Pharmaceutical Sciences & Calculations Flashcards

What is the osmolarity of normal saline (0.9% NaCl) approximately?

Answer: 308 mOsm/L

0.9% NaCl dissociates into Na+ and Cl−, each at 154 mmol/L, giving approximately 308 mOsm/L, which is isotonic with blood.

Which type of interaction occurs when two drugs compete for the same plasma protein binding site?

Answer: Pharmacokinetic displacement interaction

Protein binding displacement is a pharmacokinetic interaction where one drug displaces another from albumin or other proteins, increasing free drug concentration.

A suppository base that melts at body temperature is described as:

Answer: Theobroma oil base

Theobroma oil (cocoa butter) melts at approximately 34–35°C, close to body temperature, making it suitable for rectal suppositories.

What does 'bioavailability' refer to?

Answer: The fraction of administered drug that reaches systemic circulation

Bioavailability (F) is the proportion of an administered dose that reaches the systemic circulation unchanged. IV administration gives 100% bioavailability.

Which polymorphic form of a drug is generally more soluble?

Answer: Amorphous form

Amorphous solids lack a regular crystal lattice, making them more soluble and often more bioavailable than crystalline forms of the same drug.

In a first-order elimination process, when plasma concentration doubles, the elimination rate:

Answer: Doubles

In first-order kinetics, the rate of elimination is proportional to the drug concentration. If concentration doubles, so does the elimination rate.