Tuesday, March 8, 2011

Iron compounds (Pharmacology)

Iron occurs as tin in the liver and spleen from where it is released and utilized in the heme portion of hemoglobin, which constitutes about 65 % of the total iron in the body.

Daily requirement:
Daily iron requirement is about 0.5-1mg in normal adults.

Mechanism of action:
In the first step, Heme portion of hemoglobin is formed.

In the second step, Hemoglobin is formed.Hemoglobin is the compound for the transportation of oxygen from the lungs to the tissues.

Administration:
It can be given orally or parenterally.

Pharmacokinetics:
Absorption:
It is readily absorbed from duodenum and proximal jejunum. It is more easily absorbed in the form of ferrous ions (Fe2+) than ferric ions (Fe3+).

Distribution:
Ferrous ion is converted into ferric ion and is actively transported in the mucosal cells of the intestine. It is actively transported into the plasma through transferrin. In the liver and spleen, it is converted to ferritin and hemosiderin with the help of certain proteins and get stored.

Elimination:
Approximately 1 mg of the iron is wasted, by the shedding of the tissue surface of the intestinal mucosal cells, through feces and little amount is excreted via urine, sweat and bile.

Iron deficiency:
Iron deficiency occurs in:
1. Chronic or acute loss of blood
2. Inadequate taking in of iron by the children during the period of rapid growth
3. In severely menstruating or pregnant woman.

Therapeutic uses:
The above mentioned deficiencies can be removed by taking sufficient amount of iron in the form of its compounds from outside.

Oral iron preparations can be used for infants and the children in the period of rapid growth as well as for pregnant and lactating women. Whereas parenteral preparations can be taken by the patients who are unable to take orally or who have chronic or acute blood loss.

Dosage:
Oral preparations of iron such as ferrous fumarate, ferrous gluconate and ferrous sulfate can be taken as 3-4 tabs per day in divided doses. Whereas, parenteral preparation is available in the form of iron-sorbitol-citric acid complex and can be taken as 1.5 mg/kg IM upto a maximum of 100 mg per injection in single daily dose.

Adverse effects:
Oral iron preparations can cause nausea, constipation, abdominal cramps and epigastric discomfort. Whereas, parenteral preparations can cause headache, nausea, vomiting, fever, flushing, local pain and tissue staining.
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