Resp. Pharmacology and Lungs as Route Of Drug Delivery

Question 1

what are premedicant drugs

Answer 1

drugs given prior to a general anaesthetic

typically a sedative-opiod combo

Question 2

what are induction durgs

Answer 2

usually IV agents

used to achieve the transition from consciousness to unconsciousness

Question 3

what are maintenance drugs

Answer 3

usually inhalational agents

drugs used to maintain the anaesthetic state

Question 4

what is the overton and meyer theory

Answer 4

increase lipid fluidity changes lipid bilayer dimensions or permeability

Question 5

what is the current view on lipids

Answer 5

1. receptor/protein targets now recognized
2. lipid solubility important in reaching target

Question 6

what is the blood:gas partition coefficient

Answer 6

low b:g gives rapid induction/recovery

Question 7

what is the oil:gas partition coefficient

Answer 7

high o:g gives high potency

Question 8

what are the physiological factors of anaesthetic agents that affect speed of induction/recovery

Answer 8

1. alveolar ventilation rate
2. cardiac output

Question 9

what is the metabolism of anaesthetics

Answer 9

liver –> extent depends on agent

litter influence on duration of action

potential toxic metabolites (risk to patient and staff)

Question 10

how are inhalational agents (anaesthetics) eliminated

Answer 10

primarily by exhalation

determines duration of action

Question 11

what are halogenated anaesthetic compounds

Answer 11

halothane

isoflurane

sevoflurane

desflurane

Question 12

what are other anaesthetic agents

Answer 12

nitrous oxide

xenon

Question 13

what is minimum alveolar concentration (MAC)

Answer 13

the minimum alveolar concentration at which 50% of patients will not respond to a particular stimulus

compares the potency of different inhalational agents

relates to the percentage of drug in the inspired air

Question 14

what factors can alter MAC

Answer 14

1. species
2. age (MAC lower in geriatrics & neonates)
3. pregnancy (MAC reduced)
4. hypothermia (MAC reduced)
5. drugs –> premedicants can greatly reduce MAC (ex. opioids)

Question 15

what is the sympathetic control of bronchial tone

Answer 15

no innervation but dilated by circulating adrenaline

B2 adrenoceptors –> increased cAMP in bronchial smooth muscle –> relaxation of bronchial smooth muscle

also inhibit release of histamine from mast cells

Question 16

what is the parasympathetic control of bronchial tone

Answer 16

muscarinic acetylcholine receptors

M3: increases IP3, increases [Ca2+]

constriction of bronchial smooth muscle

Question 17

how can bronchodilation be achieved pharmacologically (3)

Answer 17

1. B-adrenergic agonists
2. anticholinergic (antimuscarinic) drugs
3. methylxanthines (PDE inhibitors)

Question 18

what are examples of B2 adrenoceptor agonists

Answer 18

terbutaline, salbutamol, salmeterol, clenbuterol

Question 19

how do B-adrenoceptor agonists work

Answer 19

stimulate adrenergic pathways

Question 20

what is an emergancy drug used to treat life threatening bronchoconstriction

Answer 20

adrenaline (epinephrine)

Question 21

what are the side effects of B-adrenoceptor agonists

Answer 21

CVS: increased heart rate, palpitations

skeletal muscle: tremors

Question 22

what is the mechanisms of anticholinergic (antimuscarinic) drugs

Answer 22

block endogenous parasympathetic tone (ex. atropine)

Question 23

what are the side effects of anticholinergic (antimuscarinic) drugs

Answer 23

CNS stimulation

GI inhibition

Question 24

how are anticholinergic (anitmuscarinic) drugs administered

Answer 24

topical vs systemic

Question 25

what is ipratropium bromide

Answer 25

quaternary derivative of atropine, limited absorption therefore minimal systemic side effects

Question 26

what are methylxanthines

Answer 26

theobromine, caffiene, theophyline, etamiphylline

Question 27

what are the mechanism of action of methylxanthines

Answer 27

PDE inhibitors --\> increase cAMP --\> bronchial smooth muscle relaxation decrease inflammatory mediators, adenosine inhibition

Question 28

what are the side effects of methylxanthines

Answer 28

GI cardiac CNS

Question 29

what physiochemical property of halogenated agents gives info on ease of vaporization

Answer 29

vapour pressure (mmHg) the higher it is --\> the more sensitive it is to changes in environmental temp (boiling point) ex. desflurane has high vapour pressure --\> any small change in temp will affect its availability b/c its boiling point is 23 degrees

Question 30

what values give info on potency in halogenated agents

Answer 30

1. MAC (%) 2. oil:gas partition coefficient

Question 31

what does a low MAC (%) indicate

Answer 31

the more potent the drug is and the less you need of it

Question 32

what does a high oil:gas partition coefficient mean

Answer 32

most potent correlated inversely with MAC

Question 33

why is the % metabolized a concern in halogenated agents

Answer 33

doesn't have anything to do with duration of action --\> concern is with toxic metabolites