chapter 4 part 2

Question 1

Indirect interactions

Answer 1

Drug A alters the endogenous levels and affects Drug B

1. diuretics decrease K+ plasma conc, and enhance digoxin and glycoside toxicity.

2.MAO I- inhibit metabolism of Ne AND SO Ne WILL INCREASE in levels, tyramine and ephedrine

3. H-1 receptors antagonists mepyramine, which causes drowsiness and if taken with alcohol can lead to accidents

Question 2

Age on drug response :

Answer 2

Drug responses can vary due to: DIMINISHED CARDIAC OUTPUT (heart attack)

• diminish hepatic metabolism
  -can prolong the duration of the drug action

-Increasing body fat will increase Vd levels, and decrease plasma protein binding. this promotes the accumulation of highly lipid-soluble agents : diazepam (valium) and thiopental (pentothal).

Question 3

age

Answer 3

neonates immature organs: reduced hepatic metabolism and renal excretion

elders: difference in Vd, renal clearance, absorption, hepatic metabolism

Question 4

CYP3A4 (inhibitor)

Answer 4

Grapefruit juice are potent inhibitors of this in the intestine wall of mucosa

Question 5

CYP1A2(inducer)

Answer 5

VEGETABLES LIKE brussel sprouts, cabbage, califlower and hydropcarbons in broiled meat

Question 6

tetracyclines and fluoroquinolone antibiotics

Answer 6

calcium in dairy products can chelate these drugs

Question 7

cigarette smokers have rapid metabolism compared to nonsmokers

Answer 7

b/c of enzyme inducer CYP1A

Question 8

industrial workers exposed to pesticides will

Answer 8

metabolize certain drugs rapidly

Question 9

drug-drug interactions

Answer 9

at the same time, one drug will affect and produce a pharmacological response

pharmacokinetics and pharmadynamic interactions

Question 10

pharmadynamic interactions

Answer 10

direct interaction - drug A blocks drug b target site and diminishes or antagonizes drug b effect

ex; B-adrenoreceptors antagonists diminishes B-receptor agonists (propranolol salbutamol and terbutaline)

indirect interactions - drug A alters the endogenous levels of actions of Drug B

ex. diuretics will decrease k concentrations and enhance glycoside toxicity and digoxin

ex. MAO inhibitors will inhibit NE metabolism and increase NE levels like ephedrine and tyramine

ex. H-1 receptors antagonists like mepyramine cause drowsiness and when mixed with alcohol leads to accidents

Question 11

pharmacokinetic interactions-clinically relevant

Answer 11

drug response cure is STEEP
therapeutic range is NARROW

EX. anti convulsions, antiarrhythmics, antithrombotics, antineoplastics, immunosuppressants, lithium

Question 12

in vitro drug interactions

Answer 12

one drug interacts in vitro with another drug can inactive one or both drug

ex. thiopentone and suxamethonium - not in the same syringe but a complex is formed

ex. heparin is highly charged and interacts with basic drugs like this

Question 13

absorption

Answer 13

gi absorption is slowed when drug inhibits emptying of gastric (Atropine and opiates)

gi absorption is accelerated by drugs like metoclopramide

calcium and iron with tetracycline will cause an insoluble complex which decreases absorption

cholestyramine is a bile acid binding resin used to treat hypercholesteremia and binds with warfarin and dioxin to prevent absorptions

epinephrine and anesthetic causes vasoconstriction and slows the anesthetic absportions

Question 14

distributions

Answer 14

displacement of drug from binding site and increase conc of free drug

then an increase excretion produces a new steady state of drug conc in plasma is decrease but free drug conc is the same as before displacing drug

toxicity from displacement can occur BEFORE NEW steady state

Question 15

displacing agents

Answer 15

aspirin and sulfonamides like hydrate choral because of tight/strong binding to plasma albumin

ex aspirin displaces warfarin and valproate

Question 16

metbolism

Answer 16

inducer and subsrate = increase clearance

inhibitor and substrate= decrease clearance

Question 17

inducer that enhances mebotlism

Answer 17

st johns wort ritonavir and rifapim

Question 18

inhibotors that inhibit metbolism

Answer 18

itraconazole and grapefruit juice

Question 19

rate of renal excretion is affected by

Answer 19

inhibiting the tubular secretion
altering urine flow and urine ph
altering plasma protein binding and filtration

Question 20

example of inhibition of tubular secretion

Answer 20

probenecid inhibits penicillin secretions so prolong action and also inhibits AZT

Question 21

alteration of urine flow and pH

Answer 21

loop and thiazide diuretics increase Li reabsorption, so li toxicity occurs when there is li carbonate for mood disorders

Urine pH- helps to detect the treatment for poisoning not cause of interactions