This document discusses hematinics and maturation factors required for red blood cell formation. It focuses on vitamin B12 and folic acid, explaining their roles, dietary sources, daily requirements, pharmacokinetics, metabolic functions, deficiencies, and therapeutic uses. Erythropoietin, which stimulates red blood cell production, is also covered briefly. The key relationship discussed is how vitamin B12 and folic acid work together in methylation reactions important for DNA synthesis and preventing megaloblastic anemia.

1. *Hematinics- Maturation Factors
*Erythropoetin
Dr Advaitha M. V
Pharmaceutical Physician
S. Demonstrator
K.S. Hegde Medical Academy,
Mangalore, India

2. • Hematinics are the nutrients required for the
formation of RBCs.
1. Fe ( ↓↓ microcytic Hypochromic Anemia)
2. Vit B12, Folic Acid are maturation Factors
(↓↓ Megaloblastic Anemia; Premature RBCs
will have hard time to synthesize DNA.)

5. Cobalamin (vitamin B12)
• COBALAMIN exists in a number of different
chemical forms.
• All have a cobalt atom at the center of a corrin
ring.

6. • Natural or Active or coenzyme forms of
Cobalamin:
2-deoxyadenosyl (ado) form located in
mitochondria.
Methylcobalamin present in plasma and in cell
cytoplasm (given therapeutically).
• Dietary Forms or Stable forms (are generally
called Vit B12)
Cyanocobalamin
Hydroxocobalamin
Used therapeutically.

7. DIETARY SOURCES :
• Cobalamin is synthesized solely by
microorganisms.
• Only source for humans is food of animal origin
e.g., meat, fish, and dairy products.
• Vegetables, fruits, and other foods of non-animal
origin are free from cobalamin unless they are
contaminated by bacteria

8. • Daily requirement:
*1–3 μg
** Pregnancy and lactation : 3–5 μg.
• Body stores are of the order of 2–3 mg,
sufficient for 3–4 years if supplies are completely
cut off.

9. Pharmacokinetics
• Vit B12 present in food as protein conjugates
is released by cooking or by proteolysis in
stomach facilitated by gastric acid.

10. • Intrinsic factor (a glycoprotein) secreted by
stomach forms a complex with B12
• They attach to specific receptors present on
intestinal mucosal cells at the ileum.
• Absorbed by active carrier mediated transport
• Vit B12 is transported in blood in combination
with a β globulin, transcobalamin II (TCII).

11. • Excess Vit B12 is stored in liver cells as 5’-
deoxyadenosylcobalamin.
• It is not degraded in the body.
• It is secreted in bile (normally) or excreted in
urine by glomerular filtration (when
administered in therapeutic doses).

12. Folic (Pteroylglutamic) acid
• Contains 2 to 8 molecules of glutamic acid.
• Humans do not synthesize FA and meet the
need from green leafy vegetables (spinach),
egg, meat, milk.
• It is synthesized by gut flora, but this is largely
unavailable for absorption

13. • Daily requirement of an adult : 0.2 mg/day.
• During pregnancy, lactation: 0.8 mg/day.
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• Folate is easily destroyed by heating, particularly
in large volumes of water.
• Total body folate in the adult is ~10 mg, (Mainly
stored in liver),
• Stores are sufficient for only 3–4 months.

14. Pharmacokinetics:
• Absorbed in proximal Jejunum.
• Folic acid is present in food as polyglutamates
(absorbable but less efficient).
• So, in the lumen or inside the mucosa, they are
hydrolysed to monoglutamates (5- Methyl
Tetra Hydro Folate OR 5-MeTHF ,easily
absorbable), before entering portal circulation.

15. • Folate is transported in plasma about one-third
is loosely bound to albumin, and two-thirds is
unbound.
• Methyltetrahydrofolate (Me-THF) is the
principal folate congener supplied to cells.
• Folic acid is rapidly extracted by tissues and
stored in cells as polyglutamates.

16. • Liver takes up a large part and secretes
methyl-THFA in bile which is mostly
reabsorbed from intestine (enterohepatic
circulation).
• Alcohol interferes with release of methyl-THFA
from hepatocytes.
• Pharmacological doses are excreted in urine.

