Pharmacology Exam I part 2
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Pharmacology Exam I part 2
octanl; water partitioning coefficent that tels you how lipid soluble a chemical is, the drug is added to water and octanol and is then measured to see how much is in the water or octanol phase
a surrogate for fat
Log KOW is 1
drug is water soluble
Log KOW is 10
the drug is lipid soluble
Most drugs have a KOW of?
log KOW of 1-4; most drugs are not lipid soluble because if it was lipid soluble then it would go to the fat which is distributed to the whole body
Ibuprofen with a pH 1 has a log KOW of? ph 7?
pH 1 log KOW
pH 7 log KOW
charge equates the
lipid solubility fo the drugs
the amount of drugs that reaches blood stream; ex. propanolol ~20% Bioavailable dose of propanol
route that most drugs take; some drugs are so small they can diffuse through nuclear pores such as ethanol
pH 1 then 99.9% of it is neutral/nonionized form so it will absorb easily in acidic environment (stomach)
Absorption in lungs (asthma)
does not take long because doesn't need to diffuse 100% of what is inhaled goes into the body
Absorption through the skin
most drugs can't penetrate into the blood by the skin
Factors affecting absorption
EDTA or co-solvents can increase absorption
3 factors limiting absorption
GI motility (are you eating? is your stomach active?), blood flow, and gastric emptying
GI motility example
you take a drug and then you eat something, the food will push the drug to the small intestine therefore the drug won't work
Surface area can also limit absorption because
the intestines contain many folds (everyone has different number of folds in the intestine)
Why do people have to sometimes take food siwth drugs?
to prevent ulcers
Volume of distribution (VOD)
measure of how widely distributed a drug is in the body. this measure tells us where the drug goes
dose/ in plasma ; we usually don't want a drug to distribute all over the body
Drugs can be stored in:
plasma proteins (esp. albumin protein), liver and kidney, bone, fat and hydrophobic components
Drugs bound to albumin
increases the residence time in plasma
Drugs unbound to albumin
goes to the liver and tissues
Cmax depends on
absorption, distribution, metabolism, and excretion
recieves 25% of CO and some drugs can be actively secreted into glomerulus into tubules
when the drug goes from the large intestine back to the liver through the portal vein
drug being reabsorbed in liver (ex. birth control drug); we are not able to control it but it is important to be aware of it
What is a good VOD?
the smaller the VOD the better. usually durgs are less than or equal to 3 are good. if the VOD value is closer to the value fo the plasma concentration the drug is more effective
Drugs that have a VOD less than or equal to 3
heparin and insulin
Drugs that have a VOD greater than 20
diazepam (valium) and ethanol (vod of 40-50)
Why does ethanol distribute so well?
it is so small so it has the ability to travel through pores
blood flow and solubility
Most profused organs
brain, liver, kidneys, lungs and heart
generally happens int he liver but many other tissues are also metabolic
detoxification and bioactivation
The two stages of metabolism
Phase I and Phase II
Phase I of metabolism
oxidation, reduction, hydrolysis; most drugs go through this phase to make it more reactive
Phase II of metabolism
conjugation enzymes; phase II is to make drugs more water soluble to be eliminated easily
Phase I enzymes
superfamily (there are subgroups such as CYP450 1 and CYP450 2) of heme containing proteins; contained in the endoplasmic reticulum
Induction causes enzymatic activity to increase or decrease?
Scenario: if drug A induces CYP450 1 and drug B is metabolized by CYP450 1 then what effect will this cause?
if they are taken together drug B will be metabolized faster so the therapeutic affects of it are shorter
Inhibition causes enzymatic activity to increase or decrease?
Scenario: if drug A inhibits CYP450 1 and drug B is metabolized by CYP450 1 then what effect will this cause?
if they are taken together then drug B cannot be metabolized which increases half life of body