Week 3- Pharmacokinetics Flashcards
Which test is most specific in regards to renal functioning and drug clearance?
Creatinine clearance; uses age, serum creatinine and predicted creatinine production rate
Where is it easier for acidic drugs to be absorbed?
Stomach; low pH; stays in non-ionized form here
Describe what happens in a conjugation metabolic reaction (Phase 2 RXN)Describe what happens in a conjugation metabolic reaction (Phase 2 RXN)
Glucuronic acid compound added to drugs to make them more polar
more polar = more hydrophilic = easier to excrete
What is the main benefit of a time release capsule?
Bits of the drug within the capsule break down at different rates so there is a longer duration of action
How does the Na/K ATPase pump use active diffusion
The pump moves sodium out of the cell and decreases potassium entering the cell > creates gradient that allows for movement of substances into cell
True or False:
At steady state, even though the blood levels of a drug fluctuate above and below the mean concentration and the drug tends to have peaks and troughs during dosing intervals, the fluctuations remain within a constant range.
True
What are the disadvantages of rectal medications?
Erratic absorption
Which drug is more easily absorbed in the stomach
weak acid drugs
Which of the following statements about elimination is NOT true?
A. Clearance is the most important factor in determining drug dosages
B. Liver, kidneys, GI tract are primary sites of elimination
C. Not all drugs are eliminated by the kidneys
D. The proximal tubule is where active tubular secretion occurs and is poorly developed until about the age of 12
D. The proximal tubule is where active tubular secretion occurs and is poorly developed until about the age of 12 years
What are the three classes of pharmacogenomic study?
Drug metabolizing pharmacogenetics
Drug transporter pharmacogenetics
Drug target pharmacogenetics
You are about to prescribe a medication that has a high affinity for binding to albumin when it is in the bloodstream. The patient’s albumin level is low. How would this impact the dose prescribed for the patient?
a) The dose would need to be increased
b) The dose would need to be decreased
c) This medication should not be prescribed for this patient
B. The dose would need to be decreased
True/False:
Only unbound drugs can be excreted
True
Describe the difference between renal clearance and liver clearance
Renal clearance: unchanged drug
Liver clearance: via transformation of drug into metabolite(s)
Most drugs are absorbed through the GI tract by: A. Facilitated diffusion B. Passive diffusion C. Active transport D. pH dependent ionization
B. passive diffusion
Explain the difference between phase I and phase II metabolic reactions
Phase I: drug converted to metabolite that is more polar or water soluble to ease excretion process
Phase II: drugs that cannot become more water soluble instead conjugate with another substance in order to be excreted
Whats the difference between passive and active diffusion
Passive diffusion requires no energy, substance travels on concentration gradient from high to low
Active diffusion requires energy, uses Na/K ATPase pump to move substance
True/False:
The hepatic route of drug elimination often causes nausea/diarrhea
True
What are the primary sites of elimination and what are the additional sites?
Primary sites: kidneys (urine), liver (biliary), GI tract (feces)
Additional sites: lungs, breast milk, saliva, sweat, hair, skin
\_\_\_\_\_ is the most important concept to consider with long term drug administration: A. Distribution B. Clearance C. Absorption D. Metabolism
B. Clearance
What is half life?
The time it takes peak drug level to drop by half from elimination
Related to drugs duration of action
What are the three main factors that effect the rate of metabolism?
- Age; elderly and young children/infants can’t break down drugs as efficiently
- Liver disease ie. cirrhosis, hepatitis
- Drug tolerance; liver produces more enzymes to break down drug over time
What is distribution
Movement of drug through the body from blood to
- site of action (receptor site)
- storage sites (Fat)
- Elimination sites (kidneys)
An advantage of prescribing a sublingual medication is that the medication is:
a. excreted rapidly
b. has less side effects
c. distributed equally
d. avoids first pass metabolism effect
D. Avoids first pass metabolism effect
True/False:
Lipophilic drugs have large volume of distributions
TRUE
Phase 1 metabolic reactions are caused by why system of enzymes?
CYP450 isoenzyme system
True/False:
The clearance of a drug is affected in patients with impaired kidney function. These patients are at an increased risk for drug toxicity
True
At what sites can metabolism occur?
Liver (main site) Intestines Skin Lungs Kidney Brain
True/False:
Drugs that can’t be made more polar are metabolized by Phase 2 reactions or conjugation reactions and added to bile for excretion through the feces
True
Age can affect biotransformation. Which of the following is NOT a true statement?
