FOOOOOOD and DRUG interactions Flashcards
Examples of Binding of drugs by food
divalent cations in diary can be chelated by certain drugs, rendering them ineffective
high fat meals can increase solubility of lipophilic drugs
high fiber diets can decrease water soluble drug absorption
What can alter normal function of GI tract can affect absorption of drugs
changes in transit time (slower or faster) will affect absorption rate
electrolyte imbalances may affect how drug is transported into cells of the gut
changes in gut pH can alter drug solubility, or can alter the chemistry of the drug
Worst case scenario meal
High calorie (800-1000) High fat ~50% of calories are from fat
Drug uptake/efflux in enteric cells are mediated by
OATP
P-gp
First pass drug metabolism in enteric cells is mediated by
SULT
Esterase
CYP3A
SULT
modify xenobiotics and hormones by adding sulfur gropus
inhibited by foods high in flavanoids - fruit juice, tea - prevents normal catecholamine deactivation = blood pressure changes, migrane headaches, atrial fibrillation
Esterase
many drugs require cleavage of an ester group to become active
inhibition of esterase results in ester group being stabilized, results in a build up of pro-drug
resutls in much more of drug being passed into the plasma, where rapid hydrolysis by plasma proteins will give you sudden burst of active drug
CYP450
oxigenases
donate electrons from NADPH to O2 and the substrate
many diff types
rich in the liver, where it is involved in breakdown of drugs (deactivation)
Intestinal CYPs involved with first pass metabolism
CYP3A predominant form in enterocytes and responsible for oxidative metabolism of over half of drugs on market
Inhibition of CYP will
lead to enhanced systemic drug exposure
can be lethal
Antioxidants and furanocoumarins are major inhibitors of
CYP3A
found in Tea, coffee, red wine, beer, fruit juices (tomato, bitter orange, Grapefruit juice)
Grapefruit juice
high in furanocoumarins
also has components shown to inhibit other enterocyte proteins G-pg (meant P-gp?), OATP, esterase, SULT - flavanoids
Number of known interactions with Grapefruit juice
over 85 different drugs
43 of which are listed as severe
one of the more severe side effects is rare ventricular tachycardia (torsade de points)
Drugs known to interact with GFJ
statins
calcium channel blockers
meds that treat - anxiety, heart arrhythmia, depression, seizures, malaria and insomnia
Do not eat/drink what when taking antibiotics?
Milk/dairy
these will chelate divalent cations, such as Ca+2, Mg+2
they will bind up and block drug absorption
ex: tetracyclines, fluoroquinolones (cipro)
food ex: dairy (calcium), antacids (calcium, Mg) supplements (iron, ca, mg)
Action of Warfarin
anticoagulant
vit K agonist
blood clotting enzymes require modification by Vit K dep. enzyme to become active - Warfarin interferes with this process and helps to prevent clots
Diets high in Vit K can alter
the effectiveness of Warfarin treatments
drug is notoriously difficult to dose correctly - dietary changes can make prescribed dose ineffective
Foods high in Vit K
green, leafy vegetables - collards, mustard greens, turnip greens, spinach
Cruciferous foods: kale, brussel sprouts, broccoli
MAOIs
monoamine oxidase inhibitors are used to treat depression
foods high in Tyromides have been shown to produce severe hypertensive crisis in pts taking MAOIs
-such a bad problem, that MAOIs are under utilized
Cheese Reaction
Tyromide containing foods
Matured cheese, red wine, bananas, yogurt, shrimp paste, salami
mostly in fermented foods
Licorice contains
chemical called glycyrrhizin - acts as a potent inhibitor of 11 beta-hydroxyl steroid dehydrogenase
leads to increase in mineralcorticoid receptors, leading to sodium retention and potassium depletion
sometimes found in teas and herbal blends - so warn pts
Net effect of Licorice and Antihypertensives
will interfere with antihypertensives and antiarrhythmics
high intake of licorice linked to edema, increased blood pressure, and suppression of renin-angiotensin-aldosterone system
Mechanisms that Alcohol can interfere with
broken down in liver so can decrease efficiency of drug break down
- can lead to increase in system drug toxicity
- liver damage can occur
- universal solvent so if taken with drug could enhance solubility
Alcohol is amphipathic so
it can increase the solubility of both lipophilic and hydrophilic drugs, increasing bioavailability
What does Alcohol irritate?
stomach lining
can increase absorption of drug
if paired with a drug which is also an irritant (NSAIDs) an damage stomach lining
Bronchodilator
have stimulating effects on CNS
ex: theophylline, albuterol, epinephrine
Bronchodilators and Caffeine
both xanthine/xanthine derivatives
have similar effects, taking together could amplify effects leading to nausea, vomiting, irritability, increased heart rates
puts pts at increased risk of drug toxicity
Bronchodilators and caffeine: Foods to avoid
chocolate
Tea
coffee
