70 Questions
What does ADME stand for in the context of drug pharmacokinetics?
Absorption, Distribution, Metabolism, Excretion
What is the main factor influencing oral bioavailability of a drug?
Solubility
What does the term 'elimination' represent in the context of drug pharmacokinetics?
Metabolism + Excretion
What determines the overall exposure and bioavailability of a drug?
Ability to overcome barriers in pharmacokinetic processes
Which term describes the required parts of solvent to dissolve 1 part of solute?
Sparingly soluble
Which phase of the body is considered interesting for drug solubility?
Water and lipoid phases
What is the primary mechanism for drug absorption in the bloodstream?
Convection and diffusion
Which characteristic is a desirable requirement for an orally administered drug?
Survive a range of pHs
What is the primary mechanism for drug diffusion in the body?
Mostly passive trans-bilayer diffusion
Which phase of the body is involved in drug excretion?
Urine
What is the primary mechanism for drug distribution in the body?
Transport into the extracellular space and into cells in tissues
Which characteristic is a barrier for orally administered drugs?
Cross membranes in villi and capillary walls
What is the primary mechanism for drug metabolism?
Bilayer buildup in some cases
Which term describes the solubility of a drug requiring 100-1000 parts of solvent to dissolve 1 part of solute?
Slightly soluble
What is the primary mechanism for drug excretion in the body?
Filtration
Which phase of the body is involved in drug accumulation?
Plasma
What does ADME stand for in the context of drug pharmacokinetics?
Absorption, Distribution, Metabolism, Excretion
What is the primary mechanism for drug absorption in the bloodstream?
Passive diffusion
Which characteristic is a barrier for orally administered drugs?
Low solubility
What is the primary mechanism for drug distribution in the body?
Bloodstream transport
What is the main factor influencing oral bioavailability of a drug?
Solubility
Which term describes the solubility of a drug requiring 100-1000 parts of solvent to dissolve 1 part of solute?
Poorly soluble
What is the primary mechanism for drug metabolism?
Enzymatic and spontaneous
Which phase of the body is involved in drug excretion?
Urine, sweat, expired air, feces
Which phase of the body is considered interesting for drug solubility?
Gastrointestinal tract
What does the term 'elimination' represent in the context of drug pharmacokinetics?
Metabolism + Excretion
What is the primary mechanism for drug diffusion in the body?
Passive diffusion
What is the primary mechanism for drug accumulation?
Tissue retention
In the context of drug solubility, what term describes a drug requiring 30-100 parts of solvent to dissolve 1 part of solute?
Sparingly soluble
Which phase of the body is involved in drug distribution and is considered interesting for drug solubility?
Extracellular space
What is a desirable requirement for an orally administered drug, besides stability and proper protein binding?
Permeability for membranes by passive transbilayer diffusion
What determines the overall exposure and bioavailability of a drug, underlined by the Biopharmaceutic Classification System?
Permeability and aqueous solubility
What does the term 'elimination' represent in the context of drug pharmacokinetics?
Excretion of the drug from the body
Which phase of the body is involved in drug excretion through urine?
Urine
What is the primary mechanism for drug absorption in the bloodstream?
Trans-bilayer diffusion
What is the primary mechanism for drug diffusion in the body, occasionally hindered by efflux distribution?
Endo-/exocytosis
What is the primary mechanism for drug metabolism, involving bilayer buildup in some cases?
Bilayer buildup
What is the main factor influencing oral bioavailability of a drug, as underlined by the Biopharmaceutic Classification System?
Permeability and aqueous solubility
What is the phase of the body involved in drug accumulation in hypoxic cancer cells and lysosomes?
Mitochondria
Which term describes the solubility of a drug requiring 1000-10,000 parts of solvent to dissolve 1 part of solute?
Very slightly soluble
Which of the following is an organ participating in drug excretion?
Liver
Which part of the kidney is responsible for reabsorption of physiologically important metabolites, ions, and water?
Renal Cortex
Which phase of the body is involved in drug excretion of orally administered drugs that are not completely absorbed?
Gastrointestinal tract
Which part of the kidney is responsible for the formation of urine?