A. P450, blood-brain barrier, intestinal enzymes, renal system not fully developed in babies up to one year
B. Diminished absorption, distribution, creatinine clearance may occur in older adults
C. Older adults lose 50% of hepatic metabolism ability
D. The renal system is not fully developed until the age of 2 years
D. The renal system is not fully developed until the age of 2 years
T/F most drugs are weak acids or weak bases
TRUE
T/F Ionized drugs are more lipid soluble
FALSE ionized drugs are less lipid soluble bc the charges of the drugs and membrane fats are opposing
If a patient has hypoalbuminemia and is given Drug A, which is highly bound to albumin, what may happen to the drug’s effects?
Select one:
a. Albumin binding does not affect the drug.
b. More of Drug A is free and is therefore able to produce greater effects.
c. The dose of Drug A may need to be increased to address larger volume of distribution.
d. Drug interactions would be unlikely to occur with Drug A.
Feedback
B. More of Drug A is free and therefore able to produce greater effects
True/False:
Only highly lipophilic drugs can pass through the blood brain barrier
True
What are the two main types of drug binding proteins in the blood?
- Albumin (most common)
2. Glycoproteins (binding sites for several drugs and increase in inflammatory states)
Therapeutic drug levels are drawn when a drug reaches steady state. Drugs that have a multiple dosing regimen reach steady state
Select one:
a. After the second dose
b. After four to five half-lives
c. When the patient feels the full effect of the drug
d. One hour after IV administration
B. After four to five half-lives
What is the disadvantage of intramuscular medications?
Irritating
What are the disadvantages of the inhalation route?
Goes straight from lungs to heart
Ex. adrenaline used to be used for asthma but was d/c bc then went straight to heart and caused increased HR
What factors affect distribution of a drug?
- Molecular size; easier for smaller drugs to distribute
- Lipid solubility; lipophilic drugs more inclined to distribute
- pH/Acidity of environment;
- Ionization
- Protein binding properties
___________ determines the time taken to reach steady state on multiple dosing
Half Life
What is pharmacogenomics?
Choosing medications based on one’s unique genetic makeup
True/False:
The larger the volume of distribution of a drug the faster the clearance
True
What is a prodrug?
Any drug that is a precursor to an active drug
Drug is inactive upon administration and becomes active form through metabolism
What is the major drug binding protein in the bloodstream and where is it produced
Albumin; produced in the liver
What is steady state?
Drug concentration that is high enough to maintain effect but low enough to prevent toxicity
>rate of absorption and elimination are in equilibrium
Pharmacogenetics VS. Pharmacogenomics
Pharmacogenomics = refers to single or a few gene variations on drug therapy Pharmacogenetics = refers more broadly to the genome-wide effects on drug therapy
What is absorption
the rate that a drug leaves the site of administration and passes to the systemic circulation
What factors affect the rate of absorption?
- Route of administration
- Dosage
- Lipid solubility
- Ionization
- Presence/absence of food in GI tract
- Size of molecule
- Blood flow to the area
- Formulation of drug
- Mechanics of absorption
- Cellular environment
- Mechanics of absorption
____________ determines the time it takes to reach steady state
Half Life; ~5x half life = steady state
What is the onset of action of intramuscular medications?
-15 minutes
what are the two mechanisms by which drugs are transported through membranes
active diffusion
passive diffusion
How would a poor nutritional status effect protein binding
Less nourishment means less available proteins for binding to drugs
Need lower doses of medications
what can increase drug absorption
inhibition of P-glycoprotein
gut wall metabolism
lipophilicity
What are the advantages of intramuscular medications?
Provides reservoir for drug; extended duration of action bc absorbed over time
True/False:
In some cases increased metabolism can lead to toxicity of certain drugs
True
True/False:
The salt form of a drug can contribute to its bioavailability in solubility
True
What is meant by parenteral routes of administration
Injection directly into body bypassing skin/mucous membranes; aka outside of alimentary canal
Requires aseptic technique
Which of the following are methods of excretion of drugs: A. Renal B. Biliary C. Fecal D. Sweat E. All of the above
E. All of the above
True/False:
Drugs are typically administered at intervals close to half life
True
Drugs that use CYP 3A4 isoenzymes for metabolism may
Select one:
a. Induce the metabolism of another drug
b. Inhibit the metabolism of another drug
c. Both A and B
d. Neither A nor B
C. Both A and B
True/False:
The shorter the half life of a drug, the faster the clearance
True
You prescribe a medication for a patient that is typically highly protein bound. The patient's albumin is 2.5g/dL. In terms of drug availability you would: A. Check the liver/renal function B. Increase the dose of the medicaiton C. Decrease the dose of the medication D. Not give the medication
C. Decrease the dose of the medication
What is the goal of drug administration?: A. Bioavailability B. Distribution C. Metabolism D. Elimination
A. Bioavailability
True/False:
Metabolites remain in the collecting tubules and are excreted
True
What is the P450 System
Large family of enzymes that are responsible for most phase 1 reactions
75% of total drug metabolism
What can decrease drug absorption?
