Sources of Drugs

Drugs are derived from various natural and synthetic sources. The major sources include:

1. Plant Sources

• Many drugs are obtained from different parts of plants.
• Leaves: e.g., Digoxin (from Digitalis purpurea – foxglove) used for heart conditions.
• Roots: e.g., Atropine (from Atropa belladonna) used as an antispasmodic.
• Seeds: e.g., Physostigmine (from Physostigma venenosum) used in glaucoma treatment.
• Bark: e.g., Quinine (from Cinchona bark) used for malaria.
• Flowers: e.g., Vinca alkaloids (from Catharanthus roseus) used in cancer chemotherapy.

2. Animal Sources

• Drugs extracted from animal tissues or secretions.
• Hormones: e.g., Insulin (from pancreas of pigs or cattle), Thyroid hormones.
• Enzymes: e.g., Pepsin, Trypsin (from animal digestive glands).
• Vaccines and Sera: e.g., Antivenoms from horse serum, Hepatitis B vaccine (recombinant but originally animal-derived).

3. Microbial Sources

• Microorganisms (bacteria, fungi) produce antibiotics and other therapeutic agents.
• Antibiotics:
  
  • Penicillin (from Penicillium notatum)
  • Streptomycin (from Streptomyces griseus)
  • Erythromycin (from Streptomyces erythreus)
• Vitamins: e.g., Vitamin B12 (from Streptomyces species).

4. Mineral Sources

• Inorganic compounds or metals used therapeutically.
• Iron: Ferrous sulfate for anemia.
• Magnesium: Magnesium sulfate (epsom salt) used as a laxative or in eclampsia.
• Zinc: Zinc oxide in skin ointments.
• Calcium: Calcium carbonate for antacid and supplementation.

5. Synthetic Sources

• Chemically synthesized in laboratories (most modern drugs).
• Advantages: Purity, consistency, cost-effective, scalable production.
• Examples:
  
  • Paracetamol (acetaminophen)
  • Aspirin (acetylsalicylic acid)
  • Ibuprofen
  • Most oral contraceptives and antihypertensives

6. Semi-Synthetic Sources

• Natural compounds chemically modified to improve efficacy, reduce toxicity, or enhance stability.
• Examples:
  
  • Semi-synthetic penicillins: Amoxicillin, Ampicillin
  • Codeine derivatives: Hydrocodone

7. Biotechnology and Genetic Engineering

• Drugs produced using recombinant DNA technology.
• Examples:
  
  • Human insulin (Humulin®)
  • Erythropoietin (for anemia)
  • Monoclonal antibodies (e.g., Rituximab)
  • Vaccines (e.g., HPV vaccine – Gardasil®)

Preparation of Medicines

Medicines are formulated into various dosage forms to ensure stability, accurate dosing, patient compliance, and targeted delivery.

Common Dosage Forms and Preparation Methods

1. Solid Dosage Forms

• Tablets: Compressed powders; may be coated for taste masking or controlled release.
• Capsules: Powder or granules in gelatin shell; hard or soft.
• Powders: Fine particles for oral or topical use.
• Lozenges: Slow-dissolving for throat infections.

2. Liquid Dosage Forms

• Solutions: Drug dissolved in solvent (e.g., syrups, elixirs).
• Suspensions: Insoluble drug particles dispersed in liquid (shake well before use).
• Emulsions: Oil and water mixture stabilized by emulsifiers.
• Injectables: Sterile solutions/suspensions for IV, IM, SC administration.

3. Semi-Solid Dosage Forms

• Ointments: Oil-based, for skin application.
• Creams: Water-in-oil or oil-in-water emulsions.
• Gels: Semi-solid with jelly-like consistency.
• Pastes: Thick ointments with high powder content.

 4. Gaseous and Inhalation Forms

• Aerosols: Fine mist for lung delivery (e.g., salbutamol inhalers).
• Vapors: Volatile liquids for inhalation.

5. Specialized Forms

• Suppositories: For rectal/vaginal use (melts at body temperature).
• Transdermal Patches: Controlled drug release through skin.
• Implants: Long-acting (e.g., contraceptive implants).

Steps in Drug Manufacturing

1. Research & Development (R&D): Discovery and testing of new compounds.
2. Extraction/Synthesis: Obtaining active ingredient from source.
3. Purification: Removing impurities.
4. Formulation: Mixing with excipients (binders, fillers, preservatives).
5. Quality Control: Testing for potency, purity, stability.
6. Packaging & Labeling: In blister packs, bottles; with dosage, expiry, warnings.
7. Distribution: Through regulated supply chains.

Importance in Midwifery

• Understanding sources helps assess natural vs. synthetic drug safety in pregnancy.
• Knowledge of preparation ensures proper storage, administration, and patient counseling (e.g., shake suspensions, refrigerate injectables).
• Enables identification of allergens (e.g., gelatin in capsules) or contraindications