Drug Absorption

Question 1

what is the pharmaceutical phase of drug dosage?

Answer 1

disintegration of the dose, dissolution of the drug

Question 2

what is pharmaceutical availability?

Answer 2

the drug now being available for absorption after dissolution

Question 3

what is the pharmacokinetic phase?

Answer 3

absorption, distribution, metabolism and excretion

Question 4

what is pharmacological availability?

Answer 4

the drug is now available for action

Question 5

what is the pharmacodynamic phase?

Answer 5

the drug and receptor interaction that causes the effect

Question 6

after what stages can metabolic inactivation occur?

Answer 6

after absorption or after the drug pools inside the body

Question 7

what follows metabolic inactivation?

Answer 7

excretion

Question 8

what are the 3 options that the drug can take effect following pooling?

Answer 8

metabolic activation, tissue storage or targeting the site of action

Question 9

what determines the peak activation?

Answer 9

the balance of absorption and elimination

Question 10

how is the therapeutic range created?

Answer 10

the dosage being maintained by administrating a series of doses after a specific time

Question 11

what is the toxic and ineffective range?

Answer 11

toxic range is above the therapeutic window and the ineffective range is below

Question 12

what is the minimum effective concentration?

Answer 12

the lowest concentration while still having effect

Question 13

what is the maximum safe concentration?

Answer 13

the highest concentration that can be given while still being safe

Question 14

how do you calculate the therapeutic index?

Answer 14

MSC/MEC

Question 15

what is an example of a drug that has a narrow therapeutic window?

Answer 15

warfarin

Question 16

what routes of administration are enteral?

Answer 16

oral, rectal and sublingual

Question 17

what routes of administration are parenteral?

Answer 17

injected doses, inhaled, transdermal and topical

Question 18

what are the benefits of oral administration?

Answer 18

convenient, economical, non-painful, portable, can be removed

Question 19

what are the cons of oral administration?

Answer 19

need patient concordance and variable absorption

Question 20

what is bioavailability?

Answer 20

the proportion of the drug dosage that enters the systemic circulation

Question 21

what things hinder bioavailability?

Answer 21

destroyed in stomach or intestine, drug may not be absorbed, destroyed by gut wall or the liver

Question 22

what is first-pass metabolism?

Answer 22

drug passes through the intestinal wall and goes to the liver via the portal vein, where the liver extracts and metabolises some of the drug

Question 23

what are some drugs that undergo a high amount of first-pass elimination?

Answer 23

glyceryl trinitrate, lignocaine, morphine and propranolol

Question 24

what are the advantages for rectal administration?

Answer 24

useful in presence of vomiting, reduces first-pass elimination

Question 25

what is an advantage of sublingual administration?

Answer 25

enables the drug to bypass the gut wall and the liver

Question 26

what are the different types of injected administration?

Answer 26

intradermal, subcutaneous and intramuscular

Question 27

what are the types of injected/infused administration?

Answer 27

intravenous, intra-arterial, intracardiac, intraperitoneal or intrathecal

Question 28

what is intra-arterial administration good for?

Answer 28

chemotherapy

Question 29

what is intra-peritoneal administration?

Answer 29

injection into the peritoneal cavity of the abdomen

Question 30

what is intrathecal administration? how can it be useful?

Answer 30

direct access to the spinal fluid, enables access to the blood brain barrier with antibiotics

Question 31

what are the types of inhaled medication?

Answer 31

systemic effecting or topical effecting

Question 32

what are types of systemic or topical effecting medication?

Answer 32

anaesthetics and bronchodilators

Question 33

why might topical administration used?

Answer 33

applied directly to the skin or mucous membrane for local effect

Question 34

what is the definition of drug absorption?

Answer 34

the process of incorporation of a drug into the blood stream

Question 35

what properties does a drug need to have to pass through the membrane?

Answer 35

able to dissolve in an aqueous environment as well as being lipid soluble

Question 36

what are the 4 ways that drugs cross membrane barriers?

Answer 36

direct diffusion, carrier-mediated, diffusion through pores and pinocytosis

Question 37

what is pinocytosis useful for?

Answer 37

macromolecules

Question 38

what factors effect diffusion?

Answer 38

surface area, concentration, molecular size and lipid solubility

Question 39

how does molecular size effect diffusion?

Answer 39

smaller molecules are more mobile and so they diffuse faster

Question 40

what is more important, molecular size or lipid solubility and why?

Answer 40

lipid solubility as molecular size doesn't vary very much in drugs

Question 41

how does lipid solubility effect diffusion?

Answer 41

lipid solubility effects the substances ability to penetrate the membrane

Question 42

how do you calculate the lipid solubility coefficient?

Answer 42

concentration in oil/concentration of water

Question 43

what does a high lipid solubility coefficient mean?

Answer 43

the higher the value the higher the lipid solubility

Question 44

what molecules are lipid soluble?

Answer 44

gases, non-polar molecules, and small polar molecules

Question 45

what molecules are not lipid soluble?

Answer 45

ions and large polar molecules

Question 46

what are the features of non-polar drug molecules?

Answer 46

electrons evenly distributed, dissolve in lipids and penetrate membranes

Question 47

what are the features of polar drug molecules?

Answer 47

positive and negative, the more polar the molecule the lower the lipid solubility and higher the water solubility

Question 48

can the ionised or unionised form of a drug be absorbed and why?

Answer 48

unionised as it is lipid soluble

Question 49

what is a weak acid?

Answer 49

a neutral molecule that can dissociate into an anion and a hydrogen atom

Question 50

how does the ionisation of a weak acid change at a low pH?

Answer 50

the more acidic the more H atoms there are and so the molecules are in the ionised form as a full molecule

Question 51

what environments would favour the absorption of a weak acid?

Answer 51

acidic as this causes them to be unionised

Question 52

what is a weak base?

Answer 52

neutral molecule that can form a cation by combining with a hydrogen ion

Question 53

in what state is a weak base ionised?

Answer 53

when combined with a hydrogen ion

Question 54

what environments favour the absorption of a weak acid and why?

Answer 54

alkaline environment as less H atoms at a higher pH which causes dissociation so that it becomes unionised