too hydrophilic
too lipophilic
______ is the minimum amount of a drug that will have inhibitory effects on the growth of a specific organism
*We want to use the lowest effective dose
Minimum inhibitory concentration (MIC)
Accumulation of a drug is detectable if the dosing interval is less than ______ half lives
4
True/False:
The efficacy of antivirals can vary depending on where its transporter is located?
True
True/False:
Orally administered drugs may sometimes bypass the first pass effect and enter straight into the circulation
FALSE; orally administered drugs all go through the first pass effect before entering circulation
What is the cell membrane made of
phospholipid bi-layer
What are some benefits of pharmacogenomics?
- Understanding why pt’s with the same disease respond differently to a certain medication
- Minimize Adverse drug reactions
- Help maximize drug efficacy
Explain Pharmacokinetics VS. Pharmacodynamics
Pharmacokinetics (effect of body on drug)
Drug administration > Absorption, Distribution, Metabolism, Elimination > concentration of drug in plasma
Pharmacodynamics (effect of drug on body)
Concentration of drug at site of action > drug effect
Kidney failure would disrupt which phase of pharmacokinetics? A) Metabolism B) Distribution C) Absorption D) Excretion
A. Metabolism
Which routes of drug administration are not subjected to the first pass effect? A. IV B. Sublingual C. Inhalation D. All of the above
D. All of the above
What does a small volume of distribution of a drug indicate about its distribution?
Small volume of distribution = less drug distribution to tissues and more in the blood
What is the onset of action for rectal medications?
30 minutes
What are the parenteral routes of administration?
IV IM SubQ Intrarterial Intra-articular
True/False:
The degree of drug-protein binding present in the bloodstream effects the drugs ability to create an effect
TRUE; the more protein binding, the less free drug there is to cause an effect
What is elimination/excretion?
Process of drugs being transferred from inside the body to outside the body
Steady state refers to:
A. The time it takes for half of the drug to be eliminated by the body
B. The concentration that will eventually be achieved when the drug is being administered at a constant rate
C. Rate at which the drug leaves the site of administration and passes to the systemic circulation
D. The time it takes drugs to be completely eliminated by the body
B. The concentration that will eventually be achieved when the drug is being administered at a constant rate
What tests might we incorporate to determine renal function?
BUN Creatinine & creatinine clearance Glomerular filtration rate Albumin to creatinine ratios Plasma drug concentration
Rifampin is a nonspecific CYP450 inducer that may:
a. Lead to toxic levels of rifampin and must be monitored closely
b. Cause toxic levels of drugs, such as oral contraceptives, when coadministered
c. Induce the metabolism of drugs, such as oral contraceptives, leading to therapeutic failure
d. Cause nonspecific changes in drug metabolism
c. Induce the metabolism of drugs, such as oral contraceptives, leading to therapeutic failure
What are the rectal dosage forms?
Suppository in oil form
Where does most of the metabolism of a drug occur?
Liver
What factors affect Vd?
Kidney disease; bc fluid is retained and the plasma and extravascular fluid volumes are higher
Liver disease bc protein binding is affected
What is normal GFR and at when level would we dose adjust a drug?
100-120ml/min
GFR <60 you would adjust
Explain why the blood brain barrier is hard for many drugs to cross
The blood vessels in the brain are surrounded by two different layers of cells, therefore drugs have to be very fat soluble to get through 2 different cell membranes
Explain the distribution pathway that a PO drug could undergo
Oral ingestion > is either excreted or crosses membranes in stomach or intestine to hepatic portal vein > enters liver where it could be metabolized > enters blood stream as either metabolite or free drug > could be bound to plasma proteins in bloodstream, enter tissue reservoir, go to site of action or go to kidney > excreted from kidney or reabsorbed into bloodstream
Drugs that are highly lipophilic often accumulate where?
in fat cells
Disadvantages of the oral route?
