FPGEE Pharmaceutical Chemistry 3 — Questions and Answers
Question 1: The log P value of a drug compound represents:
- The dissociation constant at physiological pH
- The partition coefficient between octanol and water (Correct answer)
- The rate constant for hydrolysis
- The molar absorptivity in UV spectroscopy
Correct answer: The partition coefficient between octanol and water
Log P (partition coefficient) measures how a drug distributes between n-octanol (lipid) and water, indicating its lipophilicity.
Question 2: Glucuronidation is an example of which type of drug metabolism?
- Phase I oxidation
- Phase I reduction
- Phase II conjugation (Correct answer)
- Phase I hydrolysis
Correct answer: Phase II conjugation
Glucuronidation is a Phase II conjugation reaction catalyzed by UDP-glucuronosyltransferases, adding glucuronic acid to the drug.
Question 3: Which spectroscopic technique is most useful for determining the complete carbon-hydrogen framework of an organic drug molecule?
- UV-Vis spectroscopy
- Infrared spectroscopy
- Nuclear magnetic resonance (NMR) spectroscopy (Correct answer)
- Mass spectrometry
Correct answer: Nuclear magnetic resonance (NMR) spectroscopy
NMR spectroscopy provides detailed information about the carbon-hydrogen framework, connectivity, and stereochemistry of organic molecules.
Question 4: Warfarin exists as two enantiomers. The S-enantiomer is approximately 5 times more potent than the R-enantiomer. This difference is an example of:
- Pharmacokinetic stereoselectivity only
- Pharmacodynamic stereoselectivity (Correct answer)
- Constitutional isomer activity differences
- Tautomeric equilibrium effects
Correct answer: Pharmacodynamic stereoselectivity
When enantiomers differ in pharmacological potency at a receptor, this reflects pharmacodynamic stereoselectivity due to chiral receptor binding sites.
Question 5: Which of the following best describes a bioisostere?
- A salt form of a parent drug
- A group that replaces another with similar size and electronic properties but potentially different pharmacokinetics (Correct answer)
- An inactive metabolite of a drug
- A chelating agent used in formulation
Correct answer: A group that replaces another with similar size and electronic properties but potentially different pharmacokinetics
Bioisosteres are atoms or groups that can replace each other while maintaining similar biological activity through comparable size, shape, and electronic properties.
Question 6: The Maillard reaction in pharmaceutical formulations primarily involves:
- Oxidation of unsaturated fatty acids
- Reaction between reducing sugars and primary amines (Correct answer)
- Hydrolysis of lactam rings
- Photodegradation of aromatic rings
Correct answer: Reaction between reducing sugars and primary amines
The Maillard reaction occurs between reducing sugars (e.g., lactose) and amine-containing drugs, causing browning and potential loss of potency.
Question 7: Which functional group undergoes N-acetylation as a Phase II metabolic pathway?
- Carboxylic acid
- Primary aromatic amine (Correct answer)
- Tertiary amine
- Phenol
Correct answer: Primary aromatic amine
N-acetyltransferases conjugate an acetyl group to primary aromatic amines (and hydrazines/sulfonamides) as a Phase II detoxification pathway.
FPGEE Pharmaceutical Chemistry 3
The log P value of a drug compound represents: