MPharm Master of Pharmacy Master of Pharmacy: Pharmaceutical Formulations and Dosage Forms 5 — Questions and Answers
Question 1: Which sterilization method is preferred for heat-sensitive parenteral formulations and is validated by sterility assurance level (SAL) of 10⁻⁶?
- Dry heat sterilization at 160 °C
- Autoclaving at 121 °C for 15 minutes
- Aseptic filtration through 0.22 µm membrane (Correct answer)
- Gamma irradiation
Correct answer: Aseptic filtration through 0.22 µm membrane
Aseptic filtration through a validated 0.22 µm filter removes microorganisms from heat-sensitive solutions, achieving SAL 10⁻⁶ when combined with aseptic filling.
Question 2: In nanotechnology-based drug delivery, which system consists of a drug-loaded solid lipid core stabilized by surfactants?
- Liposome
- Solid lipid nanoparticle (SLN) (Correct answer)
- Polymeric micelle
- Dendrimer
Correct answer: Solid lipid nanoparticle (SLN)
SLNs comprise a solid lipid matrix (solid at body temperature) that entraps drug and is stabilized by surfactant shell, offering controlled release and physical stability.
Question 3: Accelerated stability studies (40 °C/75% RH for 6 months) are used under ICH Q1A guidelines primarily to:
- Determine final shelf life with certainty
- Predict long-term stability and identify potential degradation products in less time (Correct answer)
- Establish microbiological safety of the product
- Test mechanical strength of packaging
Correct answer: Predict long-term stability and identify potential degradation products in less time
Accelerated conditions speed degradation kinetics, allowing early prediction of stability profile, though real-time data are required for official shelf-life claims.
Question 4: Which rheological property describes a material that flows when stress exceeds a yield value but behaves as a solid below it — important for semisolid formulations?
- Newtonian behavior
- Pseudoplastic (shear-thinning) behavior
- Plastic (Bingham) behavior (Correct answer)
- Dilatant (shear-thickening) behavior
Correct answer: Plastic (Bingham) behavior
Plastic flow (Bingham body) requires a minimum yield stress before flow begins, characteristic of structured semisolids like certain ointments and gels.
Question 5: Poorly water-soluble drugs formulated as nanosuspensions exhibit enhanced dissolution primarily due to:
- Increased drug crystallinity
- Increased surface area-to-volume ratio as particle size decreases to nanometer range (Correct answer)
- Conversion to amorphous form by milling
- Increased drug hydrophilicity
Correct answer: Increased surface area-to-volume ratio as particle size decreases to nanometer range
Reducing particle size to the nanometer range dramatically increases surface area, accelerating dissolution rate according to the Noyes-Whitney equation.
Question 6: In quality by design (QbD) for pharmaceutical development, the term 'design space' refers to:
- The physical space allocated to formulation labs
- The multidimensional combination of input variables within which quality is assured (Correct answer)
- The number of excipients permissible in a formulation
- The ICH guideline governing stability testing
Correct answer: The multidimensional combination of input variables within which quality is assured
The design space defines the ranges of process parameters and material attributes within which the product consistently meets its quality target product profile (QTPP).
Question 7: Mucoadhesive drug delivery systems use polymers such as carbopol and chitosan primarily to:
- Mask the bitter taste of the drug
- Increase residence time at mucosal surfaces by adhering to the mucus layer (Correct answer)
- Accelerate tablet disintegration
- Serve as lubricants during compression
Correct answer: Increase residence time at mucosal surfaces by adhering to the mucus layer
Mucoadhesive polymers form non-covalent bonds (hydrogen bonds, electrostatic interactions) with mucin glycoproteins, prolonging contact time and improving drug absorption.
MPharm Master of Pharmacy Master of Pharmacy: Pharmaceutical Formulations and Dosage Forms 5
Which sterilization method is preferred for heat-sensitive parenteral formulations and is validated by sterility assurance level (SAL) of 10⁻⁶?