively. Determination of FZ also was performed by LC/mass spectrometry (MS) with an atmospheric-pressure chemical-ionization interface (APCI) system. The LC/MS-APCI system is more applicable for qualitative analysis than quantitative analysis because the drug detection limit (about 0.1 microgram/L) is almost the same as that of the LC-UV detector.

Liquid chromatographic determination of furazolidone in shrimp

A liquid chromatographic (LC) method was developed for the quantitation of furazolidone residues in shrimp muscle. The shrimp homogenate (1.0 g) is extracted with acetonitrile, and the extract is taken to dryness. The residue is dissolved in acetonitrile, and the solution is passed through alumina and C18 cleanup columns. The eluate is taken to dryness and reconstituted in a suitable solvent for reversed-phase (C18) LC with UV detection at 365 nm. Recoveries of furazolidone from shrimp homogenates spiked from 5 to 80 ng/g ranged from 74.3 to 79.7%, and relative standard deviations (RSDs) were 5.0-8.9%. RSDs for incurred furazolidone quantitated at 5.9 and 9.2 ng/g were 6.6 and 7.6%, respectively.

Simultaneous determination of nitrofurazone, nitrofurantoin, and furazolidone in channel catfish (Ictalurus punctatus) muscle tissue by liquid chromatography

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitrofurazone (NFZ), nitrofurantoin (NFT), and furazolidone (FZD) in catfish muscle tissue. The drugs were extracted from the tissue with acetonitrile, and the lipids were removed from the extract with hexane. The acetonitrile extract was evaporated by rotary evaporation, and the resultant drug residues were dissolved with LC mobile phase. The mixture was sonicated, centrifuged, and filtered. The drugs were determined by using LC with a C18 reversed-phase (ODS Hypersil) column, a mobile phase of acetonitrile-1% aqueous acetic acid (25 + 75), and a photodiode array ultraviolet detector at 375 nm. NFZ, NFT, and FZD were each determined in catfish tissue at 5 fortification levels (80, 40, 20, 10, and 5 ng drug/g tissue). Average recoveries of each of the 3 drugs at each level ranged from 70.7 to 101.5%, and relative standard deviations ranged from 2.2 to 18.6%. The limit of detection of each drug was approximately 1 ng drug/g tissue, and the limit of quantitation was 5 ng drug/g tissue. In the second part of the study, the method was used to determine nitrofuran residues incurred in catfish tissue. Live channel catfish were intravascularly doses (10 mg/kg body wt) with NFZ to generate drug-incurred fish muscle tissue. Incurred NFZ levels exceeded 400 ng drug/g tissue at 2 h after dosing but decreased rapidly to approximately 1 ng drug/g tissue by 8 h after dosing, as determined by this method.

Simultaneous determination of nitrofurazone and furazolidone in shrimp (Penaeus vannamei) muscle tissue by liquid chromatography with UV detection

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitrofurazone (NFZ) and furazolidone (FZD) in shrimp muscle tissue. The drugs are extracted from the tissue with acetonitrile, and the lipids and lipophilic pigments are removed from the extract with hexane. The remaining acetonitrile extract is evaporated by rotary evaporation, and the resultant residues are dissolved with LC-grade water, applied to a preconditioned C18 solid-phase extraction column, and eluted with acetonitrile. The acetonitrile eluant is then dried under nitrogen, and the resultant drug residues are dissolved with mobile phase and filtered. The drugs are determined by LC by using a C18 reversed-phase (octyldecylsilyl Hypersil) column, a mobile phase of acetonitrile--1% aqueous acetic acid (25 + 75, v/v), and a photodiode array UV detector at 375 nm. NFZ and FZD were determined in shrimp tissue at each of 5 spiking levels (64, 32, 16, 8, and 4 ng drug/g tissue). Absolute recoveries ranged from 70.6 to 78.4%, and relative standard deviations ranged from 4.0 to 13.6%. The limit of detection of pure standard of each drug was approximately the equivalent of 1 ng drug/g tissue, and the limit of determination in a sample was 4 ng drug/g tissue.

