Pharmaceutical Chemistry Flashcards

The log P value of a drug compound represents:

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.

Glucuronidation is an example of which type of drug metabolism?

Answer: Phase II conjugation

Glucuronidation is a Phase II conjugation reaction catalyzed by UDP-glucuronosyltransferases, adding glucuronic acid to the drug.

Which spectroscopic technique is most useful for determining the complete carbon-hydrogen framework of an organic drug molecule?

Answer: Nuclear magnetic resonance (NMR) spectroscopy

NMR spectroscopy provides detailed information about the carbon-hydrogen framework, connectivity, and stereochemistry of organic molecules.

Warfarin exists as two enantiomers. The S-enantiomer is approximately 5 times more potent than the R-enantiomer. This difference is an example of:

Answer: Pharmacodynamic stereoselectivity

When enantiomers differ in pharmacological potency at a receptor, this reflects pharmacodynamic stereoselectivity due to chiral receptor binding sites.

Which of the following best describes a bioisostere?

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.

The Maillard reaction in pharmaceutical formulations primarily involves:

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.

Which functional group undergoes N-acetylation as a Phase II metabolic pathway?

Answer: Primary aromatic amine

N-acetyltransferases conjugate an acetyl group to primary aromatic amines (and hydrazines/sulfonamides) as a Phase II detoxification pathway.

Which functional group is responsible for the acidic properties of aspirin?

Answer: Carboxylic acid group

The carboxylic acid (-COOH) group in aspirin (acetylsalicylic acid) donates a proton, conferring its acidic properties.

The term 'prodrug' refers to a compound that:

Answer: Requires metabolic conversion to exert its effect

A prodrug is pharmacologically inactive until metabolized in the body to its active form.

Which bond type is hydrolyzed during the metabolism of ester prodrugs?

Answer: Ester bond

Esterases in plasma and tissues cleave the ester bond, releasing the active drug from an ester prodrug.

The Henderson-Hasselbalch equation is used primarily to predict:

Answer: The degree of ionization of a drug at a given pH

The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of ionized to unionized drug forms.

Which class of reaction is CYP3A4-mediated hydroxylation classified as?

Answer: Phase I oxidation

CYP3A4 is a cytochrome P450 enzyme that catalyzes Phase I oxidation reactions, including aromatic and aliphatic hydroxylation.

Isomerism involving non-superimposable mirror images of a molecule is called:

Answer: Enantiomerism

Enantiomers are non-superimposable mirror images of each other, differing in the spatial arrangement around a chiral center.

Which property of a drug is most directly improved by salt formation?

Answer: Aqueous solubility

Salt formation converts a poorly water-soluble drug into an ionized form that typically has significantly greater aqueous solubility.

Which analytical technique provides definitive molecular weight determination for a pharmaceutical compound?

Answer: Mass spectrometry

Mass spectrometry measures the mass-to-charge ratio (m/z) of ions, providing precise molecular weight and fragmentation pattern information.

The chelation of metal ions by tetracycline antibiotics is clinically significant because:

Answer: It reduces absorption when taken with calcium, magnesium, or iron-containing products

Tetracyclines form insoluble chelate complexes with divalent and trivalent metal ions (Ca2+, Mg2+, Fe3+), significantly reducing oral absorption.

Polymorphism in pharmaceutical solids refers to:

Answer: The ability of a compound to exist in more than one crystalline form

Polymorphs are different crystalline arrangements of the same molecule, which can differ in melting point, solubility, dissolution rate, and bioavailability.

Which reaction is responsible for the yellow discoloration seen when phenothiazine drugs degrade?

Answer: Oxidation of the sulfur atom forming sulfoxides

Phenothiazines are oxidized at the sulfur atom to form sulfoxide metabolites and degradation products, producing characteristic colored compounds.

The Hammett sigma (σ) constant in quantitative structure-activity relationship (QSAR) studies describes:

Answer: Electronic effects (electron-donating or electron-withdrawing) of aromatic substituents

The Hammett σ constant quantifies the electronic effect of a substituent on an aromatic ring, with positive values indicating electron withdrawal and negative values indicating electron donation.

Which type of covalent bond formation between a drug and its target is associated with irreversible inhibition?

Answer: Alkylation of a nucleophilic residue

Covalent alkylation of nucleophilic residues (e.g., cysteine, serine) by reactive drug electrophiles creates a permanent drug-protein bond, irreversibly inhibiting the target.