Biomedical Engineering Reference
In-Depth Information
including the identii cation of the target centers. And, indeed, research in this area is now slowly
gaining momentum.
10.1.1 E
SSENTIAL
AND
N
ONESSENTIAL
E
LEMENTS
Essential metals (Table 10.1) are commonly found as natural constituents in proteins where
they perform a wide spectrum of specii c functions associated with biological processes.
Metalloproteins with catalytic properties, metalloenzymes, implement chemical transformations
of certain substrate molecules, and almost half of all enzymes in the human organism depend
on the presence of one or more metal ions. Obviously, these metal ions are key pharmaceutical
targets for drugs.
Pharmaceuticals may control metabolism of essential elements in two ways:
1. Supply of specii c drugs with target properties may enable delivery or removal of elements
to/from specii c sites.
2. The natural physiological pathways may be blocked by the drug.
Nonessential (or toxic) elements can be useful in medicine since they either show insignii cant
toxic effect in a certain limited concentration range (left-hand side of Figure 10.1) or because
their pharmaceutical benei t overrules their toxic effect. Such compounds are potentially of phar-
macological interest, e.g., in killing certain cell types, as cancer cells or microorganisms while
only expelling minor harm to the host. The examples include drugs based on platinum, gold,
antimony, and bismuth complexes, which are described in more detail in Section 10.6. Their
toxicity depends on concentration, oxidation state, and ligand and thus should be administered
TABLE 10.1
Constitution of the Human Organism (Adult 70 kg)
Recommended
Daily Dose (mg)
Recommended
Daily Dose (mg)
Element
Mass (g)
Element
Mass (g)
Oxygen
45,500
Copper
0.11
3-5
Carbon
12,600
Aluminum*
0.1
Hydrogen
7,000
Lead*
0.08
Nitrogen
2,100
Antimony
0.07
Calcium
1,050
800-1200
Cadmium*
0.03
Phosphorous
700
800-1200
Tin*
0.03
Sulfur
175
10
Iodine
0.03
0.15
Potassium
140
2000-5500
Manganese
0.03
2-5
Chlorine
105
3200
Vanadium*
0.02
Sodium
105
1100-3300
Selenium
0.02
0.05-0.07
Magnesium
35
300-400
Barium*
0.02
Iron
4.2
10-20
Arsenic*
0.01
Zinc
2.3
15
Boron*
0.01
Silicon
1.4
Nickel*
0.01
Rubidium*
1.1
Chromium
0.005
0.05-0.2
Fluorine
0.8
1.5-4.0
Cobalt
0.003
0.2
Bromium*
0.2
Molybdenum
<0.005
ca. 0.1
Strontium*
0.14
Note:
Elements marked with * are either nonessential, or their function is unknown.
