DHA Pharmacist Sterile & Non-Sterile Preparations 2 — Questions and Answers
Question 1: What is the standard technique for performing aseptic transfer of a drug from a vial into an IV bag?
- Swab the vial top with 70% isopropyl alcohol, use a sterile needle and syringe, and transfer inside the laminar flow hood (Correct answer)
- Use bare hands inside the cabinet without alcohol swabbing
- Prepare outside the laminar flow hood if quickly done
- Transfer through the IV bag's outer plastic wrapper
Correct answer: Swab the vial top with 70% isopropyl alcohol, use a sterile needle and syringe, and transfer inside the laminar flow hood
Aseptic technique requires alcohol disinfection of the vial septum and the use of sterile equipment inside an ISO 5 environment to prevent microbial contamination of the final product.
Question 2: Which emulsifying agent is commonly used in oral non-sterile pharmaceutical preparations to create stable oil-in-water emulsions?
- Polysorbate 80 (Tween 80) (Correct answer)
- Talc
- Magnesium stearate
- Microcrystalline cellulose
Correct answer: Polysorbate 80 (Tween 80)
Polysorbate 80 is a non-ionic surfactant widely used as an emulsifying agent in oral and topical preparations to reduce interfacial tension and stabilise oil-in-water emulsions.
Question 3: What is the importance of tonicity in ophthalmic preparations?
- Ophthalmic preparations must be isotonic (~0.9% NaCl equivalent) to avoid eye irritation, tearing, and corneal damage (Correct answer)
- Hypertonic solutions are preferred for maximum drug penetration
- Tonicity is irrelevant for eye drops
- Only pH matters for ophthalmic preparations
Correct answer: Ophthalmic preparations must be isotonic (~0.9% NaCl equivalent) to avoid eye irritation, tearing, and corneal damage
Isotonic ophthalmic preparations match the osmolality of tear fluid (~285–310 mOsm/kg), preventing cell shrinkage or swelling and avoiding irritation or damage to the delicate ocular surface.
Question 4: Which test is used to check the uniformity of drug content across tablets in a batch?
- Content uniformity test (USP <905>) (Correct answer)
- Dissolution test
- Disintegration test
- Hardness test
Correct answer: Content uniformity test (USP <905>)
The content uniformity test (USP <905>) measures the drug content in individual dosage units to ensure each tablet delivers a consistent and accurate drug amount within specified limits.
Question 5: What is the primary purpose of using a viscosity-enhancing agent in ophthalmic preparations?
- To increase contact time of the drug with the eye surface, improving bioavailability (Correct answer)
- To reduce the drug concentration
- To make the preparation more acidic
- To prevent all preservatives from working
Correct answer: To increase contact time of the drug with the eye surface, improving bioavailability
Viscosity enhancers such as hydroxypropyl methylcellulose (HPMC) slow the drainage of eye drops from the ocular surface, prolonging drug contact and improving therapeutic bioavailability.
Question 6: In the preparation of total parenteral nutrition (TPN), which electrolyte must be added last and slowly to avoid precipitation?
- Phosphate (must be added before calcium to avoid calcium phosphate precipitation) (Correct answer)
- Potassium chloride
- Magnesium sulphate
- Sodium chloride
Correct answer: Phosphate (must be added before calcium to avoid calcium phosphate precipitation)
Calcium and phosphate in TPN can precipitate as calcium phosphate; phosphate must be added and diluted well before calcium is introduced to prevent this dangerous and potentially fatal precipitate.
DHA Pharmacist Sterile & Non-Sterile Preparations 2
What is the standard technique for performing aseptic transfer of a drug from a vial into an IV bag?