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B Shaikh

Publications and source records attributed to B Shaikh.

At least 19 recordsLinked to original sources
PubMed2006

Metabolism and depletion of albendazole in the muscle tissue of channel catfish following oral treatment.

The residue depletion of albendazole (ABZ) and its metabolites was studied in channel catfish muscle tissue. Channel catfish were dosed once with 10 mg/kg ABZ via stomach tube with manual restraint. Muscle tissue samples were collected at 8, 16, 24, 48, 72, 96 and 120 h postdose. A high-performance liquid chromatographic method was used to assay ABZ and its major metabolites: ABZ sulfoxide (ABZ-SO), ABZ sulfone (ABZ-SO2) and ABZ aminosulfone (ABZ-2-NH2SO2) in the muscle tissue. The results indicate that ABZ and ABZ-SO were present in low concentrations, i.e. <15 and <10 microg/kg, respectively, at 8 h postdose in catfish muscle with and without skin. ABZ-SO2 was present at 1 microg/kg concentration levels until 48 h in muscle alone and 72 h in muscle with skin. ABZ-2-NH2SO2 was not detected at any withdrawal periods.

Administration, Oral↗
PubMed2004

Determination of 14C residue in eggs of laying hens administered orally with [14C] sulfaquinoxaline.

Ten layer hens were dosed for 5 consecutive days with 6.2 mg kg(-1) [14C] sulfaquinoxaline (SQX). Eggs were collected from the hens during the 5-day dosing period and during a 10-day post-dose withdrawal period. Egg yolk and albumen were separated and assayed for total radioactive residues (TRR) using a combustion oxidizer and liquid scintillation counting techniques. Significant amounts of radioactivity were detected on the second day of dosing (greater than 24h after the initial dose) in both egg yolk and albumen. First eggs were collected about 8 h after dosing; the second-day eggs were collected during 8-h period after the second dose. Radioactive residues reached a maximum on the fifth day of dosing in albumen, whereas on the second day of withdrawal in egg yolk, the peak TRR levels in albumen were about threefold higher than in yolk. Thereafter, the TRR levels declined rapidly in albumen and were detectable up to withdrawal day 6, whereas the TRR levels in egg yolk declined more slowly and were detectable up to withdrawal day 10. High-performance liquid chromatography analysis indicated that the parent drug sulfaquinoxaline was the major component in both the egg albumen and yolk. Additionally, this work suggests that egg yolk is the appropriate matrix for monitoring SQX residues

Administration, Oral↗
PubMed2003

Metabolism and residue depletion of albendazole and its metabolites in rainbow trout, tilapia and Atlantic salmon after oral administration.

Metabolic and residue depletion profiles of albendazole (ABZ) and its major metabolites in three fish species, rainbow trout, tilapia and Atlantic salmon are reported. Based on these profiles, similarities (or dissimilarities) between species will determine the potential to group fish species. ABZ at 10 mg/kg body weight was incorporated into fish food formulated in a gelatin base or in gel capsule and fed as a single dose to six fish from each species. Rainbow trout were held three each in a partitioned 600-L tank. Tilapia and Atlantic salmon were housed in separate 20-L tanks. Samples of muscle with adhering skin were collected at 8, 12, 18, 24, 48, 72, and 96 h postdose from trout kept at 12 degrees C, at 4, 8, 12, 24, 48, 72, 96, 120, and 144 h postdose from tilapia kept at 25 degrees C and at 8, 14, 24, 48, 72, and 96 h postdose from Atlantic salmon kept at 15 degrees C. The samples were homogenized in dry ice and subjected to extraction and cleanup procedures. The final extracts were analyzed for parent drug ABZ and its major metabolites, albendazole sulfoxide (ABZ-SO), albendazole sulfone (ABZ-SO2) and albendazole aminosulfone using high-performance liquid chromatography with fluorescence detection. ABZ was depleted by 24 h in trout and tilapia and by 48 h in salmon; ABZ-SO, a pharmacologically active metabolite, was depleted by 48 h in tilapia, by 72 h in rainbow trout and was present until 96 h in salmon; and low levels of ABZ-SO2 and albendazole aminosulfone, both inactive metabolites, were detectable at least till 96 h in all three fish species.

