Formulation and evaluation of TDDS MCQs With Answer

Formulation and evaluation of TDDS MCQs With Answer offers a focused practice set for M. Pharm students studying Drug Delivery Systems (MPH 102T). Transdermal drug delivery systems (TDDS) require judicious design of layers (backing, drug matrix/adhesive, rate-controlling membrane, and release liner), careful selection of polymers/adhesives and permeation enhancers, and robust evaluation by physicochemical, mechanical, and biopharmaceutical tests. This quiz covers key concepts including drug suitability criteria, matrix and reservoir designs, diffusion principles, permeation enhancement, adhesive characterization, in vitro/ex vivo release studies, kinetic modeling, and safety/stability assessments. Each question aims to reinforce applied understanding needed for formulation development, regulatory readiness, and troubleshooting of TDDS in advanced pharmaceutics practice.

Q1. Which set of drug properties is most desirable for successful transdermal delivery?

• Molecular weight >700 Da, logP >5, dose >50 mg/day, melting point >250°C
• Molecular weight <500 Da, logP 1–3, daily dose <10 mg, melting point <200°C
• Molecular weight 500–800 Da, logP <1, daily dose 20–40 mg, melting point >220°C
• Molecular weight <300 Da, logP >6, daily dose <5 mg, melting point >220°C

Correct Answer: Molecular weight <500 Da, logP 1–3, daily dose <10 mg, melting point <200°C

Q2. Which expression correctly represents the steady-state flux (Jss) across skin for a drug in a TDDS according to Fick’s first law?

• Jss = (h × ΔC)/(D × K)
• Jss = (D × K × ΔC)/h
• Jss = (D × h)/K × ΔC
• Jss = K/(D × h × ΔC)

Correct Answer: Jss = (D × K × ΔC)/h

Q3. What is the principal mechanism by which oleic acid enhances transdermal permeation?

• By forming covalent bonds with keratin
• By increasing dermal blood flow
• By disrupting stratum corneum lipid packing to increase partitioning and diffusion
• By increasing drug ionization at skin pH

Correct Answer: By disrupting stratum corneum lipid packing to increase partitioning and diffusion

Q4. For a drug-in-adhesive patch requiring high tack and low skin irritation, which pressure-sensitive adhesive is most suitable?

• Silicone pressure-sensitive adhesive
• Acrylic pressure-sensitive adhesive
• Polyisobutylene pressure-sensitive adhesive
• Hydroxypropyl methylcellulose

Correct Answer: Silicone pressure-sensitive adhesive

Q5. Which material is commonly used as a rate-controlling membrane in reservoir-type TDDS?

• Ethylene-vinyl acetate (EVA) copolymer
• Polyvinyl alcohol (PVA)
• Sodium alginate
• Gelatin

Correct Answer: Ethylene-vinyl acetate (EVA) copolymer

Q6. Which property is most appropriate for the backing layer of a TDDS?

• High water permeability to reduce occlusion
• Permeable to drug and enhancers to reduce accumulation
• Impermeable to drug/enhancers and moisture, flexible, and occlusive
• Water-soluble to facilitate quick removal

Correct Answer: Impermeable to drug/enhancers and moisture, flexible, and occlusive

Q7. Which is a commonly used release liner for TDDS?

• Cellulose acetate membrane
• Siliconized polyester film
• Polycarbonate porous sheet
• Nylon mesh

Correct Answer: Siliconized polyester film

Q8. The Higuchi model is most appropriately used to describe which process in TDDS?

• Zero-order release from reservoir systems
• First-order release from swelling polymers
• Square-root-of-time release from a homogeneous drug-loaded matrix
• Michaelis–Menten transport through skin enzymes

Correct Answer: Square-root-of-time release from a homogeneous drug-loaded matrix

Q9. Which evaluation best ensures consistent drug load per unit area across patches?

• Thickness uniformity
• Folding endurance
• Drug content per unit area (assay/cm²)
• Probe tack

Correct Answer: Drug content per unit area (assay/cm²)

Q10. Which adhesive test quantifies resistance to debonding under a constant shear load over time?

• Rolling ball tack
• Probe tack
• 180° peel adhesion
• Shear adhesion (static shear)

Correct Answer: Shear adhesion (static shear)

Q11. Which statement regarding moisture vapor transmission rate (MVTR) of the backing layer is most accurate?

• Higher MVTR increases occlusion and skin hydration
• Lower MVTR increases occlusion and may increase flux by hydrating the stratum corneum
• MVTR has no impact on percutaneous absorption
• Lower MVTR always reduces risk of skin maceration

Correct Answer: Lower MVTR increases occlusion and may increase flux by hydrating the stratum corneum

Q12. Which apparatus is the gold standard for in vitro/ex vivo permeation studies of TDDS?

• USP Apparatus I (basket)
• USP Apparatus II (paddle)
• Franz diffusion cell
• Flow-through dissolution cell without membrane

Correct Answer: Franz diffusion cell

Q13. Which skin model most closely mimics human skin barrier properties for ex vivo permeation testing?

• Mouse abdominal skin
• Porcine ear skin
• Rat dorsal skin
• Chicken skin

Correct Answer: Porcine ear skin

Q14. In TDDS evaluation, the enhancement ratio (ER) is best defined as:

• The ratio of donor concentration to receptor concentration
• The ratio of flux with enhancer to flux without enhancer
• The ratio of steady-state time with enhancer to lag time without enhancer
• The ratio of patch area to thickness

Correct Answer: The ratio of flux with enhancer to flux without enhancer

Q15. From a cumulative amount permeated per unit area versus time plot, how are flux and lag time determined?

• Flux from y-intercept; lag time from slope
• Flux from slope at steady state; lag time from the x-intercept of the linear region
• Flux from area under the curve; lag time from maximum y-value
• Flux from initial burst; lag time from equilibrium concentration

Correct Answer: Flux from slope at steady state; lag time from the x-intercept of the linear region

Q16. Which observation most strongly indicates drug crystallization within a TDDS during stability testing?

• Decrease in peel strength
• Appearance of a distinct drug melting endotherm in patch DSC thermogram
• Increase in moisture content
• Higher MVTR of backing

Correct Answer: Appearance of a distinct drug melting endotherm in patch DSC thermogram

Q17. In iontophoretic enhancement adjunct to TDDS, which parameter primarily governs the rate of drug transport?

• Applied voltage alone
• Current density across the skin
• Patch thickness
• Skin temperature only

Correct Answer: Current density across the skin

Q18. Which test is traditionally used to assess primary skin irritation potential of a TDDS in animals?

• Human repeat insult patch test (HRIPT)
• Draize dermal irritation test
• In vitro cytotoxicity on L929 fibroblasts
• Ames mutagenicity test

Correct Answer: Draize dermal irritation test

Q19. Which TDDS design incorporates the drug directly within the adhesive layer without a separate rate-limiting membrane?

• Reservoir system
• Matrix system with polymeric disc
• Drug-in-adhesive system
• Osmotically driven transdermal system

Correct Answer: Drug-in-adhesive system

Q20. Which TDDS design carries a higher risk of dose dumping upon accidental rupture?

• Matrix diffusion-controlled system
• Drug-in-adhesive system
• Reservoir system
• Multilaminate membrane-free system

Correct Answer: Reservoir system

Download