Drug Nutrient Interactions Flashcards
what is drug-nutrient interaction?
alteration of kinetics or dynamics of a drug or nutritional elements, or a compromise in nutr status as result of addition of drug
3 drug related outcomes:
increased activity of drug, decreased activity, doesn’t do anything
3 mechanisms of drug interaction
pharmaceutical, pharmacokinetic, pharmacodynamic
this mechanism occurs before administration of drug
pharmaceutical
this mechanism affects absorption, distribution, metabolism / excretion of drug
pharmacokinetic
this mechanism modifies drug activity at receptor level
pharmacodynamic
major metabolism site for drugs
liver
rate limiting step in drug absorption
solution
factors affecting oral absorption?
drug and formulation (solid/liquid, regular/slow release, chem nature); GI motility (food/fluids, pain/stress); blood flow to absorption area; activity of transporters/metabolizing enzymes; changes in normal flora
active transport mechanisms important in drug absorption:
ATP binding cassette, solute-linked carriers
drug metabolizing enzymes:
cytochrome P450, monamine oxidase, alcohol dehydrogenase, esterases, amidases, etc
what is the first pass effect?
loss of active drug in GI tract and first pass thru liver before drug enters systemic circulation, determines bioavailability
what contributes to FPE?
metabolism in gut wall and liver, transporter activity
effects of balanced meal on GI tract
delay in gastric emptying, ^ secretions, ^ motility, ^ fluid volumes
potential effects of meal on drug absorption, delayed/reduced absorption
delayed response due to slower absorption rate, increased breakdown of acid labile drugs, increased complexation with food constituents, premature release of enteric coated drugs, retention of undissolved tablets in stomach
examples of increased absorption?
poorly soluble (acne meds), decrease in metabolism (antidepressant), increased bile secretion (phenytoin), surfactant activity
if ____ F, take drug at least 1 hr before or 2 hrs after meal; if _____ F, take drug w/ or immediately after meals
decreased; increased
what is F?
fraction of drug absorbed
_____ in food form insoluble chelates with susceptible drugs, excreted in feces
metallic ions
important examples of chelating drugs:
tetracyclines, quinolones, bisphosphonates
fibre may reduce absorption by bind to certain drugs like:
digoxin, lovastatin
fibre may prolong absorption and provide level serum [ ] with drugs like:
levodopa
____ responsible for majority of metabolized drugs
phase 1 Cytochrome P450 family
what are Phase 2?
UDP glucoronosyltransferases (UGTs)
metabolism of drugs found in:
GI tract, liver, lungs, skin, kidney
^ CHO and fat ____ metabolism of certain drugs, leading to ____ serum levels
decreases; increased (eg. theophylline for COPD)
^ protein can ___ metabolic activity, leading to ___ serum levels of drug
increases; decreased (eg. warfarin)
phytochemicals that can inhibit or induce metabolic enzymes/transporters:
polyphenols, carotenoids, furanocoumarins, glucosinolates
what does grapefruit do?
inhibits CYP3A4 in gut wall and OATP/p-glycoprotein; significantly ^ F of drugs with high FPE and v F of drugs absorbed via OATP
why pt on warfarin advised not to use cranberry juice?
inhibits CYP3A and CYP2C9
nutr needed for normal fx of drug metabolizing enzymes:
folic acid, pyridoxine, vit c (deficiency may cause decreased clearance of drug)
____ diets could theoretically increase unbound drug concentrations
low protein, high fat
what is interaction of low protein and basic drugs?
decreased rate of excretion of basic drugs, increase in urine pH
lithium food interactions?
cause sodium depletion, and lithium reabsorption, possible toxicity probs with peppers/oregano/rhubarb which are diuretic
what is interaction of MAOIs and tyramine?
buildup of norepinephrine in neurons, ^ BP, headache, nausea, palpitations, potential for MI/stroke
foods containing tyramine?
fermented, spoiled, protein-rich
what is interaction of vit K with warfarin?
antagonizes effect of oral anticoagulants like warfarin (new class of DOACs not affected by diet)
food constituents with potential for anticoagulant activity:
garlic, cayenne, turmeric, cloves, ginger, flaxseed, fish oil, resveratrol
hypokalemia is a concern with ___
digoxin (for heart failure, arrhythmias)
hyperkalemia caused by:
ACE inhbitors plus K-sparing diuretics
large amts of Ca and vit D with calcium channel blockers causes:
blunted antihypertensive effects of CCBs (IV infusion only)
folate and nitroglycerin interaction?
more folic acid (tetrahydrobiopterin) prevent tolerance and increase therapeutic effect of nitrates
ppl with higher risk of drug nutrient interaction?
elderly, very young, pt. receiving multiple drug therapies, pt with marginal nutr intake, declining renal/hepatic function
why elderly more at risk?
GI lower absorption, kidneys, liver, more meds and illnesses, social isolation, mobility issues
drug therapy may impact negatively on nutr status by altering nutr____:
intake, digestion/absorption, metabolism/transport, excretion, requirement
examples of drugs that cause altered taste (dysgeusia)
antineoplastic (methotrexate), antiinfective (like clarithromycin), cardiovascular/antihyperlipidemic, CNS, misc
examples of drugs that cause anorexia:
antiinfectives, antineoplastics, bronchodilators, cardiovascular, stimulant
examples of drugs that increase appetite:
psychotropics, antipsychotics, antidepressants, anticonvulsants, hormones
these drugs cause prolonged dry mouth caused by decreased saliva production that decreases taste sensation and ^ risk of dental caries
drugs with anticholinergic effects (tricyclic antidepressants, antipsychotics)
ulcerogenic drugs
aspirin, NSAIDs
drugs that should be taken with lots of water and not lying down
bisphosphanates, extended release K salts, iron salts, NSAID, quinidine, tetracycline
these interrupt acid production in stomach, impairing B12 absorption
proton pump inhibitors
long term use of____ cause steatorrhea and decreased absorption of fat soluble vits
cholestyramine
drugs that cause diarrhea:
antigout, antineoplastic, antiinfective, antiviral, GI, antihyperglycemic
isoniazid interferes with ___ metabolism
B6 (via decreasing pyridoxal phosphate synth)
mech of action for warfarin:
exerts effect by inhibiting hepatic reductase, converting storage form of vit K to active form (competitive inhibition of vit K activity)
glucocorticoid effects on metabolism:
^ BG, decrease protein synth, ^ protein degradation, bone loss, round face and wt gain in abdomen
phenytoin cause ____ deficiency
folate (^ folate turnover)
what is filtration
bring things out of bloodstream in to tube where urine is made
what is reabsorption
take some stuff from urine and put back into blood
what is secretion
from blood back into urine by very specific transporter
how does potassium depleting diuretic work?
^ Na excretion and also K excretion, causing decreased serum K
types of potassium depleting diuretics:
loop diuretics (furosemide) and thiazides
mechanism of loop diuretics:
they promote Na excretion by decreasing Na reabsorption in Loop of Henle–>more Na presented to distal tubule so more is reabsorbed there in exchange for equivalent amt K secreted (increasing K excretion in aldosterone regulated step)
mechanism of thiazides:
promote Na excretion by decreasing Na reabsorption in proximal tubule–>more Na presented to distal tubule than usual so more is reabsorbed there in exchange for = amt K secreted
example of potassium sparing diuretic
spironolactone
how does potassium sparing diuretic work
decrease Na reabsorption in distal tubule–>this means K secretion also decreases
how does long term broad spectrum antibiotics ^ risk of Vit K deficiency?
depressing gut bacterial synth of vit