Renal Pelvis
Which organ is responsible for excretion of volatile drugs and metabolites?
Lungs
Which part of the kidney is responsible for the collection of urine before it moves to the ureters?
Renal Pelvis
Which organ is involved in drug excretion through biliary excretion?
Liver
Which part of the kidney is responsible for the filtration of blood to form urine?
Renal Cortex
Which organ is responsible for excretion of some water-soluble drugs and metabolites?
Skin
Which part of the kidney is responsible for carrying urine from the renal pelvis to the urinary bladder?
Renal Vein
Which drugs are not expected to achieve distribution equilibrium?
Drugs completely ionized in urine acids even under most acidic conditions (pH ~4.5), i.e., having pKa < 2.5 bases even under most basic conditions (pH ~8), i.e., having pKa > 10
What does drug clearance (Cl) characterize?
Drug elimination (excretion + metabolism)
What are the units of drug clearance (Cl)?
mL/min or L/hr
What is the comparison made to assess drug clearance?
Drug clearance vs. measured inulin clearance
What does a drug clearance (Cl) value of < 1 indicate?
Reabsorption rate > secretion rate
What does a drug clearance (Cl) value of = 1 indicate?
Filtration only
What does a drug clearance (Cl) value of > 1 indicate?
Secretion rate > reabsorption rate
What is the primary mechanism for the determination of renal clearance?
Measurement of drug excretion through urine
What is the comparison made to determine renal clearance?
Drug clearance vs. measured inulin clearance
How is the volume of urine (VUr) collected between t1 and t2 used to determine renal clearance?
It is used to calculate the slope of drug clearance
What is the approximate renal blood flow rate?
1.2 L/min
What is the approximate glomerular filtration rate in a standard patient?
120 mL/min
Where does active renal secretion mainly occur?
Proximal convoluted tubule
What is the primary site for tubular reabsorption of drugs?
Proximal convoluted tubule
What is the pH range of urine?
4.5 to 8.0+
What determines the rate of passive transport of drugs back into the bloodstream?
Permeability coefficient
Where does endocytosis take place in the kidney?
Proximal convoluted tubule
What influences the passive reabsorption extent of drugs in the kidney?
Equilibrium urine/plasma ratio
What is the primary factor influencing the permeability coefficient for ionizable drugs?
Membranes/lumen partition coefficient
What determines the extent of passive reabsorption of drugs in the kidney?
Lipophilicity and pH of urine
Study Notes
Ureter Kidney: Function and Structure
- The kidney serves as the main excretory organ with endocrine functions including erythropoietin and renin/aldosterone for homeostasis.
- The kidney has two main regions - the cortex and the medulla, and renal blood flow is approximately 1.2 L/min.
- Glomerular filtration rate is around 120 mL/min in a standard patient, and urine represents only about 1% of the filtered volume.
- The renal excretion of drugs involves glomerular filtration, active tubular secretion, and tubular reabsorption.
- The kidney contains about a million nephrons, with different types located in the cortex and medulla.
- Active renal secretion involves carrier-mediated and energy-dependent transport, mainly occurring in the proximal convoluted tubule.
- Tubular reabsorption is the only way to decrease drug excretion rate, involving active and passive processes, and endocytosis.
- Passive tubular reabsorption occurs throughout the tubule, while endocytosis takes place in the proximal tubule.
- The rate of passive transport of drugs back into the bloodstream is influenced by factors such as lipophilicity and pH of urine.
- The pH of urine ranges from 4.5 to 8.0+ and can be affected by factors like nutrients and urinary tract infections.
- The permeability coefficient for ionizable drugs is proportional to the membranes/lumen partition coefficient and depends on pH and counterions.
- Passive reabsorption extent is determined by the equilibrium urine/plasma ratio and is influenced by factors like lipophilicity and pH of urine.
Test your knowledge of biopharmaceutical barriers to drug action with this quiz. Explore topics such as solubility, cell permeability, and the Biopharmaceutical Classification System. Understand the impact of ADME on drug bioavailability and the role of solubility in oral bioavailability.
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