Essential Principles of Pharmacology and Therapeutics

Part 1: General Pharmacology

1. Pharmacology

Definition: Pharmacology is the study of drugs, their sources, properties, actions, uses, and effects on living organisms.

Main Branches

• Pharmacodynamics: What the drug does to the body.
• Pharmacokinetics: What the body does to the drug.
• Clinical Pharmacology: The study of drugs in humans.
• Pharmacotherapeutics: The use of drugs in treatment.
• Toxicology: The study of the harmful effects of drugs and poisons.

2. Pharmacokinetics ⭐⭐⭐⭐⭐

Definition: Pharmacokinetics is the study of what the body does to a drug.

ADME

• A — Absorption: Movement of a drug from the site of administration into the blood.
• D — Distribution: Movement of a drug from the blood to the tissues.
• M — Metabolism: Chemical alteration of a drug, occurring mainly in the liver.
• E — Excretion: Removal of a drug or its metabolites from the body, mainly through the kidneys.

Factors Affecting Absorption

• Route of administration
• Blood flow
• Solubility
• Food
• Gastrointestinal (GI) condition
• Drug formulation

Factors Affecting Excretion

• Renal function
• Renal blood flow
• Urine pH
• Age
• Disease condition

3. Pharmacodynamics ⭐⭐⭐⭐⭐

Definition: Pharmacodynamics is the study of what a drug does to the body.

Mechanism of Action

Drugs may act through:

• Receptors
• Enzymes
• Ion channels
• Transport systems

Basic Sequence

Drug → Target → Biological response → Clinical effect

4. Manifestations of Pharmacological Actions ⭐⭐⭐⭐⭐

1. Stimulation: An increase in the activity of a tissue or organ.
2. Depression: A decrease in the activity of a tissue or organ.
3. Irritation: A local stimulation or inflammatory response.
4. Replacement: The supply of a substance deficient in the body.
5. Cytotoxic Action: The destruction or inhibition of cells.

5. Classification According to Selective Action

• Selective Action: The drug produces a greater effect on a particular tissue, organ, or receptor.
• General/Non-selective Action: The drug produces effects on several tissues or systems.

Exam line: Selectivity means relative preference for a particular target; it does not always mean complete specificity.

6. Drug Dosage

Definition: Drug dosage is the amount of drug given to a patient to produce the desired therapeutic effect.

Factors Affecting Dosage

• Age
• Body weight
• Disease
• Route of administration
• Severity of condition
• Other medicines
• Renal and liver function

7. Methods of Administration

Enteral

• Oral
• Sublingual
• Rectal

Parenteral

• IV (Intravenous)
• IM (Intramuscular)
• SC (Subcutaneous)

Other

• Topical
• Inhalational

Notes on Routes:

• Oral: Convenient and common.
• IV: Rapid action and complete systemic availability.
• IM: Useful for systemic administration.
• Topical: Mainly local action.
• Inhalational: Useful for respiratory, local, or systemic effects.

8. Chemical and Physical Basis of Pharmacology

Drug action depends on physical and chemical properties such as:

• Chemical structure
• Molecular size
• Solubility
• Stability
• Ionization
• Lipid/water solubility

These properties influence the sequence of: Absorption → Distribution → Metabolism → Excretion → Drug action.

Part 2: Allergy, Toxicity, and Adverse Effects ⭐⭐⭐⭐⭐

9. Drug Allergy

Definition: Drug allergy is an immune-mediated reaction to a drug.

Features

• Occurs in susceptible individuals.
• May occur after sensitization.
• May range from mild to severe.
• Severe allergic reactions can cause anaphylaxis.

10. Idiosyncrasy

Definition: Idiosyncrasy is an unusual and unpredictable response to a drug.

Difference: Allergy is immune-mediated, whereas idiosyncrasy is an unusual individual response.

11. Anaphylaxis

Definition: Anaphylaxis is a severe, rapid, and potentially life-threatening allergic reaction.

