Chapter 1

Question 1

______________ Occurs when the true effect of one drug are change with presence another drug or food or environmental chemical agent.

Answer 1

Drug Interaction

Question 2

• not all drug interaction are ________
• It’s not just the drugs themselves that interact, it’s their ________ too.
• Many interactions are ______ related.
• Some interaction can be accommodated by using another member of the _________.

Answer 2

• bad
• metabolites
• dose
• same group

Question 3

Mechanism of drug interaction:

Answer 3

1. Pharmacokinetics Interaction
2. Pharmacodynamic interaction:

Question 4

_________ When the interaction can affect the process by which drug absorbed, distributed, metabolized, excreted (ADME)

Answer 4

Pharmacokinetics interaction

Question 5

___________ When the effect of one drug changed by presence of another drug at its site of action.

Answer 5

Pharmacodynamic interaction

Question 6

1. Pharmacokinetics interaction:
   A) Drug absorption interaction:
   - example 1:

Answer 6

1. Drug affected: penicillin.
2. Interacting drug: Neomycin.
3. Effect of interaction: Neomycin induce malabsorption stage.
4. Type of interaction: pharmacokinetic antagonism at absorption stage.

Question 7

1. Pharmacokinetics interaction:
   A) Drug absorption interaction:
   - example 2:

Answer 7

1. Drug affected: Tetracycline
2. Interaction drug: Antacid containingCa2+ , Mg2+,milk, Fe2+
3. Effect of interaction: Formation of poorly absorbed soluble chelate resulting in reduced antibiotic absorption.
4. Type of interaction: pharmacokinetic antagonism at absorption stage.

Question 8

1. Pharmacokinetics interaction:
   A) Drug absorption interaction:
   - example 3:

Answer 8

1. Drug affected: Quinolone antibiotic
2. Interaction drug: Antacid containing Al3+ , Mg2+,milk, Fe2+
3. Effect of interaction: Formation of poorly absorbed complex.
4. Type of interaction: pharmacokinetic antagonism at absorption stage.

Question 9

1. Pharmacokinetics interaction:
   B) Drug displacement (protein- binding) interaction:

Answer 9

• affect mainly the highly bound protein such as : sulfonamides, phenylbutazone.
• Type of interaction: pharmacokinetic synergism at displacement stage.

Question 10

Why Drug displacement (protein- binding) is a good interaction?

Answer 10

Some drugs bind albumin and become inactive. High protein-affinity drugs like phenylbutazone displace them, increasing their free form and distribution.

Question 11

_________ converting drug molecules into more polar compounds ( less active and water soluble ) to decrease reabsorption in the kidney and increase drug elimination.

Answer 11

metabolism

Question 12

1. Pharmacokinetics interaction:
   C) Drug metabolism (biotransformation) interaction: ( Enzyme induction )

Answer 12

1. Drug affect: corticosteroids, Theophylline
2. Inducing agent: Barbiturate , Rifampin
3. Effect of interaction: reduce effect
4. Type of interaction: pharmacokinetic antagonism at metabolism stage

Question 13

How inducing agent reduce affect of drug?

Answer 13

The inducing agent stimulates liver enzymes, so when the drug reaches the liver, its effect will be reduced.

Question 14

1. Pharmacokinetics interaction:
   C) Drug metabolism (biotransformation) interaction: ( Enzyme inhibition )

Answer 14

1. Drug affect: Anticoagulant
2. Inducing agent: phenybutazone
3. Effect of interaction: increase effect
4. Type of interaction: pharmacokinetic synergism at metabolism stage

Question 15

1. Pharmacokinetics interaction:
   C) Drug metabolism (biotransformation) interaction: ( Change in blood flow through the liver )

Answer 15

1. Interaction drug: cimetidine.
2. Effect of interaction: interaction drug decrease blood flow in the liver lead to decrease metabolism and first pass effect and increase bioavailability.
3. Type of interaction: pharmacokinetic synergism at metabolic stage

Question 16

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:

Answer 16

• Change in urinary pH
• Change in kidney blood flow
• Change in active kidney tubule excretion
• Biliary excretion and entero-hepatic shunt

Question 17

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in urinary pH ( synergism acid )

