Additives in parenteral formulations are essential excipients that ensure safety, stability and efficacy of injectable medicines. For B. Pharm students, understanding the roles of tonicity agents, buffers, preservatives, antioxidants, chelating agents, surfactants, solubilizers and co-solvents is critical for formulation design and regulatory compliance. Key considerations include compatibility with active pharmaceutical ingredients (APIs), effects on pH and osmolarity, prevention of oxidation and aggregation, and interactions with packaging materials. Knowledge of sterilization methods, particulate control, and preservative selection for single- versus multi-dose products is also important. This set emphasizes practical examples, typical concentrations and stability implications. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which additive is primarily used to adjust osmolarity and achieve isotonicity in parenteral formulations?
- Sodium chloride
- Sodium metabisulfite
- Polysorbate 80
- EDTA
Correct Answer: Sodium chloride
Q2. Which class of additives is used to prevent oxidative degradation of susceptible APIs?
- Antioxidants
- Preservatives
- Buffers
- Surfactants
Correct Answer: Antioxidants
Q3. Which preservative is commonly avoided in neonates due to toxicity concerns?
- Benzyl alcohol
- Phenol
- m-Cresol
- Chlorobutanol
Correct Answer: Benzyl alcohol
Q4. EDTA in parenteral formulations acts primarily as a:
- Chelating agent
- Tonicity agent
- Solubilizer
- Preservative
Correct Answer: Chelating agent
Q5. Which surfactant is frequently used to prevent protein adsorption and aggregation in injectables?
- Polysorbate 80
- Sodium chloride
- Sodium metabisulfite
- Propylene glycol
Correct Answer: Polysorbate 80
Q6. Which buffer system is commonly used to maintain pH around physiological pH in parenterals?
- Phosphate buffer
- Acetate buffer
- Sulfate buffer
- Borate buffer
Correct Answer: Phosphate buffer
Q7. Which additive improves solubility of poorly water-soluble drugs by inclusion complex formation?
- Cyclodextrin
- EDTA
- Phenol
- Sodium chloride
Correct Answer: Cyclodextrin
Q8. Terminal sterilization by moist heat can degrade certain additives; which additive class is most at risk?
- Protein stabilizers and some antioxidants
- Inorganic salts like NaCl
- Cyclodextrins
- Silicone oil
Correct Answer: Protein stabilizers and some antioxidants
Q9. Which co-solvent is commonly used to increase solubility but can cause hemolysis at high concentrations?
- Propylene glycol
- Sucrose
- Polysorbate 20
- EDTA
Correct Answer: Propylene glycol
Q10. What is the main function of preservatives in multi-dose parenteral formulations?
- Prevent microbial growth after vial entry
- Adjust pH
- Enhance solubility of API
- Control osmolarity
Correct Answer: Prevent microbial growth after vial entry
Q11. Which preservative is frequently used in insulin formulations?
- m-Cresol
- EDTA
- Ascorbic acid
- Sodium chloride
Correct Answer: m-Cresol
Q12. Phenol acts in parenterals primarily as a:
- Preservative with bactericidal activity
- Buffer component
- Chelating agent
- Solubilizer
Correct Answer: Preservative with bactericidal activity
Q13. Which test monitors particulate contamination in parenteral products?
- Particulate matter test (light obscuration)
- Sterility test
- Pyrogen test
- Assay by HPLC
Correct Answer: Particulate matter test (light obscuration)
Q14. Which antioxidant works by donating hydrogen atoms to free radicals and is sometimes used in parenterals?
- Ascorbic acid (vitamin C)
- Polysorbate 80
- Benzalkonium chloride
- Sodium chloride
Correct Answer: Ascorbic acid (vitamin C)
Q15. Sodium metabisulfite in parenteral formulations is used as an:
- Antioxidant/reducing agent
- Preservative
- Buffering agent
- Tonicity agent
Correct Answer: Antioxidant/reducing agent
Q16. Which additive can leach from rubber stoppers and affect drug stability?