Slow onset of action
GI irritation
Amount absorbed is erratic
Inactivation by liver
Once they have been metabolized by the liver, the metabolites may be
Select one:
a. More active than the parent drug
b. Less active than the parent drug
c. Totally “deactivated” so they are excreted without any effect
d. All of the above
D. All of the above
What happens in biliary secretion of drugs?
Bile flows from liver to intestine via biliary drugs; excreted through feces
Which routes of administration are not enteral or parenteral?
- Inhalation
- Transdermal “patches”
- Topical
What is capacity limited protein binding?
drugs can only bind to available proteins and this binding changes depending on rate of elimination
Does a large volume of distribution indicate that there would be more or less of the drug in the tissues of the body?
Large volume of distribution = more drug distribution to tissues and less in blood
What is enzyme inhibition?
Decrease in CYP450 enzyme action
>drugs will build up with potential for toxicity
What is the most important factor in determining drug concentration?
Clearance
True/False:
Drugs that have longer half lives have a greater risk for toxicity
True
What factors should be considered in when determining route of administration for a drug?
- Drug properties; ie. insulin can’t be taken orally bc it is digested in the GI tract
- Onset of action; ie. do you need a more immediate effect like for anaphylaxis
- Convenience for patient
- Cost
Factors that affect gastric drug absorption include:
a. Liver enzyme activity
b. Protein-binding properties of the drug molecule
c. Lipid solubility of the drug
d. Ability to chew and swallow
C. Lipid solubility of the drug
What three processes do the kidneys use for drug secretion/excretion?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
Pharmacogenetic testing is required by the U.S. Food and Drug Administration prior to prescribing:
a. Erythromycin
b. Digoxin
c. Plavix
d. Rifampin
C. Plavix
What factors affect metabolism?
Age Gender Drug tolerance Co-morbidities Drug-drug interactions Genetic differences Diet and environmental factors Liver dysfunction
Which of the following variables is a factor in drug absorption?:
a. The smaller the surface area for absorption, the more rapidly the drug is absorbed.
b. A rich blood supply to the area of absorption leads to better absorption.
c. The less soluble the drug, the more easily it is absorbed.
d. Ionized drugs are easily absorbed across the cell membrane.
B. A rich blood supply to the area of absorption leads to better absorption
True/False:
Bioavailability is the goal of drug administration
True
When prescribing medications we must concern ourselves with interactions that may increase the activity of other important CYP450 isoenzymes. This process is called: A. Glucoronidation B. Enzyme induction C. Hydrolysis D. Enzyme inhibition
B. enzyme induction
True/False:
Metabolism of a drug cannot destroy of eliminate the drug, only change it
True
What factors affect bioavailability?
How drug is administered
How the drug transports across membranes
How drug is affected by acid environ. in stomach
How the drug is formulated
What is meant by enteral routes of administration?
administration thru the GI tract
What is the onset of action for oral meds
-30 minutes
What does a metabolic reaction do to a drug?
Changes it into an inactive form that is more easily excreted
What are the advantages of rectal medications?
Can be used with infants
Can be used with unconscious patients
True/False:
Excretion can happen by renal or hepatic routes
True; among other routes
True/False:
At a steady state dose = clearance
True
Three broad classes of genes exist, which have been recognized to influence how genes interact with a given drug. The role of human variation in genes is known as: A. drug transporter pharmacogenetics B. drug eliminating pharmacogenetics C. drug metabolizing pharmacogenetics D. drug target pharmacogenetics
C. drug metabolizing pharmacogenetics
What are factors that affect pharmacokinetics?
age pregnancy hepatic/ renal disease drug/food interactions perfusion of target organs ethnicity metabolism nutritional status
Explain glomerular filtration of the kidneys
Free drug is filtered along with a high volume of fluid
When is it best to measure drug levels and why?
Best to measure drug levels at lease 2hrs after PO administration bc this is when it will usually be distributed to tissues
>Some meds take longer
What are the 2 main metabolic reactions that drugs can go through?
- Destructive Rxn or Phase 1
2. Conjugation Rxn or Phase 2
What is pharmacokinetics
What the body does to the drug
Which routes of administration bypass the first pass effect?
Parenteral: IV, IM, Subcutaneous
Enteral: Sublingual, rectal
Other: Inhalation, topical, transdermal
what is ionization
the loss or gain of electrons which alters the charge
True/False:
Overweight people store more fat-soluble drugs than thin people
TRUE
Give some examples of substances that can cause enzyme induction
Phenobarbital Rifampin Foods Chemicals Pollutants
What is a metabolite?
