Challenges in Topical & TransdermalDrug Delivery:

Overcoming the Stratum Corneum Barrier

Bozena B. Michniak-Kohn, Ph.D.Ernest Mario School of Pharmacy, Rutgers-The State University

of NJLaboratory for Drug Delivery, NJ Center for Biomaterials

michniak@biology.rutgers.edu

Laboratory for Drug Delivery

• Optimization of transdermal and topical drugdelivery: formulations, carriers (nanospheres)

• Skin constructs /models for testing drugpermeability & irritation

• Drug permeability enhancement: physical &chemical approaches (chemical enhancers/retardants)

• Investigation of drug permeation pathways• In vivo animal pharmacokinetics• Computational modeling and mathematical

predictions

Screening Systems

• Human cadaver/surgical biopsy skin• Human buccal, uterine membrane models• Skin constructs /models for testing drug

permeability & irritation• Normal & transformed human keratinocytes &

fibroblasts for cell toxicity testing• Animal skins: hairless mouse etc.• Polymeric membranes

H & E section of human skin

Corneocyte

Intercellular Transcellular

Intercellular lipids

Transepidermal permeation routes

1. Camouflage

2. Protective layer

3. Insect repellent4. Antimicrobial/Antifungal

Drug dissolves,diffuses, releasesfrom vehicle

Partition/diffusion,stratum corneum

1. Emolliency

2. Keratosis (Exfolients)

TRANSEPIDERMAL

1. Antiperspirant

2. Exfolient

3. Antibiotic/Antifungal4. Depilatory

Pilosebaceousunit

Eccrinegland

Partition/diffusion,viable epidermis

Partition/diffusion, dermis

Removal via circulation

1. Antiinflammatory2. Anesthetic

3. Antipuritic

4. Antihistamine

TRANSAPPENDAGEAL

INTERFACIALBOUNDARIES

PENETRATION ROUTES SOME TREATMENTS

SURFACE

STRATUMCORNEUM

APPENDAGES

VIABLEEPIDERMIS

DERMIS

CIRCULATION1. Transderm system2. Nitroglycerin

I. Development of a tissueengineered human skin model

(HSE)

Significance

• Collagen-based HSEs available :Living SkinEquivalent® /Apligraf ® (Organogenesis) &Orcel ®(Ortec International, Inc.) for clinicalapplications

• Other models consist of epidermis only(Epiderm ®, Skinethic®, and Episkin®)

• Newest is EpidermFT®- MatTek Corp, MA

Formation of Human Skin Equivalent

Franz Diffusion Cell Apparatus

(A) Donorcompartment

(B) Sampling port (C) Clamp (D) Receptor

compartment (E) Water out (F) Water in

Lipid Supplementation of HSE

Aim• To provide skin lipid precursors (in conjunction with bovine serum

albumin as carrier) to the HSE during the growth period.

Approach• Tissue culture medium was supplemented with

• palmitic acid• linoleic acid• oleic acid• arachidonic acid• Cholesterol• bovine serum albumin with 0.1% DMSO (as vehicle)

Optimized HSE: Permeation of Caffeine through HSE,Epiderm-FT™ and Human Cadaver Skin, n=3-6

Mean amount vs. Time

0

100

200

300

400

500

600

0 10 20 30

Time (hr)

Cu

mu

lati

ve A

mo

un

t o

f

Caf

fein

e (µ

g/c

m2 ) Epiderm FT

HSE

Human cadaver

skin

Light microscopy of HSE control and with clofibrate (300 µM). Arrowsindicate keratohyalin granules.

Control

10 days

Clofibrate

Control With Supplements

20 days

HSE with lipid supplements, ascorbic acid (100µg/ml) andclofibrate (300µM) at 34 days. Arrows indicate keratohyalin

granules

Improving mechanical strength ofHSE model

Human dermal fibroblasts growing onan electrospun polymer mesh

Cells stained with Alexa fluor Phalloidin 594 (RED).Nucleus stained using DAPI (4',6-Diamidino-2-

phenylindole; BLUE) Microscope: Zeiss Apotome®.Images using Axiovision LE®

II. Chemical enhancement

Site of Penetration EnhancerActivity

• Site A - Polar head groups of lipids• Site B - Solvent action (water, propylene glycol, ethanol)• Site C - Lipid packing in the stratum corneum

