Chapter 6 - Drug Interactions

Question 1

What are the three possible outcomes when drugs interact?

Answer 1

(1) one drug may intensify the effects of the other,
(2) one drug may reduce the effects of the other, or
(3) the combination may produce a new response not seen with either drug alone.

Question 2

Propranolol, a drug for cardiovascular disorders, can act in the lung to block the effects of

Answer 2

albuterol

Question 3

What are the four basic mechanisms that drugs can interact?

Answer 3

(1) direct chemical or physical interaction
, (2) pharmacokinetic interaction,
(3) pharmacodynamic interaction, and
(4) combined toxicity.

Question 4

What are the two principal mechanisms by which one drug can alter the distribution of another?

Answer 4

(1) competition for protein binding (2) alteration of extracellular pH.

Question 5

How many isoenzymes in the P450 group are responsible for metabolism of drug? What are their names?

Answer 5

Five - CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4

Question 6

Inducing agents ____ the rate of drug metabolism

Answer 6

increase

Question 7

Interactions that occur at the same receptor are almost always _______

Answer 7

inhibitory

Question 8

The interaction between calcium-containing foods and tetracycline antibiotics is a classic example of food

Answer 8

reducing drug absorption which will reduce antibacterial effects.

Question 9

High fiber foods can reduce absorption of what drug?

Answer 9

Digoxin(Lanoxin)

Question 10

What will double the absorption of saquinavir(invirase)

Answer 10

Food. Be sure the patient takes this medicine with food.

Question 11

Grapefruit juice can _____ the metabolism of certain drugs, thereby ____ their blood levels.

Answer 11

inhibit ; raising

Question 12

Specifically, grapefruit juice inhibits _______

Answer 12

CYP3A4

Question 13

What’s in grapefruit juice that can inhibit CYP3A4?

Answer 13

bergapten and 6′,7′-dihydroxybergamottin—are furanocoumarins.

The other two—naringin and naringenin—are flavenoids.

Question 14

If an MAO inhibitor is combined with foods rich in tyramine(cheese, yeast extracts, chianti wine) what is the consequence?

Answer 14

Blood pressure can rise to life-threatening levels.

Question 15

foods rich in vitamin K (eg, broccoli, brussels sprouts, cabbage) can reduce the effects of

Answer 15

warfarin, an anticoagulan – It inhibits vitamin K

Question 16

How does Vitamin K foods inhibit warfarin?

Answer 16

warfarin acts by inhibiting vitamin K–dependent clotting factors. Accordingly, when vitamin K is more abundant, warfarin is less able to inhibit the clotting factors, and therapeutic effects decline.

Question 17

How does Vitamin K foods inhibit warfarin?

Answer 17

warfarin acts by inhibiting vitamin K–dependent clotting factors. Accordingly, when vitamin K is more abundant, warfarin is less able to inhibit the clotting factors, and therapeutic effects decline.