FPGEE Pharmaceutical Chemistry 5

Question 1

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

Accepted Answer

Mass spectrometry

Answer

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

Question 2

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

Accepted Answer

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

Answer

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

Question 3

Polymorphism in pharmaceutical solids refers to:

Accepted Answer

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

Answer

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

Question 4

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

Accepted Answer

Oxidation of the sulfur atom forming sulfoxides

Answer

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

Question 5

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

Accepted Answer

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

Answer

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.

FPGEE Exam Practice Test

FPGEE Exam Practice Test

FPGEE Pharmaceutical Chemistry 5