Term
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Definition
rate of drug metabolism is directly proportional to the free drug concentration
fraction of the drug is metabolized per unit time |
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Term
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Definition
rate of drug metabolism remains constant
constant amount of drug is metabolized per unit time
ie alcohol |
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Term
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Definition
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Term
Phase I
oxidation/reduction |
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Definition
usually either increases or decreases effectivenss
extensively involved in first-pass metabolism
rapid, enzymatic attack on chemical structure
changes the structure |
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Term
| reactions of drug metabolism happen where? |
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Definition
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Term
Phase II
conjugation with other water soluble molecules |
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Definition
may or may not impact effectivness
durg is conjugated with another chemical that is very water soluble= increases water solubility |
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Term
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Definition
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Term
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Definition
metabolizes 40% of drugs that undergo metabolism
Phase I |
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Term
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Definition
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Term
| familes of cytocrome P450 enzymes (CYP's) are based on what? |
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Definition
| amino acid sequence similarities |
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Term
| Stimulation of the MFO system |
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Definition
via induction
which means an increase in enzyme synthesis
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Term
| inhibition of the MFO system is via |
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Definition
a decrease in the activity of existing enzyme
almost always results of direct competitive antagonist |
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Term
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Definition
phenytoin
carbamazepine
rifampin
dexamethasone |
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Term
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Definition
cimetidine (Tagamet)
omeprazole (Prilosec)
Erythomycin
Ketaconazole
Ritonavir (Norvir) |
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Term
| Phase II Conjugation Reactions |
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Definition
glucuronidation
glutathione
amino acid
sulfate
acetylation
methylation |
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Term
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Definition
1. oxidation
2. reactive intermediate
3. glutathione conjugation
4. hapatic cell death |
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Term
| First- Pass effect occurs when there is a high |
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Definition
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Term
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Definition
| subtract how much is being made by how much is being used (leaves the cell) |
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Term
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Definition
kidney
liver (bile)
lungs
excretion from bile is usually when drugs are conjugated and very large |
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Term
| glomerular filtration rate (GFR) |
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Definition
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Term
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Definition
| volume of blood that has been cleared of drug per unit time (ml/sec or ml/min) |
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Term
| what is used to calculate maintainence dose? |
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Definition
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Term
| where does active secretion take place? |
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Definition
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Term
| where does passive reabsorption take place? |
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Definition
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Term
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Definition
represents a clearance of plasma
only unbound drug is filtered
plasma protein binding of drug prevents filtration
molecular size |
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Term
| Proximal tubular secretion |
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Definition
active transport
organic acids
organic bases
no effect of protein binding on this process |
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Term
| distal tubular reabsorption |
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Definition
passive transport
pH, conc, size, lipid solubility, ionization
acid urine favors reabsorption of weak acid |
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Term
| Hepatic or Biliary Excretion |
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Definition
some organic acids and bases are actively secreted into the bile
some drugs are secreted into the bile
glucuronides of steriods and morphine are actively secreted |
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Term
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Definition
1. portal vein
2. liver
3. common bile duct
4. small intestine |
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Term
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Definition
exposed to flora and sometimes bacteria will clip off the conjugated part and ACTIVE drug is reabsorbed
prolongs the half life of a drug |
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Term
| pulmonary excretion factors |
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Definition
plasma solubility of drug
cardiac output
respiration
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Term
| Things that may alter elimination of drug |
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Definition
age : renal and hepatic metabolism
renal disease
liver disease
drug interactions |
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Term
| when you turn 50, you los what percent of renal loss every year? |
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Definition
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Term
| Clinical important of renal disease |
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Definition
renal excretion of active drug is = or greater than 50%
if it drops below 50% its not good
drug has low therapeutic index |
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Term
| Clinical importance of liver disease |
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Definition
parenchymal liver disease
hepatic perfusion: cardiac failure, cirrhosis
affects mainly those drugs with high extraction ratios |
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Term
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Definition
| chew up drug quickly and keep plasma levels low |
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Term
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Definition
| drug levels will be higher |
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