Structures of the Compounds

F

N-

O

S+

CH3

CH3

Br

N-

O

S+

CH3

CH3

I

N-

O

S+

CH3

CH3

N-

O

S+

CH3

CH3

CH3

N-

O

S+

CH3

CH3

CH3

QH1

QH2

QH3

QH4

QH5

Experimental Methods

• Drug : Hydrocortisone (HC)• Vehicle: Propylene glycol (PG)• Enhancers: QH1, QH2, QH3, QH4, QH5• Diffusion cells: Vertical Franz diffusion cells (5.1 ml, 0.64 cm2)• Skin: Human Cadaver Skin

Permeation Study

Franz diffusion cells

Human Cadaver Skin1. Permeation profile

Cumulative amount of HC penetrated through human cadaver skin over 24hrs

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

0 5 10 15 20 25

time (hr)

cu

mu

lati

ve

am

ou

nt

of

HC

( µg

/cm

2)

control

QH1

QH2

QH3

QH4

QH5

Permeation Study for QH2

0

1

2

3

4

5

6

7

8

9

10

control 0.1M 0.2M

QH2

En

han

cem

en

t ra

tio

ERQ24

ERFlux

ERTlag

III. Cell Toxicity Studies

MTT Assay for QH Compounds on HumanDermal Fibroblasts

MTT Assay for QH Compounds on HumanEpidermal Keratinocytes

IV. Physical Enhancement

Microneedle Approach

• Novel approach, minimally invasive,painless

• Consist of small arrays of needles• Needles made of : silicon, metal,

biodegradable polymers• Uses MEMS (Micro Electro Mechanical

Systems): microfabrication,micromachining, microelectronic circuitry

Microneedles arrays (silicon)

Surface Morphology- 600 µ needle

Microneedles for transdermaldelivery

Total amount in micrograms of lidocaine hydrochloride permeated throughhuman cadaver skin at end of 5 hours through different size microneedles.

0

100

200

300

400

500

600

700

800

600 microns control for 600 300 microns control for 300

Treatment

Am

ount perm

eate

d in

5 h

rs

V

+-

D+ D+ D+

D+

D+

D+

D+

D+

D+

D+ D+ D+D+

D+

AnodeCathode

Skin

Systemic circulation

Iontophoretic device

Effect of iontophoresis & chemical enhancers(human skin) on buspirone permeation

V. EM and FTIR Studies

EM of Human Skin

Skin surface /5% oleic acid for3 h and iontophoresis for 24h

Epidermis/5% oleic acid andiontophoresis for 24h

Treatment with10% oleic acidfor 3 hourfollowed byiontophoresisfor 24 hours

Treatment with5% oleic acidfor 3 hourfollowed byiontophoresisfor 24 hours

Treatment with5% oleic acidfor 1 hourfollowed byiontophoresisfor 24 hours

Treatment with2.5% oleic acidfor 1 hourfollowed byiontophoresisfor 24 hours

Treatment with5% oleic acid for1 hour

Iontophoresis for24 hours

IR Spectroscopic Imaging of SkinJ. Biomed. Optics (2003), 8, 185-190.

Top, from left: Loreto Valenzuela, Peter Zhang, Sonali Bose, Lawrence Hu, LarisaSheihet

Bottom, from left: Rashmi Thakur, Prafulla Chandra, Diksha Kaushik, Priya Batheja

Acknowledgements• Ph.D. students:Rashmi ThakurPriya BathejaDiksha KaushikLawrence HuYiping WangYifan SongQuixi FanMohammad Al-KhaliliHui Chen Chen

• Post Doctoral/FacultyR. Mendelssohn, Ph.D.V. Meidan, Ph.D. (U.K.)J. Kohn, Ph.D.P. Chandra, Ph.D.J. Chapman, Ph.D. (USC)P. Wertz, Ph.D. (Iowa)Funding:NJ Center for Biomaterials, US

Army Contract # W81XWH-04-2-003, Coulter Foundation,Apogee Technologies, Inc. ,Norwood, MA.

Thank you