Lecture 4 - Pharmacokinetics (Kinetics and Definitions) Flashcards

1
Q

What is the definition of first-order kinetics regarding drug clearance?

A

The rate of elimination of a drug where the amount of drug decreases at a rate proportional to the concentration of drug remaining in the body.

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2
Q

What is the definition of zero-order kinetics regarding drug clearance?

A

A constant amount of drug is removed per unit time independent of the remaining concentration of drug in the body.

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3
Q

What is first-order kinetics and what is the equation?

A
First-order kinetics is the rate of drug removal dependent on the remaining concentration of drug in the body. Applies to most drugs in clinical use.
T1/2= Vd x 0.7/Cl
T1/2 is half-life
Vd is Volume of distribution
Cl is Clearance
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4
Q

What is zero-order kinetics?

A

A constant amount of drug is removed per unit time. Alcohol is removed at a constant rate = zero-order kinetics.

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5
Q

What do graphs of zero and first order kinetics look like?

A
Zero-order = straight line sloping downwards
First-order = curved line like an exponential curve on its side slowing downwards
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6
Q

What is the definition of first-pass metabolism?

A

Any metabolism that occurs before the drug enters the systemic circulation.
- Phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it enters systemic circulation

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7
Q

What is the definition of Bioavailability?

A

Proportion of the administered drug that is available within the body to exert its pharmacological effect.

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8
Q

What is the definition of Apparent Volume of Distribution?

A

The Volume in which a drug appears to be distributed.

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9
Q

What is the definition of Biological Half-Life?

A

Time taken for the concentration (in blood/plasma) of drug to fall to half its original value.

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10
Q

What is the definition of Clearance?

A

Blood/plasma clearance is the volume of blood/plasma from which drug is removed per unit time.

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