Liquid chromatography-electrochemical detection of furazolidone and metabolite in extracts of incurred tissues

One-day-old chicks were raised to maturity on a diet fortified with 0.0055% furazolidone. Analyses of tissue extracts by a liquid chromatographic-electrochemical detection screening procedure for nitro-containing drugs disclosed, in addition to the parent drug, an unidentified metabolite in the liver and breast tissue of the mature birds sacrificed while on the fortified feed. No evidence of residues of the drug or metabolite was found in birds removed from the medicated feed 48 h prior to sacrifice. In view of the rapid in vivo and postmortem metabolism of the parent drug in liver tissue, the metabolite can serve as an alternative means of detecting furazolidone residues in chicken tissues.

Detection of furazolidone in human biological fluids by high performance liquid chromatography

Furazolidone has normally been administered as a non-absorbable antimicrobial agent for use in gastrointestinal infections. However, in India and Mexico it has been used successfully for the treatment of typhoid fever. We measured concentrations of furazolidone by high performance liquid chromatography (HPLC) in several biological fluids, after a single oral dose (5 mg/kg). Six healthy adult volunteers and seven children with typhoid fever and ten children with purulent meningitis were studied. In adults the peak serum concentration was less than or equal to 0.84 mg/l and less than or equal to 4.78% of the ingested dose was excreted in the urine. In the children concentrations were similar to those found in volunteers. The cerebrospinal fluid/serum ratio ranged from 1.02 to 5.95 in the meningitis patients. HPLC is a rapid and sensitive method for the quantitation of furazolidone in biological fluids. The minimum detectable concentration was 0.05 mg/l, with a precision of 6% from peak area and an average recovery of 98%.

Liquid chromatographic method for determination of furazolidone in premixes and complete feeds: collaborative study

A liquid chromatographic (LC) method for determining furazolidone in finished feeds and premixes was collaboratively studied. Finished feed sample is extracted with acetone-water (93 + 7) on a Goldfisch apparatus, extracting solvent is removed, and the residual material is dissolved in warm DMF. A solution of tetraethylammonium bromide is added, the fat layer is removed, and the sample is clarified by filtration and injected onto a reverse phase LC system with detection at 365 nm. Premixes, extracted by shaking with DMF and diluted so that the final furazolidone concentration is about 55 micrograms/mL, are chromatographed and detected the same as finished feed samples, using a mobile phase of acetonitrile-2% acetic acid (20 + 80). Ten commercial feed samples were preweighed and supplied to 14 collaborators. The 5 matched pairs were chosen to represent the following allowed levels: 0.0055, 0.022, 0.033, 2.2, and 22%. Two familiarization samples at the 0.0055 and 11% levels were also supplied. Instructions called for a single analysis of each sample. Two results were eliminated by the Dixon test. The coefficients of variation, following treatment by the ranking test, ranged from 2.0 at the 22% level to 6.5 at the 0.0055% level. Calculated F-values are not significant (P greater than 0.01) except for the 0.0055% level samples extracted overnight. This method has been adopted official first action.

Liquid chromatographic monitoring of the depletion of carbadox and its metabolite desoxycarbadox in swine tissues

A liquid chromatographic method was used to monitor a depletion study of carbadox (and its most important metabolite, desoxycarbadox) in young pigs fed carbadox-treated rations for 1 week. Carbadox was found in blood (20 ppb), blood serum (26 ppb), and muscle tissue 24 h after withdrawal from treated ration; residues were reduced to a trace (less than 2 ppb) in 48 h, and eliminated by 72 h. Desoxycarbadox, although not detected in blood, was found in muscle (17 ppb) 24 h after withdrawal; it was reduced to 9 ppb at 48 h and to a trace by 72 h. Although no carbadox was detected in liver 24 h after withdrawal, appreciable desoxycarbadox (125 ppb) was found in liver 24 h after withdrawal; it was reduced to 17 ppb at 48 h and to a trace by 72 h. Whereas only a trace of carbadox was found in kidney 24 h after withdrawal, 186 ppb desoxycarbadox was found in kidney at 24 h, 34 ppb at 48 h, and a trace at 72 h. No metabolite of carbadox other than desoxycarbadox was found in extracts of swine tissues during this medicated feed trial, and no metabolite was found in blood extracts by using the established methodology. The effect of tissue storage (aging) at -20 degrees C on levels of the drug and its metabolite was a modest alteration of residue levels. The inadvertent use of feed adulterated with furazolidone and initially medicated with chlortetracycline, sulfamethazine, and penicillin G, did not affect the uptake of carbadox in this depletion study or interfere with the analytical methodology.

