Food-Nutrient Interactions Pt. 1

Question 1

define: drug-nutrient interaction

Answer 1

the results of the action between a drug and a nutrient that would not happen with the nutrient or drug alone

Question 2

define: drug metabolism

Answer 2

may activate or inactivate a drug; more commonly drug metabolism means breakdown/inactivation
occurs in liver and intestines

Question 3

define: first pass metabolism

Answer 3

when the drug is absorbed via portal vein and goes into the liver

Question 4

define: absorption

Answer 4

movement from site of administration to blood stream

Question 5

define: bioavailability

Answer 5

degree to which a drug or other substance reaches circulation and becomes available to the target organ or tissue

Question 6

define: pharmacokinetics

Answer 6

movement of a drug through the body by absorption, distribution, metabolism, and excretion

Question 7

define: pharmacodynamics

Answer 7

physiologic and biochemical effects of a drug or combination of drugs; the drug’s action

Question 8

define: pharmacogenetics

Answer 8

genetically determined variations revealed solely by the effects of drugs

Question 9

factors that influence drug absorption (4)

Answer 9

• drug solubility and other properties
• concentration/dose
• blood flow to the GI tract (less blood, less absorption)
• altered stomach pH

Question 10

factors that influence drug distribution (7)

Answer 10

• volume distribution (dosage might be dependent on size of person)
• blood flow and supply to target organ
• drug transport (albumin in the body)
• concentration/storage in adipose/other tissue
• blood-brain barrier
• inflammation (increases permeability)
• pts body composition, age, sex, etc.

Question 11

factors that influence drug metabolism (2)

Answer 11

• general organ function (liver, intestines, kidney)
• cytochrome P-450 system (and other enzymes CYP3A4)

Question 12

factors that influence drug excretion (6)

Answer 12

• if drug is eliminated as original compound or metabolite
• renal excretion
• fecal, enterohepatic circulation
• drug doses assumes normal liver and kidney function
• fluid status/electrolytes, urinary pH
• pts body composition, age, sex, etc.

Question 13

differences in sex that impact drugs in the body (3)

Answer 13

• altered distribution (lower body weight + lean mass)
• altered clearance (lower GFR)
• decreased metabolism (decreased activities of certain enzymes - CYP3A4)

Question 14

examples of pharmacogenomics that influence metabolism (3)

Answer 14

• differences in cytochrome P450 enzymes (some higher + some lower) based on genes
• altered activity of hepatic acetyl transferase (decreased acetylation -> increased half life; increased acetylation -> decreased half life)
• glucose-6-phosphate dehydrogenase (G6PD) deficiency results in oxidative damage in response to certain drugs/nutrients

Question 15

drug-nutrient interaction of: Fosamax

Answer 15

must be taken 30-60 mins before food
presence of anything in the stomach will decrease absorption to 0%

Question 16

drug-nutrient interaction of: Levothyroxine

Answer 16

food and coffee decrease the absorption

Question 17

what is a chelation reaction?

Answer 17

when two compounds bind together tightly so neither can be active

Question 18

what does Fosamax do?

Answer 18

promotes bone health

Question 19

what does Levothyroxine do?

Answer 19

replaces T4 in the body

Question 20

drug-nutrient interaction of: entacapone (Comtan)

Answer 20

chelates with iron supplements

Question 21

what does entacapone (Comtan) do?

Answer 21

Parkinson drug

Question 22

drug-nutrient interaction of: tetracycline + ciprofloxacin

Answer 22

chelates with calcium-containing foods

Question 23

what do tetracycline + ciprofloxacin do?

Answer 23

antibiotics

Question 24

drug-nutrient interaction of: Levodopa

Answer 24

high protein intake (and B6) will decrease absorption

Question 25

nutritional factors that influence drug absorption (4)

Answer 25

• food in GI tract (can increase or decrease, depending on the drug)
• fiber and phytates decrease absorption
• chelation reactions (iron and calcium) decrease absorption
• high protein intake

Question 25

which amino acid is the precursor to dopamine?

Answer 25

tyrosine

Question 25

nutritional factors that influence drug metabolism (2)

Answer 25

• grapefruit inhibits the cytochrome P-450 system; this increases the risk for toxicity because the drug is not inactivated
• st john’s wort activates CYP3A4 production; this increases the risk for therapeutic failure because too much of the drug is inactivated

Question 25

what is the active compound in grapefruit juice?

Answer 25

furanocoumarins

Question 26

what determines if a drug is impacted by grapefruit juice?

Answer 26

drugs that are metabolized in the intestines will have a higher impact on their concentration than those not metabolized in the intestine

Question 26

how does albumin contribute to the drug’s blood distribution?

Answer 26

albumin binds to the drug in the blood rendering it inactive
if the pt has low albumin, the drug might have higher active concentration rates
examples: warfarin, phenytoin