The transformed version of a drug; is inactive
What are the disadvantages of intravenous medications?
Most dangerous route
True/False:
When the effect of a drug has ended, it does not necessarily mean the drug has been eliminated from the body. Rather it could have just redistributed to other parts of the body (inactive sites)
True, such as fat, muscle
What is the onset of action of the inhalation route?
minutes
ex. bronchodilators
True/False:
If a person has poor circulation, drugs will not distribute as well
True
True/False:
In regards to metabolism, some drugs only need to go through phase 1 reactions, but most need to go through both.
TRUE
In order for a phase II metabolic reaction to occur what two things are needed?
- Energy
2. Transfer enzymatic activity
When a medication is added to a regimen for a synergistic effect, the combined effect of the drug is:
a. The sum of the effects of each drug individually
b. Greater than the sum of the effects of each drug individually
c. Less than the effect of each drug individually
d. Not predictable, as it varies with each individual
B. Greater than the sum of the effects of each drug individually
Is elimination faster or slower for drugs that are highly protein bound?
Slower
What is bioavailability?
The percent of unchanged drug that reaches systemic circulation
What is volume of distribution?
Theoretical measurement of the space in the body available to contain the drug
>compares drug distribution to tissues to amt. in blood
What is the onset of action for sublingual medications?
Minutes
EX. nitro
which drug is more easily absorbed in the intestine
weak basic drugs
\_\_\_\_\_\_\_ is the movement of a drug from its site of administration into the central compartment and the extent to which this occurs: A. Distribution B. Absorption C. Excretion D. Metabolism
B. Absorption
The major reason for not crushing a sustained-release capsule is that, if crushed, the coated beads of the drugs could possibly result in
Select one:
a. Disintegration
b. Toxicity
c. Malabsorption
d. Deterioration
B. Toxicity
True/False:
The drug absorbed from the mouth and rectum goes to the liver for metabolism
FALSE
sublingual meds and rectal suppositories are absorbed directly into bloodstream and into heart
What are enteral routes of administration
Oral
Sublingual
Rectal
What is the first pass effect?
First pass of a drug through the liver where it is often metabolized
What is the onset of action of subcutaneous medications?
-10 miutes
ex insulin, TB
What are the 4 phases of pharmacokinetics?
Absorption
Distribution
Metabolism (biotransformation)
Elimination/Excretion
True/False:
Water soluble drugs would have a volume of distribution similar to plasma volume
TRUE; bc most of it stays in the blood anyways
A result of upregulation of receptors may cause:
a. A synergistic response to a drug
b. A complete lack of response
c. An exaggerated response if the drug is withdrawn suddenly
d. A complete lack of response if the drug is withdrawn
C. An exaggerated response if the drug is withdrawn suddenly
Describe the types of destructive metabolic reactions (Phase 1 RXNS)
- hydrolysis; water is incorporated into structure splitting the molecule
- oxidation; hydrogen atoms are remove from the molecule or oxygen atoms are added
- reduction; hydrogen atoms are attached to molecule
- deamination; nitrogen atoms are removed from molecule
Which of the following is never involved in the metabolism of drugs?
a. Liver
b. Blood
c. GI tract
d. Kidneys
e. None of the above
E. None of the above
True/False:
Protein binding allows for drug distribution as opposed to passive diffusion
True
Which of the following statements about the major distribution barriers (blood-brain or fetal-placental) is true?:
a. Water soluble and ionized drugs cross these barriers rapidly.
b. The blood-brain barrier slows the entry of many drugs into and from brain cells.
c. The fetal-placental barrier protects the fetus from drugs taken by the mother.
d. Lipid-soluble drugs do not pass these barriers and are safe for pregnant women.
B. The blood-brain barrier slows the entry of many drugs into and from brain cells
The time it takes for the plasma concentration to be reduced by 50%: A. Half life B. Steady State C. Minimum effective concentration D. Saturble elimination
A. Half life
Which of the following statements is NOT correct about volume of distribution (Vd)?
A. Water soluble drugs have Vd similar to plasma
B. Lipophilic drugs have low Vd
C. Drugs with large Vd concentrate in tissues
D. Drugs with smaller Vd concentrate in plasma
B. Lipophilic drugs have low Vd
What is the result of Phase 1 metabolic reactions on the drug?
Increases polarity and solubility of drug to allow easier excretion
True/False:
A drug that is administered IV has 100% bioavailabitity
True
Factors that may cause variations in drug responsiveness include:
A. Changes in the number or function of receptors
B. Tachyphylaxis
C. Idiosyncratic drug response
D. Hypersensitivity reaction
E. All of the above
E. All of the above
Which enzymes are responsible for phase I metabolic reactions and which one in particular is the major enzyme responsible for almost 50% of all drug metabolism?
