SMEDDS preparation and stability MCQs With Answer

SMEDDS Preparation and Stability MCQs With Answer

Self‑microemulsifying drug delivery systems (SMEDDS) are powerful lipid-based carriers that enhance solubility and bioavailability of poorly water‑soluble drugs, a core focus in Modern Pharmaceutics (MPH 103T). This quiz helps M. Pharm students master formulation strategy, component selection, optimization tools like pseudoternary phase diagrams, and critical stability assessments. You will revisit the roles of oils, surfactants, and co‑solvents; understand self‑emulsification mechanisms; and evaluate robustness to dilution, droplet size, cloud point, and digestion effects. Questions also cover solidification approaches, capsule compatibility, ICH stability protocols, and in vitro lipolysis. Use this set to test your depth of understanding and to connect theory with formulation practice for successful SMEDDS development and lifecycle stability.

Q1. In SMEDDS, self-emulsification upon aqueous dilution primarily occurs because of

• High system viscosity that traps aqueous phase
• Reduction of interfacial tension and favorable entropy of dispersion
• Electrostatic repulsion from cationic surfactants only
• Formation of lamellar liquid crystals exclusively

Correct Answer: Reduction of interfacial tension and favorable entropy of dispersion

Q2. A typical droplet size range expected after dilution of a well-optimized SMEDDS is

• 10–100 nm with high clarity (microemulsion region)
• 300–1000 nm with visible turbidity
• 1–10 µm with creaming tendency
• 0.5–1.0 mm with phase separation

Correct Answer: 10–100 nm with high clarity (microemulsion region)

Q3. For SMEDDS, the most suitable surfactants are generally

• Nonionic surfactants with HLB ≥ 12 (e.g., Tween 80, Cremophor EL)
• Cationic surfactants with HLB ≤ 5
• Anionic surfactants exclusively used with ethanol
• Fluorosurfactants with HLB between 3 and 6

Correct Answer: Nonionic surfactants with HLB ≥ 12 (e.g., Tween 80, Cremophor EL)

Q4. One practical criterion indicating a clear microemulsion after SMEDDS dilution is

• Percent transmittance ≥ 90% at 650 nm
• Viscosity ≥ 1000 cP
• Zeta potential ≥ +50 mV mandatory
• Turbidity ≥ 1000 NTU

Correct Answer: Percent transmittance ≥ 90% at 650 nm

Q5. The preferred method to identify self-microemulsifying regions during formulation optimization is

• Higuchi plot construction
• Pseudoternary phase diagram via aqueous titration at varying Smix ratios
• Korsmeyer–Peppas fitting
• Intrinsic dissolution rate in glass apparatus

Correct Answer: Pseudoternary phase diagram via aqueous titration at varying Smix ratios

Q6. Which combination most commonly constitutes a SMEDDS preconcentrate?

• Oil + high HLB surfactant + co-surfactant/cosolvent
• Water + polymer + buffer
• Coarse emulsion with suspending agent
• Oil only with no surfactant

Correct Answer: Oil + high HLB surfactant + co-surfactant/cosolvent

Q7. A key difference between SMEDDS and SNEDDS in practice is that SMEDDS typically forms

• Thermodynamically stable microemulsions upon dilution
• Kinetically stable macroemulsions only
• Suspensions with Ostwald ripening
• Gels that need mechanical agitation

Correct Answer: Thermodynamically stable microemulsions upon dilution

Q8. During excipient screening, a drug is considered promising for SMEDDS if it shows

• High equilibrium solubility in selected oils/surfactants and no precipitation upon dilution
• High solubility in water only
• Solubility only in ethanol but not in lipids
• Crystalline stability in phosphate buffer

Correct Answer: High equilibrium solubility in selected oils/surfactants and no precipitation upon dilution

Q9. For enhancing lymphatic transport via SMEDDS, the most appropriate choice is

• Long-chain triglyceride oils facilitating chylomicron formation
• Short-chain alcohols as sole lipid phase
• Medium-chain monoglycerides only
• Silicone oils