Possible Features

• Difficulty in breathing
• Fall in blood pressure
• Swelling
• Skin manifestations

Emergency medical treatment is required.

12. Drug Toxicity

Definition: Drug toxicity refers to harmful effects produced by excessive or abnormal exposure to a drug.

Causes

• Excessive dose
• Prolonged use
• Accumulation
• Impaired metabolism
• Impaired excretion

13. Adverse Drug Reaction

Definition: An adverse drug reaction is an unwanted and harmful response to a drug at normal therapeutic doses.

Important Types

• Side effect
• Secondary effect
• Toxic effect
• Intolerance
• Idiosyncrasy
• Drug allergy
• Photosensitivity

14. Side Effect

An unwanted effect occurring along with the desired therapeutic effect. For example, some medicines may cause drowsiness while producing their intended therapeutic effect.

15. Secondary Effect

An indirect or unintended effect produced by a drug.

16. Toxic Effect

A harmful effect produced due to excessive drug exposure or excessive pharmacological action.

17. Intolerance

An exaggerated response to a drug at a normal dose.

18. Photosensitivity

An abnormal skin reaction associated with exposure to light while taking or using certain substances.

19. Tolerance

Definition: Tolerance is a condition in which repeated use of a drug produces a reduced response. Therefore, a larger amount may be needed for the same effect.

20. Drug Dependence

Definition: Drug dependence is a condition in which a person becomes physically or psychologically dependent on a drug.

Types

• Physical dependence
• Psychological dependence

21. Drug Abuse

The improper or non-medical use of drugs that may cause harm, dependence, or other problems.

22. Withdrawal Reaction

Symptoms occurring after the reduction or stopping of a drug on which dependence has developed.

23. Cumulative Action

Cumulative action occurs when repeated doses accumulate in the body and produce an increased effect.

Causes

• Frequent dosing
• Slow elimination
• Impaired renal function
• Long duration of action

24. Drug-Induced Disease

A disease or abnormal condition caused by a drug.

25. Poisoning

A harmful condition produced by exposure to a poisonous or excessive amount of a substance.

Part 3: CNS Drugs ⭐⭐⭐⭐⭐

26. Central Nervous System

The CNS consists of the Brain and Spinal Cord. CNS drugs can produce:

• Stimulation or Depression
• Sedation and Hypnosis
• Analgesia and Anesthesia
• Control of seizures
• Changes in mental functions

27. General Anesthetics

Definition: General anesthetics produce a reversible loss of consciousness and sensation.

Important Drugs

• Propofol: Used for induction and maintenance of anesthesia. Adverse effects include hypotension and respiratory depression.
• Nitrous Oxide: An inhalational anesthetic used for anesthesia and analgesia. Adverse effects include nausea and vomiting.
• Isoflurane: An inhalational anesthetic used for general anesthesia. Adverse effects include hypotension and respiratory depression.

28. Alcohols

Ethanol Main Effects:

• CNS depression.
• At lower exposure, it may cause disinhibition.
• At higher exposure, it causes marked CNS depression.
• Chronic excessive use can cause dependence and organ damage.

29. Alkaloids

Alkaloids are naturally occurring nitrogen-containing compounds, many of which have important pharmacological actions. Examples include Morphine, Atropine, Caffeine, and Quinine.

30. Narcotic/Opioid Analgesics

• Morphine: Used for severe pain. Adverse effects include respiratory depression, constipation, and drowsiness.
• Codeine: Used for pain and cough. Adverse effects include drowsiness and constipation.

31. Antipyretics

Definition: Drugs that reduce fever.

• Paracetamol: Used for fever and mild-to-moderate pain. Adverse effect includes liver toxicity in overdose.

32. Hypnotics

Definition: Drugs that produce sleep.

• Zolpidem: Used for insomnia. Adverse effects include drowsiness and dizziness.