Determination of furazolidone residues in eggs by HPLC followed by confirmation with a diode-array UV/Vis detector

A sensitive HPLC method for the determination of furazolidone residues in eggs (10-1,000 micrograms/kg) is described. Recovery is about 86%. With the aid of a UV/Vis Diode-Array detector confirmation up to the 15-ppb level was possible. In order to test this method with "real" samples, three laying hens received 30 mg each of furazolidone in feed (single dose). The eggs were collected for five days. After five days traces of furazolidone (5 micrograms/kg) could still be detected.

Furazolidone residues in chicken and swine tissues after feeding trials

Broiler chickens and swine fed furazolidone in their diet were sacrificed, and samples of liver, kidney, skin/fat and muscle were harvested and analyzed for furazolidone residue. Chickens fed 200 g of furazolidone/ton of feed were withdrawn from treatment 21, 14, 7, 5, 3, or 0 days before slaughter. Birds withdrawn from medication more than 5 days prior to slaughter had no residues in any of the tissues sampled. One of the 12 birds in each of the 5 day and 3 day withdrawal groups had detectable residues in the skin/fat. Seven of the 12 birds in the 0 day withdrawal group had residues of less than 2 ppb in skin/fat samples. Chickens fed 400 g furazolidone/ton of feed were withdrawn from treatment 0 days before slaughter. Residues of 0.7 to 3.5 ppb were found in the skin of these birds; residues were not found in other tissues. Swine were fed 300 g furazolidone/ton of feed for 2 weeks or 150 g/ton for 5 weeks. They were withdrawn from treatment 10, 7, 5, 3, or 0 days before slaughter. Tissue samples taken from these swine did not contain detectable furazolidone residues.

High pressure liquid chromatographic determination of nitrofurazone and furazolidone in chicken and pork tissues

A high pressure liquid chromatographic (HPLC) procedure is presented for the determination of nitrofurazone and furazolidone in chicken and pork tissues in the 2-40 ppb range. Muscle, liver, and kidney are homogenized with cold methanol and water (50 + 50). Following methanol evaporation, the nitrofurans are partitioned into ethyl acetate and cleaned up on an alumina column. After elution with 20% methanol in ethyl acetate and evaporation to dryness, residues are determined by HPLC, using a reverse phase analytical column. Overall average recoveries for nitrofurazone and furazolidone were 65.7 and 73.5%, respectively. Average relative standard deviations of 11.9% (nitrofurazone) and 9.5% (furazolidone) at the 2 ppb level were achieved.

Some pharmacological and toxicological properties of furazolidone

The pharmacological and toxicological properties of furazolidone have been briefly reviewed. Among the most important pharmacological actions of furazolidone is the inhibition of mono- and diamine oxidase activities, which seem to depend, at least in some species, on the presence of the gut flora. The drug also seems to interfere with the utilization of thiamin, which is probably instrumental in the production of anorexia and loss of body weight of the treated animals. Furazolidone is known to induce a condition of cardiomyopathy in turkeys, which could be used as a model to study alpha 1-antitrypsin deficiency in man. The drug is most toxic to ruminants. The toxic signs observed were of nervous nature. Experiments are in progress in this laboratory to try to explain the mechanism(s) by which this toxicity is brought about. It is uncertain whether the use of furazolidone at the recommended therapeutic dose would result in drug residues in tissues of treated animals. This is a matter of public health importance as the drug has been shown to possess a carcinogenic activity. It is important that a simple and reliable method of identification and estimation of furazolidone residues be devised. More work is needed to elucidate the mode of action and biochemical effects caused by the drug in both the host and the infective organisms.