- Butylated compounds or plasticizers
- Sodium chloride
- Cyclodextrin
- EDTA
Correct Answer: Butylated compounds or plasticizers
Q17. For sterile filtration of solutions containing proteins, which filter pore size is commonly used to remove bacteria while minimizing protein loss?
- 0.22 µm
- 0.45 µm
- 1.2 µm
- 5.0 µm
Correct Answer: 0.22 µm
Q18. Which additive class can stabilize proteins by preferentially excluding solvent and increasing native conformation?
- Polyols (e.g., sucrose, trehalose)
- Preservatives like phenol
- Antioxidants like BHT
- Chelating agents like EDTA
Correct Answer: Polyols (e.g., sucrose, trehalose)
Q19. Which preservative is a quaternary ammonium compound sometimes used in ophthalmic but rarely in parenterals due to toxicity?
- Benzalkonium chloride
- m-Cresol
- Chlorobutanol
- Phenol
Correct Answer: Benzalkonium chloride
Q20. Which factor often accelerates oxidation of APIs in parenteral formulations?
- Presence of transition metal ions
- Use of isotonic sodium chloride
- Low buffer capacity
- High surfactant concentration
Correct Answer: Presence of transition metal ions
Q21. Polysorbates can degrade and generate which harmful species affecting proteins?
- Peroxides and free radicals
- EDTA complexes
- Inorganic salts
- Isotonic sugars
Correct Answer: Peroxides and free radicals
Q22. Chlorobutanol is used in parenterals primarily as a:
- Preservative and mild local anesthetic
- Buffering agent
- Chelator
- Solubilizer
Correct Answer: Preservative and mild local anesthetic
Q23. Which excipient can protect against metal-catalyzed oxidation by complexing trace metals?
- EDTA
- Polysorbate 80
- Cyclodextrin
- Propylene glycol
Correct Answer: EDTA
Q24. For parenteral pH adjustment, which acid/base pair is commonly used?
- Hydrochloric acid and sodium hydroxide
- Acetic acid and ammonium hydroxide
- Citric acid and sodium citrate
- Boric acid and sodium borate
Correct Answer: Hydrochloric acid and sodium hydroxide
Q25. Which additive is used to reduce surface tension and help solubilize lipophilic drugs?
- Surfactants (e.g., polysorbates)
- Buffers
- Preservatives
- Chelating agents
Correct Answer: Surfactants (e.g., polysorbates)
Q26. Which concern is critical when selecting a preservative for a protein therapeutic?
- Preservative-induced protein aggregation or denaturation
- Effect on osmolarity only
- Ability to chelate metals
- Enhancement of viscosity
Correct Answer: Preservative-induced protein aggregation or denaturation
Q27. Which additive class is used to buffer solutions and resist pH changes upon dilution or addition?
- Buffers
- Antioxidants
- Surfactants
- Co-solvents
Correct Answer: Buffers
Q28. Which container–closure interaction can lead to loss of drug potency via adsorption?
- Adsorption of drug to glass or rubber surfaces
- Increase in isotonicity
- Change in buffer capacity
- Formation of EDTA complexes
Correct Answer: Adsorption of drug to glass or rubber surfaces
Q29. Which regulatory reference provides standards for additives and quality tests in parenteral formulations?
- USP–NF (United States Pharmacopeia–National Formulary)
- ICH Q9 only
- ISO 9001 exclusively
- CFR Title 21 Part 11 exclusively
Correct Answer: USP–NF (United States Pharmacopeia–National Formulary)
Q30. Which method is preferred to sterilize heat-sensitive parenteral solutions without terminal sterilization?
- Aseptic processing with sterile filtration (0.22 µm)
- Autoclaving at 121°C for 15 minutes
- Dry heat sterilization at 160°C
- Gamma irradiation of aqueous solution
Correct Answer: Aseptic processing with sterile filtration (0.22 µm)
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.
Mail- Sachin@pharmacyfreak.com