DRUGS ACTING ON BLOOD AND BLOOD FORMING ORGANS: A TEACHER’S COMPREHENSIVE GUIDE
Welcome, future pharmacologists and healthcare professionals!
The haematologic system includes the blood and blood-forming organs. The main function of the blood is the transportation of oxygen and nutrients required by the cells and elimination of wastes from the body. It also transports hormones released by the endocrine system. White blood cells (leukocytes) are also required in the prevention of infection. The process of blood making is known as haematopoiesis.
As a pharmacology educator with years of experience teaching haematological pharmacology, I have observed that students often find this topic challenging due to the complex coagulation cascade and the various drug classes. Let me tell you: Understanding drugs acting on blood and blood-forming organs is essential for managing anaemia, thrombosis, and bleeding disorders.
In this comprehensive guide, I will walk you through the major classes of haematological drugs—haematinics (iron, folic acid, vitamin B₁₂), anti-coagulants, anti-platelet agents, and thrombolytic agents. By the end of this article, you will have a thorough understanding of these essential pharmacological agents. Let us begin!
Dpharmguru’s exam insights:
Haematological drugs are frequently tested in pharmacology exams. Remember: Haematinics treat anaemia—iron, folic acid, and vitamin B₁₂ are essential. Anti-coagulants prevent clot formation—heparin (injectable) and warfarin (oral). Anti-platelet agents prevent platelet aggregation—aspirin, clopidogrel. Thrombolytics dissolve existing clots—streptokinase, alteplase. These are classic exam questions!
1. HAEMATINICS
Haematinics are involved in the formation of blood and are used in the treatment of anaemia. Anaemia is generally caused by deficiency of:
- Iron
- Folic acid
- Vitamin B₁₂
A) IRON
A healthy adult human body contains around 3.5 g of iron, of which about 2/3 is found in the blood, while the remaining portion is preserved in the bone marrow, spleen, and muscles as ferritin and haemosiderin.
Oral Iron Preparations
| Salt | Dose |
|---|---|
| Ferrous sulphate, hydrated* | 0.3 g tid |
| Ferrous sulphate, dehydrated | 0.2 g tid |
| Ferric ammonium citrate | 1.0 g tid |
| Reduced iron | 0.5 g tid |
| Ferrous gluconate* | 0.6 g tid |
| Ferrous fumarate* | 0.2 g tid |
| Ferrocholinate | 0.5 g tid |
Parenteral Iron Preparations:
Total dose (mg) = 4.4 × Body Wt. in kg × Haemoglobin deficit in g/100 ml blood- Intramuscular: Iron Dextran Injection (Imferon) — 50 mg/ml elemental iron. Daily 1–4 ml deep IM using Z-track technique.
- Intravenous: Iron dextran injection free of preservatives. First dose limited to 25 mg, increased to 100 mg/day.
B) FOLIC ACID
Folic acid (pteroylglutamic acid) belongs to the B complex group of vitamins. Deficiency causes megaloblastic anaemia.
Pharmacological Actions:
- Digestive System: Improves lipid deposition, reduces liver inflammation, increases appetite
- Brain: Important for proper brain functioning, mental and emotional health; helps in DNA and RNA production
- Blood: In combination with vitamin B₁₂, helps in RBC production
Indications: Nutritional megaloblastic anaemia, megaloblastic anaemia of pregnancy, infancy and childhood, associated with alcoholism and liver disease, sprue, coeliac disease, malignant disease.
Adverse Effects: Rare. Large doses may counteract antiepileptic effect of phenytoin and phenobarbitone.
C) VITAMIN B₁₂ (CYANOCOBALAMIN)
Around 0.6–1.2 mcg of vitamin B₁₂ is required daily. Total vitamin B₁₂ stored in human adults is around 5 mg.