Furazolidone in turkey tissues following a 14-day feeding trial

Feed supplemented with furazolidone was fed to turkeys on a research farm near Modesto, CA. The birds fed furazolidone-medicated feed were housed in isolated pens in a manner to prevent any cross contamination from an adjoining treatment. Furazolidone-medicated feed was supplied to the ration for 14 days prior to withdrawal with two exceptions; the controls were not fed medicated feed, and a 400 g/ton treatment was fed for 24 hr prior to processing. Treatments, representing different withdrawal periods, ranged from 0 to 21 days. Two 400 g/ton treatments with 0-day withdrawal periods were included in the study. One of these treatments involved a 14-day medicated feeding period while the other was for 24 hr. All other treatments were fed medicated feed at the rate of 200 g/ton. Tissue samples from the processed birds included skin, fat, liver, kidney, as well as breast and thigh muscle. No detectable residues were found in any of the liver, kidney, fat, or muscle tissues at any of the withdrawal periods including the 0-day withdrawal groups. Skin tissues contained detectable furazolidone residues only in the 0-day withdrawal treatments, and even these levels were below the 2 ppb level.

Ultra trace determination of furazolidone in turkey tissues by liquid partitioning and high performance liquid chromatography

A simple and sensitive procedure is presented for the determination of furazolidone in turkey tissues, using liquid partitioning followed by high performance liquid chromatography (HPLC). Fat, liver, kidney, skin, and muscle tissues are ground with methylene chloride in a Polytron homogenizer, followed by solvent removal, partitioning in hexane-0.01M acetic acid, and back-partitioning the 0.01M acetic acid with methylene chloride. The determination by HPLC used a reverse phase Ultrasphere-ODS 5 micrometer column. The method is sensitive to 0.5 ppb, with a standard deviation of 6.39% at the 2 ppb fortification level. Recovery from fortified tissues averaged 84% from samples fortified with 0.5-10 ppb furazolidone. An alternative cleanup procedure using a Sep-Pak C18 cartridge is also presented.

High performance liquid chromatographic determination of furazolidone in feed and feed premixes

Furazolidone is separated from finished feeds by acetone-water extraction on a Goldfisch apparatus. Extracting solvent is removed, and the residue is dissolved in dimethylformamide-5% tetraethylammonium bromide (1 +1), clarified, and chromatographed on a reverse phase C1 column. The mobile phase is CH3CN-2% acetic acid (20 + 80) with detection at 365 nm. The method was tested for linearity, recovery, and ruggedness, and compared with the AOAC colorimetric assay by using field samples containing 0.0055-0.055% furazolidone. Precision data suggest a cumulative relative standard deviation of 1.43% within days and 1.78% between days. The ruggedness test predicts a between-laboratory relative standard deviation of 3.67%. Recovery was 97.5 +/- 2.0% and linearity was excellent (r2 = 0.9994) up to 0.06% furazolidone. Premixes are extracted by shaking with dimethylformamide. An aliquot of the extract is diluted (1 + 1) with 5% tetraethylammonium bromide, clarified, and chromatographed.

Simultaneous spectrophotometric determination of nifuroxime and furazolidone in pharmaceutical preparations

Two spectrophotometric methods have been developed for the simultaneous determination of nifuroxime and furazolidone in their pharmaceutical preparations. No preliminary separation step is required in either method. The first, a modified Vierordt method, gives accurate and reproducible results for both drugs. Mean percent recoveries for nifuroxime and furazolidone were 99.50 +/- 1.59 and 100.20 +/- 1.16 (P = 0.05), respectively. This method also gives accurate and reproducible results for the determination of nifuroxime and furazolidone in their pharmaceutical preparations: Tricofuran vaginal suppositories and powder. The second method, which involves the use of the first-derivative curves, gives unreliable results; the reasons for these are discussed.

Sample preparation of carbadox, furazolidone, nitrofurazone, and ethopabate in medicated feeds for high pressure liquid chromatography

Medicated feeds (pelleted or mash) containing guarantees of carbadox, furazolidone, nitrofurazone, and ethopabate are pretreated with water, extracted with 95% dimethylformamide overnight at room temperature, cleaned up on a column of alumina, and injected into a high pressure liquid chromatograph for quantitative measurement. Carbadox, nitrofurazone, and furazolidone can be separated; chromatograms show excellent baseline resolution, and results are in good agreement with colorimetric methods. The same extraction and cleanup can be used to improve colorimetric methods for furazolidone and nitrofurazone.