Pharmacology: Overview of Medication Development and Interaction

Definition of Pharmacology

• Study of medications or chemical compounds interacting with living systems.
• Aims to produce specific effects on molecules, cells, tissues, and organisms.

Medication Development Process

Stages of Development

1. Discovery
   • Candidate compound identified for a specific disease.
2. Pre-Clinical Research
   • Testing on cell cultures and animals (mice, rats).
   • Assess potential harm to living organisms.
3. Clinical Development
   • Conduct clinical trials on humans to determine safety and efficacy.

Clinical Trials Phases (Mnemonic: All Medications Need the Seal of Approval)

• Phase 1:
  • Tests safety on a small group of healthy individuals.
• Phase 2:
  • Evaluates effectiveness and optimal dosing on a moderate-sized group with the condition.
• Phase 3:
  • Compares the new medication with standard treatments in a larger population.
  • Aims to replicate real-life conditions for regulatory approval.
• Phase 4:
  • Post-market surveillance for long-term or rare side effects.
  • May lead to recalls if unsafe.

Medication Naming

• Chemical Name: Describes chemical structure (e.g., N-acetyl-P-aminophenol).
• Generic Name: Shortened version of the chemical name (e.g., Paracetamol or Acetaminophen).
• Brand/Trade Name: Names by pharmaceutical companies (e.g., Panadol or Tylenol).

Drug Interaction with the Body

Pharmacokinetics

• Refers to what the body does to the medication:
  • ADME: Absorption, Distribution, Metabolism, Excretion.

Pharmacodynamics

• Refers to what the medication does to the body:
  • Interaction with cell receptors leads to changes in cell function (e.g., protein production, DNA replication).
  • Ideal medications provide specific therapeutic effects but often cause side effects (e.g., nausea, fatigue).

Therapeutic Index

• Ratio of toxic dose to effective dose:
  • Calculated as TD50 (median toxic dose) / ED50 (median effective dose).
  • A higher therapeutic index indicates a safer medication.
• Medications with a low therapeutic index (e.g., warfarin, lithium) require close monitoring.

Drug Interactions

Types of Interactions

• Pharmacokinetic Interactions:
  • One medication alters the absorption, distribution, metabolism, or excretion of another.
• Pharmacodynamic Interactions:
  • Medications influence each other's effects directly (synergistic or antagonistic effects).

Summary Recap

• Medication development consists of: Discovery, Pre-Clinical, and Clinical phases.
• Each medication has three names: Chemical, Generic, and Brand.
• Pharmacokinetics studies body effects on medication; Pharmacodynamics studies medication effects on the body.
• Medications with narrow therapeutic indices require monitoring to prevent toxicity.
• Drug interactions can occur at both pharmacokinetic and pharmacodynamic levels.