Answer 17

1. Affect drug: Acid
2. Interacting agent: Acid (e.g: ammonium chloride)
3. Effect of interaction: Decreases ionization → decreases excretion → increases effect
4. Type on interaction: pharmacokinetic synergism at excretion stage

Question 18

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in urinary pH ( antagonism acid )

Answer 18

1. Affect drug: Acid
2. Interacting agent: base (e.g: sodium bicarbonate)
3. Effect of interaction: increase ionization → increase excretion → decreases effect
4. Type on interaction: pharmacokinetic antagonism at excretion stage

Question 19

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in urinary pH ( synergism base )

Answer 19

1. Affect drug: bas
2. Interacting agent: base (e.g: sodium bicarbonate )
3. Effect of interaction: Decreases ionization → decreases excretion → increases effect
4. Type on interaction: pharmacokinetic synergism at excretion stage

Question 20

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in urinary pH ( antagonism base )

Answer 20

1. Affect drug: base
2. Interacting agent: acid (e.g: ammonium chloride)
3. Effect of interaction: increase ionization → increase excretion → decreases effect
4. Type on interaction: pharmacokinetic antagonism at excretion stage

Question 21

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in kidney blood flow

Answer 21

• NSAID (non steroidal anti inflammatory drug) - e.g: phenylbutazone:
  It decrease blood flow in Kidney and decrease excretion of another drug

Question 22

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in active kidney tubule excretion

Answer 22

• Some drug compete the site of excretion of other drug at the kidney tubule.

Question 23

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Change in active kidney tubule excretion:

Answer 23

1. Effect drug: penicillin
2. Interaction drug: probenecid
3. Interaction effect: reduces active excretion of penicillin, allowing it to be passively reabsorbed by the kidneys.
4. Type of interaction: pharmacokinetics antagonism at excretion stage

Question 24

1. Pharmacokinetics interaction:
   D) Interaction due to change in excretion:
   
   • Biliary excretion and entero-hepatic shunt

Answer 24

1. normal circulation (entro intestine hepatic circulation):
   - Lipid soluble drug exerted in bile - metabolized by gut flora - return parent compound - reabsorb drug (this process elongate the drug action)
2. Abnormal circulation (entero hepatic shunt):
   - antibiotic reduce the flora action - quick loss of drug.

Question 25

2. Pharmacodynamic interaction:

Answer 25

1. Additive or synergistic interaction and combined toxicity. 2. Antagonistic or opposing interaction. 3. Interaction due to change in drug transport mechanism.

Question 26

2. Pharmacodynamic interaction: A) Additive or synergistic interaction and combined toxicity:

Answer 26

1. Drug: Nephrotoxic drug + Nephrotoxic drug ( gentamicin - gram(-) + cephalothin - gram(+) ) 2. Result of interaction: increase nephrotoxitycity. 3. Pharmacodynamics synergism

Question 27

2. Pharmacodynamic interaction: A) Additive or synergistic interaction and combined toxicity:

Answer 27

1. Drug: Neuromuscular blocker + Neuromuscular blocking effect (Gallamine + Aminoglycosides) 2. Result of interaction: Increase Neuromuscular blocking 3. Pharmacodynamics synergism at neuromuscular

Question 28

2. Pharmacodynamic interaction: B) Antagonistic or opposing interaction

Answer 28

1. Drug effect: Anticoagulant - heparin 2. Drug interactions: vitamin K 3. Result of interaction: decrease anticoagulant effect 4. Type of interaction: pharmacodynamic antagonism

Question 29

2. Pharmacodynamic interaction: B) Antagonistic or opposing interaction

Answer 29

1. Drug effect: hypnotic drug 2. Drug interactions: caffeine 3. Result of interaction: decrease hypnotic effect 4. Type of interaction: pharmacodynamic antagonism

Question 30

2. Pharmacodynamic interaction: B) Antagonistic or opposing interaction

Answer 30

1. Drug effect: Bactericidal agent 2. Drug interactions: Bacteriostatic agent 3. Result of interaction: Decrease bactericidal effect 4. Type of interaction: pharmacodynamic antagonism

Question 31

Examples - bacteriostatic

Answer 31

1. Tetracycline 2. Aminocyclitols 3. Macrolides 4. Sulfonamides 5. CHPC 6. Lincosamides

Question 32

Examples - bactericidal:

Answer 32

1. beta - lactams 2. Aminoglycosides 3. Fluoroquinolones