. Why is cytochrome P-450 so important? - answers-o Microsomal enzymes; aid in
metabolism of medications; target lipid soluble (non-polar, lipophilic, fat-loving)
drugs, which are typically difficult to eliminate
What happens when grapefruit juice is taken with a drug that interacts with
cytochrome P-450? - answers-
o Side effect: - answers-: expected averse drug reaction
Undesirable = unexpected (i.e. allergic reaction: hypersensitivity response
involving immune system)
o Adverse reaction: - answers-: any undesirable drug occurrence
Adverse reaction: Idiosyncratic reaction: - answers-occurs unexpectedly in
individual patient; genetically inherited traits
Idiosyncratic reaction:
• Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD): - answers-): when
exposed to drugs such as sulfonamides, anti-malarials, and aspirin, patients may
,suffer life-threatening hemolysis of RBCs; (13-20%) African-American, Kurdish
Jewish (50%), Sardinians (14%)
adverse reaction: Drug-induced teratogenesis - answers-: cause fetal structural
defects; BLACK BOX WARNING
adverse reaction: Mutagenic effects: - answers-permanently changes genetic
composition of living cells
Adverse reactions: carcinogenic reactions - answers-cancer causing
adverse reactions: drug-drug interactions - answers-when two or more drugs
come together and either work together to create a synergistic, antagonistic, or
additive effect
o Agonist: - answers-drug binds to the receptor, there is a response
Ex: morphine stimulates opioid receptors
Partial Agonist: - answers-drug binds to receptor, diminished response
,o Antagonist: - answers-drug binds to receptor; there is no response. Drug
prevents binding of agonist.
Ex: Narcan (naloxone) displaces morphine
Competitive antagonist: - answers-compete with agonist for binding; if it binds,
there is no effect
Non-competitive antagonist: - answers-combine with different parts of receptor
to inactivate it
o Synergists: - answers-drug molecules work with other drug molecules
Produces greater effects than sum of individual drug actions
• 1+1 > 2
Can produce toxic effects
ETOH + tranquilizer = toxicity!
Therapeutic drug serum levels - answers-narrow range of medication in
bloodstream, for desired results; clinical status of patient is appropriate for
condition; peak and trough levels (measured by serum blood levels)
, nontherapeutic drug serum levels can be either: - answers-undertherapeutic or
toxic
toxic drug serum levels - answers-greater than therapeutic dose range;
increased adverse effects
under-therapeutic drug serum levels - answers-not enough drug for desired
effect; may contribute to drug-resistant organisms
o Drug Bioavailability - answers-% of active drug absorbed that reaches target
tissues
o Drug Bioavailability: determinants - answers-route/form of drug; blood flow;
liver/kidney function; acid-base environment; presence of food, resident bacteria,
motility in GI tract; presence of pain/stress; other drugs
o Oral Absorption (PO): - answers-absorbed from GI tract to body tissues; slower
-Diffuses across cell membrane; assisted by carrier enzymes or proteins;
engulfed by cellular membranes (pinocytosis)