Administration, Oral↗
PubMed2000

Determination of total 14C residues of sarafloxacin in eggs of laying hens.

[14C]sarafloxacin was orally administered to six laying hens for five consecutive days. Eggs were collected for 15 days after the initial drug treatment. Egg yolk and egg albumen were separated and assayed for total radioactive residues (TRR) using a combustion oxidizer and scintillation counting techniques. Radioactivity was detected in egg yolk and egg albumen on the second day of dosing and reached a maximum at 24 h after drug withdrawal. Thereafter, the sarafloxacin TRR levels in egg albumen declined rapidly and were undetectable 2 days after the last dose, whereas the levels in egg yolk declined at a much slower rate and were undetectable 7 days after drug withdrawal. In both the egg albumen and yolk, HPLC analysis indicated that the parent sarafloxacin was the major component.

Administration, Oral↗
PubMed2000

Distribution of total 14C residue in egg yolk, albumen, and tissues following oral [14C]sulfamethazine administration to hens.

The distribution of total 14C residues was studied in egg yolk and albumen after administration of either single or multiple oral dosages of [14C]sulfamethazine (SMZ). One day after a single dose of [14C]SMZ (121 mg of sulfamethazine, 2.42 x 10(7) dpm), the 14C residue concentration peaked in egg albumen and egg yolk with the concentration in the former >4-fold greater than in the latter. Three days postdose, the 14C residue concentration in the yolk was approximately 7-fold higher than in the egg albumen. A multiple dose of [14C]SMZ containing sulfamethazine mass equivalent of an average therapeutic dose (282 mg, 2.9 x 10(7) dpm) for chickens was also administered orally for six consecutive days to hens. A significantly reduced level of egg production was observed during the medication, and most of the hens stopped laying eggs after the last dose. The 14C residue concentrations peaked on the last day (sixth) of medication in egg albumen and yolk. The 14C residue concentrations were also measured in liver, muscle, blood, and plasma of chickens sacrificed at 1, 24, 48, and 72 h after the last dose. Highest concentrations of 14C residue were accumulated in liver followed by, in decreasing order, blood, plasma, and muscle.

Administration, Oral↗
PubMed1998

Determination of trichlormethiazide in bovine milk by high-performance liquid chromatography.

A liquid chromatographic procedure was developed and validated for the quantitative determination of trichlormethiazide (TCMTZ) in bovine milk. Whole milk was defatted by initial centrifugation at 4 degrees C. The resulting skim milk was treated with lead acetate and acetonitrile, vortex mixed, and centrifuged. The acetonitrile from the supernatant was back extracted in ethyl acetate. The organic solvent mixture which contained TCMTZ was further treated with sodium tungstate, vortex mixed, and centrifuged. The top organic layer was removed and evaporated to dryness; the resulting residue was reconstituted in the mobile phase, and the final extract was analyzed by high-performance liquid chromatography (HPLC). The HPLC conditions employed included a polymer column, a mobile phase consisting of 30% acetonitrile or 30% acetonitrile-tetrahydrofuran (2:1, v/v) in a phosphate buffer (pH 3), and a UV detection at 225 nm. The average recoveries of TCMTZ from milk fortified at 7, 14, 35, 70, and 140 ppb were 88, 93, 117, 110, and 99%, respectively, with corresponding C.V. values of 7, 18, 11, 9, and 21%. The method was validated by assaying milk obtained from a cow dosed with Naquasone. TCMTZ concentration was detected only in the 8 h post dose milk samples and was determined to be 6 ppb.

Animals↗
PubMed1997

Determination of gentamicin in bovine milk using liquid chromatography with post-column derivatization and fluorescence detection.

