47 Questions
Which process is responsible for transporting Vitamin B12 across the gut wall?
Endocytosis
What is the main factor affecting drug absorption discussed in the text?
Effect of pH
Why do weak acids pass through membranes more readily?
Because the uncharged, protonated form can permeate through membranes
What determines the distribution of a drug between its ionized and unionized forms?
pKa and ambient pH of the drug
What is the most common and safest route of drug administration?
Oral
Why are oral drugs easily self-administered?
They can be swallowed
What complicates the pathways involved in oral drug absorption?
Low gastric pH
Why is activated charcoal used in cases of oral drug overdose?
To prevent drug absorption
What does Volume of Distribution (Vd) compare the distribution of a drug with?
Volumes of the water compartments in the body
Which compartment has a low Volume of Distribution similar to plasma volume?
Plasma compartment
What is bioavailability?
The percentage of a drug that reaches the systemic circulation after a specific route of administration
In which compartment would a hydrophilic drug with low molecular weight distribute more readily?
Extracellular fluid
Why does orally administered drugs often undergo first-pass metabolism?
Because the liver metabolizes the drug before it reaches the systemic circulation
What is the formula for calculating Volume of Distribution (Vd)?
Vd = Dose / C0
What does the area under the curve (AUC) measure in pharmacokinetics?
Total drug exposure over time after administration
How does first-pass hepatic metabolism affect bioavailability?
Decreases the amount of unchanged drug reaching the systemic circulation
Volume of Distribution (Vd) has a physiologic or physical basis.
False
A drug with high molecular weight or extensive protein binding would have a low Volume of Distribution (Vd).
True
Heparin shows characteristics of distribution similar to Extracellular Fluid.
False
A hydrophilic drug with a low molecular weight can easily distribute into the interstitial fluid.
True
Metabolism leads to production of products with decreased polarity.
False
Most drugs are eliminated according to zero-order kinetics.
False
Drug clearance estimates the amount of drug cleared from the body per unit of volume.
False
Kidneys can efficiently eliminate lipophilic drugs that are reabsorbed in the distal convoluted tubules.
False
Drug excretion may occur via sweat, saliva, tears, hair, and skin to a large extent.
False
Total body clearance and drug half-life are not important measures of drug clearance.
False
The liver does not contribute to drug clearance through metabolism or excretion into the bile.
False
The kidney is not a major organ of excretion in drug clearance.
False
Patients with diminished renal or hepatic blood flow may experience a decrease in drug half-life.
False
Increased hepatic blood flow can lead to a decrease in the half-life of a drug.
True
Patients with decreased ability to extract drug from plasma may require an increase in drug dosage.
False
Which process is NOT involved in the elimination of drugs through the kidneys into urine?
Metabolism
What is the normal glomerular filtration rate (GFR) approximately in mL/min?
125
Which factor does NOT influence the passage of drugs into the glomerular filtrate during glomerular filtration?
Molecular weight
Where do drugs that were not transferred into the glomerular filtrate leave the glomeruli to enter the proximal tubule?
Efferent arterioles
Why is intravenous (IV) injection considered the most common parenteral route of drug administration?
It allows for rapid drug delivery to the systemic circulation.
What distinguishes depot preparations used in intramuscular (IM) drug administration from aqueous solutions?
They are usually suspended in a nonaqueous vehicle.
Which factor contributes to the higher peak plasma concentrations seen when drugs are administered as an IV bolus compared to IV infusion?
Immediate full delivery to the systemic circulation
What is a disadvantage associated with the intradermal route of drug administration?
High potential for pain and fear
Which organ is primarily involved in the elimination of anesthetic gases?
Lungs
Excretion of most drugs into which of the following occurs only to a small extent?
Saliva
Total body clearance is the sum of clearances from which drug-processing and drug-eliminating organs?
Liver and Kidneys
What is a potential source of undesirable side effects to a breast-feeding infant regarding drug clearance through metabolism?
Medications taken by the mother
What is the primary location where secretion of drugs occurs in the kidneys?
Proximal tubules
How does manipulating urine pH help increase drug clearance in the kidneys?
By increasing the fraction of ionized drug in the lumen
Which process is responsible for increasing the elimination of weak bases from the body?
Acidification of the urine
What can be done to decrease the reabsorption of weak acids in a patient presenting with an overdose?
Alkalinization of the urine
Test your knowledge on determining bioavailability of drugs for nonintravenous routes of administration. Learn how bioavailability is calculated by comparing drug levels after oral and IV administration.
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