Drugs are usually man made , so naturally they are the by products of analogy meaning they are built on the basis of analogy. Analogical source being mainly the human body biomolecules but the difference in them being in their efficacy of action.

• Agonists
• Antagonists
• Parasympathomimetics
• Sympathomimetics
• Blockers
• Simulators

Considering the analogy , blockers would resemble objects which can be used for blockade like stones , hammers , locks whereas simulators would be something like key , wheels , arrows.

• Drug
  • types of drug action
    • Stimulation
    • Depression
    • Irritation
    • Replacement
    • Cytotoxic