KAPS Pharmaceutical Chemistry and Analysis 4

Question 1

A drug with a pKa of 4.5 is administered orally. In the stomach (pH 1.5), the drug exists predominantly as:

Accepted Answer

Ionized (acid form)

Answer

For a weak acid with pKa 4.5 at pH 1.5, the pH < pKa, so the drug is predominantly in the ionized (protonated acid) form — actually unionized for a weak acid; at pH 1.5 (below pKa 4.5), the acidic drug is predominantly unionized (HA form).

Question 2

Which analytical technique provides both molecular weight and structural fragmentation information simultaneously?

Accepted Answer

Mass spectrometry

Answer

Mass spectrometry ionizes molecules and measures mass-to-charge ratios of the parent ion and fragment ions, giving MW and structural data.

Question 3

The Maillard reaction in pharmaceutical formulations occurs between:

Accepted Answer

Primary amines and reducing sugars

Answer

The Maillard reaction is a non-enzymatic browning reaction between primary amines (e.g., drug amine groups) and reducing sugars used as excipients.

Question 4

In titrimetry, what is the primary purpose of a primary standard?

Accepted Answer

To standardize the concentration of the titrant solution accurately

Answer

A primary standard is a highly pure, stable compound used to accurately determine (standardize) the exact concentration of a titrant.

Question 5

Which phenomenon describes the ability of a drug molecule to exist in multiple crystalline forms with different physicochemical properties?

Accepted Answer

Polymorphism

Answer

Polymorphism refers to the existence of a drug in two or more distinct crystalline forms with different packing arrangements, affecting solubility and stability.

(KAPS) Knowledge Assessment of Pharmaceutical Sciences Practice Test

(KAPS) Knowledge Assessment of Pharmaceutical Sciences Practice Test

KAPS Pharmaceutical Chemistry and Analysis 4