Pharmacology

• What does the acronym ADME stand for, and why is it important in pharmacology?

  •  ADME stands for Absorption, Distribution, Metabolism, and Excretion. These processes determine the drug's bioavailability, distribution to tissues, metabolism into active/inactive forms, and elimination from the body, ultimately influencing its therapeutic effects and safety
• What factors affect the absorption of a drug

  • The route of administration, local blood flow, drug solubility, ability to cross membranes, and whether the drug is ionized affect its absorption
• What is the difference between Phase 1 and Phase 2 drug metabolism?

  • Phase 1 involves catalytic reactions (e.g., oxidation by cytochrome P450 enzymes) to produce reactive metabolites.
  • Phase 2 involves conjugation reactions that make the metabolites more water-soluble and easier to excrete.
• Define bioavailability. How is it affected by first-pass metabolism?

  • Bioavailability refers to the proportion of a drug that enters systemic circulation. First-pass metabolism, occurring in the liver or gut, reduces the amount of drug reaching circulation after oral administration.
• What is the difference between affinity and efficacy in pharmacodynamics?

  • Affinity is the ability of a drug to bind to a receptor.
  • Efficacy is the ability of a bound drug to activate the receptor and produce a biological response.
• What are the main differences between agonists and antagonists?

  • Agonists bind to receptors and activate them to produce a biological response.
  • Antagonists bind to receptors but do not activate them; they block agonists or natural ligands from binding
• What does ED50 represent, and why is it significant?

  • ED50 is the dose required to produce 50% of the maximum therapeutic effect in a population. It helps determine the drug's potency and safe dosage range.
• List four types of drug targets and provide an example of each.

  • Enzymes: ACE inhibitors (e.g., captopril) block angiotensin-converting enzyme.
  • Transport proteins: SSRIs (e.g., fluoxetine) block serotonin reuptake.
  • Receptors: Salbutamol acts on β2-adrenergic receptors for asthma relief.
  • Ion channels: Lidocaine blocks Na+ channels as a local anesthetic.
• What is the mechanism of action for beta-blockers?

  • Beta-blockers bind to β1-adrenergic receptors, inhibiting cAMP production, which reduces heart rate, force of contraction, and blood pressure.
• What is a GPCR, and how do agonists and antagonists affect it?

  • PCRs (G-protein-coupled receptors) are cell surface receptors that transmit signals inside the cell.
  • Agonists activate GPCRs, triggering intracellular signaling pathways.
  • Antagonists block the receptor, preventing activation by natural ligands or agonists.
• Compare the cellular effects of agonist and antagonist binding to GPCRs.

  • Agonists: Induce conformational changes in GPCRs, activating intracellular G-proteins and leading to downstream effects like increased cAMP production.
  • Antagonists: Bind to GPCRs without activating them, blocking agonists from inducing these intracellular changes.
• How does salbutamol, a β2-adrenergic receptor agonist, help in asthma?

  • Salbutamol activates β2-adrenergic receptors in bronchial smooth muscle, increasing cAMP levels, causing relaxation, and easing breathing.
• Explain the difference between pharmacokinetics and pharmacodynamics.

  • Pharmacokinetics studies how the body processes drugs (ADME).
  • Pharmacodynamics studies what drugs do to the body, focusing on mechanisms of action and effects.
• What are the key parameters measured in drug plasma concentration studies?

  • Half-life: Time taken for the plasma concentration of a drug to reduce by half.
  • Clearance: The rate at which a drug is eliminated relative to plasma concentration
• Why might lipid-soluble drugs have a prolonged effect?

  •  Lipid-soluble drugs can readily cross membranes and distribute into tissues, often resulting in slow clearance and prolonged effects.