17. Relationships Between Vitamin B12 and
Folic Acid
• Property : Its all about Methylation and one
carbon transfer !!!!

19. Metabolic functions of cobalamin
• The active forms are essential for cell growth and
replication.
• 5-Deoxyadenosylcobalamin is required for the re-
arrangement of methylmalonyl CoA to succinyl
CoA (for fatty acid synthesis in neural tissue)
• Methylcobalamin is required for the conversion
of homocysteine to methionine.

20. • In vitamin B12 deficiency , MeTHF becomes
"trapped" as to cause a functional deficiency
of other required intracellular forms of folic
acid.
(Folate trap or Methyl Folate trap !!!!)
• So, B12 is required to support folate
metabolism.

21. Etiology : Vit B12 deficiency
• Addisonian pernicious anaemia
• Gastric mucosal damage: chronic gastritis, gastric
carcinoma, gastrectomy, etc.
• Malabsorption due to bowel resection,
inflammatory bowel disease.

22. • Consumption by abnormal flora in intestine
(blind loop syndrome) or fish tape worm.
• Nutritional deficiency in strict vegetarians.
• Increased demand in pregnancy, infancy.

23. Manifestations of B12 deficiency
• Megaloblastic anaemia (generally the first
manifestation), neutrophils with
hypersegmented nuclei, giant platelets.
• Glossitis, g.i. disturbances.

24. • Neurological: subacute combined
degeneration of spinal cord.
*peripheral neuritis, diminished vibration and
position sense, paresthesias.
• Neuropsychiatric: poor memory, mood
changes, hallucinations, etc. are late effects.

25. Metabolic functions of Folic acid
• Conversion of Homocysteine to Methionine:- Me-
THF (using vitamin B12 as a cofactor).
• Conversion of Serine to Glycine:-
*THF acts as an acceptor of a methylene group
from serine (using pyridoxal phosphate as a
cofactor).
*It results in the formation of 5-Methylene THF an
essential coenzyme for the synthesis of
thymidylate.

26. • Synthesis of Thymidylate:
5-Methylene THF donates a methylene group
and reducing equivalents to deoxyuridylate for
the synthesis of thymidylate—a rate-limiting
step in DNA synthesis.

27. • Histidine Metabolism:
THF also acts as an acceptor of a formimino
group in the conversion of formiminoglutamic
acid to glutamic acid.
• Synthesis of Purines:
Helps to add carbon atoms into the growing
purine ring.

28. Folate deficiency : Etiology
• Inadequate dietary intake
• Malabsorption: especially involving upper
intestine.
• Chronic alcoholism: intake of folate is generally
poor. Its release from liver cells and recirculation
are interfered.
• Increased demand: pregnancy, lactation, rapid
growth Periods.

29. • Drug induced:
Anticonvulsants on prolonged therapy
(phenytoin, phenobarbitone)
Oral contraceptives: interfere with absorption
and storage of folate.

30. Manifestations of folate deficiency
• Megaloblastic anaemia: indistinguishable from
that due to vit B12 deficiency.
• Epithelial damage: glossitis, enteritis,
diarrhoea, steatorrhoea.
• Neural tube defects : including spina bifida in
the offspring, due to maternal folate
deficiency

31. • Neurological symptoms do not appear in pure
folate deficiency.

32. BIOCHEMICAL BASIS OF
MEGALOBLASTIC ANEMIA
• The common feature of megaloblastic anemias
is a defect in DNA synthesis that affects rapidly
dividing cells in the bone marrow.

33. • In deficiencies of either folate or cobalamin,
*There is failure to convert deoxyuridine
monophosphate (dUMP) to deoxythymidine
monophosphate (dTMP), the precursor of dTTP .
OR
*There is misincorporation of uracil into DNA
because of a buildup of deoxyuridine
triphosphate (dUTP).