A method capable of separating and quantifying the three major and one minor components of gentamicin in milk has been developed. The method is capable of detecting 15 ng/ml gentamicin, based on a total of the four components. Milk samples are centrifuged at 4 degrees C, the fat layer removed, and the samples deproteinated with 30% trichloracetic acid. After a second centrifugation, the supernatant is passed through a C18 solid-phase extraction column. The column is washed with water, water-methanol (50:50) and methanol. Ammonium hydroxide (16%) in methanol is used to elute the gentamicin. The eluent is evaporated to near dryness and taken up with water. An aliquot of the sample is then mixed with an ion-pairing reagent for chromatography. Separation is achieved using pentanesulfonic acid in a water-methanol mobile phase on a C18 reversed-phase column. The o-phthalaldehyde fluorescence derivatives of gentamicin are formed post-column and are detected with excitation at 340 nm and emission at 430 nm. The percent recovery of gentamicin averaged 72, 78 and 88% from milk samples fortified at 15, 30 and 60 ng/ml, respectively.

Animals↗
PubMed1994

Disposition and bioavailability of neomycin in Holstein calves.

The disposition and absorption kinetics of neomycin were studied in healthy ruminating dairy calves (n = 6), approximately 3-months-old. The calves were treated with single intravenous (i.v.) (12 mg/kg), intramuscular (i.m.) (24 mg/kg), oral (p.o.) (96 mg/kg) and repeated p.o. (96 mg/kg, b.i.d., 15 1/2 days) doses of neomycin. A 3-week rest period was allowed between treatments A and B, and B and C. Baseline and serial venous blood samples were collected from each calf. Plasma concentrations of neomycin were determined by a high performance liquid chromatography procedure. The resulting data were evaluated by using compartmental pharmacokinetic models and nonlinear least squares regression analysis. The mean of some selected parameters were t1/2 lambda 3 7.48 +/- 2.02 h, Clt = 0.25 +/- 0.04 L/h/kg, Vd(ss) = 1.17 +/- 0.23 L/kg, and MRT = 4.63 +/- 0.87 h for the i.v. data and t1/2 = 11.5 +/- 3.8 h, MRTabs = 0.960 +/- 1.001 h, F = 127 +/- 35.2%, and Clt/F = 0.199 +/- 0.047 L/h/kg for the i.m. data, respectively. Only one calf absorbed neomycin to any significant degree (F = 0.0042) after a single p.o. dose. Selected mean parameters determined after repeated oral dosing were: F = 0.45 +/- 0.45%, Cmax = 0.26 +/- 0.37 microgram/ml, and tmax = 2.6 +/- 2.9 h. Terminal half-lives determined for the i.v. and i.m. treatments were considerably longer than those reported previously in the literature.

Animals↗
PubMed1993

Liquid chromatographic analysis of antibacterial drug residues in food products of animal origin.

This paper reviews recent developments in the liquid chromatographic (LC) methods of analysis for the residues of antibiotics (aminoglycosides, chloramphenicol, sulfonamides, tetracyclines, macrolides, beta-lactams, etc.) in food products of animal origin. The review also covers clean-up procedures, such as, ultrafiltration, liquid-liquid partition, solid-phase extraction, immunoaffinity, and matrix solid-phase dispersion, for use as extraction, deproteination, and concentration steps. The LC methods offer considerable potential for rapid automated analysis, and some may be used as direct screening for residues in meat and milk.

Animals↗
PubMed1991

Determination of neomycin in plasma and urine by high-performance liquid chromatography. Application to a preliminary pharmacokinetic study.

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of neomycin in plasma and urine. The plasma was deproteinated with trichloroacetic acid and centrifuged. The supernatant was mixed with ion-pair concentrate and centrifuged again. The resultant supernatant was analyzed by HPLC. Urine was centrifuged to remove debris, if any, mixed with ion-pair concentrate and analyzed directly by HPLC. The HPLC conditions consisted of an ion-pairing mobile phase, a reversed-phase column, post-column derivatization with o-phthalaldehyde (OPA) reagent and fluorescence detection. The overall average recovery of neomycin was 97 and 113% from plasma spiked at 0.25-1.0 micrograms/ml, using standard curves prepared in plasma extract and in water, respectively, and 94% for urine spiked at 1-10 micrograms/ml using a standard curve prepared in water. The method was used to detect neomycin in plasma and urine obtained from animals injected intramuscularly with neomycin. Various pharmacokinetic parameters of neomycin were also determined from its profile of plasma concentration versus time.

