Q: Which equation correctly represents the calculation of osmolarity for a solution containing NaCl?

$$\text{Osmolarity} = 2 \times \text{Molarity of NaCl}$$

Question 1

Which of the following best describes the term 'solubility' in the context of pharmaceutical solutions?

Accepted Answer

The ability of a solute to dissolve in a solvent to form a homogeneous mixture.

Question 2

Why is tonicity important in pharmaceutical solutions intended for injection?

Accepted Answer

It ensures the solution matches the osmotic pressure of plasma, preventing cell damage.

Question 3

A red blood cell placed in a hypertonic solution will:

Accepted Answer

Shrink due to water leaving the cell.

Question 4

Which equation correctly represents the calculation of osmolarity for a solution containing NaCl?

Accepted Answer

$$	ext{Osmolarity} = 2 	imes 	ext{Molarity of NaCl}$$

Question 5

Which method can be used to adjust the tonicity of a pharmaceutical solution?

Accepted Answer

Concentration method, freezing point depression method, and NaCl equivalent method.

Question 6

A 0.9% w/v NaCl solution is considered isotonic with human plasma. What is its approximate osmolarity?

Accepted Answer

$$308 	ext{ mOsmolar}$$

Question 7

If a drug solution has an osmolarity of 125 mOsmoles/L, how much NaCl (in grams per liter) is needed to adjust it to plasma osmolarity (325 mOsmoles/L)? (NaCl molar mass = 58.5 g/mol)

Accepted Answer

$$5.85 	ext{ g/L}$$

Question 8

Which property is considered a 'colligative' property in pharmaceutical solutions?

Accepted Answer

Osmotic pressure

Question 9

What is the freezing point depression of a 1 Osmolar aqueous solution?

Accepted Answer

$$-1.86^\circ 	ext{C}$$

Question 10

Which of the following is NOT a strategy to increase the solubility of poorly soluble drugs?

Accepted Answer

Adding preservatives

Question 11

A pharmaceutical solution contains 5% w/v Drug X (NaCl equivalent = 0.07). How much NaCl (% w/v) is needed to make the solution isotonic (0.9% w/v NaCl)?

Accepted Answer

$$0.55\% 	ext{ w/v}$$

Question 12

Which of the following statements about iso-osmotic and iso-tonic solutions is correct?

Accepted Answer

Iso-tonic solutions refer specifically to biological systems and match the osmotic pressure of plasma.

Question 13

Which component is commonly added to pharmaceutical solutions to enhance stability?

Accepted Answer

Stability enhancers

Question 14

What is the main physiological reason for adjusting the tonicity of injectable solutions?

Accepted Answer

To prevent red blood cells from swelling or shrinking.

Question 15

Which calculation method matches the osmolarity of a solution to the freezing point depression caused by plasma and tears?

Accepted Answer

Freezing point depression method

Question 16

A solution is considered iso-tonic to plasma if:

Accepted Answer

There is no net movement of water across the biological membrane.

Question 17

Which of the following is a real-world consequence of injecting a hypotonic solution?

Accepted Answer

Red blood cells may swell and burst.

Question 18

What is the osmolarity of plasma in humans?

Accepted Answer

$$325 	ext{ mOsmolar}$$

Question 19

Which of the following is NOT a component typically found in pharmaceutical solution formulations?

Accepted Answer

Color enhancers

Question 20

If a drug and a preservative are both present in a solution, how is the total tonicity calculated?

Accepted Answer

By adding the contributions of each ingredient in osmolarity mode.

Pharmaceutical Solutions and Tonicity: Principles and Calculations

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