Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
22 Cards in this Set
- Front
- Back
|
Define: drug distribution
|
Transportation of absorbed drug from plasma to tissues; dependent upon molecular size + attraction for endogenous molecules (Warfarin binds to plasma proteins -> large complex -> cannot leave plasma)
|
|
|
In what tissues do opiates and barbiturates accumulate in?
|
Fat tissue
|
|
|
What are the water soluble drugs we need to know?
|
Alcohol, gabapentin
|
|
|
What are the factors affecting drug distribution?
|
1. Solubility (depends upon pKa to c which part of the body it will move), 2. blood flow to organs/tissues, 3. tissue mass, 4. plasma binding proteins
|
|
|
Which tissues receive more drug due to blood flow and less drug due to blood flow?
|
Highly perfused tissues = receive more drugs = liver, kidney, brain, muscles, lungs; poorly perfused tissues = less drugs received = bone + adipose
|
|
|
Which type of tissues due to being larger has ↑ drug distribution?
|
Skin + skeletal muscle are larger/bulkier -> receives more blood -> thus receives more drug
|
|
|
What are the plasma binding -proteins?
|
1. Human serum albumin= binds acidic drugs, 2. glycoproteins = binds basic drugs, 3. lipoproteins= binds neutral drugs
|
|
|
Which plasma binding protein attaches to acidic drugs? Basic drugs? Neutral drugs?
|
Acidic drugs(salicylates, warfarin, ampicillin, levodopa) = albumin , basic drugs(allopurinol, chloroquine, fluphenzaine) = glycoproteins, neutral drugs = lipoproteins
|
|
|
What is a potential adverse drug interaction in plasma protein interaction?
|
Drug A displacing drug B in plasma protein complex -> free [drug B] is now increasing -> toxicity of drug B
|
|
|
What type of patient may have a potential for toxic reaction due to ↓ plasma protein binding?
|
Malnutrition, hepatic disease, renal disease -> ↓ quality/quantity of drug-binding plasma proteins
|
|
|
What is the function of liver relative to drugs?
|
1. Decontamination role -> major site of drug metabolism/excretion, 2. causes first pass ratio to occur, 3. enterohepatic circulation(drug is co-released w/bile salts -> reabsorbed by small intestine -> ↑ plasma half-life of drug (ie colchicine)
|
|
|
What is the function of kidneys relative to drug distribution?
|
1. Kidney receives 25% cardiac output -> thus receives lots of drug, 2. renal disease could cause accumulation of drug due to ↓ excretion
|
|
|
What type of drugs are able to cross the BBB?
|
Only lipid-soluble (ie thiopental) + low molecular weight(200 Da - 300 Da)
|
|
|
What are the exceptions in ways drugs can get to the brain?
|
1. Circumventricular organs (naturally leaky areas in BBB -> drugs can enter the CNS), 2. meningitis-induced inflammation - allows access to lare molecueles (ie penicillin), 3. brain tumors
|
|
|
What size drugs readily cross placenta to enter fetal circulation?
|
MW < 500 Da + takes 40 mins for equilibrium between maternal blood and fetal tissues
|
|
|
What is the function of adipose in relation to drug distribution?
|
Adipose tissues = poorly perfused tissues -> allows slow accumulation of drugs (barbiturates + opiates) -> thus can become a reservoir of drugs
|
|
|
What is the equation for volume of distribution (Vd)?
|
Vd = dose (mg)/plasma concentration (mg/ml)
|
|
|
What is the reason for Vd being greater then total body fluid volume?
|
Drug is extensively bound in body tissues as well as in circulation
|
|
|
What happens to Vd when u have an annorexic person?
|
Vd increases b/c there is ↓ plasma protein binding
|
|
|
How does Vd decrease?
|
Vd decreases when there is an increase in plasma binding aka ↓ tissue binding of drug
|
|
|
400 mg of drug is administered + Drug measured in plasma 1 ug/ml
|
400 mg/ 1ug/ml = 400e-3/1e-6=400,000.0 ml high Vd = drug is mostly in the tissue not the blood plasma
|
|
|
Plasma concentration = 1000ug/ml + Vd = 8000 mL
|
x/1000ug/ml = 8000 mL -> 8000*1000e-6 = 8.0 grams -> X = 8g
|
