14 Questions
Which mechanism of drug movement requires a carrier and energy?
Active transport
Which mechanism of drug movement does not require a carrier or energy?
Passive diffusion
Which mechanism of drug movement is necessary for the transport of endogenous compounds with slow movement by simple diffusion?
Facilitated diffusion
What is the main mechanism for transport of the majority of drugs in the body?
Passive diffusion
Which mechanism involves the transport of drugs by being engulfed within molecular vesicles?
Pinocytosis
Which mechanism of drug movement involves the movement of a drug molecule according to concentration gradient?
Passive diffusion
Which type of drug is less ionized in an acidic medium?
Weak acidic drugs
What is the definition of pKa?
The pH at which the drug is 50% ionized and 50% unionized
Which barrier primarily allows drugs to cross by simple diffusion?
Placental barrier
What does the blood-brain barrier mainly protect against?
Circulating toxins or pathogens
Which factor determines the extent of drug absorption through the placental barrier?
All of the above
What determines the passage of a drug across a cell membrane?
$pH$ gradient across the cell membrane and drug pKa
What is the main function of the blood-brain barrier?
To regulate the movement of drugs between blood and brain
Which type of drug is less ionized in an alkaline medium?
Weak basic drugs
Study Notes
Mechanisms of Drug Movement
- Active transport requires a carrier and energy.
- Passive transport does not require a carrier or energy.
- Facilitated diffusion is necessary for the transport of endogenous compounds with slow movement by simple diffusion.
- Passive transport is the main mechanism for the transport of the majority of drugs in the body.
Transport Mechanisms
- Endocytosis involves the transport of drugs by being engulfed within molecular vesicles.
- Simple diffusion involves the movement of a drug molecule according to its concentration gradient.
Drug Ionization
- A basic drug is less ionized in an acidic medium.
- The pKa is the pH at which a drug is 50% ionized and 50% non-ionized.
Barriers to Drug Movement
- Lipid-soluble drugs can cross the blood-brain barrier by simple diffusion.
- The blood-brain barrier mainly protects against the passage of hydrophilic substances.
- The extent of drug absorption through the placental barrier is determined by the drug's lipophilicity.
- The passage of a drug across a cell membrane is determined by its lipophilicity and the concentration gradient.
- The main function of the blood-brain barrier is to protect the central nervous system from toxic substances.
- An acidic drug is less ionized in an alkaline medium.
Test your knowledge on the mechanisms of drug movement during ADME (Absorption, Distribution, Metabolism, and Excretion). Learn about passive diffusion, active transport, facilitated diffusion, and pinocytosis as mechanisms for drug transport in the body.
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