Pharmacology I - Introduction

Pharmacology I - Introduction

• Course instructor: Roger K. Verbeeck, Ph.D. and D.F Chuma
• Institution: UNAM (School of Pharmacy)
• Contact: [email protected]

Contents

• Definitions
• History of pharmacology
• Development of a new drug

Pharmacology

• Broad subject encompassing the source, physical and chemical properties, compounding, physiological actions, absorption, fate, excretion, and therapeutic uses of drugs. (Goodman & Gilman The Pharmacological Basis of Therapeutics, 1st edition, 1941)
• Studies how drugs work (pharmacodynamics) and their processing by the body (pharmacokinetics).
• Crucial for: discovering new drugs, improving drug effectiveness, reducing side effects, and understanding patient response differences.

What is a Drug?

• Active chemical entity in a prescribed medicine
• Used for diagnosis, prevention, treatment, or curing a disease.
• Derived from the French word "drogue," meaning "dried herb".
• WHO defined it as any substance or product used or intended to modify or explore physiological systems or pathological states for recipient benefit (1966)

Nomenclature of Drugs

• Every drug has three names:
  • Chemical name: Describes the drug's chemical nature (e.g., (RS)-2-(4-(-2-methylpropyl) phenyl) propanoic acid (Ibuprofen))
  • Non-proprietary/Generic name: Authoritatively accepted by a scientific body. All WHO member nations use a single recommended International Non-proprietary Name (rINN). (e.g., Ibuprofen)
  • Proprietary/Brand name: Owned and designated by the manufacturer (e.g., Brufen®, Combiflam®, Unafen®, Advil®, etc.)

Pharmacodynamics and Pharmacokinetics

• Pharmacodynamics: Relationship between drug's blood concentration, and desired/adverse (toxic) effects in the body.
• Pharmacokinetics: Time course of drug absorption, distribution, metabolism, and excretion (ADME) as a function of time.

History of Pharmacology

• Started mid-19th century with increasing knowledge of normal/abnormal body function.
• First department of pharmacology established in Dorpat (Estonia) in 1847.
• Oswald Schmiedeberg (1838-1921), a student of Rudolph Buchheim, is considered the founder of modern pharmacology.
• Concept of receptors proposed by John Newport Langley (1852-1925) in 1905.
  • Paul Ehrlich (1854-1915) further refined this concept in 1907.
• Key discoveries: Penicillin (1928), Sulfonamides (1935), etc.
• 20th century saw major developments in drug classes.
• History timeline includes discoveries and developments from ancient times (e.g., Sumeria, 2000 BC - aspirin).
• Including morphine discovery and synthesis dates.

Sources of Drugs

• Natural Sources: Plants, Animals, Microbiota, Minerals
• Key examples of plant-derived drugs include:
  • Leaves: Digoxin, digitoxin, atropine
  • Flowers: Vincristine, vinblastine
  • Fruits: Physostigmine
  • Seeds: Strychnine, morphine
  • Roots: Emetine, reserpine
  • Bark: Quinine, atropine
  • Stem: Tubocurarine
• Animal Sources: Whole animals (leeches, etc.), organs (cod liver oil, insulin), glandular products (vaccines, sera).
• Microbiota Sources: Penicillin, chloramphenicol, streptomycin
• Mineral Sources: Ferrous sulfate, magnesium sulfate, potassium iodide, iodine, radioisotopes of iodine and other minerals.
• Semi-synthetic Sources: Alteration of the chemical structure of a natural drug (e.g., homatropine, heroin, ampicillin).
• Synthetic Sources: Chemical synthesis; altered structure, not naturally occurring (pure chemicals, better cost-effectiveness, improved safety).

Drug Development

• Historical: Discovering active ingredients in traditional remedies or through accidental discoveries.
• More recently: High-throughput screening and rational drug design (targeting receptors and biological processes).
• Computer-aided drug design: Predicting whether a molecule binds to a target.
• Small organic molecules: Primary drug type until recent advancements in DNA technology.
• Recombinant DNA technology: Enables the synthesis of proteins by various organisms, including biopharmaceuticals like human insulin.
• Regulatory aspects:
  • 1937: Sulfanilamide elixir disaster leads to the Federal Food, Drug, and Cosmetic Act (FD&C Act) of 1938.
  • 1956: Thalidomide disaster leads to more structured drug regulations (Kefauver-Harris Amendment).
• Clinical development: Preclinical (physicochemical, cell cultures), clinical trials (Phase I, II, III, IV) and regulatory review for marketing authorisation.
• Post marketing Surveillance: Pharmacovigilance to monitor the safety and efficacy of drugs after approval.

Drug Development (Regulatory Aspects)

• Price considerations: Patient prices, wholesale prices.
• Specific examples: Omeprazole, Eculizumab.

Bioequivalence Study

• Comparing generic and reference drug formulations (using Acyclovir as an example) - similar blood concentration profiles.

Principles and Modes of Drug Administration

• Principles: "Do No Harm" as primary, with five rights (patient, drug, dose, time, route).
• Modes (Routes): Oral, sublingual, rectal, application to mucous membranes, inhalation, injection (various types).

Preparations of Drugs and Dosage Forms

• Dosage Forms: Tablet, capsule, caplet, syrup, cream, ointment, lotion, liniment, gel/jelly, paste, lozenge, troche, solution (aqueous/suspension), aerosol, elixir, extract, powder, suppository; tincture, transdermal patch.

This quiz covers the foundational concepts of pharmacology, including definitions, historical context, and the drug development process. Explore essential pharmacological principles, such as pharmacodynamics and pharmacokinetics, which are vital for understanding drug interactions and therapeutic applications.