Drugs online research references
J Chromatogr. 1991 Apr 5;564(2):567-78.
Rapid high-performance liquid chromatographic determination with fluorescence detection of furosemide in human body fluids and its confirmation by gas chromatography-mass spectrometry.
Saugy M, Meuwly P, Munafo A, Rivier L.
Unite d'Analyse du Dopage, Universite de Lausanne, Switzerland.
Furosemide (FD: Lasix) is a loop diuretic which strongly increases both urine flow and electrolyte urinary excretion. Healthy volunteers were administered 40 mg orally (dissolved in water) and concentrations of FD were determined in serum and urine for up to 6 h for eight subjects, who absorbed water at a rate of 400 ml/h. Quantification was performed by HPLC with fluorescence detection (excitation at 233 nm, emission at 389 nm) with a limit of detection of 5 ng/ml for a 300-microliters sample. The elution of FD was completed within 4 min using a gradient of acetonitrile concentration rising from 30 to 50% in 0.08 M phosphoric acid. The delay to the peak serum concentration ranged from 60 to 120 min. FD was still easily measurable in the sera from all subjects 6 h after administration. In urine, the excretion rates reached their maximum between 1 and 3 h. The total amount of FD excreted in the urine averaged 11.2 mg (range 7.6-14.0 mg), with a mean urine volume of 3024 ml (range 2620-3596 ml). Moreover, the urine density was lower than 1.010 (recommended as an upper limit in doping analysis to screen diuretics) only for 2 h. An additional volunteer was administered 40 mg of FD and his urine was collected over a longer period. FD was still detectable 48 h after intake. Gas chromatography-mass spectrometry with different types of ionization was used to confirm the occurrence of FD after permethylation of the extract. Negative-ion chemical ionization, with ammonia as reactant gas, was found to be the most sensitive method of detection.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1874858&dopt=Abstract
J Pharm Sci. 1987 Sep;76(9):731-7.
Evidence for solid- and liquid-state interactions in a furosemide-polyvinylpyrrolidone solid dispersion.
Doherty C, York P.
Postgraduate School of Pharmacy, Bradford University, West Yorks, UK.
The solid-state interactions between furosemide (FUR) and polyvinylpyrrolidone (PVP) in a solid dispersion system have been investigated by dispersive and Fourier Transform IR. Using spectral subtraction procedures, shifts to lower frequencies are seen in FUR-NH stretching vibrations in amorphous FUR-PVP systems in comparison with the crystalline FUR spectrum. The magnitude of shifts are similar to those seen when FUR is dissolved in the hydrogen-bonding solvent 1,4 dioxan (0.015-0.155 M, 20 degrees C). Spectral assignment indicates the FUR sulfonamide group binds to PVP in preference to the FUR secondary amine which is shown to possess an intramolecular hydrogen bond by analysis of published X-ray crystal data. With a molecular graphics computer program, the FUR crystal unit cell was compiled, and analyses of nonbonded intermolecular distances are useful in interpreting IR shift data in amorphous solid dispersions. A study of FUR-PVP interactions in solution, examined by proton NMR, reveals a downfield shift of the FUR sulfonamide proton resonance. This shift exhibits dilution and temperature (298-338 K) dependence consistent with an intermolecular hydrogen bond. The secondary amine proton resonance exhibits temperature but not dilution or solvent bonding potential dependence, characteristics of an intramolecular hydrogen bond. The proposed hydrogen bond FUR-PVP interaction may account for the formation and stabilization of the amorphous solid dispersion.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11002811&dopt=Abstract
Am J Hosp Pharm. 1983 Apr;40(4):612-5.
Stability of three oral liquid drug products repackaged in unit dose containers.
Christensen JM, Lee RY, Parrott KA.
Stability of oral liquid forms of cimetidine hydrochloride, furosemide, and theophylline repackaged in polypropylene oral syringes and glass vials was assessed. Commercial preparations of each product were used; 2-ml quantities were placed in both types of container and stored at 4, 25, 44, 60, and 76 degrees C. Six samples from each container type at each temperature were tested at various times. Stability was defined as no greater than 10% loss of labeled potency. Assay was by high-performance liquid chromatography. All three drugs retained more than 90% of label claim in both types of containers after 180 days at 4 degrees C and 25 degrees C. For cimetidine hydrochloride and furosemide at these temperatures, there was no significant difference in concentration by container type; at the higher storage temperatures, the degradation rate in polypropylene syringes was significantly faster. For theophylline, loss of volume of 10% or greater occurred after 60 days at temperatures greater than 25 degrees C for both container types. Drug loss at higher temperatures was attributed to precipitation of theophylline out of the elixir rather than chemical degradation. Oral liquid cimetidine hydrochloride, furosemide, and theophylline repackaged in either polypropylene oral syringes or glass vials can be stored at 4 degrees C and 25 degrees C for 180 days with less than 10% loss of potency.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6846370&dopt=Abstract
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