Absorption

Question 1

Pharmacology consists of two processes

Answer 1

Pharmacokinetics and pharmacodynamics

Question 2

Pharmacokinetics

Answer 2

how the body affects a specific drug after administration; BODY TO DRUG

Question 3

Pharmacodynamics

Answer 3

How a drug affects the body system after administration; DRUG TO BODY; drug action

Question 4

Processes of PK

Answer 4

ADME

Question 5

Foundation to all ADME processes

Answer 5

Drug transport

Question 6

Physicochemical determinants of drug passage

Answer 6

Membrane characteristics; drop properties

Question 7

Mechanism of drug transport

Answer 7

passive diffusion; carrier-mediated transport; bulk flow; filtration, etc.

Question 8

Membrane characteristics

Answer 8

Bilayer of amphipathic lipids and embedded proteins = barriers.

Question 9

Drug properties

Answer 9

molecular weight, shape, and size; water solubility and lipid solubility; and ionization

Question 10

Molecular weight, shape, and size

Answer 10

Small molecules - more chance of crossing membrane.

Question 11

Lipid solubility

Answer 11

Movement directly through the lipid bilayer requires that the substance dissolve into the lipid bilayer

Question 12

Partition coefficient (Kp)

Answer 12

solubility in lipid/solubility in water.

Question 13

Relationship: lipid solubility and Kp

Answer 13

Increase LS, increase Kp

Question 14

Relationship: Kp and Permeability

Answer 14

Increase Kp, increase permeability

Question 15

Ionization: General rules

Answer 15

drugs usually exist in two forms: ionized and unionized.

Question 16

Unionized drugs: diffusion

Answer 16

Can passively diffuse across membrane; the ratio of drug will indicate direction of passive diffusion.

Question 17

Ionization: Factors

Answer 17

pH of hte medium; pKa of the drug.

Question 18

Ionization: Acidic

Answer 18

Acidic drugs ionize more in basic medium; pH - pKa = log (ionized/nonionized)

Question 19

Ionization: Basic

Answer 19

Ionize more in acidic medium; pH - pKA = log (nonionized/ionized).

Question 20

Henderson-Hasselbach Eqn

Answer 20

pH = pK + log (H+ acceptor/H+ donor).

Question 21

Mechanisms of Drug Transport: Transcellular

Answer 21

Passive diffusion, carrier-mediated transport (facilitated diffusion and active transport); ion-pair transport; endocytosis or pinocytosis.

Question 22

Mechanisms of Drug Transport: Paracellular transport

Answer 22

bulk flow; filtration

Question 23

Requirements of passive diffusion

Answer 23

drugs must be lipid soluble, unionized form, move according to a concentration gradient.

Question 24

Carrier mediated transport

Answer 24

Facilitated diffusion and active transport

Question 25

Facilitated diffusion

Answer 25

carrier needed (can be saturated), no energy required, move along concentration gradient

Question 26

Active Transport

Answer 26

carrier needed (can be saturated), energy required, move against concentration gradient.

Question 27

Bulk flow

Answer 27

move drug out of blood vessel

Question 28

Filtration

Answer 28

excrete drug

Question 29

Absorption

Answer 29

the rate and extent at which a drug leaves its site of administration; %Abs = % of first pass effect + %bioavail

Question 30

Bioavailability

Answer 30

the extent to which a drug reaches its site of action, or to a biological fluid (eg plasma) from which the drug has access to its site of action; not the same as abs.

Question 31

Factors affecting drug absorption

Answer 31

Dose, concentration, and rate of administration; dosage forms; physical and chemical properties of drugs; physiological factors; routes of drug administration.

Question 32

Dosage forms

Answer 32

Afx drug abs; depend on how well they can be dissolved (LIBERATION process)

Question 33

Factors affecting drug abs: physicochemical properties

Answer 33

acid or base; degree of ionization; molecular weight; lipid solubility or Kp

Question 34

Lipid solubility and Abs

Answer 34

Lower Kp = lower % absorbed.

Question 35

Factors affecting drugs abs: Physiological factors

Answer 35

Gastric motility; gastric emptying time; pH at the abs site; area of absorbing surface; blood flow; ingestion with or without food.

Question 36

Factors: Area of surface

Answer 36

Larger SA = more %abs.

Question 37

Oral (PO) Absorption Factors

Answer 37

dosage form, drug concentration, SA of abs, blood flow to GI, GI activity, food, bacteria in GI, first pass effect (hepatic metabolism; entero-hepatic cycle

Question 38

Parenteral administration

Answer 38

subcutaneous, intramuscular, intra-peritoneal; IV/Intra-artertial

Question 39

Parenteral administration: Subcutaneous abs

Answer 39

slow abs

Question 40

Parenteral administration: Intramuscular abs

Answer 40

fast abs

Question 41

Parenteral administration: Intraperitoneal abs

Answer 41

rapid, large abs

Question 42

Parenteral administration: IV, Intra-arterial abs

Answer 42

No abs

Question 43

Route: Pulmonary

Answer 43

Inhalation; absorbed by pulmonary epithelium and mucous membrane of respiratory tract. Almost instaneous abs; avoids first-pass; local application

Question 44

ROA: Topical

Answer 44

Abs is proportional to SA; more rapid through burned/abraded skin; inflammation increases cutaneous BF and abs; enhanced by suspension in oily vehicle rubbing into skin

Question 45

ROA: Epicutaneous

Answer 45

local effect. no abs (frontline plus)

Question 46

Bioavailability (F)

Answer 46

Fraction of a dose that reaches the systemic circulation in a chemically unaltered form. NO UNITS (percentage or decimal).

Question 47

Incomplete Oral F

Answer 47

1. Failure of dissolution, 2. chemical, enzymatic or bacterial attack, 3. failture of abs and pGP, 4. first pass metabolism in gut wall or liver.