Introduction: Vehicles for parenteral formulations are sterile, pyrogen-free excipients that carry active drugs for intravenous, intramuscular, or subcutaneous administration. B.Pharm students must understand aqueous vehicles (Water for Injection, normal saline, dextrose), non‑aqueous/oily vehicles (sesame, soybean oil), co‑solvents (PEG, propylene glycol), surfactants, buffers, tonicity agents, preservatives and antioxidants. Key considerations include sterility, isotonicity, solubility enhancement, compatibility, stability and safety for specific routes (e.g., intrathecal, neonatal). Mastery of vehicle selection and formulation principles is essential for designing safe, effective injectables. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary role of a vehicle in parenteral formulations?
- To provide a sterile, isotonic, non‑reactive medium for drug delivery
- To act as the active pharmaceutical ingredient
- To increase tablet compressibility
- To prevent oral absorption of the drug
Correct Answer: To provide a sterile, isotonic, non‑reactive medium for drug delivery
Q2. What does WFI mean in the context of parenteral vehicles?
- Water for Injection (WFI)
- Weighted Formulation Ingredient
- Water for Infusion
- Weak Friction Inhibitor
Correct Answer: Water for Injection (WFI)
Q3. Which method is commonly used to manufacture Water for Injection to ensure pyrogen removal?
- Distillation or reverse osmosis with appropriate microbial control
- Simple tap filtration only
- Autoclaving of raw seawater
- Addition of preservatives to tap water
Correct Answer: Distillation or reverse osmosis with appropriate microbial control
Q4. Which of the following is a commonly used isotonic aqueous vehicle for parenteral use?
- 0.9% w/v sodium chloride (Normal saline)
- 10% sodium chloride
- Distilled water with no salt
- 50% ethanol solution
Correct Answer: 0.9% w/v sodium chloride (Normal saline)
Q5. Which oily vehicle is traditionally used for depot intramuscular injections to prolong drug release?
- Sesame oil
- Glycerin
- Water for Injection
- 0.9% sodium chloride
Correct Answer: Sesame oil
Q6. Which vehicle should be avoided for neonatal injections due to toxicity concerns?
- Bacteriostatic water containing benzyl alcohol
- Sterile Water for Injection (single use)
- 0.9% sodium chloride
- Water for Injection prepared by distillation
Correct Answer: Bacteriostatic water containing benzyl alcohol
Q7. Which co‑solvent is commonly employed to solubilize poorly water‑soluble drugs for parenteral administration?
- Polyethylene glycol (PEG)
- Sodium chloride 0.9%
- Distilled water without sterilization
- Calcium carbonate
Correct Answer: Polyethylene glycol (PEG)
Q8. Surfactants used in parenteral formulations (e.g., polysorbate 80) primarily serve to:
- Stabilize emulsions and solubilize lipophilic drugs
- Increase microbial growth
- Act as primary active pharmaceutical ingredients
- Raise formulation pH to 12
Correct Answer: Stabilize emulsions and solubilize lipophilic drugs
Q9. Which emulsion type is suitable for intravenous lipid nutrition and many parenteral lipid products?
- Oil-in-water (O/W) emulsion
- Water-in-oil (W/O) emulsion
- Microcrystalline suspension
- Solid dispersion
Correct Answer: Oil-in-water (O/W) emulsion
Q10. Which parameter is most critical to match when preparing parenteral solutions to avoid hemolysis or irritation?
- Isotonicity (osmolarity/osmolality)
- Color of the solution
- Molecular weight of the solvent
- Melting point of the solvent
Correct Answer: Isotonicity (osmolarity/osmolality)
Q11. Which preservative is often present in bacteriostatic water for multi‑dose parenteral use?
- Benzyl alcohol
- Ascorbic acid
- Hydrochloric acid
- Sodium chloride
Correct Answer: Benzyl alcohol
Q12. Which analytical test is commonly used to detect bacterial endotoxins (pyrogens) in parenteral vehicles?
- Limulus amebocyte lysate (LAL) test
- Biuret protein test
- Ninhydrin test
- pH meter reading only
Correct Answer: Limulus amebocyte lysate (LAL) test
Q13. Which antioxidant is commonly used to protect parenteral formulations from oxidation?
- Sodium metabisulfite
- Sodium chloride
- Benzyl alcohol
- Magnesium stearate
Correct Answer: Sodium metabisulfite
Q14. What is the primary function of tonicity-adjusting agents in parenteral vehicles?
- To match osmotic pressure to body fluids and prevent cell damage
- To increase the color intensity of the solution
- To act as the main surfactant
- To sterilize the formulation
Correct Answer: To match osmotic pressure to body fluids and prevent cell damage
Q15. Which chelating agent is used in some parenteral formulations to bind metal ions and enhance stability?
- Disodium EDTA
- Sodium chloride
- Calcium hydroxide
- Polyvinylpyrrolidone (PVP)
Correct Answer: Disodium EDTA
Q16. Which phospholipid is a major constituent of liposomal parenteral vehicles?
