Drug reactions Flashcards
what happens when patients are taking multiple medications
- the potential for adverse drug events (ADEs) with medications and food in an increased concern
what is the drug-drug interaction
- the pharmacological or clinical response to the administration of a drug combination
- different from that anticipated from the known effects of the two drugs when given alone
what are the two possible results from a drug-drug interaction
- additive (synergistic)
- antagonistic, where two drugs have opposing activities
what is recommended for dental clinicians to have available regarding prescribing medications and drug interactions
- a drug handbook and/or
- a computerized version of drug interactions (LexiComp)
what are risk factors that increase the incidence of a drug interaction
- medication factors (protein binding, small therapeutic window, effects on enzymes)
- patient factors (age, sex and medical conditions)
how are drug interactions rated
- according to the severity of the interaction ie life threatening or mild
what are the two main types of drug interactions (regarding the body not the drugs)
- pharmacokinetic: a change in the pharmacokinetics of one drug caused by the interacting drug or food. ex: tetracycline + dairy products/antacids
- pharmacodynamic: a change in the pharmacodynamics of one drug by the interacting drug. ex: Advil + lasik -> fluid retention -> worsening of CHF
what are 3 other types of drug interactions
- addition: the effect of two or more drugs when administered together is the same as if the drugs were given separately. 1 + 1 = 2
- synergism: the effect of two or more drugs when administered together is greater than if the drugs were given separately; may produce responses equivalent to overdosage. 1 + 1 = 3
- antagonism: the effect of two or more drugs when administered together is less than when the drugs are given separately. 1 + 1 = 1, ex Advil + lasik
how can absorption be affected in drugs
- presence of food or supplement can = decreased absorption into the blood
what are other factors that can affect absorption
- gastric (stomach) pH (delay)
- changes in gastrointestinal motility that alter transit time within the intestines (delay)
how can the absorption of antibiotics be altered
- many antibiotics should be taken on an empty stomach due to food interactions
- 1 hour before or 2 hours after meals
- exception: penicillin V, amoxicillin, doxycycline, minocycline
- while other antibiotics should be given with food to minimize gastric upset (ie clavulin)
what are free drugs
- drugs that aren’t bound to plasma proteins in the blood
- drugs that are bound to plasma proteins are too big to diffuse through membranes
what will happen if two drugs have affinity for the same bidding site on a protein molecule in the blood
- may compete for the binding site
- one molecule will displace the other drug from the protein molecule
what do the cytochrome P450 enzymes do
- metabolize drugs involving the alteration of groups on the drug molecule
- mostly found in the liver
- also found in the intestines, lungs and other organs
- key pathway for drug metabolism
what is a substrate
- a drug that is metabolized by a specific CYP450 isoenzyme
what is an inhibitor
- a drug that inhibits or reduces the activity of a specific CYP450 isoenzyme
what is an inducer
- a drug that increases the amount and activity of that specific CYP450 isoenzyme
what are the major isoenzymes that are responsible for most drug metabolism
- CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 AND CYP3A4
why should we avoid grapefruits when using medications
- grapefruit juice inhibits CYP3A4 in the small intestine
how do oral contraceptives work
- become activated in the intestines by the gastrointestinal flora
see lists of clinically significant drug-drug interactions in dentistry from slides 34-39
see lists of clinically significant drug-drug interactions in dentistry from slides 34-39
what are drug-disease interactions
- refers to a patient who has an allergy to a certain drug or a systemic disease that would contraindicate the use of a drug
- ex. patient with ulcerative colitis should not be prescribed clindamycin
see lists of clinically significant drug-disease interactions in dentistry slide 41
see lists of clinically significant drug-disease interactions in dentistry slide 41
what are some examples of drug-food interactions
- grapefruit juice
- caffeine
- alcohol
see lists of clinically significant drug-food interactions in dentistry slide 43
see lists of clinically significant drug-food interactions in dentistry slide 43
