Pharmaceutical Chemistry and Analysis Flashcards

Which metabolic reaction is considered a Phase I biotransformation reaction?

Answer: Oxidation via CYP450

CYP450-mediated oxidation is a Phase I reaction that introduces or unmasks a functional group on the drug molecule.

In UV-Vis spectroscopy, Beer-Lambert's law states that absorbance is directly proportional to:

Answer: Concentration and path length

Beer-Lambert's law: A = εcl, where absorbance is proportional to molar absorptivity, concentration, and path length.

Which functional group undergoes hydrolysis most readily under aqueous conditions, making it a common instability site in drugs?

Answer: Ester

Ester bonds are susceptible to hydrolysis by water (acid- or base-catalyzed), making esters a frequent degradation site in pharmaceuticals.

What does a positive ninhydrin test indicate in the analysis of pharmaceutical compounds?

Answer: Presence of primary or secondary amines (amino acids)

Ninhydrin reacts with primary and secondary amines to produce a purple color (Ruhemann's purple), used to detect amino acids.

Which parameter in chromatography is defined as the ratio of the time a solute spends in the stationary phase to the time it spends in the mobile phase?

Answer: Retention factor (k)

The retention factor k = (tR - tM) / tM, representing the ratio of time spent in stationary versus mobile phase.

Oxidative stability of a drug formulation can be improved primarily by:

Answer: Adding antioxidants such as BHA or ascorbic acid

Antioxidants like BHA, BHT, and ascorbic acid scavenge free radicals or reduce oxidizing species to protect drug molecules.

Which reaction mechanism involves simultaneous bond breaking and bond formation in a single concerted step, commonly seen in SN2 reactions?

Answer: Backside attack with inversion of configuration

SN2 reactions proceed via backside nucleophilic attack with simultaneous leaving group departure, resulting in Walden inversion.