Pharmaceutical Chemistry: Principles, Tests, and Standards
Radiations and Radiopharmaceuticals
Properties of Alpha (α), Beta (β), and Gamma (γ) Radiations
- Alpha (α): Helium nuclei (+2 charge), high mass, low penetration, high ionization. Stopped by paper.
- Beta (β): High-speed electrons/positrons (±1 charge), small mass, moderate penetration/ionization. Stopped by aluminium.
- Gamma (γ): Electromagnetic waves (no mass/charge), speed of light, high penetration, low ionization. Stopped by lead/concrete.
Precautions for Radiopharmaceuticals
- Use protective gear (gloves, goggles).
- Utilize lead shielding and containers.
- Minimize exposure time and maintain distance.
- Regularly monitor radiation levels and dispose of waste per safety regulations.
Antidotes and Emetics
Comparison
- Antidotes: Neutralize poisons (e.g., Sodium Thiosulphate).
- Emetics: Induce vomiting to remove poisons (e.g., Copper Sulphate).
Sodium Thiosulphate (Na₂S₂O₃·5H₂O)
Used for cyanide poisoning. Prepared by boiling sodium sulphite with sulphur. Properties: Colourless, odourless crystals, freely soluble in water.
Copper Sulphate (CuSO₄·5H₂O)
Formerly used as an emetic. Prepared by reacting copper oxide with sulphuric acid. Properties: Bright blue crystals, metallic taste.
Haematinics and Expectorants
Haematinics: Ferrous Sulphate
Increases hemoglobin and RBCs. Prepared by reacting iron with sulphuric acid. Properties: Pale green crystals, oxidizes in air.
Expectorants: Ammonium Chloride
Loosens mucus. Prepared by neutralizing ammonia with hydrochloric acid. Properties: White crystalline powder, acidic in solution.
Cathartics and Antacids
Cathartics
- Magnesium Sulphate: Saline laxative.
- Kaolin: Adsorbent for diarrhea.
- Bentonite: Suspending agent.
Antacids
- Sodium Bicarbonate: Systemic antacid.
- Aluminium Hydroxide Gel: Non-systemic antacid for gastric protection.
Physiological Solutions and Balance
Isotonic Solutions
Solutions with osmotic pressure equal to body fluids (e.g., 0.9% NaCl). Essential for IV fluids and ophthalmic preparations.
Oral Rehydration Solution (ORS)
Contains NaCl, Glucose, KCl, and Trisodium Citrate to treat dehydration.
Acid-Base Balance
Maintained at pH 7.35–7.45 via buffers, lungs, and kidneys.
Dental Products
Fluoride (NaF, SnF₂) prevents dental caries by converting hydroxyapatite to acid-resistant fluorapatite.
Replacement Therapy
Administration of electrolytes (NaCl, Calcium Gluconate) to restore physiological function.
Limit Tests
Principles
- Arsenic: Gutzeit apparatus; yellow/brown stain on HgCl₂ paper.
- Chloride: AgNO₃ forms white AgCl turbidity.
- Sulphate: BaCl₂ forms white BaSO₄ turbidity.
- Iron: Thioglycolic acid forms pink/purple complex.
Pharmaceutical Impurities
Unwanted substances affecting drug quality. Sources include raw materials, manufacturing processes, reagents, storage conditions, packaging, and microbial contamination.