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Flashcards in Drugs and Membrane Transport Deck (9)
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1
Q

What are the 4 pharmacokinetic processes?

A

Absorption, Distribution, Metabolism and Excretion

2
Q

What properties effect the ability of something diffusing through lipids?

A

Drug size, lipid solubility, concentration gradient, Surface area, and Degree of ionization ( pKa of drug and pH of medium determine rate of passage)

3
Q

Are drugs able to diffuse through pores in lipid bilayers?

A

No; Usually too large to diffuse through pores and gaps, and must pass through lipid bilayer

4
Q

Discuss passive diffusion through lipids.

A

Only lipid soluble drugs cross by diffusion. The driving force is the concentration gradient of the free non-ionizing drug. Protein-bound and ionized drugs don’t affect the gradient.

5
Q

Discuss the degree of ionization for drugs.

A

Only non-ionized form diffuses across lipid membranes; pKa and pH influence diffusion

6
Q

Relate the ionization of a drug to the pH and the pKa.

A

If the pH is equal to the pKa, the ionized and non-ionized forms are in equal amounts. At low pH, there is more non-ionized drug. At high pH, there is more ionized drug. For weak bases: there is more non-ionized drug when the pH is greater than the pKa

7
Q

Describe Facilitated Diffusion

A

The driving force is the concentration gradient. It is selective and saturable; Competition among chemically related compounds.

8
Q

Describe Active Transport

A

Energy is necessary; Transport is against concentration gradient. Energy dependency, selectivity, saturation, and competition are all features.

9
Q

Describe Pino/Endocytosis

A

Large and/or lipid insoluble molecules can pass through biological membranes through membrane invagination; Requires energy.