Drug interaction Flashcards
Name 3 categories of drug interactions
Incompatibility, Pk interaction, Pd interaction
Two types of incompatibilities
Physical and chemical
Three types of chemical incompat
Precipitation, chelation, binding
Effects of incompatibilities (4)
Damage from toxic compound, particle emboli, change pH leading to tissue irritation, therapeutic failure
Name the 6 drugs incompatible with any others
ADDPNT- aminoglycosides, diazepam, digitalis, pentobarbital, NaHCO3, theophylline
Effect of ket and valium
Precipitate
Effect of doxy and calcium gluconate
Chelation from pH difference
Doxy + anything with a metal ion
Precipitate- poop it out, less efficacy
Name two drugs that interact with IV tubing
Plastic binding- insulin and diazepam
4 changes due to Pk interaction
Change absorption, distribution, metabolism, elimination
What is the most common type of drug interaction
Pk
Omperazole and ketoconazole
Omep increases pH = decreased keto absorption by 50%
Effect of antacids on absorption
Increased pH = decreased abs of weak acids and increased abs of weak bases
Effect of infection or any decrease in pH
Increased abs of weak acids and decreased abs of weak bases
Metaclopramide + digoxin
Increased gastric emptying = dec abs of delayed release Rx
Epinephrine and lidocaine
Increased vasoconstriction leads to prolonged local effect
Insulin and NaCl
Decreased absorption due to pH change leads to hyperglycemia
When two drugs compete for protein binding- what happens
The more potent drug will become even more potent bc it loses the competition for protein binding- increased toxicity risk
Phenobarb and kepra
Phenobarb increases enzymes to speed metabolism- leads to need for 30% more levetiracetam for efficacy
Phenobarb + ammonium chloride
Increased elimination
Phenobarb + NaHCO3
Decreased elimination
Pharmacodynamic effects of interaction
Synergistic or antagonistic
Methods of Pd interaction
Same receptor, common process (diff recep), same final pathway
B blockers and Ca blockers
Bradycardia
NSAIDs and steroids
Ulcers
Aminoglycosides and amphoteracin B
synergistic
Digoxin + furosemide
Antagonistic
Digoxin and hypokalemia
Digoxin inhibits NaK pump, increasing intracell Ca- when K low, increased binding occurs- toxicity
Digoxin and hyperkalemia-
Decreased binding and decreased efficacy
Digoxin and quinidine
Compete for receptors- leads to decreased renal clearance of digoxin
Digoxin and diuretics-
Digoxin leads to hypokalemia - increaed binding- toxicity
Hypercalcemia and digoxin
Increased effects
Hypomagnesemia and digoxin
Arrhythmias
Steroids - effect on lab tests
Increased ALP
KBr- - effect on lab tests
Artifact increase in Cl
Phenobard- effect on lab tests
Increased liver enzymes, neutropenia
Methimazole, acetominophe- effect on lab tests
Methemoglobinemia
NSAIDs- effect on lab tests
Platelet dysfunction
Chemo, estrogen, griveofulvin, phenylbutazone- effect on lab tests
Bone marrow suppression
Levetiracetam- cautions
Decreaed efficacy with phenobarb
Diazepam- cautions
Precipitate with ketamine, not compatible with anything
Sucralfate- cautions
Binds with many drugs (tetracyclines, FQs, cimetidine, phenytoin, phenobarb, griseofulvin, milk)
Ketoconazole- cautions
With antacid increases pH decreasing absorption by 50% or more
Digoxin- type of interaction
inhibitor (Slow metabolism = increase concentration)
Digoxin + metoclopramide
Increased gastric emptying = decreased absorption
What drugs inhibit p450
Cimetidine, chloramphenicol, ketoconazole, omeprazole
What drugs are inducers
Levetiracetam, phenobarbitol
What drugs are inhibitors
Ketoconazole, cimetidine,
Define inducer
Induce metabolism- Decrease the potency or duration of others
Define inhibitor
Slowing metabolism to increase plasma concentration- Increase duration and potency of other drugs
Levetiracetam- MOA
Anticonvulsant SVA2 binder
Levetiracetam- type
Inducer
Levetiracetam with phenobarbital
Need 30% more leve because of increased enzymes from phenobarb use
Phenobarbital - MOA
Barbituate - EP/NE inhib, GABA mimetic
Phenobarbital + Ammonium chloride
Increased elimination
What drug increases the phenobarbital effect
Chloramphenicol
Phenobarbital + NaHCO3
Decreased elimination
Phenobarbital - type
Inducer
Phenobarbital - drugs effected
Cyclosporine, levetiracetam, Bblockers, metronidazole
Cimetidine- MOA
H2 inhibitor
Cimetidine- type
Inhibitor
Cimetidine- interactions
Decreased metabolism/increased effectiveness of diazepam, chloramphenicol, lidocaine, metronidazole
Chloramphenicol- MOA
50S cidal, p450 inhibitor
Chloramphenicol- effect on anesthesia
Prolongs
Chloramphenicol + cimetidine
increased chlor toxicity due to decreased metabolism
Ketoconazole- MOA
Antifungal azole- membranes, p450 inhibitor
Ketoconazole- type
Inhibitor
Ketoconazole- effects
Increases efficacy of benzos, cyclosporine, digoxin
Ketoconazole + H2 blockers or PPI
decreased efficacy
Omeprazole- MOA
PPI (blocks HCl), p450 inhibitor
Omeprazole- effects
increased pH decreases acidic drug absorption (ex. ketoconazole); prolonged duration/increased bioavailability of diaz, cyclo, digoxin)
Sucralfate- binds:
Tetracyclines, FQs, cimetidine, phenobarb
Diazepam- MOA
Serotonin agonist, increased GABA
Diazepam- Interactions
Cimetidine, ketoconazole, omeprazole increase levels; phenobarb decreases
Diazepam- type
Metabolites formed
KBr- additive effect
Increase sedation
KBr- what effects efficacy negatively
Increased salt in diet
Digoxin + diuretics
Decreased potassium
What drugs decrease digoxin efficacy
Alluminum hydroxide, antacids, sucralfate, chloramphenicol, cimetidine, phenobarb
What drugs increase digoxin efficacy
Cyclosporine, diazepam, ketoconazole, omeprazole
Chloramphenicol- interactions
dec digoxin
Cimetidine- interactions
dec digoxin, keto; inc chloram/diaz
Diaz– interactions
Increase digoxin
Keto- interactions
inc diaz/digoxin/cyclosporin
Omeprazole- interactions
decrease keto; inc digoxin/diaz
Phenobarb- interactions
Lower levetiracetam, diaz
Digoxin + increased K
decreased binding/efficacy
Digoxin + decreased K
increased binding/toxicity
Digoxin + increased Ca
Inc efficacy and Ca
Digoxin + decreased Mg
Arryhthmias
Digoxin + quinidine
Decreased renal clearance