Preparation of drug solutions and grouping of animals MCQs With Answer

Introduction: This set of MCQs focuses on the practical aspects of preparing drug solutions and proper grouping of laboratory animals — topics central to pharmacological and toxicological screening. Designed for M.Pharm students, the questions cover dose calculations, solvent selection, solubility enhancement, isotonicity, sterile handling, routes and maximum injection volumes, and ethical, statistical and logistical considerations in animal grouping (controls, randomization, group size, acclimatization). Each item tests both theoretical understanding and hands-on decision-making required for designing screening experiments and preparing reproducible, safe formulations for in vivo studies. Use these MCQs to reinforce accuracy, safety and regulatory thinking when planning preclinical experiments.

Q1. Calculate the volume to inject: A mouse weighing 25 g is to receive 10 mg/kg of a drug prepared at 2 mg/mL. What volume should be administered?

• 0.125 mL
• 0.025 mL
• 1.25 mL
• 0.5 mL

Correct Answer: 0.125 mL

Q2. Which maximum concentration of DMSO is generally recommended for intraperitoneal (i.p.) administration in mice to minimize solvent toxicity?

• 1% v/v
• 5% v/v
• 10% v/v
• 50% v/v

Correct Answer: 10% v/v

Q3. What approximate osmolarity (mOsm/L) is considered isotonic for mammalian parenteral solutions?

• 150 mOsm/L
• 300 mOsm/L
• 600 mOsm/L
• 900 mOsm/L

Correct Answer: 300 mOsm/L

Q4. Which sterile filtration membrane pore size is routinely used to remove bacteria from a drug solution prior to parenteral administration?

• 0.45 μm
• 0.22 μm
• 0.1 μm
• 1.2 μm

Correct Answer: 0.22 μm

Q5. To prepare a 1:100 dilution from a concentrated stock using serial tenfold dilutions, how many successive 1:10 dilutions are required?

• 1
• 2
• 10
• 100

Correct Answer: 2

Q6. What is the primary purpose of including a positive control group in an in vivo pharmacological screening study?

• To receive vehicle only
• To confirm the assay and demonstrate sensitivity to a known active agent
• To estimate baseline variability
• To increase animal numbers for statistical power

Correct Answer: To confirm the assay and demonstrate sensitivity to a known active agent

Q7. What is a commonly recommended maximum intraperitoneal injection volume for mice expressed per body weight?

• 1 mL/kg
• 5 mL/kg
• 10 mL/kg
• 50 mL/kg

Correct Answer: 10 mL/kg

Q8. Which buffering system is most appropriate for preparing a parenteral drug solution targeted at physiological pH (~7.4)?

• Acetate buffer pH 4.5
• Phosphate buffer pH 7.4
• Citrate buffer pH 3.0
• Glycine buffer pH 9.5

Correct Answer: Phosphate buffer pH 7.4

Q9. How do cyclodextrins typically enhance the aqueous solubility of poorly water-soluble drugs?

• By forming micelles around drug molecules
• By forming inclusion complexes with hydrophobic drug moieties
• By chemically reacting to form new soluble salts
• By increasing solution temperature

Correct Answer: By forming inclusion complexes with hydrophobic drug moieties

Q10. What is the principal rationale behind performing accelerated stability studies (e.g., elevated temperature) on drug formulations?

• To sterilize the product more rapidly
• To predict long-term stability and shelf life under normal storage conditions
• To immediately determine pharmacokinetics
• To increase solubility of the drug

Correct Answer: To predict long-term stability and shelf life under normal storage conditions

Q11. What is the molarity of a 0.9% (w/v) sodium chloride solution (MW NaCl = 58.44 g/mol)?

• 0.0154 M
• 0.154 M
• 1.54 M
• 15.4 M

Correct Answer: 0.154 M

Q12. Why is a vehicle control group included in animal studies when the test compound is dissolved in a solvent or formulation vehicle?

• To increase the sample size only
• To evaluate the pharmacokinetics of the vehicle
• To control for any biological effects caused by the vehicle itself
• To test an unrelated compound

Correct Answer: To control for any biological effects caused by the vehicle itself

Q13. For intravenous bolus injection in mice, what is a commonly accepted maximum injection volume per kg body weight to avoid circulatory overload?

• 1 mL/kg
• 5 mL/kg
• 15 mL/kg
• 50 mL/kg

Correct Answer: 5 mL/kg

Q14. How much 10 mg/mL stock solution is required to prepare 100 mL of 1 mg/mL working solution?

• 1 mL stock + 99 mL diluent
• 5 mL stock + 95 mL diluent
• 10 mL stock + 90 mL diluent
• 50 mL stock + 50 mL diluent

Correct Answer: 10 mL stock + 90 mL diluent

Q15. Which risk is associated with using nonionic surfactants like Tween 80 in injectable formulations if used at high concentrations?

• Complete inactivation of the drug
• Increased hemolysis and potential hypersensitivity reactions
• Substantially lower solubility of hydrophobic drugs
• Guaranteed sterility

Correct Answer: Increased hemolysis and potential hypersensitivity reactions

Q16. Which additive is typically used to adjust isotonicity of an aqueous parenteral solution to physiological levels?

• Sodium chloride
• Sodium hydroxide
• Hydrochloric acid
• Ethylene glycol

Correct Answer: Sodium chloride

Q17. What is the main benefit of randomizing animals into experimental groups in preclinical studies?

• To ensure equal drug exposure across animals
• To reduce selection bias and confounding variables
• To reduce the number of animals required for the study
• To decrease the need for controls

Correct Answer: To reduce selection bias and confounding variables

Q18. A rat weighing 200 g is to receive 50 mg/kg of drug X. If the formulation concentration is 25 mg/mL, what is the required injection volume?

• 0.08 mL
• 0.2 mL
• 0.4 mL
• 2.0 mL

Correct Answer: 0.4 mL

Q19. Which preparation method is most appropriate for sterilizing a heat-labile aqueous drug solution intended for parenteral use?

• Autoclaving at 121°C
• Dry heat sterilization
• Sterile filtration through a 0.22 μm membrane
• UV irradiation only

Correct Answer: Sterile filtration through a 0.22 μm membrane

Q20. How many grams of a drug (MW = 300 g/mol) are required to prepare 50 mL of a 100 mM stock solution?

• 0.15 g
• 1.5 g
• 15 g
• 150 g

Correct Answer: 1.5 g

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