33. Sedatives

Definition: Drugs that reduce excitement and produce calming effects.

• Diazepam: A benzodiazepine used for anxiety, sedation, and seizures. Adverse effects include drowsiness and CNS depression.

34. Anticonvulsants

Definition: Drugs used to prevent or control seizures.

• Phenytoin: Used for seizures. Adverse effects include gingival enlargement and ataxia.
• Sodium Valproate: Used for seizures. Adverse effects include hepatotoxicity and weight gain.
• Carbamazepine: Used for seizures and neuralgia. Adverse effects include dizziness and blood dyscrasias.

35. CNS Stimulants

These drugs increase CNS activity.

• Caffeine: Used for CNS stimulation. Adverse effects include insomnia, nervousness, and palpitations.

36. Psychotherapeutic Drugs

Used in the management of mental and behavioral disorders.

Main Groups

• Antipsychotics (e.g., Chlorpromazine for psychotic disorders; may cause sedation or movement disorders).
• Antidepressants (e.g., Fluoxetine for depression; may cause nausea or insomnia).
• Anxiolytics
• Mood stabilizers

37. Drugs Acting on Pain and Inflammation

• Analgesics: Relieve pain (e.g., Morphine for severe pain, Paracetamol for mild-to-moderate pain).
• NSAIDs:
  • Ibuprofen: Used for pain and inflammation; may cause gastric irritation.
  • Diclofenac: Used for pain and inflammation; may cause gastric irritation and renal effects.

Part 4: Autonomic and Peripheral Nervous System ⭐⭐⭐⭐⭐

38. Autonomic Nervous System

Controls involuntary functions. Main divisions are Sympathetic and Parasympathetic. The focus is on Cholinergic and Adrenergic activity.

39. Cholinergic Drugs

Increase or mimic acetylcholine action.

• Neostigmine: An anticholinesterase used for Myasthenia gravis and reversal of neuromuscular blockade. Adverse effects include bradycardia and increased secretions.
• Pilocarpine: A cholinergic agonist used for glaucoma and dry mouth. Adverse effects include sweating and salivation.

40. Anticholinergic Drugs

Block cholinergic activity.

• Atropine: Used for bradycardia and pre-anesthetic care. Adverse effects include dry mouth, blurred vision, and tachycardia.

41. Adrenergic Drugs

Stimulate adrenergic/sympathetic activity.

• Adrenaline: Used for anaphylaxis and cardiac emergencies. Adverse effects include tachycardia and tremor.
• Noradrenaline: Used for severe hypotension or shock. Adverse effects include hypertension and tissue ischemia.

42. Anti-Adrenergic Drugs

Reduce adrenergic activity.

• Propranolol: A beta-blocker used for hypertension, angina, and arrhythmias. Adverse effects include bradycardia and bronchospasm.

43. Neuromuscular Junction

Definition: The junction between a motor nerve ending and a skeletal muscle fiber. Drugs can increase or decrease transmission to produce muscle relaxation.

44. Neuromuscular Blocking Drugs

Used to produce skeletal muscle relaxation or paralysis, mainly during anesthesia.

• Succinylcholine: A depolarizing blocker used for short-term relaxation. Adverse effects include hyperkalemia and prolonged apnea.
• Vecuronium: A non-depolarizing blocker used during surgery. Adverse effect includes respiratory paralysis.

45. Pupil and Ciliary Movement

• Mydriasis: Dilatation of the pupil.
• Miosis: Constriction of the pupil.
• Accommodation: The ability of the eye to change lens shape to focus on objects at different distances.
• Atropine: Causes mydriasis and cycloplegia (paralysis of the ciliary muscle causing loss of accommodation).

46. Drugs Acting on Skin

May produce local anesthesia, irritation, allergy, photosensitivity, or changes in local blood flow.

• Lidocaine: A local anesthetic used for local loss of sensation. Adverse effects include CNS or cardiovascular toxicity at excessive exposure.

