Exam #2: Drug-Nutrient Interactions Flashcards
What types of patients are at risk for experiencing an adverse effect due to a drug-nutrient interaction?
1) Long-term dosing regimen (e.g. PUD/PPI–>B12)
2) Self-medicate
3) Pre-existing nutritional disease
4) Extensive surgical history
5) Take meds at meals
6) High potency vitamins or minerals
7) High alcohol consumption
8) Receive enteral or parenteral nutrition
9) Alter diet during dosing regimen
10) Poor diet
11) Gain or lose large amounts of weight
What is Alendronate (Fosamax)?
Bisphosphate used to prevent bone resorption
What causes decreased drug absorption of Alendronate (Fosamax)?
- Must be taken during the FASTING state
- Even liquids can reduce absorption
B/c of this, it is recommended that the drug be taken 2 hours prior to a meal
What is Ondansetron (Zofran)?
Antiemetic agent
How can absorption of Ondansetron (Zofran) be increased?
- Absorption is INCREASED by presence of food in the upper GI system
Slowing down the transit time and increasing mixing/churning will increase the amount of time for absorption.
What is Ciprofloxacin (Cipro)?
Broad spectrum antimicrobial agent
What is drug chelation?
Formation of a drug-cation complex
How does chelation affect absorption of a drug?
Chelation PREVENTS absorption
Describe how Ciprofloaxcin (Cipro) is chelated.
Cipro binds divalent cations e.g. Ca++, iron, and zinc
Because of chelation, what types of foods should be avoided when taking Cipro?
- Dairy products (Ca++)
- Fortified juices
- Liquid supplements
What is Omeprazole (Prilosec)?
Proton pump inhibitor used to suppress gastric acid secretion for GERD/ PUD
What is the effect of increased gastric pH e.g. with PPIs?
Reduction in the extraction of protein bound nutrients
What can PPIs inhibit the absorption of?
B12
B12 requires gastric acid and pepsin activation. PPIs decreased acid secretion and increased pH impairs gastric acid and pepsin.
What is Colestipol (Colestid)?
Antilipidemic agent used to treat hypercholesterolemia
What is the mechanism of action of Colestipol (Colestid)?
- Drug stays in the GI tract
- Sequesters bile salts in the GI tract and prevents enterohepatic circulation
Thus, the drug increases the secretion of bile salts (formed from cholesterol), causing the body to “pull” more cholesterol out of the body
What is the negative dietary impact of Colestipol (Colestid)?
In addition to bile salts, Colestipol will also:
- Bind fat soluble vitamins
- Prevent miccelle formation
What can the negative impact of long-term CiproFloaxcin (Cipro) administration be?
Chelation will result in deficiency in divalent cations:
- Ca++
- Iron
- Zn
What will hypotroteinemia alter?
- Protein-free and protein-bound fractions of drugs
- Results in INCREASED drug bioavaliability
What drug is used as an example of a drug negatively impacted by hypoproteinemia? What is the drug used for?
Phenytoin (Dilantin)
This is an anticonvulsant to treat seizures.
What happens to Phenytoin (Dilantin) with hypoproteinemia?
Increased bioavaliability can lead to adverse effects
What is Ethinyl estradiol?
Oral contraceptive used to prevent pregnancy
What enzyme is used to metabolize Ethinyl estradiol?
CYP 3A4
What is the effect of St. John’s Wart on Ethinyl estradiol?
- St. John’s Wart increases CYP 3A4 expression
- This will INCREASE the metabolism of Ethinyl estradiol and DECREASE its therapeutic effect
What is Simvastatin (Zocor)?
HMG-CoA reductase inhibitor used to treat hypercholesterolemia
What is the impact of grapefruit juice on drug metabolism?
Grapefruit juice INHIBITS CYP 3A4
What is the effect of grapefruit juice on Simvastatin (Zocor)?
- Inhibition of CYP 3A4
- Increased bioavailability of Simvastatin (Zocor)
- Increased likelihood of adverse effects
What is Lithium (Eskalith)?
Monovalent cation used to treat Bipolar Disorder
What cation does Lithium compete with throughout the body?
Na+
How does Lithium effect the kidney?
- Na+ reabsorption is mediated by the Na+/K+ ATPase
- Na+ and Li+ compete for the same receptor
What happens to Lithium with high Na+ concentrations?
Increased Lithium excretion
What happens to Lithium concentrations with low Na+ concentrations?
Increased Lithium reabsorption
What it the important thing to remember about Na+ and Lithium interactions?
It is important to have STABLE Na+ concentrations in the diet to avoid drastic changes in Lithium therapy
What are monoamine oxidase inhibitors (MAOI) used to treat? What is their mechanism of action?
Depression and anxiety disorders that work by preventing catecholamine metabolism
What is tyramine? Where is it found?
Monoamine found in several foods:
- Cheese
- Dried meat
- Soy
- Beer
- Chocolate
What does tyramine cause? Why must it be avoided with MAOIs?
- Tyramine causes increased release of catecholamines
- Ingestion w/ MAOI can lead to HYPERTENSIVE CRISIS and CVA
What is the mechanism of action of Warfarin (Coumadin)?
- Anticoagulant that inhibits the actions of Vitamin K
- Vitamin K is necessary for production of coagulation proteins (active prothrombin)
What foods should be avoided with Warfarin (Coumadin)? Why?
- Green leafy vegetables w/ Vitamin K
- Effects of warfarin can be overcome i.e. is less effective at preventing hypercoagulation
What effects can ASA/ NSAIDs have on the gastric mucosa?
- Prostaglandins are important for mucosal health
- NSAIDs stimulate acid production
- Eating further stimulates acid secretion and can be painful to the patient
What are the effects of anticholinergics on appetite?
- Block ACh mediated smooth muscle contraction
- Decreases appetite
Note that these also block salivation.
What is the effect of Tricyclic antidepressants on weight control?
- Block H1 receptors
- Stimulate appetite and reduce sedation
- Can lead to weight gain
What is the effect of SSRIs on weight control?
- Increase accumulation of 5-HT in CNS
- Suppresses desire to eat
- May result in weight loss and anorexia
