Transdermal Drug Delivery – Design & Evaluation MCQs With Answer

Transdermal Drug Delivery – Design & Evaluation MCQs With Answer

Introduction: This quiz set focuses on transdermal drug delivery systems (TDDS) with emphasis on design principles, formulation strategies and evaluation techniques relevant to M.Pharm students. It covers skin physiology, permeation mechanisms, matrix and reservoir patch designs, role of polymers and permeation enhancers, controlled release mechanisms, and modern technologies such as microneedles and iontophoresis. Evaluation topics include in vitro permeation testing (Franz diffusion), adhesive testing, patch stability, skin irritation and pharmacokinetic assessment. These MCQs are crafted to deepen conceptual understanding and prepare students for advanced coursework and professional exams in novel drug delivery systems.

Q1. Which layer of the skin primarily controls drug permeation for transdermal delivery?

• Viable epidermis
• Stratum corneum
• Dermis
• Hypodermis

Correct Answer: Stratum corneum

Q2. What is the main mechanism by which most small lipophilic drugs cross the skin?

• Transappendageal (via hair follicles and glands)
• Transcellular through keratinocyte cytoplasm
• Intercellular lipid pathway between corneocytes
• Passive diffusion through dermal capillaries

Correct Answer: Intercellular lipid pathway between corneocytes

Q3. Which of the following is a common function of a rate-controlling membrane in reservoir transdermal patches?

• Providing adhesive properties to the patch
• Protecting drug from UV degradation
• Controlling drug flux from the reservoir to the skin
• Increasing drug solubility in the reservoir

Correct Answer: Controlling drug flux from the reservoir to the skin

Q4. Which polymer is frequently used as a matrix former in matrix-type TDDS due to its flexibility and adhesive compatibility?

• Poly(vinylpyrrolidone) (PVP)
• Ethylene-vinyl acetate (EVA)
• Sodium alginate
• Carboxymethyl cellulose (CMC)

Correct Answer: Ethylene-vinyl acetate (EVA)

Q5. Which permeation enhancer works primarily by extracting lipids from the stratum corneum and disrupting its structure?

• Propylene glycol (humectant)
• Oleic acid (fatty acid)
• Ethanol (co-solvent)
• Menthol (counter-irritant)

Correct Answer: Oleic acid (fatty acid)

Q6. In a Franz diffusion cell study, what is the typical role of the receptor medium?

• To act as the donor formulation reservoir
• To maintain sink conditions and collect permeated drug
• To mimic the stratum corneum barrier
• To provide adhesive contact for the patch

Correct Answer: To maintain sink conditions and collect permeated drug

Q7. Which metric best quantifies the steady-state permeation rate of a drug across skin in vitro?

• Lag time (tlag)
• Permeability coefficient (Kp)
• Flux (Jss)
• Partition coefficient (K)

Correct Answer: Flux (Jss)

Q8. Microneedle-assisted transdermal delivery primarily improves drug delivery by:

• Increasing drug solubility in intercellular lipids
• Creating microchannels that bypass the stratum corneum
• Altering dermal blood flow
• Acting as a chemical permeation enhancer

Correct Answer: Creating microchannels that bypass the stratum corneum

Q9. Which test is most appropriate for assessing adhesive performance of a transdermal patch?

• Patch dissolution test
• Peel strength or tack test
• Skin irritancy test
• In vitro release test (IVRT)

Correct Answer: Peel strength or tack test

Q10. For a highly potent drug requiring zero-order release over 7 days, which TDDS design is usually preferred?

• Simple ointment applied daily
• Matrix patch without rate control
• Reservoir patch with rate-controlling membrane
• Fast-dissolving adhesive patch

Correct Answer: Reservoir patch with rate-controlling membrane

Q11. Which technique provides direct visualization of skin microchannel formation after microneedle application?

• Differential scanning calorimetry (DSC)
• Confocal laser scanning microscopy (CLSM)
• UV-visible spectrophotometry
• Tape stripping without imaging

Correct Answer: Confocal laser scanning microscopy (CLSM)

Q12. Which parameter is critical when designing a transdermal system for a drug with high first-pass metabolism?

• High molecular weight to prevent systemic absorption
• Ensure drug bypasses hepatic first-pass by systemic absorption through skin
• Formulate for rapid gastrointestinal absorption
• Increase prodrug hydrophilicity

Correct Answer: Ensure drug bypasses hepatic first-pass by systemic absorption through skin

Q13. Which condition is essential to maintain in the receptor compartment of an in vitro permeation test to approximate in vivo absorption?

• Non-sink conditions to slow permeation
• Constant agitation and sink conditions
• High viscosity to mimic interstitial fluid
• Dehydrated environment to simulate skin dryness

Correct Answer: Constant agitation and sink conditions

Q14. Which of the following is a likely disadvantage of reservoir transdermal patches compared with matrix patches?

• Lower drug loading capacity
• Potential for dose dumping if the membrane is damaged
• Simpler manufacturing process
• Better mechanical robustness

Correct Answer: Potential for dose dumping if the membrane is damaged

Q15. Which analytical method is commonly used to quantify drug in receptor fluid during permeation studies?

• High-performance liquid chromatography (HPLC)
• Thermogravimetric analysis (TGA)
• Fourier-transform infrared spectroscopy (FTIR) for quantitation
• Gel permeation chromatography for small molecules

Correct Answer: High-performance liquid chromatography (HPLC)

Q16. Which property of a drug most limits its suitability for standard passive transdermal delivery?

• Low potency (requiring large systemic doses)
• Moderate lipophilicity (Log P 1–3)
• Low molecular weight (<500 Da)
• High potency (microgram doses)

Correct Answer: Low potency (requiring large systemic doses)

Q17. Which regulatory consideration is specific to transdermal systems compared with oral dosage forms?

• Requirement for disintegration testing
• Evaluation of skin irritation, sensitization and adhesion
• Mandatory enteric coating for gastric protection
• Bioequivalence is never required

Correct Answer: Evaluation of skin irritation, sensitization and adhesion

Q18. Iontophoresis enhances transdermal transport primarily by which mechanism?

• Creating microchannels mechanically
• Using a small electric current to drive charged drug molecules
• Disrupting lipid bilayers by chemical extraction
• Increasing skin temperature to enhance diffusion

Correct Answer: Using a small electric current to drive charged drug molecules

Q19. What does the term “lag time” in skin permeation studies represent?

• Time required for drug to degrade in the donor patch
• Delay before steady-state permeation is established
• Time for receptor medium to equilibrate temperature
• Duration of patch adhesive effect on skin

Correct Answer: Delay before steady-state permeation is established

Q20. Which evaluation parameter best assesses the chemical stability of the drug in the transdermal formulation during storage?

• In vitro skin permeation flux
• Assay of drug content and degradation products by stability-indicating HPLC
• Patch adhesion test at room temperature
• Short-term skin sensitization study

Correct Answer: Assay of drug content and degradation products by stability-indicating HPLC

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