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Access comprehensive study materials on Haematinics. This resource, available as a downloadable PDF, is crucial for students and healthcare professionals studying pharmacology, medicine, and hematology. You'll find clear notes and potentially PPT (PowerPoint Presentation) summaries detailing drugs used in the treatment of various types of anemia.

Download these informative notes for offline study or view the document directly online. Understand the pharmacology of key haematinic agents such as iron preparations, vitamin B12, and folic acid, including their mechanisms, indications, and management strategies for deficiency states.

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Download PDF, Haematinics Pharmacology, Anemia Treatment Notes, Iron Supplements, Vitamin B12 Deficiency, Folic Acid Deficiency, Erythropoiesis Stimulating Agents, Free Medical PDF, Slides By DuloMix.

Haematinics: Essential Agents for Blood Health and Anemia Treatment

Haematinics are substances required for the formation of blood, particularly red blood cells (erythrocytes), and are used primarily to treat anemias resulting from their deficiency. Anemia, characterized by a reduced number of red blood cells or a lower-than-normal quantity of hemoglobin, impairs the oxygen-carrying capacity of the blood, leading to symptoms like fatigue, weakness, pallor, and shortness of breath. The cornerstone haematinics are iron, vitamin B12, and folic acid, each playing a vital role in erythropoiesis (red blood cell production).

1. Iron

Iron is an essential component of hemoglobin, the protein in red blood cells responsible for oxygen transport. Iron deficiency is the most common cause of anemia worldwide (iron-deficiency anemia, IDA).

Pharmacology and Role:

• Function: Iron is central to the heme molecule in hemoglobin, myoglobin (in muscle), and various enzymes (cytochromes, catalases).
• Absorption: Dietary iron exists as heme iron (from animal sources, better absorbed) and non-heme iron (from plant sources, absorption influenced by other dietary factors). Absorption primarily occurs in the duodenum and upper jejunum. Ferrous (Fe²⁺) iron is better absorbed than ferric (Fe³⁺) iron. Vitamin C enhances non-heme iron absorption.
• Transport and Storage: Absorbed iron binds to transferrin for transport in the plasma. It is stored primarily as ferritin and hemosiderin in the liver, spleen, and bone marrow.
• Regulation: Iron homeostasis is tightly regulated by hepcidin, a liver-produced hormone that controls iron absorption and release from stores.

Iron Preparations:

• Oral Iron:
  • Examples: Ferrous sulfate, ferrous fumarate, ferrous gluconate. These are the first-line treatment for IDA.
  • Administration: Best absorbed on an empty stomach, but often given with food to minimize gastrointestinal side effects.
  • Side Effects: Nausea, epigastric discomfort, abdominal cramps, constipation, diarrhea, black stools (harmless).
• Parenteral Iron:
  • Indications: Intolerance or malabsorption of oral iron, severe deficiency requiring rapid repletion, ongoing blood loss, patients on erythropoiesis-stimulating agents.
  • Examples: Iron dextran (requires test dose due to anaphylaxis risk), iron sucrose, ferric carboxymaltose, ferumoxytol. Newer preparations have lower risks of serious allergic reactions.
  • Side Effects: Pain at injection site, flushing, headache, fever, arthralgia, rare anaphylactic reactions.

Iron Toxicity:

Acute iron poisoning (especially in children from accidental ingestion) is a medical emergency, causing severe GI damage, metabolic acidosis, and shock. Chronic iron overload (hemochromatosis) can damage organs like the liver, heart, and pancreas.

2. Vitamin B12 (Cobalamin)

Vitamin B12 is essential for DNA synthesis, red blood cell maturation, and neurological function. Deficiency leads to megaloblastic anemia (pernicious anemia if due to lack of intrinsic factor) and neurological damage.

Pharmacology and Role:

• Function: Coenzyme in two crucial reactions: conversion of methylmalonyl-CoA to succinyl-CoA, and conversion of homocysteine to methionine (important for DNA synthesis and folate metabolism).
• Sources: Animal products (meat, fish, dairy, eggs). Not found in plants.
• Absorption: Requires intrinsic factor (IF), a glycoprotein secreted by gastric parietal cells, for absorption in the terminal ileum.

Causes of Deficiency:

Pernicious anemia (autoimmune destruction of parietal cells or IF), gastrectomy, ileal resection, malabsorption syndromes (e.g., Crohn's disease), strict vegetarian/vegan diets, prolonged use of certain medications (e.g., metformin, proton pump inhibitors).

Vitamin B12 Preparations:

• Examples: Cyanocobalamin, hydroxocobalamin (preferred for longer duration of action).
• Administration: Usually given by intramuscular (IM) or deep subcutaneous injection for deficiency states. Oral high-dose preparations can be used for maintenance in some cases if absorption is not severely impaired. Nasal spray formulations are also available.
• Treatment: Initial loading doses followed by maintenance therapy, often lifelong for pernicious anemia.

3. Folic Acid (Vitamin B9)

Folic acid (folate in its natural form) is crucial for DNA synthesis, RNA synthesis, and amino acid metabolism. Deficiency also causes megaloblastic anemia, similar to vitamin B12 deficiency, but without the neurological symptoms.

Pharmacology and Role:

• Function: Converted to tetrahydrofolate (THF) and its derivatives, which are coenzymes in one-carbon transfer reactions essential for the synthesis of purines and pyrimidines (DNA bases).
• Sources: Green leafy vegetables, fruits, yeast, liver, fortified cereals.
• Absorption: Primarily in the proximal jejunum.

Causes of Deficiency:

Inadequate dietary intake, malabsorption syndromes, increased demand (pregnancy, lactation, chronic hemolytic anemias), certain drugs (e.g., methotrexate, phenytoin, trimethoprim).

Folic Acid Preparations:

• Administration: Usually given orally. Parenteral administration is rarely needed.
• Important Note: Folic acid can correct the anemia of vitamin B12 deficiency but will not prevent or treat the neurological damage. Therefore, vitamin B12 deficiency must be ruled out or treated concurrently if suspected before starting high-dose folic acid.
• Prophylactic Use: Recommended for all women of childbearing age and during pregnancy to prevent neural tube defects in the fetus.

Erythropoiesis-Stimulating Agents (ESAs)

While not haematinics in the traditional sense of being building blocks, ESAs like erythropoietin (EPO) and its longer-acting derivatives (e.g., darbepoetin alfa) stimulate red blood cell production in the bone marrow. They are used to treat anemia associated with chronic kidney disease, chemotherapy, and certain other conditions. Their use requires adequate iron stores for efficacy.

Conclusion

Haematinics are vital for managing and preventing various forms of anemia. Proper diagnosis of the underlying cause of anemia is crucial for selecting the appropriate haematinic agent and ensuring effective treatment. Iron, vitamin B12, and folic acid each have unique roles in erythropoiesis, and their deficiencies can lead to significant health problems. Understanding their pharmacology, indications, and potential side effects allows for their safe and rational use in clinical practice, contributing significantly to patient well-being.

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