CYP450 isoenzymes
>CYP3A4 is responsible for 50% of metabolism
Advantages of Oral route
safest
convenient
economical
most commonly used
True/False:
High protein binding drugs exhibit higher “free” drug concentration in the plasma when albumin and protein levels are low
True
True/False:
Differences in reaction to the same medication are caused by differences in the drug metabolizing gene expressing CYP450 enzymes.
True
Main goal of the P450 system
Make drugs more water soluble for easier excretion
What are the three major families of the P450 system
CYP1, CYP2, CYP3
CYP3A4 metabolize half of the drugs in the liver
What does a large first pass effect mean and which drugs have this?
Means that more of the drug is broken down in the liver
Ex. morphine, diazepam, propranolol
Bioavailability of oral drugs can be as low as: A. 5% B. 25% C. 50% D. 100%
A. 5%
What is clearance?
The sum of all sites of elimination of a drug
- Important to determine drug concentration
- Important in regard to toxicity
What is the difference between antiseptics and antibiotics?
Antibiotics are specific and antiseptics are not specific
Ex. Alcohol is an antiseptic bc it kills everything
True/False:
Only a drug that is NOT bound to albumin, in other words a “free” drug can attach to receptors and cause an effect
True
True or False
If an antibiotic has been shown to slow the growth of a specific bacteria, does this mean that it will also be effective in killing the bacteria?
False
Ultrarapid metabolizers of drugs may have:
a. To have dosages of drugs adjusted downward to prevent drug accumulation
b. Active drug rapidly metabolized into inactive metabolites, leading to potential therapeutic failure
c. Increased elimination of active, nonmetabolized drug
d. Slowed metabolism of a prodrug into an active drug, leading to an accumulation of prodrug
Feedback
B. Active drug rapidly metabolized into inactive metabolites, leading to potential therapeutic failure
What is enzyme induction?
Increase in CYP450 enzyme action
>causing decreased drug action of the inducer and co-administered drugs
Give an example of how competition for protein binding could result in drug toxicity
Two highly protein bound drugs can compete for attachment to albumin; this could result in more free drug of whichever drug is competitively blocked from binding to albumin
How many half lives does it take to eliminate a drug?
5
What is the main drug excretion point?
Kidneys
Why can a generic drug affect a patient differently?:
A. The drug in a generic form can be higher in potency
B. Chemically they are different
C. Molecularly they are different
D. It is not the same drug
C. Molecularly they are different
True/False:
Genetic variants of a gene can result in normal, reduced, or overactive drug metabolizing enzymes.
False
True/False:
The biliary secretion route of elimination usually happens with drugs of higher molecular weights
True
True/False:
To have drugs transported into the cell they must be lipophilic and/or hydrophobic
TRUE
Explain tubular reabsorption (Proximal tubule) of the kidneys
About half of the lipid-soluble drug that has entered the renal tubules is PASSIVELY reabsorbed back into bloodstream along with Na and H2O
True/False:
Hydrophilic drugs distribute more easily into extracellular spaces while lipophilic drugs distribute more easily into fat
True
True/False:
The patient took a BP medication. The drug get excreted by the kidneys. It is an example of pharmacodynamics.
False
True/False:
Lipid soluble drugs undergo passive reabsorption to get from renal tubules back into bloodstream and may or may not be actively transported back from the blood to the collecting tubules
True
Explain tubular secretion (Proximal tubule) of the kidneys
Certain drugs can be ACTIVELY transported using carrier proteins from the blood directly into the nephron to be quickly excreted
Ex. penicillins undergo tubular secretion process which is why their half life is so short; is not bc they are metabolized quicker than other abx
Describe tetracycline in terms of its active and inactive (redistribution) sites
Tetracycline is an antibiotic with the active site being bacteria; however it tends to accumulate in tissues containing calcium (bones/teeth) as an inactive site
*This is why is is contraindicated in children with growing bones/teeth and pregnant women
When drugs have been metabolized and reach the kidney tubule, if the drug is ionized and lipophilic the drug will tend to:
A. Be passively eliminated in the urine
B. Be actively reabsorbed through the tubular lumen
A. Be passively eliminated in the urine
What patient factors could effect distribution?
Obesity; more drug accumulation in fat stores
Nutritional status
Circulation