Part 5: Respiratory System ⭐⭐⭐⭐

47. Bronchodilators

Increase airway diameter and improve airflow.

• Salbutamol: A β2 agonist used for asthma. Adverse effects include tremor and tachycardia.
• Theophylline: A methylxanthine used for bronchospasm. Adverse effects include nausea and palpitations.

48. Expectorants

Help in the removal of sputum from the respiratory tract.

• Guaifenesin: Used for productive cough. Adverse effects include nausea and gastric irritation.

49. Antitussives

Suppress cough.

• Dextromethorphan: Used for dry cough. Adverse effects include drowsiness and dizziness.

50. Mucolytics

Reduce the thickness and viscosity of mucus.

• Acetylcysteine: Used for thick mucus. Adverse effects include nausea and bronchospasm.

Part 6: Gastrointestinal System ⭐⭐⭐⭐

51. Antacids

Neutralize gastric acid. Examples include Aluminium hydroxide (may cause constipation) and Magnesium hydroxide (may cause diarrhea).

52. Anti-Ulcer Drugs

Reduce acid or protect gastric mucosa.

• Omeprazole: A proton pump inhibitor used for peptic ulcers and GERD.
• Famotidine: An H2 blocker used for acid-related disorders.

53. Antiemetics

Reduce or prevent vomiting.

• Ondansetron: A 5-HT3 antagonist used for nausea and vomiting.
• Metoclopramide: A prokinetic used for nausea; may cause extrapyramidal reactions.

54. Laxatives

Promote bowel movement and relieve constipation (e.g., Lactulose).

55. Antidiarrhoeals

Used to reduce symptoms of diarrhea (e.g., Loperamide).

Part 7: Kidney and Uterus

56. Diuretics

Drugs that increase urine formation.

• Furosemide: A loop diuretic used for edema and hypertension.
• Hydrochlorothiazide: A thiazide diuretic used for hypertension.

57. Drugs Affecting the Uterus

• Oxytocin: A uterotonic hormone used for induction of labor and control of postpartum bleeding.

Part 8: Cardiovascular System ⭐⭐⭐⭐⭐

58. Antihypertensive Drugs

Reduce blood pressure. Main groups include ACE inhibitors (e.g., Enalapril), Beta-blockers, Calcium channel blockers (e.g., Amlodipine), Diuretics, and ARBs.

59. Antianginal Drugs

Used to prevent or relieve angina pectoris (e.g., Nitroglycerin).

60. Antiarrhythmic Drugs

Used to treat abnormal cardiac rhythms (e.g., Amiodarone).

61. Cardiac Glycosides

Digoxin: Used for heart failure and certain arrhythmias. Adverse effects include visual disturbances and nausea.

62. Blood and Blood-Forming Tissues

• Anticoagulants: Reduce clot formation (e.g., Heparin).
• Antiplatelet Drugs: Reduce aggregation (e.g., Aspirin).
• Hematinics: Treat nutritional anemias (e.g., Iron).

63. Blood Vessels

Drugs may cause Vasodilation (increasing diameter) or Vasoconstriction (decreasing diameter).

Part 9: Chemotherapy ⭐⭐⭐⭐⭐

64. Chemotherapeutic Agents

Substances used to destroy or inhibit harmful microorganisms or abnormal cells, including antibacterial, antitubercular, antifungal, antiviral, and antiparasitic agents.

65. Antibiotics

• Penicillins: e.g., Amoxicillin.
• Cephalosporins: e.g., Ceftriaxone.
• Macrolides: e.g., Azithromycin.
• Tetracyclines: e.g., Doxycycline.
• Aminoglycosides: e.g., Gentamicin.

66. Antitubercular Drugs ⭐⭐⭐⭐⭐

Key drugs include Rifampicin, Isoniazid, Pyrazinamide, Ethambutol, and Streptomycin.

67. Antifungal Drugs

Examples include Fluconazole and Amphotericin B (used for serious systemic infections).