Animals↗
PubMed1988

Californium-252 plasma desorption mass spectrometry of aminoglycoside antibiotics.

This paper presents mass spectral data of eleven aminoglycoside antibiotics by using californium-252 plasma desorption (252Cf PD) mass spectrometry. This mass spectral data could be used to develop a confirmatory method for monitoring aminoglycoside antibiotic residues isolated from food products of animal origin. Mass spectra were determined by applying time-of-flight 252Cf PD mass spectrometry to eleven aminoglycoside antibiotics, namely: neomycin, kanamycin, paromomycin, tobramycin, apramycin, streptomycin, dihydrostreptomycin, amikacin, netilmicin, sisomicin and gentamicins. All eleven antibiotics yielded positive ion spectra. These hydrophilic antibiotics were derivitized to extractable chromopheric compounds. All but two antibiotics (streptomycin and dihydrostreptomycin) yielded nitrophenyl derivatives and spectra were obtained in both negative and positive ion modes. Derivatized aminoglycosides produced cation and anion spectra with quasimolecular ions corresponding to [M + H]+., M+, [M - H]-., [M + Na]+, [M + K]+ and M-. or [M - H]- and M-. or [M - H]-. Underivatized antibiotics were best examined in the positive ion mode. 252Cf PD mass spectrometry consistently produced very strong molecular or quasimolecular ions for all aminoglycoside antibiotics.

Aminoglycosides↗
PubMed1986

Reducing the effect of chemiluminescence on the efficiency of extracting 14C-neomycin from fortified kidney tissue as measured by a liquid scintillation system.

Extraction efficiency was monitored, using 14C-neomycin and liquid scintillation counting, during development of a procedure to isolate neomycin from fortified kidney tissue. Chemiluminescence caused 119% false positive recovery at 0.16 ppm neomycin (1260 disintegrations/min (dpm) activity). However, the contribution of chemiluminescence to false positive recovery was negligible above 8 ppm neomycin (63,000 dpm activity). To reduce chemiluminescence, fortified kidney tissue was extracted with saline by homogenization, mixed with Protosol at 70 degrees C for 1 h, cooled 5 min at 4 degrees C and neutralized with acetic acid. The digest was mixed with Aquasol and incubated 1 h at 47 degrees C, followed by equilibration for 2 h in the counter. The procedure allows reliable monitoring of extraction efficiency down to about 407 dpm activity from 14C-neomycin (0.05 ppm) with maximum chemiluminescence of about 4%.

Animals↗
PubMed1982

Synthesis of primary bile acids by rat liver epithelial cell-lines.

Several lipid metabolites were identified in liver epithelial cell-lines established from different strains of rats, using high performances liquid chromatographic techniques. [14C]-acetate was shown to be incorporated by these cultured cells into cholesterol, 7 alpha-hydroxycholesterol and the primary bile acids. Labeled cholesterol was localized in the cells whereas cholic and chenodeoxycholic acids were found in the culture medium as conjugates of taurine and glycine. These conjugated primary bile acids were also detected in the extracts of culture medium, after separating them using reverse phase thin layer chromatography. Therefore, the cultured rat liver cells retain the liver-specific property of synthesizing bile acids, even after they become cell-lines.

Acetates↗
PubMed1981

High performance liquid chromatographic determination of methapyrilene hydrochloride in feed and sleep aid tablets.

Methapyrilene hydrochloride (MP-HCl) was extracted from feed with methanol and determined by reverse phase partition chromatography in less than 15 min, using isocratic elution with acetonitrile-1.1% ammonium carbonate (1 + 1) as the mobile phase. This procedure was tested on feed treated with MP-HCl at levels of 125, 500, and 2000 ppm. Recoveries were 104, 95, and 96% with coefficients of variation of 2.4, 1.6, and 0.6%, respectively. MP-HCl in feed was stable for 14 days. This method was also successfully used to determine MP-HCl in 3 sleep aid tablets.

Aminopyridines↗