Questions and Answers
What is the origin of the word 'drug'?
Drogue, meaning 'a dry herb'
According to WHO, how is a drug defined?
A substance, material or product used to modify or explore physiological processes or pathological states.
All drugs are poisons, but not all poisons are drugs.
True
Which of the following is NOT a general feature of a drug?
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What is the ideal molecular weight range for drugs?
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What influences the interaction between drug and receptor?
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Which type of drug is retained more in the body?
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What is the difference between local effect and systemic effect of drugs?
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Which level of drug action involves ion channels and enzymes?
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What happens when a ligand binds to a ligand-gated ion channel?
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Study Notes
Drug Definition and Origin
- The term "drug" originates from "Drogue," meaning ‘a dry herb.’
- WHO defines a drug as a substance used to modify physiological processes for the recipient's benefit.
- All drugs are considered poisons, but not all poisons qualify as drugs.
General Features of Drugs
- Molecular Size: Smaller molecules are absorbed more easily; ideal molecular weight is between 100-1000 Da (e.g., streptokinase: 47,286.7 Da vs. nitric oxide: 30.01 Da).
- Shape: Drugs can be globular or linear, modifying their shape based on receptor interaction. Examples include pH and temperature-responsive polymeric drugs.
- Chemical Nature: The pharmacophore is essential for optimal interactions with biological targets, influencing drug efficacy (e.g., different effects of benzoic acid vs. 5-chloro salicylic acid).
- Lipid/Water Partition Coefficient (log P): Lipid soluble drugs are retained in the body, while water-soluble drugs are more readily excreted.
- Degree of Ionization: Ionized drugs are polar and water-soluble, whereas unionized drugs are less polar and lipid-soluble; ions can pass through specific channels.
- Physical Properties: Drugs can exist as solids, liquids, or gases. Gas diffusion rates surpass those of liquids and solids.
Drug Effects
- Local Effect: Occurs at the site of application, affecting specific tissues.
- Systemic Effect: Drug action spreads throughout the body, typically via bloodstream circulation.
Mechanisms of Drug Action
- Molecular Level: Drug action involves ion channels, enzymes, and carrier molecules (e.g., aspirin inhibits COX).
- Cellular Level: Interaction with cell types, such as smooth muscle cells (e.g., calcium channel blockers).
- Tissue Level: Effects include contraction, secretion, and metabolic activity (e.g., salbutamol's bronchodilation).
- System Level: Alters functions at central and peripheral nervous systems (e.g., atorvastatin reducing LDL cholesterol).
Drug Action Mechanisms
- Ligand-Gated Ion Channels (LGIC): Open following ligand binding, allowing ion flow and altering membrane potential within 0.1 – 2 milliseconds.
- G-Protein Coupled Receptors (GPCR): Activation of G-proteins modifies ion channel states and influences cellular processing, including protein expression changes.
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Description
Explore the fundamental concepts of drug structures and their mechanisms in this informative quiz. Gain insights into how the general structure of a drug affects its physiological and pathological interactions. Perfect for pharmacy students and professionals alike.