68. Antiviral Drugs

Acyclovir: Used for herpes virus infections.

69. Antiparasitic Drugs

Albendazole: An anthelmintic used for worm infestations.

Part 10: General and Local Anesthesia

70. General Anesthesia

A reversible state of unconsciousness with loss of sensation, analgesia, and muscle relaxation.

71. Local Anesthesia

A temporary loss of sensation in a specific area without loss of consciousness (e.g., Lidocaine).

72. Effects of Anesthetics on the Eye

May affect pupil size, ocular movements, protective reflexes, and intraocular pressure.

73. Effects on the Skin

Local anesthetics produce a temporary loss of sensation and block local nerve transmission.

74. Effects on Other Physiological Systems

Anesthetics may reduce respiratory activity, affect blood pressure, and produce muscle relaxation.

Part 11: Hormones and Endocrine Drugs ⭐⭐⭐⭐

75. Hormones

Chemical messengers that regulate growth, metabolism, reproduction, and electrolyte balance.

76. Insulin

An antidiabetic hormone used for Diabetes Mellitus. The main adverse effect is hypoglycemia.

77. Thyroid Hormone

Levothyroxine: Used for hypothyroidism replacement therapy.

78. Corticosteroids

Prednisolone: Used for inflammatory and allergic conditions.

Part 12: Vitamins

79. Vitamins

• Vitamin A: Deficiency causes night blindness.
• Vitamin B1: Deficiency causes Beriberi.
• Vitamin B12: Deficiency causes megaloblastic anemia.
• Vitamin C: Deficiency causes Scurvy.
• Vitamin D: Deficiency causes Rickets.
• Vitamin K: Deficiency causes bleeding tendencies.

Part 13: Immunological Products

80. Immunological Agents

Biological substances that modify immune responses.

81. Serum

Provides passive immunity through ready-made antibodies.

82. Vaccination

Stimulates the body to develop active immunity.

Part 14: Diagnostic Agents

85. Diagnostic Agents

Substances like contrast media used to detect or identify diseases and assess organ function.

Part 15: Clinical Pharmacology

86. Clinical Pharmacology ⭐⭐⭐⭐⭐

The study of the effects, safety, and therapeutic use of drugs in human beings.

87. Pharmacotherapeutics

The study of using medicines for the prevention and treatment of diseases.

88. Mode of Action

Explains how a drug produces its effect: Drug → Target → Response → Clinical effect.

89. Rational Basis of Medical Treatment

Involves correct diagnosis, treatment, dose, route, and monitoring to ensure maximum benefit and minimum harm.

90. Prescribing

The selection and written instruction of appropriate treatment, including dose, frequency, and duration.

91. PT and OT Clinical Problems

Pharmacological knowledge is vital for Physiotherapy and Occupational Therapy as drugs may affect exercise tolerance or cause adverse interactions with treatment.

Part 16: Western and Modern Medicine

92. Western Medical Science

A scientific approach based on observation, research, and evidence-based clinical evaluation.

93. Modern Scientific System of Medicine

Used for diagnosis, prevention, treatment, and rehabilitation in both acute and chronic conditions.

Part 17: Forensic Medicine and Toxicology ⭐⭐⭐⭐

94. Forensic Medicine

The application of medical knowledge to legal matters, including death investigation and medical evidence.

95. Toxicology

The study of poisons and their harmful effects, including diagnosis and management principles.

96. Medico-Legal Aspect

Refers to situations involving both medical knowledge and legal requirements.

Part 18: Pharmacological Chemistry

97. Pharmacological Chemistry

Deals with the chemical nature, properties, and interactions of pharmacological substances.

98. Applied Pharmacology

The practical application of pharmacological knowledge in clinical practice to ensure patient safety.

99. Rational Basis of Medical Treatment

Treatment must be based on diagnosis and appropriate therapy to achieve maximum therapeutic benefit with minimum harm.