IM 6.3.7 Fundamentals of Pharmacology 1(2024)

Fundamentals of Pharmacology

Ayman El-Sahar, PhD | Pharmacology & Toxicology | NGU Email: Ayman.Elsahar@nqju.edu.eg2024-2025 | School of Pharmacy

Objectives of the Lecture

• Historical Approaches to Drug Therapy: Identify various methods employed in managing diseases through medication.

• Scope of Pharmacology: Define the field of pharmacology, emphasizing its relevance in the study of drugs.

• Sources of Drugs: Recall various origins from which drugs can be obtained.

• Molecular Targets for Drug Action: Describe different biological targets that drugs may interact with.

• Drug Safety and Regulation: Understand concepts pertaining to drug safety and the role of health regulatory bodies.

Historical Background of Pharmacology

Hippocrates: The Father of Medicine

• Responsible for the Hippocratic Collection—a seminal body of medical texts.

• His guidance on observing and examining patients laid foundational practices still prevalent today.

• Advocated for a healthy lifestyle that includes exercise and dietary management.

• Recognized the medicinal properties of herbs, such as Willow bark, known for its pain-relieving effects (salicylates).

Advances in Surgical Anesthesia

• Historical challenges faced during surgeries, particularly limb amputations due to gangrene.

• Surgeons utilized herbal anesthetics such as Henbane and Mandrake to alleviate patient suffering.

• Notable recipe by Celsus: Boiled wild poppy heads mixed with raisin wine, creating a sleep-inducing pill for patients.

Pharmacology

Definition and Development

• The term pharmacology originates from the Greek word "Pharmakon", meaning drug.

• Initially, drugs were administered based on traditional knowledge without understanding their mechanisms.

• The field has evolved towards evidence-based medicine, with a focus on understanding drug actions.

Understanding Pharmacology

• Pharmacology studies drug interactions with living systems, emphasizing the modification of existing conditions rather than creating new ones.

• Mechanism of Action: The ways through which drugs exert effects in the body—impacting proteins, cells, tissues, and organs.

• Examples include stimulants like Caffeine and depressants such as Heroin.

Sources of Drugs

A. Plant and Natural Products

• Examples include:

  • Atropine (from Atropa belladonna)

  • Digoxin (from Digitalis purpurea)

  • Opiates (from Papaver somniferum)

  • Quinine (from Cinchona Bark)

  • Cannabis (from Cannabis sativa)

  • Cocaine (from Erythroxylum coca)

B. Microorganisms

• Notable drugs derived from microbes include:

  • Penicillin (from Penicillium notatum)

  • Neomycin (from Streptomyces fradiae)

  • Vancomycin (from Amycolatopsis orientalis)

  • Cephalosporins and Botulinum toxin (from Clostridium botulinum)

C. Animal Sources

• Key drugs obtained from animals:

  • Insulin from porcine or bovine pancreas (Islets of Langerhans)

  • Exenatide, derived from Gila monster saliva, aids in diabetes treatment.

  • Allantoin, extracted from maggots, aids in wound debridement.

  • Human growth hormone from the pituitary gland.

  • Hirudin from leeches, utilized as an anticoagulant.

  • Teprotide, extracted from snake venom, serves as an ACE inhibitor.

Important Pharmacological Factors

• Mechanism of Action: Understanding how drugs interact biologically.

• Dosage: Ranges from ineffective to toxic levels.

• Selectivity: Rare for drugs to have single-target effects.

• Side Effects: Effects such as those seen in benzodiazepines, which are anxiolytic, hypnotic, relax muscles, and can cause amnesia.

• Risk-Benefit Ratio: Considerations include patient quality of life, age, and seriousness of illness.

Mechanisms of Drug Action

• Different kinds of mechanisms:

  • Physical mechanisms: e.g., osmotic laxatives.

  • Chemical mechanisms: e.g., antacids neutralizing stomach acid.

  • Biological mechanisms: Most drugs interact with protein macromolecules in cells.

Biological Targets of Drugs

Major Target Types

1. Ion Channels: e.g., local anesthetics blocking Na+ channels.

2. Enzymes: e.g., Captopril and Sildenafil, affecting pathways that lead to vasodilation.

3. Carrier Molecules: Responsible for transporting substances across membranes, such as the sodium-potassium pump.

4. Receptors: Specialized macromolecules that bind drugs, initiating pharmacological actions.

Ion Channels and Drugs

• Local anesthetics act specifically on voltage-gated Na+ channels.

Enzyme Interactions

• Enzymatic inhibition can lead to therapeutic effects, as seen with ACE inhibitors in hypertension treatment.

Carrier Molecules and Receptors

• Carrier molecules facilitate transportation, with examples like digoxin interacting with cardiac transport proteins.

• Receptors can signify various interactions:

  • Enzyme-linked receptors (e.g., insulin receptors activate tyrosine kinases).

  • G-protein coupled receptors (e.g., adrenergic receptors) affect intracellular signaling.

  • Nuclear receptors such as steroid receptors modulate gene expression.

Milestones in Drug Therapy

• Historical Events:

  • 1600 BC: Egyptian medical papyrus.

  • 1804: Sertürner isolates morphine—the first pure drug.

  • 1945: Fleming discovers penicillin, marking a significant advancement in antibiotic therapy.

Drug Safety Considerations

• Teratogenicity: Refers to drug-induced fetal malformations with historical examples like Thalidomide.

• Importance of regulatory bodies such as the Egyptian Drug Authority and MHRA in the UK for ensuring drug safety.

Suggested Reference

• Lippincott Illustrated Reviews: Pharmacology, 6th Edition by Richard A. Harvey et al.

Questions

Engage with Key Concepts

Reflect on the lecture's content and prepare to discuss prominent themes in the field of pharmacology.