Iron, Vitamin B12 and Folate Pharmacology
Iron, Vitamin B12 and Folate
• Classify the types of anaemia and list medicines indicated for each type.
• Describe the goals and pharmacological principles of management of anaemia
• Recapitulate the aetiology and pathophysiology of nutritional anaemia.
• Explain pharmacodynamics, pharmacokinetics, dosage forms, indications, therapeutic efficacy, adverse effects,
cautions, contraindications, interactions with medicines, cost and availability of medicines used in the
management of nutritional anaemia including;
♣ Iron therapy including oral and parenteral iron ♣ Vitamin B12 therapy ♣ Folate therapy
• Advise patients who are prescribed medicines for nutritional anaemia.
• Explain pharmacodynamics, pharmacokinetics, dosage forms, indications, therapeutic efficacy, adverse effects,
cautions, contraindications, interactions with medicines, cost and availability of erythropoietin.
Goals and pharmacological principles of management of anaemia
Therapeutic approaches to anemia include the use of
• blood and blood products
• immunotherapies
• hormonal/nutritional therapies and adjunctive therapies
The goal of therapy in acute anaemia is
• to restore the hemodynamics of the vascular systems
• to replace lost red blood cells
• Documentation of the etiology of anemia is essential in the selection of therapy.
• Not all microcytic anemias are caused by iron deficiency; some are iron-overloading
disorders such as thalassaemia.
• Similarly, not all megaloblastic anemias are associated with either vitamin B12 deficiency or
folic acid deficiency.
• Hereditary hemolytic disorders do not improve with corticosteroid therapy
Aetiology and pathophysiology of nutritional anaemia
Iron deficiency anaemia causes
o Poor iron intake
o Decreased absorption e.g. gut diseases, interaction with food
o Increased demand e.g. pregnancy
o Excessive blood loss e.g. menorrhagia, hook worm infestation, NSAIDs, haemorrhoids
• Macrocytic megaloblastic anaemia due to
o Folate deficiency
poor intake eg. old age
Excessive demand eg. Pregnancy
May be unmasked when on iron treatment
In malabsorption
Drugs causing folate deficiency eg. phenytoin, methotrexate
o Vitamin B12 deficiency
P.D.F. 1
, Iron, Vitamin B12 and Folate Pharmacology
Strict vegetarians
Deficient absorption
o Medicines e.g. Antiepileptic drugs
• Haemolytic anaemia due to
o Excessive destruction of red cells caused by inherited abnormalities (causes iron
overload) eg. Thalassaemia
• Aplastic anaemia
o Bone marrow failure. All 3 cell lines are affected
Iron therapy
Oral iron preparations
Oral iron dose
• Oral iron: only about 30% absorption
• Needs about 100 -200mg elemental Fe/day
• Start once/day and increase to 3 times /day
• Give until Hb% normalizes for about 2-3 months
• Then continue iron therapy for another 3/12 to replenish iron stores
Adverse effects of oral iron therapy
• GI irritation - dose related Nausea, epigastric pain, vomiting Leads to poor compliance
• During long term therapy – constipation or diarrhoea
• Acute over dosage -CVS collapse and death (eg. in children)
Methods to improve compliance
• Give with or immediately after food (but this ↓ absorption)
• Start once/day and then increase frequency
• Keep total dose less than 180mg elemental Fe/day
• Response Hb % increased by 2g/100ml in 3 weeks
• If intolerance stop & ↑weekly
Methods to improve compliance and increase absorption
• Change the preparation e.g. use Fe gluconate
• Avoid taking with tea and dairy products and calcium preparations
• Give a liquid preparation (syrup) if that is preferred (but this causes staining of teeth)
• Use sustained release preparations (expensive, not much advantage)
P.D.F. 2
Iron, Vitamin B12 and Folate
• Classify the types of anaemia and list medicines indicated for each type.
• Describe the goals and pharmacological principles of management of anaemia
• Recapitulate the aetiology and pathophysiology of nutritional anaemia.
• Explain pharmacodynamics, pharmacokinetics, dosage forms, indications, therapeutic efficacy, adverse effects,
cautions, contraindications, interactions with medicines, cost and availability of medicines used in the
management of nutritional anaemia including;
♣ Iron therapy including oral and parenteral iron ♣ Vitamin B12 therapy ♣ Folate therapy
• Advise patients who are prescribed medicines for nutritional anaemia.
• Explain pharmacodynamics, pharmacokinetics, dosage forms, indications, therapeutic efficacy, adverse effects,
cautions, contraindications, interactions with medicines, cost and availability of erythropoietin.
Goals and pharmacological principles of management of anaemia
Therapeutic approaches to anemia include the use of
• blood and blood products
• immunotherapies
• hormonal/nutritional therapies and adjunctive therapies
The goal of therapy in acute anaemia is
• to restore the hemodynamics of the vascular systems
• to replace lost red blood cells
• Documentation of the etiology of anemia is essential in the selection of therapy.
• Not all microcytic anemias are caused by iron deficiency; some are iron-overloading
disorders such as thalassaemia.
• Similarly, not all megaloblastic anemias are associated with either vitamin B12 deficiency or
folic acid deficiency.
• Hereditary hemolytic disorders do not improve with corticosteroid therapy
Aetiology and pathophysiology of nutritional anaemia
Iron deficiency anaemia causes
o Poor iron intake
o Decreased absorption e.g. gut diseases, interaction with food
o Increased demand e.g. pregnancy
o Excessive blood loss e.g. menorrhagia, hook worm infestation, NSAIDs, haemorrhoids
• Macrocytic megaloblastic anaemia due to
o Folate deficiency
poor intake eg. old age
Excessive demand eg. Pregnancy
May be unmasked when on iron treatment
In malabsorption
Drugs causing folate deficiency eg. phenytoin, methotrexate
o Vitamin B12 deficiency
P.D.F. 1
, Iron, Vitamin B12 and Folate Pharmacology
Strict vegetarians
Deficient absorption
o Medicines e.g. Antiepileptic drugs
• Haemolytic anaemia due to
o Excessive destruction of red cells caused by inherited abnormalities (causes iron
overload) eg. Thalassaemia
• Aplastic anaemia
o Bone marrow failure. All 3 cell lines are affected
Iron therapy
Oral iron preparations
Oral iron dose
• Oral iron: only about 30% absorption
• Needs about 100 -200mg elemental Fe/day
• Start once/day and increase to 3 times /day
• Give until Hb% normalizes for about 2-3 months
• Then continue iron therapy for another 3/12 to replenish iron stores
Adverse effects of oral iron therapy
• GI irritation - dose related Nausea, epigastric pain, vomiting Leads to poor compliance
• During long term therapy – constipation or diarrhoea
• Acute over dosage -CVS collapse and death (eg. in children)
Methods to improve compliance
• Give with or immediately after food (but this ↓ absorption)
• Start once/day and then increase frequency
• Keep total dose less than 180mg elemental Fe/day
• Response Hb % increased by 2g/100ml in 3 weeks
• If intolerance stop & ↑weekly
Methods to improve compliance and increase absorption
• Change the preparation e.g. use Fe gluconate
• Avoid taking with tea and dairy products and calcium preparations
• Give a liquid preparation (syrup) if that is preferred (but this causes staining of teeth)
• Use sustained release preparations (expensive, not much advantage)
P.D.F. 2
