Drug Disposition - Absorption, Distribution, and Excretion of Drugs Flashcards Preview

Pharmacology 2017 > Drug Disposition - Absorption, Distribution, and Excretion of Drugs > Flashcards

Flashcards in Drug Disposition - Absorption, Distribution, and Excretion of Drugs Deck (15):
1

Drug Elimination

Metabolism (Biotransformation; Liver) or Excretion

2

Modes of drug transportation across membranes

Passive Diffusion, Passive Transport, and Active Transport

3

2 Major classes of drug transporters

Uptake - Solute Carriers (SLC) co-transport solutes like sodium

Efflux - ABC transporters use ATP

4

Prostaglandins

Physiologically active lipid compounds that act like hormones in the body.

5

Effect of drug ionization on disposition

Drugs are weak electrolytes, Ionized forms of chemicals do not penetrate lipid membranes, and the degree of drug ionization is dependent on pKa and pH of surrounding medium.

6

Ionization of acids and bases

weak acids are ionized when pH > pKa
weak bases are ionized when pH < pKa

7

Ion Trapping

Drugs tend to stay localized in areas where they are highly ionized, highly affected by the surrounding pH

8

Properties of GI epithelium

Tight junctions
Lipid diffusion only

9

Modes of molecule transport across capillary epithelium tissue

Transcellular diffusion
Aqueous diffusion (convection, ultrafiltration)
Receptor mediated endocytocis/pinocytosis

10

Factors affecting oral absorption

Solubility
Stomach Acid
pH range
Tight Junctions, Lipid Solubility
Surface Area
Transport to Liver Portal Vein (first pass metabolism)
Intestinal Mobility, Gastric Emptying, Blood Flow

11

Enteral Drug administration

Oral
Rectal
Buccal (sublingual, ie. fentanyl and nitroglycerin)

12

Parenteral Drug administration

IV
IM
Sub Q
Inhalational
Nasal
Transdermal
Topical

13

Bioavailability

The fraction or percent of administered dose that reaches systemic circulation.

Affected by the dissolution of substrate in GI fluids, absorption and first pass metabolism in liver.

14

Volume distribution of drugs

amount of drug (mg) / plasma concentration (mg/ml)

15

Consequence of drug binding to plasma proteins

Only free drugs are active and can cross membranes
Onset of drug action is slowed; reduction in rate of equilibration
Decrease in Vd (app)