Phosphate binders
Phosphate binders are drugs (usually for dialysis patients ) that bind the phosphate in the intestine that is ingested with food and thus inhibit its absorption into the body. Calcium and aluminum salts, sevelamer (a polymer ) and lanthanum carbonate are currently used as phosphate binders .
Classification of phosphate binders
Metal-containing phosphate binders
Phosphate binders containing aluminum
Phosphate binders containing aluminum are not used as often these days. It is true that aluminum has very high binding properties, which means that these phosphate binders are very effective. With small doses, a lot of phosphate can be bound and excreted. But aluminum accumulates in the body, i.e. H. it is deposited. It is toxic in high doses and can damage the nervous system. Phosphate binders containing aluminum are therefore often given for a limited period in order to reduce very high phosphate levels quickly.
Phosphate binders containing lanthanum
A relatively new metal-containing phosphate binder is lanthanum ; it is used as lanthanum carbonate . One advantage is that relatively few tablets need to be chewed with lanthanum. However, a potential problem could arise from the fact that lanthanum is absorbed in small quantities by the body and it can build up in the bones and liver. It is not yet fully known whether this will have consequences in the long term. A final certainty about this can only be given by long-term observations.
Calcium-containing phosphate binders
Calcium-containing phosphate binders are often used. They are effective and have low costs.
In contrast to people with healthy kidneys, dialysis patients cannot excrete excess calcium in the urine, and the bones usually do not absorb the calcium either. There is a risk that the calcium will settle in blood vessels and soft tissues.
The calcium intake in dialysis patients is already high due to the food and the calcium-containing dialysate. Therefore the total intake of calcium should be "capped". This should also be taken into account when administering calcium-containing phosphate binders.
In certain patient groups, the administration of calcium-containing phosphate binders should be reconsidered according to international guidelines ( KDIGO : Kidney Diesease Global Outcomes - Initiative):
- If there is hypercalcaemia (too much calcium in the blood)
- If there are already calcifications (visible in x-rays, among others)
- If there is an "adynamic bone disease", i.e. the bone metabolism is clearly disturbed
- If the parathyroid hormone level is persistently very low
Calcium and metal free phosphate binders
Colestilan and Sevelamer are phosphate binders that contain neither calcium nor metal. This means that neither can be deposited in the body. These phosphate binders effectively lower the phosphate level. Possible consequential damage as with aluminum is avoided. In addition, no additional calcium is supplied, which can lead to additional calcifications.
Dosage / dosage forms
Adjustment of the dosage of phosphate binders is essential to avoid undesirable hypophosphataemia . In the beginning this means weekly, later monthly monitoring of the plasma values of phosphate, possibly also calcium and parathyroid hormone .
Phosphate binders are available in various forms: as film-coated tablets, as chewable tablets and as a powder that is taken with a little water.
literature
- Rainer Denz: Care specifically Urban & Fischer, 2007, ISBN 3437262912 , p. 386.
