Final Flashcards
T/F: We can find information about a drug’s pharmacokinetic characteristics in the drug monograph?
True
Pharmacokinetics is the study of:
What the body’s physiological system does to the drug. Also, PK is considered as the time course of plasma drug concentrations in the body or the absorption, distribution, metabolism, and excretion of the drug.
Sally and George have taken acetaminophen according to the label instructions to relieve their headaches. Twenty minutes later, Sally’s headache is still as painful as ever but George has experienced significant relief from his headache. Differences in the therapeutic outcome between Sally and George could be due to:
Sally did not absorb acetaminophen well
George’s headache pain receptors are more sensitive to acetaminophen than Sally’s
George absorbed acetaminophen more quickly than Sally
Write in logarithmic form: 8 =2^3
log(2)8=3
As an area of study, pharmacokinetics evaluates the change in plasma drug concentrations with change in time. It is important to know the change in drug plasma drug concentrations with time because:
Such information provides guidance as to how long a pharmacological effect might persist following a dose administration
Plasma drug concentrations have a relationship with drug effect.
Plasma drug concentration versus time data allows us to calculate pharmacokinetic parameters.
Write in logarithmic form: 100 =10^2
log(10)100=2
Write in exponential form: log10 100,000 = 5
10^5=100000
Write in exponential form: log(2)32 = 5
2^5=32
Which of the following represents a first-order rate process?
A. As concentration increases the rate of change in concentration remains the same.
B. As concentration increases the rate of change in concentration increases proportionally with the increase in concentration.
B
A describes a zero-order process where rate does not change with a change in concentration.
which are correct regarding the statement “Take 500 mg acetominophen every 8 hours for your headache”?
A. Is an example of an empirical dosing regimen.
B. Is guaranteed to alleviate headache symptoms in all patients.
C. Will produce therapeutically effective plasma drug concentrations in most but not all patients
D. Might produce toxicity in a few patients
A, C, D
The range of plasma drug concentrations that produce an appropriate therapeutic response in an individual patient is referred to as the:
Therapeutic window
With regards to clinical response which of the following are true?
A. Onset of clinical response depends on how quickly plasma drug concentrations reach the therapeutic window following a dose administration.
B. Duration of clinical response depends on how long plasma drug concentrations stay within the therapeutic window.
C. Intensity of drug effect depends on the height of the plasma drug concentration following a dose administration
D. We want to minimize adverse drug effects while optimizing the appropriate therapeutic effect.
all of the above
The predictable relationship between plasma drug concentration and concentration at the drug site of action to result in the clinical response is:
Kinetic homogeneity
T/F: Extravascular administration is the injection of drug directly into the systemic circulation.
False
Another term for the ‘DME’ part of ADME is:
disposition
which factors determine the shape of the plasma drug concentration versus time curve?
route of administration
metabolism of the drug
bioavalability of the drug
(dose size/formulation, dosage form, ADME)
What is the main difference between therapeutic window and therapeutic range?
The therapeutic window is the plasma drug concentration range that produces the desired clinical response and is applied on an individual basis. Therapeutic range is a population derived value which encompasses those plasma drug concentrations where the probability of desired clinical response is high in most patients and undesired clinical response low.
Many drugs are dosed according to empirical dosage regimens because:
The therapeutic window is very wide so a standard dose will result in drug concentrations that fall within the therapeutic window regardless of the differences in pharmacokinetic processes acting on the dose between different individuals.
Many drugs exhibit a wide therapeutic index so interindividual differences in pharmacokinetics is not a concern.
To achieve therapeutic concentrations quickly in a patient, we need to administer a:
loading dose
To maintain plasma drug concentrations in the therapeutic window, we need to administer a:
maintenance dose
If a drug has a half-life of 2 hours, how many hours will it take to reach a steady state plasma concentration?
10-14
T/F: Doubling the dose will double the plasma drug concentration.
True
what are the primary pharmacokinetic parameters?
Cls, F, Vd Ka
The drug concentration at the pharmacological receptor site is determined by:
Distribution of drug from systemic circulation to the biophase.
How quickly the drug is eliminated from the body.
The extent to which the drug is liberated from the drug product.
The extent to which the drug is absorbed from the gastrointestinal tract.
The extent to which the drug is distributed to tissues other than the biophase.
Polarized epithelia have the following characteristics:
Polarity with a distinct apical and basolateral surface
Result in the net movement of drugs in one direction
Provide a protective barrier to tissues and organs of the body
Contain drug metabolizing enzymes that can eliminate drug during its attempt to transfer from one side to the other side of the epithelium.
Mechanisms of transcellular transport include:
Passive diffusion, facilitated diffusion (carrier-mediated), active transport (carrier-mediated), endocytosis/exocytosis
Small lipophilic drugs typically cross plasma membranes and polarized epithelia:
By passive diffusion
Down a concentration gradient
At a rate proportional to the concentration difference on either side of the membrane
When passive diffusion is responsible for transport across the membrane, the rate of transport:
Will increase with increasing surface area of the membrane
Active transport and facilitated diffusion are characterized by:
Need for a transport protein to move drug across the membrane
A maximum transport rate due to saturation of the transporter at high enough drug concentration.
Ability to be inhibited when two drugs that share the same transporter are administered together.
A weekly acidic drug has a lower concentration in breastmilk (pH 6.8) than in plasma (pH 7.4). This is an example of:
ion trapping
The partition coefficient and apparent partition coefficient give an indication of a drug’s lipophilicity. In applying these concepts to drug administration to patients, which provides the best understanding of a drug’s lipophilicity - the partition coefficient or the apparent partition coefficient? Explain briefly.
Apparent partition coefficient. Drugs are either weak organic acids or bases. Depending upon the relative pKa and pH values, many drugs have some degree of ionization at the body pH of 7.4. Ionized drug is more hydrophilic and unionized drug is more lipophilic in nature. Hence, the apparent partition coefficient takes into consideration the relative degree of ionization of drugs in the physiological system.
In the study of Biopharmaceutics, the rate and extent of drug absorption can be influenced by:
Nature of the dosage form
Route of administration
Physicochemical properties of the drug
Clinical response (or therapeutic outcome) refers to:
onset, duration, and intensity of effect
For a patient experiencing a headache, what is most important:
Quick onset and high intensity of effect
For a patient experiencing a serious life-threatening infection, would you administer the drug intravenously or orally? Explain briefly.
Intravenously. This route of administration results in rapid high levels of drug to ensure rapid killing of bacteria. If given orally, the drug must undergo absorption and, therefore, it will take some time for concentrations to reach levels that will kill bacteria. Furthermore, the amount absorbed is usually lower than the administered dose so more drug is needed to produce concentrations in the body that will kill the drug. With intravenous administration, 100% of the drug is made available to the systemic circulation.
According to the Noyes-Whitney equation for drug dissolution from a solid dosage form:
Formulation of a drug as a salt will increase the driving force for dissolution
