Principles of drug interactions Flashcards
usually the drugs forms chemical bonds with specific sites, called _______ within the body
Receptor
the study of the interactions between drugs and their receptors and the series of events that result in a pharmacologic response
pharmacodynamics
drugs that interact with a receptor to stimulate a response
agonists
drugs that attach to a receptor but do not stimulate a response
antagonists
drugs that interact with a receptor to stimulate a response but inhibit other responses
partial agonists
route that the drug is administered directly into the gastrointestinal (GI) tract by the oral, rectal, or nasogastric tube
enteral
route bypasses the GI tract with the use of subcutaneous, intramuscular, or intravenous injection
parenteral
route involves drugs being absorbed through the skin and mucous membranes. methods include: inhalation, sublingual (under the tongue), and topical (on the skin) administration
percutaneous
the study of the mathematic relationship among the ADME features of individual medicines over time
pharmacokinetics
the rate of absorption when a drug is administered by a parenteral route depends
on the rate blood flow through the tissues
have the slowest absorption rate, especially is peripheral circulation is impaired
subcutaneous (subcut) injections
are more rapidly absorbed because of greater blood flow per unit weight of muscle as compared with subcutaneous tissue
intramuscular (IM) injections
organs with the most extensive blood supplies
heart, liver, kidneys, brain
areas with less extensive blood supplies
muscle, skin, fat
two factors that influence drug distribution
protein binding and lipid fat solubility
most drugs are transported in combination with plasma protein specially ________
Albumin
have a high affinity for adipose tissue, which serves as a repository site for these agents
lipid-soluble drugs
is the process whereby the body inactivates drugs
metabolism
the two primary routes of excretion
GI tract into the feces and renal tubules into the urine
other routes of excretion
evaporation through the skin, exhalation from the lungs, and secretion into saliva and breast milk
is defined as the amount of time required for 50% of the drug to be eliminated from the body
half-life
half-life of 36 hours
Digoxin
half-life of 5 hours
Aspirin
peak action
is the time at which the drugs reaches the highest concentrations on the target receptor sites, thereby inducing the maximal pharmacologic response for the dose given
time-response curve
demonstrates the relationship between the administration of a drug and the associated response
examples of drugs that are important to be measured to ensure that the drug level is between therapeutic range
anticonvulsants, aminoglycoside antibiotics
the classes of medicines that account for the largest number of ADRs
antibiotics, cardiovascular medicines, cancer chemotherapy agents, analgesics, and anti-inflammatory agents
idiosyncratic reaction
occurs when something unusual or abnormal happens when a drug is first administered
life-threatening reaction that cause respiratory distress and cardiovascular collapse
anaphylactic reaction
occur when the action of one drug is altered by the action of another drug
drug interaction
antacids
inhibit the dissolution of ketoconazole tablets by increasing the gastric pH
Aluminum-containing antacids
inhibit the absorption of tetracycline
the anticoagulant action of warfarin is increased by
administration with furosemide, which is a loop diuretic
furosemide
displaces warfarin from albumin-binding sites, thereby increasing the amount of unbound anticoagulant
medications known to bind to enzymes and to slow the metabolism of other drugs
verapamil, chloramphenicol, ketoconazole, amiodarone, cimetidine, erythromycin
inhibits the metabolism of theophylline
erythromycin
common drugs that bind to an enzyme that increases its metabolism of the drug (enzyme inducers)
phenobarbital, carbamazepine, rifampin, phenytoin
rapidly metabolized drugs
disopyramide, doxycycline, griseofulvin, warfarin, metronidazole, mexiletine, quinidine, theophylline, verapamil
acetazolamide
elevates urine pH and quinidine
the alkaline urine produced by acetazolamide causes
quinidine to be reabsorbed in the renal tubules, which potentially increases the physiologic and toxic effects of quinidine
two drugs with similar actions are taken for an increased effect.
hydrocodone + acetaminophen = added analgesic effect
additive effect
the combined effect of two drugs is greater than the sum of the effect of each drug given together
aspirin + codeine = much greater analgesic effect
synergistic effect
one drug interferes with the action of another
tetracycline + antacid = decreased absorption of the tetracycline
antagonistic effect
the ________ of the first drug from protein-binding sites (bound drugs are inactive) by a second drug increases the activity of the first drug because more unbound drug is available
warfarin + valproic acid = increased anticoagulant effect
displacement
the first drug inhibits the metabolism or excretion of the second drug, thereby causing increased activity of the second drug
probenecid + ampicillin = prolonged antibacterial activity of ampicillin because probenecid blocks the renal excretion of ampicillin
interference
the first drug is chemically incompatible with the second drug, thereby causing deterioration when the drugs are mixed in the same syringe or solution or are administered together at the same site; signs include haziness, formation of a precipitate, or a change in the color of the solution when the drugs are mixed
ampicillin + gentamicin = ampicillin inactivates gentamicin
incompatibility
