RESUMEN
The radiochemical purity of 131I-hippuran determined by radiochromatographic analysis using Whatman No 3 MM paper and a mixture of n-butanol, acetic acid and water as developer, was 97.3 +/- 1.2%. O-131IB acid and less than 1% of free 131I were separated from the preparation. No radioactivity which would correspond to O-131IB acid was observed on the radiochromatogram when 131I-hippuran was incubated with HSA and heparin. Protein binding of 131I-hippuran as a function of radiochemical purity, and HSA and heparin concentrations were determined by the method of equilibrium dialysis. No effect of radiochemical purity on protein binding of 131I-hippuran was observed, the value obtained being 1.3 +/- 0.1%. Higher HSA concentrations increased protein binding but decreased retention activity on the dialysing membrane. Heparin decreased protein binding of 131I-hippuran by 47%. The biological half-times of excretion of 131I-hippuran with heparin were 4 min for the fast phase and 107 min for the slow phase. The results of biodistribution in experimental animals showed increased localization of 131I-hippuran with heparin in the kidneys and liver during the first 15 min after injection.
Asunto(s)
Heparina/farmacología , Ácido Yodohipúrico/metabolismo , Animales , Cromatografía en Papel , Interacciones Farmacológicas , Ácido Yodohipúrico/análisis , Cinética , Unión Proteica/efectos de los fármacos , Ratas , Ratas Endogámicas , Factores de Tiempo , Distribución TisularRESUMEN
The results of analysis of 99mTc-Pyrophosphate (99mPyP), taken as a representative of the group of compounds having an organic P-O-P bond, and of the three diphosphonate compounds: methylene diphosphonate (MDP), 2,3-dicarboxy propane diphosphonate (DPD) and ethane-1-hydroxy-1, 1-diphosphonate (EHDP), which differ in their chemical structure, are shown. Also, some physicochemical parameters such as chloroform-water apparent partition coefficient, the osmotic pressure and pH values in final preparations were studied. The radiochemical purity of these radiopharmaceuticals was determined by the two methods: Sephadex chromatography for separation of 99mTc-hydrolysate and TLC on silica gel with 85% methanol for the determination of free 99mTcO-4. The yield of labelling for both methods was over 90%. Also, pharmacokinetic parameters such as binding to the plasma proteins and to erythrocytes were determined. 99mTc-PyP binding to plasma proteins was higher than the binding of diphosphonate compounds. The quantitative distribution of preparations was determined in experimental animals.
Asunto(s)
Difosfonatos/normas , Polifosfatos/normas , Compuestos de Tecnecio , Pirofosfato de Tecnecio Tc 99m , Tecnecio/normas , Polifosfatos de Estaño/normas , Animales , Difosfonatos/metabolismo , Cinética , Unión Proteica , Control de Calidad , Ratas , Tecnecio/metabolismo , Polifosfatos de Estaño/metabolismoRESUMEN
Labelling yield and radiochemical purity, higher than 95%, of 99mTc-colloid preparations were determined by using the paper chromatography method. Less than 3% of labelled citric acid, added to the preparation as a buffer solution, has been found in 99mTc-sulphur colloid. High radiochemical purity and optimum size of colloid particles has also been proved by biodistribution studies on experimental animals. The analysis performed has shown that more than 50% of 99mTc-colloid preparations excreted by urine is 99mTcO-, the remaining past 50% being protein bound 99mTc. Biological half-time of excretion of the fast phase is the same for both preparations, i.e. 10 min, while for the slow component it is 120 min in 99mTc-S-colloid and 160 min in 99mTc-Sn colloid.