34. Preparations, dose, administration of Vitamin
B12:
• Available for injection and oral administration.
• Combinations with other vitamins and minerals
also can be given orally or parenterally.
• The choice of a preparation always depends on
the cause of the deficiency.

35. • Oral preparations may be used to supplement
deficient diets.
• They are of limited value in the treatment of
patients with deficiency of intrinsic factor or
ileal disease

36. • Cyanocobalamin: inj. 500 μg, 1000 μg
• Hydroxocobalamin: inj. 100mcg
• Methylcobalamin (Oral/I.M/I.V) 500mcg, 1500
mcg
• Cyanocobalamin injection is safe when given
by the I.M or deep S.C (but never be given I.V).
*Rare reports of transitory exanthema and
anaphylaxis after IV injection.

37. • Some popular trends of usage:
 Cyanocobalamin:
*100 μg i.m./s.c. daily for 1 week,
* Then weekly for 1 month
*Then monthly for maintenance indefinitely.
Methylcobalamin (Oral, 1500mcg) has been
promoted for correcting the neurological defects
in diabetic, alcoholic and peripheral neuropathy.

38. Important Note for Vit B12:
• In megaloblastic anemia, apart from b12, it is
rational to add 1–5 mg of oral folic acid and an
iron preparation.
(because reinstitution of brisk haemopoiesis
may unmask deficiency of these factors)

39. • Responses :
Symptomatic improvement starts in 2 days--
appetite improves, patient feels better.
mucosal lesions heal in 1–2 weeks
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Hb% and haematocrit start rising after 2 weeks.
Time taken for complete recovery of anaemia
depends on the severity of disease.
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Neurological parameters improve more slowly—
may take several months.
(full recovery may not occur in chronic patients)

40. Folic acid in therapeutics
1. Megaloblastic anaemia
 Oral folic acid 2–5 mg/day is adequate.
 In acutely ill patients, 5 mg/day (IV/IM/SC)
Response occurs as quickly as with vit B12.
2. Increased demand: pregnancy, lactation upto
5mg/day.
3. Pernicious anaemia: Folic acid has only
secondary and adjuvant role in this condition.

41. • Folic acid should never be given alone to
patients with megaloblastic anemia.
• Because haematological response may occur,
but neurological defect may worsen due to
diversion of meagre amount of vit B12 present
in body to haemopoiesis.

42. 3. Methotrexate (anticancer, DHFRase inhibitor)
toxicity
• Folinic acid (Leucovorin, citrovorum factor, 5-
formyl-THFA)
It is an active coenzyme form which does not
need to be reduced by DHFRase before it can act.
Dose : 3.0 mg i.v. repeated as required. Oral
forms are also available (Dose upto 15mg).
Folinic acid is comparatively expensive.

43. 4. In methanol Poisoning : folinic acid serves as
THFA to eliminate formic acid formed.

44. Erythropoietin (EPO)
• Glycoprotein hormone (MW 34000) produced
by peritubular cells of the kidney that is
essential for normal erythropoiesis.
• Anaemia and hypoxia are sensed by kidney
cells and induce rapid secretion of EPO

45. • It acts on erythroid marrow
 Stimulates proliferation of colony forming cells
of the erythroid series.
 Induces haemoglobin formation and
erythroblast maturation.
It induces erythropoiesis in a dose dependent
manner.

46. Therapeutics
• Epoetin α, β : The recombinant human
erythropoietin.
Administered by i.v. or s.c. injection
Plasma t½ of 6–10 hr, but action lasts several
days.
Given thrice weekly , Max 600 U/kg/week
• Darbepoetin : longer acting, given once a week.

47. Indications of epoetin :
• Chronic kidney disease –Associated Anemia.
• Chemotherapy –Related Anemia.
• Preparation for surgery with high risk of blood
loss.
• Anaemia in AIDS patients treated with
zidovudine.

48. Adverse effects
• Increased blood viscosity and peripheral vascular
resistance.
• Increased clot formation in the A-V shunts (most
patients are on dialysis)
• Hypertensive episodes
• Serious thromboembolic events
• Flu like symptoms lasting 2–4 hr occur in some
patients.

49. Thank you