Kerja dan Efek Obat

Main ideas / concepts covered

• Continuing lecture topic: basic drug morphology, focusing on pharmacodynamics (what drugs do—the work/effects of drugs). This follows the prior session on pharmacokinetics and drug effects.
• Drug “journey” through the body (overview):
  • After administration, a drug undergoes pharmacokinetics, including:
    • Absorption / administration
    • Distribution
    • Metabolism (biotransformation)
    • Excretion / elimination
  • It then reaches pharmacodynamics, which explains:
    • What the drug does to the body
    • How it produces its effects
• Core pharmacodynamics concept:
  • A drug typically does not create an entirely new mechanism, but regulates existing body systems.
  • Drug action is described as a mechanism of action followed by effects.

Methodology / “flow” of drug action (structured steps)

1. Mechanism of action (how it works)
   • The drug interacts with the body by altering an existing system, such as by:
     • Inhibiting enzymes
     • Inducing enzymes
2. Produces effects
   • A good drug provides a therapeutic (beneficial) effect (e.g., improves symptoms or cures the condition).
3. May also cause unwanted effects
   • In addition to therapeutic effects, drugs can produce:
     • Side effects
     • Toxic effects
     • Abnormal reactions

Types of targets and drug–target interactions

• Specific interactions (mediated)
  • A drug interacts via specific drug targets, such as:
    • Receptors
    • Enzymes
    • Carrier molecules
• Nonspecific interactions (not mediated by a specific target)
  • Effects occur through physicochemical mechanisms rather than a single defined receptor/target.
  • (Implied examples involve physical/chemical property–driven effects rather than receptor binding.)

Classification of drug effects (by relation to dose)

• Quantal effect
  • Not related to dose
  • Often all-or-none
  • Examples/themes mentioned:
    • Sedative effect (sleep)
    • Vomiting
• Graded (dose-related) effect
  • Related to dose
  • As dose increases, effect increases (e.g., intensity)
  • Examples/themes mentioned:
    • Heart rate / cardiotonic effects (digoxin used as an example)

Main vs secondary vs abnormal vs side effects (what happens and how it’s classified)

1) Main (primary) effects

• Desired therapeutic goals
• Example:
  • Diphenhydramine: main effect as an antihistamine (anti-allergy)

2) Secondary effects

• Additional effects occurring along with the main effect
• Can be:
  • Desired (beneficial)
  • Undesired
• Example (diphenhydramine):
  • Main effect: antihistamine/anti-allergy
  • Secondary effect (desired): sedation/sleep can help rest when coughing
  • Secondary effect (undesired): drowsiness, which is not ideal for driving/alert-required tasks

3) Side effects / unwanted effects

• Unwanted effects such as:
  • Nausea
  • Vomiting
• Discussed as effects that may appear during use depending on dose and patient response.

4) Abnormal effects (occur only in certain groups/individuals)

• Not experienced by everyone
• Examples/mechanisms mentioned:
  • Tolerance
  • Intolerance
  • Idiosyncratic reactions
  • Allergy / hypersensitivity
  • Anaphylaxis
  • Pseudo-tolerance
  • True intolerance/tolerance described as involving changes in drug handling or target tissue response

Tolerance and intolerance (with examples and distinctions)

• Tolerance
  • Requires a higher dose to achieve the same effect
  • Example:
    • A patient using paracetamol: usually one tablet works, but with tolerance it may stop working and require higher dose
• Intolerance
  • A deviation in drug response (different from what is expected)
  • Types mentioned:
    • True intolerance / true tolerance vs pseudo-tolerance
    • Genetic / idiosyncratic influences
• Genetic/inborn differences
  • Example:
    • Primaquine causing hemolysis, depending on genetic susceptibility

Allergy, hypersensitivity, and anaphylaxis

• Allergy mechanism
  • Triggered by antigen–antibody reactions
  • Results can include:
    • Itching
    • Hives/lumps
• Anaphylaxis
  • A rapid antigen–antibody reaction
  • Can occur quickly after drug injection
  • Symptoms mentioned:
    • Seizures
    • Swelling
• Prevention step described
  • Skin testing before antibiotics:
    • Inject a small dose (subcutaneous/intradermal) to test for allergy
    • If reaction occurs: patient is allergic; avoid the full dose

Toxic effects (severe unwanted effects)

• Toxic effects are described as unwanted harmful effects.
• Examples given:
  • Chloramphenicol: severe hepatotoxicity (liver damage)
  • Paracetamol overdose / repeated high use: kidney damage
• Toxicity is tied to organ/system vulnerability (e.g., liver/kidneys).

“Place of work” (site of drug action) and its use

• The drug’s “place of work” is where it acts in the body.
• Knowing this helps:
  • Understand how the drug works
  • Classify drugs based on site of action (not only chemical class)
• Example sites and drug examples mentioned:
  • Application site
    • Example: bacitracin ointment on wounds
  • Transport process
    • Mentioned: osmotic diuretics
  • In the cell / extracellular locations
    • Example (extracellular): atropine (noted as acting outside the cell)
  • Cell membrane / surface
    • Examples: heparin (anticoagulant; tied to cell surface context), penicillin
  • Nervous system
    • Mentioned: drugs acting in the nervous system

Mechanism examples tied to prior/advanced concepts (imaging/chemistry notes)

• Brief educational examples were mentioned, including themes related to:
  • Diagnostic/imaging contrast or diagnostic agents (e.g., radio/contrast concepts like X-ray/iodinated contrast, mentioned vaguely)
  • Acid-base properties
  • Absorption of toxins (a “diarrhea medicine to absorb toxins” idea is referenced, though details are unclear due to subtitle errors)

Speakers / sources featured

• Main speaker: the course lecturer (name not clearly stated; addressed as “Miss/Ms” and “everyone/students”).
• No external sources: no authors, papers, or named organizations are identifiable from the subtitles.
• Examples of drugs/agents mentioned (not speakers):
  • mefenamic acid, sodium diclofenac, diphenhydramine (Benadryl/antihistamine context), trimeton (mentioned), CTM (mentioned), digoxin
  • paracetamol, tetracycline, primaquine
  • chloramphenicol, bacitracin ointment
  • atropine, heparin, penicillin
  • osmotic diuretics
  • radioactive/diagnostic contrast agents (mentioned vaguely)