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A rapid method for the quantitative analysis of radiopaque contrast media HPLC is described. Method can greatly help in solving problems of clinical and forensic interest.
[125I]iothalamic acid clearance is used for the estimation of glomerular filtration rate. Therefore, we developed a coupled-column liquid chromatography for the simultaneous determination of iothalamic acid and creatinine in human serum and urine samples to calculate their clearance. The liquid chromatograph consisted of an automatic injector, four columns and four switching valves. Timing of sample injection and switching of valves were controlled by a combination of timer units. Diluted samples were injected into a column of weakly acidic ion exchanger (Asahipak ES-502C, 30 degrees C, C1), and iothalamic acid excluded from the column was purified by gel chromatography on a hydrophilic gel (Asahipak GS-320H, 50 degrees C, C2) and then by ion exchange chromatography on a weakly basic anion exchanger (Asahipak ES-502N, 50 degrees C, C3). Creatinine that was eluted from C1 after iothalamic acid was transferred to Asahipak GS-320H (37 degrees C, C4) and C1 was backflushed until 10 min before the next sample was injected. Samples were injected every 55 min. The mobile phase was a sodium propionate buffer prepared by dissolving 0.035 mol of NaOH and 0.35 mol of propionic acid in 1 kg of ultra pure water, and its flow rate was 1.1 ml per min. Creatinine clearance calculated from the data obtained by this method was higher than that obtained by Jaffé's method, because serum creatinine concentrations obtained by this method were lower than those obtained by Jaffé's method. Iothalamic acid clearance (y) calculated from the data on serum and urine samples of clearance time 105-135 min showed a close correlation with inulin clearance (x) calculated from the data obtained by the anthrone method, for which aliquots of the same samples were used (y = 1.066 x -1.429 ml/min, r = 0.997, n = 15).
A paired ion reversed-phase high performance liquid chromatographic method for simultaneous determination of iothalamic acid (Io) and para aminohippuric acid (PAH) in urine is described. The method uses a single internal standard for both drugs. The only sample preparation required is dilution of urine (1:100 or 1:500) with deionized water. The internal standard is added to a small aliquot of the diluted specimen and injected. For HPLC, a C8 column and a mobile phase consisting of potassium phosphate buffer with dodecyl triethylammonium phosphate IP reagent, 25% organic modifier with UV detection at 254 nm was used. Within day and between day variation for the assay were in the range of 1.48-9.46% for iothalamic acid and 1.84-10.36% for para aminohippuric acid for four levels of concentration. Limits of quantitation were 50.0 micrograms ml-1 for iothalamic acid and 75.0 micrograms ml-1 for para aminohippuric acid. Mean recovery was 98.55% for Io and 97.79% for PAH. This isocratic HPLC assay is simple, rapid and relatively inexpensive.
A simple, rapid and sensitive method for the determination of iothalamic acid (IA) in both plasma and urine is reported. After extraction with ethyl acetate, IA was determined by strong anion-exchange high-performance liquid chromatography with ultraviolet detection at 254 nm. The lower limit of detection was 0.5 micrograms/ml. The average recovery was 73 and 57% from plasma and urine, respectively. Linearity was found over the investigated concentration range (up to 500 micrograms/ml for plasma and up to 10.0 mg/ml for urine). The reproducibility of the technique was good (coefficient of variation less than 6%) as was the precision and accuracy (coefficient of variation less than 2.5%). No interference from endogenous substances or any of the common drugs tested was found.
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A column-switching liquid chromatographic method for simultaneous determination of iothalamate and creatinine in human serum and urine was developed. Iothalamate and creatinine were separated on a weakly acidic ion-exchange column (C1) by ion-exclusion chromatography and iothalamate excluded from the column was purified by gel chromatography on a hydrophilic gel column (C2) and then by ion-exchange chromatography on a weakly basic ion-exchange column (C3). Creatinine that was eluted from C1 after iothalamate was transferred to a hydrophilic gel column (C4) and then to a strongly acidic ion-exchange column (C5). The mobile phase for C1-C4 was a pH 3.8 propionate buffer (propionic acid-NaOH = 0.35 + 0.035 mol/kg in water) and a pH 5.6 propionate buffer (propionic acid-NaOH = 0.04 + 0.035 mol/kg in water) was used for C5. Diluted serum and urine samples could be injected directly on to C1, as the matrix of C1 is hydrophilic and C1 is backflushed after the transfer of the creatinine fraction from C1 to C4. Iothalamate and creatinine in the eluates were determined by measuring their ultraviolet absorption at 245 and 234 nm, respectively. The precision (R.S.D.) of the chromatographic method was 1.6% (n = 7) and 0.36% (n = 6) for diluted serum and urine with iothalamate concentrations of 1.0 and 10.0 mumol/l, respectively, and 0.85% (n = 7) and 0.55% (n = 7) for diluted serum and urine with creatinine concentrations of 5.77 and 272 mumol/l, respectively.
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The effects of electrolytes, osmolality, pH, PaO2, PaCO2, hematocrit, blood volume and coagulation occurring after a rapid intra-aortic injection of a monomer and a dimer (salts of methylglucamine of the iothalamic and iocarmic acids) were compared. The effects of the monomer agreed with previous results but the effects of the dimer differed from those reported in the literature.
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The chemistry, clinical use, pharmacokinetics, adverse reactions, dosages, and formulary recommendations for intravascular ionic contrast media routinely used in radiologic procedures are reviewed. The meglumine, sodium, or combined meglumine-sodium salts of triiodinated benzoic acid derivatives, diatrizoic and iothalamic acid, are commonly used as intravascular ionic contrast media for radiographic visualization of blood vessels and the urinary tract. Meglumine salts of iodoxamate and iodipamide are used for intravenous cholangiography. The iodine in the contrast medium is responsible for the absorption of x-rays and the resulting opacification of the organ system or other area under investigation. Adverse reactions to intravascular ionic contrast media broadly include hypersensitivity and chemotoxic reactions. The incidence of major life-threatening hypersensitivity reactions, such as severe hypotension, cardiac arrhythmias or arrest, pulmonary or laryngeal edema, and convulsions, is estimated at 0.01-0.1% of the population receiving these agents. Dose- and concentration-dependent chemotoxic reactions result from the direct effects of the contrast medium on the blood vessels or organs being perfused. The meglumine salts of diatrizoic acid and iothalamic acid are less toxic in the cerebral circulation than sodium salts; hence, diatrizoate meglumine or iothalamate meglumine are recommended for cerebral angiography. In coronary angiographic examinations, combined meglumine and sodium (6.6 parts meglumine to 1 part sodium) formulations of diatrizoate are recommended because they consist predominantly of the meglumine salt with minimal but adequate amounts of sodium to prevent ventricular fibrillation. Predominantly meglumine salts of diatrizoic and iothalamic acid are also used for peripheral angiography, computerized tomography, and digital subtraction angiography. The dosages of ionic contrast media vary considerably depending on the nature of the radiological examination, the respective technique employed, and the age and condition of the patient. The cost differences between diatrizoate and iothalamate media are typically minimal. Formulary recommendations regarding the appropriate chemical nature of these media are based on the reported adverse reactions with these agents.