Correct Answer: Long-chain triglyceride oils facilitating chylomicron formation

Q10. A robustness-to-dilution study for SMEDDS commonly evaluates

• Stability upon dilution 1:50 to 1:1000 in water, 0.1 N HCl, and pH 6.8 buffer
• Only dilution in organic solvents
• Only neat (undiluted) preconcentrate viscosity
• Only osmolarity in distilled water

Correct Answer: Stability upon dilution 1:50 to 1:1000 in water, 0.1 N HCl, and pH 6.8 buffer

Q11. The cloud point test for SMEDDS containing nonionic surfactants is critical because

• Cloud point below 37°C risks phase separation in vivo
• Cloud point above 5°C guarantees freezing stability
• Cloud point determines capsule shell hardness
• Cloud point affects only zeta potential sign

Correct Answer: Cloud point below 37°C risks phase separation in vivo

Q12. A common accelerated thermodynamic stability protocol for SMEDDS preconcentrates includes

• Heating–cooling cycles, centrifugation, and freeze–thaw cycles
• Only room temperature storage
• Exposure to UV light for 5 minutes
• Testing only at −80°C

Correct Answer: Heating–cooling cycles, centrifugation, and freeze–thaw cycles

Q13. In vitro lipolysis models help predict SMEDDS performance by

• Simulating digestion with pancreatic lipase and monitoring drug precipitation
• Measuring compressibility index
• Assessing polymer erosion in acidic media
• Evaluating oxygen permeability

Correct Answer: Simulating digestion with pancreatic lipase and monitoring drug precipitation

Q14. A practical range for surfactant concentration in SMEDDS preconcentrates is often

• 30–60% w/w, depending on oil and drug load
• 1–5% w/w maximum
• 80–95% w/w always
• 0% (surfactant-free systems)

Correct Answer: 30–60% w/w, depending on oil and drug load

Q15. Which co-surfactant/cosolvent is frequently used to improve self-emulsification and drug solubility?

• Transcutol P (diethylene glycol monoethyl ether)
• Liquid paraffin
• Calcium carbonate
• Magnesium stearate

Correct Answer: Transcutol P (diethylene glycol monoethyl ether)

Q16. A typical criterion for droplet quality in diluted SMEDDS measured by DLS is

• Polydispersity index (PDI) ≤ 0.3
• PDI ≥ 1.0
• Only negative zeta potential
• Conductivity ≥ 10 S/m

Correct Answer: Polydispersity index (PDI) ≤ 0.3

Q17. A common cause of capsule incompatibility for liquid SMEDDS fills is

• Cosolvent-induced softening or leakage of gelatin shells
• High melting point of the drug
• Use of enteric polymers in the fill
• Presence of water-insoluble dyes

Correct Answer: Cosolvent-induced softening or leakage of gelatin shells

Q18. Solidification of SMEDDS (S‑SMEDDS) to enhance stability can be achieved by

• Adsorption onto porous carriers like Neusilin or Aerosil
• Only by freeze crystallization of water
• Magnetically stirring with steel beads
• Coating with shellac only

Correct Answer: Adsorption onto porous carriers like Neusilin or Aerosil

Q19. Under ICH Q1A(R2), an appropriate accelerated stability condition for SMEDDS in HDPE bottles is

• 40°C/75% RH for 6 months
• 25°C/40% RH for 1 week
• 5°C/ambient RH for 1 month
• 60°C/0% RH for 1 day

Correct Answer: 40°C/75% RH for 6 months

Q20. To minimize drug precipitation upon gastrointestinal dilution of SMEDDS, a useful strategy is

• Include polymeric precipitation inhibitors (e.g., HPMC, PVP) in the system
• Eliminate surfactant completely
• Use only short-chain alcohol as the oil phase
• Reduce oil to zero and add more water

Correct Answer: Include polymeric precipitation inhibitors (e.g., HPMC, PVP) in the system

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