- Phosphatidylcholine
- Sodium lauryl sulfate
- Polysorbate 80
- Ethyl cellulose
Correct Answer: Phosphatidylcholine
Q17. For terminal sterilization of heat‑sensitive parenteral drugs, which aseptic process is typically used?
- Sterile filtration through 0.22 µm membrane followed by aseptic filling
- Autoclaving at 121°C for 30 minutes after filling
- Dry heat sterilization of the final vial at 200°C
- Exposure to tap water for dilution
Correct Answer: Sterile filtration through 0.22 µm membrane followed by aseptic filling
Q18. Which statement describes the Hydrophilic–Lipophilic Balance (HLB) concept used for selecting surfactants in parenteral emulsions?
- HLB indicates the balance between hydrophilic and lipophilic character to choose appropriate emulsifiers
- HLB measures the microbial contamination level
- HLB is a pH scale for aqueous vehicles
- HLB specifies the particle size in suspensions
Correct Answer: HLB indicates the balance between hydrophilic and lipophilic character to choose appropriate emulsifiers
Q19. Which buffer system is commonly used to maintain pH in parenteral formulations?
- Phosphate buffer system
- Acetone buffer
- Sugar alcohol buffer
- Hydrochloric salt buffer (non‑standard term)
Correct Answer: Phosphate buffer system
Q20. Which of the following is a parenteral lipid vehicle used in injectable lipid emulsions for nutrition?
- Soybean oil stabilized with egg phospholipids
- Polyethylene glycol 400 only
- Distilled water with added sugar
- Isopropyl alcohol
Correct Answer: Soybean oil stabilized with egg phospholipids
Q21. Which statement about preservatives in parenteral vehicles is correct?
- Preservatives are generally avoided in intrathecal and neonatal products
- All parenteral products must contain preservatives
- Preservatives increase the sterility assurance to 100%
- Preservatives make solutions hypertonic by default
Correct Answer: Preservatives are generally avoided in intrathecal and neonatal products
Q22. Which medium‑chain triglyceride brand or type is commonly used as a non‑reactive oily vehicle?
- Miglyol (medium‑chain triglycerides)
- Sodium lauryl sulfate
- Polyvinyl alcohol
- Hydrochloric acid solution
Correct Answer: Miglyol (medium‑chain triglycerides)
Q23. Why are parenteral emulsions required to have controlled droplet size distribution?
- To prevent embolism and ensure physical stability
- To improve taste for oral administration
- To increase tablet hardness
- To promote microbial growth
Correct Answer: To prevent embolism and ensure physical stability
Q24. Which solvent is UNSUITABLE as a parenteral vehicle due to toxicity when used systemically?
- Absolute ethanol at high concentrations
- Sterile Water for Injection (single use)
- 0.9% sodium chloride
- Phosphate buffered saline
Correct Answer: Absolute ethanol at high concentrations
Q25. Which of the following is an effect of incorrect tonicity in parenteral vehicles?
- Local tissue irritation, pain, or hemolysis
- Improved drug potency always
- Guaranteed extended shelf life
- Automatic sterilization
Correct Answer: Local tissue irritation, pain, or hemolysis
Q26. Which additive is commonly used to chelate trace metals and improve parenteral formulation stability?
- EDTA (ethylenediaminetetraacetic acid)
- Glycerol
- Magnesium stearate
- Sodium chloride
Correct Answer: EDTA (ethylenediaminetetraacetic acid)
Q27. Which choice is the best approach to solubilize a lipophilic drug for parenteral injection when aqueous solubility is very low?
- Use co‑solvents (PEG, propylene glycol) or suitable surfactants to form a safe injectable solution or emulsion
- Dilute the drug in tap water without sterilization
- Mix the drug with table salt to increase solubility
- Freeze the drug until it dissolves
Correct Answer: Use co‑solvents (PEG, propylene glycol) or suitable surfactants to form a safe injectable solution or emulsion
Q28. What is a key safety requirement for parenteral vehicles regarding microorganisms?
- They must be sterile and free of pyrogens
- They must contain live cultures to stimulate immunity
- They should always include a nutrient medium
- They must be opaque to light
Correct Answer: They must be sterile and free of pyrogens
Q29. Which statement about liposomal vehicles for parenteral drug delivery is TRUE?
- Liposomes encapsulate drugs in phospholipid bilayers to modify pharmacokinetics and reduce toxicity
- Liposomes are identical to simple oil droplets with no bilayer
- Liposomes are always contaminated with endotoxins
- Liposomes cannot be sterilized or used parenterally
Correct Answer: Liposomes encapsulate drugs in phospholipid bilayers to modify pharmacokinetics and reduce toxicity
Q30. What is the standard autoclave condition commonly used for terminal sterilization of heat‑stable parenteral containers and solutions?
- 121°C for 15 minutes at approximately 15 psi
- 60°C for 5 minutes at atmospheric pressure
- 200°C for 1 minute
- Storage at room temperature for 24 hours
Correct Answer: 121°C for 15 minutes at approximately 15 psi
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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