Pharmacology Concepts and Calculations Part 1

Pharmacology at a Glance: Concepts and Calculations (Part 1)

• Pharmacology is the study of drugs and their effects on living systems
• Pharmacodynamics describes the effects of a drug on the body; e.g., Paracetamol's mechanism depends on prostaglandin inhibition.
• Pharmacokinetics describes the body's effects on a drug, including absorption, distribution, metabolism, and excretion (ADME).
• Drugs are classified by therapeutic class, chemical properties, and mechanism of action.
• Drug naming can vary considerably between chemical, IUPAC, and trade names, making classification challenging.
• Drug targets are molecular recognition sites on which drugs bind.
• Most drug targets are proteins, including receptors, enzymes, ion channels, and transporters.
• Approximately 73% of drug targets are human, 16% are microbial/viral, and 11% are miscellaneous.
• Drug targets may be identified by analyzing disease pathways or genetic determinants of disease susceptibility.
• The Human Genome Project and modern molecular biology techniques have accelerated the identification and characterization of drug targets.
• Some drug discoveries result from investigations targeted at specific diseases, but others are accidental.
• Examples of drugs with specific roles include anti-tuberculosis drugs, antibacterial drugs, anti-cancer drugs, and anti-gout drugs
• Important figures in pharmacology include Paul Ehrlich (interested in staining cellular components and pioneered syphilis treatment), and Hitchings and Elion (pioneered the understanding of disease mechanisms and drug synthesis).
• Examples of accidental discoveries are the drug amphetamine, initially used as a headache remedy, later discovered to decrease agitation in children which then led to the development of Ritalin for ADHD.
• The concept of 'magic bullets' developed from Ehrlich's theory of targeted drug development, ideally with specific effects minimizing systemic toxicity.
• Langley's work on neuromuscular junction interactions introduced the concept of receptor interactions with drugs.
• Drugs act through receptors, and these receptors interact with specific compounds to trigger reactions.
• Receptors can be intracellular or cell membrane-bound.

Learning Objectives

• Define pharmacology, drug, medicine, pharmacokinetics, pharmacodynamics
• Explain the difference between a medicine and a drug.
• Explain the receptor concept and its development and how drugs are classified based on their action, drug class, and chemical properties.
• Explain the role of human genome mapping projects and molecular biological techniques in identifying drug targets.
• Define drug target, receptor, enzyme, ion channel, and transporter.
• Recognize the difference between 'conventional drug target' (analyzing pathophysiology and mechanisms) and 'Trawling the genome' (identifying disease genes).
• Understand the concept of transgenic models in studying drug responses.

Drug Targets

• Approximately 600–1500 identified drug targets (overlap between druggable genome, disease modifying genes, and human genome)

Question Time

• Approximately 39 drugs were FDA approved in 2021, and this was lower than 2020.