| Autor: |
Cargill, Robert W, Dutkowskij, Michael, Prescott, Ann, Fleming, Laura W, Stewart, William K |
| Zdroj: |
Journal of Pharmacy and Pharmacology; January 1989, Vol. 41 Issue: 1 p11-16, 6p |
| Abstrakt: |
Several aluminium-containing substances, including antacids used as phosphate-binders in treating renal failure, have been analysed in-vitro under different pH conditions for the release of Al3+ions and for binding of phosphate. Control experiments on different forms of pure aluminium hydroxide validated the methods. At pH 2 it was the most amorphous forms which released Al3+most rapidly. These aluminium ions, available for absorption by the patient, were released from all antacids tested, but no firm phosphate-binding was detected while the pH remained at 2. Phosphate was bound at pH 8, by adsorption onto the surface of aluminium hydroxide. No significant amounts of free Al3+exist in solution at pH 8, since at that pH aluminium hydroxide is precipitated. The most amorphous forms of this solid were the most efficient phosphate-binders. Alumino-silicate salts require prior exposure to acid to produce free Al3+before they can act as phosphate-binders, whereas amorphous aluminium hydroxide acts as an efficient phosphate-binder without prior exposure to acid. Chemical principles are employed to show why aluminium release and phosphate-binding are separate and independent processes. Methods are proposed for maximizing the activity of phosphate- binders in-vivo, while minimising aluminium release. |
| Databáze: |
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