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34 Cards in this Set

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What are the types of interactions between drugs and nutrients?
Medications affect food intake (eg, appetite)

1. absorption
2. metabolism
3. excretion

(food IN meds)
Meds for obesity suppress what?
Appetite
Besides meds for obesity what kinds of med may affect appetite?
1. Amphetamines suppress appetite

2. Some anti-depressants lead to wt gain
Sedatives often lead to what?
Decreased intake of food
Any med that causes ? or ? may decrease food intake.
Nausea or indigestion
Foods affect the absorption of ?.
Meds
Give an example of why it is important not to generalize about food affecting the absorption of meds?
For example, food reduces the absorption of captopril, but it improves the absorption of hydralizine, both of which are hypertensives. Recommendations: take captopril on an empty stomach, but hydralazine with food.
Give an example of a trade-off concerning meds and absorption?
Aspirin is best absorbed on an empty stomach but it may lead to nausea.
What foods substances reduce absorption?
Food substances that bind meds.
Give 4 examples of food substances that may bind meds and reduce their absorption?
1. Minerals (in foods and antacids)

2. Fiber

3. Phytates (husk of grains, legumes, and seeds)

4. Oxalates (eg, rhubarb, spinach, beets, nuts, chocolate, tea, wheat bran, strawberries)
Not only does food sometimes affect the absorption of meds but meds may also affect the absorption of food. How do laxatives do this?
They reduce the time in the intestine, and therefore reduce absorption. Mineral oil may reduce ADEK. Regular use may lead to dependence.
How might enzyme replacements affect absorption?
They may increase absorption (eg, lactase)
Give an example of a mutual interaction?
Tetracycline and calcium (or iron) adversely affects each other's absorption (leading to excretion of both).

Recommendation: Take Tet on an empty stomach (1hr to 2hrs after meals, including milk, milk products, antacids with calcium, mineral supplements)
Give an example of foods affecting drug metabolism?
Vitamin K (clotting factor) intake affects appropriate dosing of warfarin (coumadin, an anti-coagulant), which affects blood clotting. So a prescribed dose of warfarin depends upon vitamin K intake, and so may need to be adjusted if food intake changes significantly (eg, if more lettuce and greens are eaten in the summer)
What is a generalization made about herbs and supplements and their relationship to coumadin?
They can (in some cases) reduce or (in others) increase the effectiveness of coumadin.
Because of the effects herbs and supplements have on coumadin what has to be done with their use?
The use of these must be either avoided or consistent.
List 6 herbs?
1. garlic

2. ginger

3. ginkgo

4. St. john's wort

5. echinacea

6. feverfew
Name 3 supplements?
1. Coenzyme Q

2. Omega-3 FAs

3. Vitamin E
Nutrients are ? in order for some meds to be ?.
They are reqd in order for some meds to be effective.
Give an example of a nutrient that is required for a med to be effective.
Fosamax (alendronate), for the tx of osteoporosis, reqs Vit D and calcium.
What does grapefruit juice do to metabolism?
It inhibits intestinal CYP3A4 enzymes (part of the cytochrome P450 system), which plays an important roles in the elimination of many drugs.

This affects AUC,Cmax, and half-life, generally increasing plasma concentration.

The effect is seen with whole grapefruit, juice, and concentrate, though the extent is variable.
Caffeine is a what?
CNS stimulant
How does caffeine affect the metabolism of meds?
It potentiates actions of CNS-stimulant meds (eg, amphetamines)

It limits the effectiveness of depressants (eg, barbituates)
How might licorice affect the metabolism of meds?
(natural licorice, not the artificial stuff in some candy/breath fresheners) Promotes Na+ retention and K+ excretion. May interfere with diuretics and antihypertensives.
How might corticosteroids affect the metabolism of food?
They are anti-inflammatory and immunosuppressive. They interfere with the met. of calcium and vit D, leading to a loss of Ca++ from bones. This increases the risk of osteoporosis.
Anyone on long term steroid therapy should consider taking what?
Vit D supplements and possibly Ca++
How does methotrexate affect the metabolism of food?
It is structurally similar to, and may interfere with metabolism of, folate. This is usually not a problem when used at low doses for the tx of arthritis, lupus, psoriasis, asthma, or inflammatory bowel disease. However, it is used at higher concentrations in the tx of cancer, and at these levels it may interfere with the action of folate. So folate supplementation may be appropriate.
How might aspirin affect the metabolism of food?
It competes with folate for its protein carrier, and so may limit the bioavailability of folate. This is only a problem when aspirin is taken regularly. (eg, 650mg q 4hrs for several days)
How is tyramine involved in metabolism?
It is an AA found in many foods.

It stimulates the release of norepinephrine which may cause severe headaches, and may cause HTN.

It can be, and usually is, inactivated.

Monoamine Oxidase Inhibitors (MAOIs) which are used to tx some forms of severe depression, block this inactivation pathway.

So anyone taking MAOIs must restrict their tyramine intake.
How might Vit C (nutrient) affect excretion of meds?
It increases the acidity of the urine, which decreases the excretion of aspirin, which increases the plasma conc of aspirin.
How might sodium (a nutrient) affect the excretion of meds?
It decreases the lithium (used to tx psychiatric disorders), raising the plasma conc. of lithium.

So it is important to keep the sodium intake constant so to keep the Li conc constant.
How might diuretic meds affect nutrient excretion?
They increase the excretion of calcium, potassium, magnesium, and zinc.
How might amphotericin-B affect the excretion of nutrients?
It is an anti-fungal agent that increases the excretion of potassium and magnesium.
List 6 possible ingredients in meds that may be a cause for concern.
1. Sugar (diabetics)

2. Lactose (Lactose intol)

3. Aspartame (PKU)

4. Sorbitol (diarrhea)

5. Sodium (salt-sensitivity)

6. Caffeine (diuretic)

(small amts may not be a problem but you need to watch total intake)