Development of pilosebaceous gland-targeted drug products ...

Development of pilosebaceous gland-targeted drug products and

potential impact on BE testing

Guang Wei Lu, Ph.D. Allergan

March 12, 2013

PQRI Workshop on the Evaluation of New and Generic Topical Drug Products – Current Challenges in Bioequivalence, Quality, and Novel Assessment Technologies March 11-13, 2013, U.S. Pharmacopeia Meeting Center, Rockville, MD 20852

I. Development process of dermal drug products and BE considerations II. Methods explored for the investigation of pilosebaceous gland-targeted drug products

Developing a new dermal drug product

• Parachuting – Minoxidil: from a oral product for treating hypertension to a topical

solution for treating hair loss – Retinoids: topical tretinoin, tazarotene, adapalene for treating acne and

psoriasis

• Product enhancement – Microsponge drug delivery systems for tretinoin and benzoyl peroxide – New combination products: clindamycin/tretinoin, adapalene/benzoyl

peroxide

• Discovery of new molecule for dermal indication – Androgen receptor antagonist for the topical treatment of excess sebum

and androgenetic alopecia – Tyrosinase inhibitor for treating skin hyperpigmentation – Estrogen receptor agonist for reduction of wrinkles – Inhibitor of the intracellular esterification of cholesterol with CoA-

activated fatty acids to produce cholesterol esters for excessive sebum production

First generation Second generation Third generation

Tazarotene

Bexarotene

Adapalene

Discovery and Development of Retinoids

Tretinoin

Retinol

Isotretinoin

Alitretinoin

Etretinate

Acitretin

Recently approved new molecules for dermal indications

Molecule Product Manufacturer Indication Date approved by FDA

Ingenol mebutate Picato gel Leo Actinic keratosis 1/23/2012

Spinosad Natroba Parapro Head lice 1/18/2011

Retapamulin Altabax GSK Skin infection 4/12/2007

Sinecatechins Veregen Medigene External genital warts 10/31/2006

Sertaconazole Ertaczo Valeant Skin infection 12/10/2003

Pimecrolimus Elide Valeant Eczema 12/13/2001

Docosanol Abreva GSK Cold sores/fever blisters 7/25/2000

Aminolevulinic acid HCI

Levulan/ Kerastick

DUSA Non-hyperkeratotic actinic keratoses

12/3/1999

Alitretinoin Panretin Eisai Visceral Kaposi-s sarcoma

2/2/1999

Tazarotene Tazorac Allergan Acne, Psoriasis 6/17/1997

Penciclovir sodium Denavir Novartis Cold sores 9/24/1996

Butenafine HCl Mentax Mylan Fungal infection 10/18/1996

Azelaic acid Azelex Allergan Acne 9/13/1995

Adapalene Differin Galderma Acne 5/31/1996

Calcipotriene Dovonex Leo Scalp Psoriasis 12/29/1993

year

1 2 3 4 5 6 7 8 9 10 11 12

Timeline and Stages of Drug Product Development

Bridge from 1 2 4 to 5

3

R&D Research Early Development Late Development Commercialization

Clinical Development Hit to lead Pre-clinical Phase I Phase II Phase III NDA - Phase IV

Drug Product Development Research Formulation Tox Formulation Phase I/II Formulation Phase III Formulation Final Drug Product

Drug Product Production Scale Lab batch, <10 g GLP, 1-5 kg GMP, 5-20 kg GMP, >20 kg Commercial Scale

Key Activities in Early-stage Development of Dermal Products

Functions Lead selection Pre-clinical

Phase I/II

Chemistry -Identify leads -Synthetic feasibility

- Structural alert - Scale up (steps, raws, stereocenters, COG, Impurities )

- API scale up -Process optimization

Pharmaceutics - Initial solubility - Calculated Log P/pKa

-Solubility/Excipient compatibility/Solid form characterization & selection - UV spectrum for phototoxicity assessment/ Analytical method -Vehicle/formulation development for tox/Phase I/II -API and formulation stability

-Develop and validate analytical and microbial methods for quality control - GLP/GMP manufacture -Stability

ADME - Systemic exposure in animal models/Skin permeation and retention - Clearance in animal models/Major clearance mechanisms and metabolites - Plasma protein binding - PK/PD assessment/Prediction ADME in human and clinical dose/dosing regimen

Pharmacology - In vitro functional binding/assay

-In vitro assay - in vivo efficacy models/Biomarker

Safety -Acute dose study -Safety pharmacology: neuro, pulmonary and cardiovascular functions -Repeated-dose studies: rats and minipigs -Genetic tox studies -Special studies: photoirritation, local lymph node assay, reversibility

Bridging study if formulation is changed

Clinical - IND strategy/Early clinical development plan - Protocol for Phase I/II

- Clinical trials -Bridging study if formulation is changed

Regulatory -IND strategy/Pre-IND meeting -IND filing

Legal Freedom to operate and patent opportunity for indications/molecules/API solid form/formulation

Commercial/ Marketing

- IND strategy - Input to Target Product Profile

Acceptable

Formulation /

Packaging?

Y

Formulation/Packaging Stability Studies

Vehicle

Related?

Systemically &

Topically Safe

Terminate

N

NN

N

Safe

Evaluate

Formulation

against MI

Criteria

Terminate

File IND/

CTX

Phase 1

Clinical

Supplies

& Studies

Y

lead

Formulation

& Analytical

Development

Phase 2a

Clinical

Supplies &

Studies

Lead Compound

Identified

Safety StudiesCandid

ate

N

Late

Dev

Late

Dev

Pre-Clinical

Studies

Phase 2b

Clinical

Supplies &

Studies

N

Terminate

Y

N

Y

Safe

Manufacture

Phase 2b Clinical

Supplies

POC

N

Early

Formulation

Development

Y Y

Bridging Safety

Studies

(if needed)

MIF

Packaging

Development

Y Market Image

Consumer

Evaluation

Delivery

Equivalency

Studies

Y

Decision

to Initiate MIF

Development

MIF

Formulation

Development

Phase 3

API, <100 g

Manufacture

& Release

Y

N

Phase 2b

API Manufacture

& Release

API, <10 g

Manufacture &

Release

Packaging/

Applicator

Development

$

Y

$

Supply Chain/

Outsourcing

Manufacture

Late dev team

API, 1-5 kg

Manufacture

& Release

Research and Early Development Formulation

• Developed for non-clinical studies and Phase I/II studies • Limited quantity of API

– Starting with 50-100 mg – Effect of impurities

• Short development timeline – < 1 month for research formulation – 3-9 months for early development formulation depending on front-loading

or staged strategy

• Simple formulation preferred – Solutions, simple gels or ointments

• Excipients selection – Solubilizer, stabilizer, volatile solvent – Permeation enhancer or retarder (BE effect if changes) – Safety – Antimicrobial activity – Aesthetics (cosmetic elegancy)

Change of formulations

• Dosage form change • Excipient change

– Change of excipient manufacture process – Different grade

• Stability Issue – Short term stability for Phase I/II, and long term stability for Phase III – Packaging compatibility or change

• Efficacy issue – Proof of mechanism (POM) vs. Proof of concept (POC) – Potency – Drug delivery profile – Placebo effect

• Safety issue – Irritation and sensitization – Systemic exposure

• In-use compatibility with other topical products

Approaches in developing dermal products

• Targeted dermal drug concentration

– Established effective drug concentrations in dermal tissue following oral dosing

– Set the target drug concentrations for evaluation of topical delivery

• In vitro study

– Skin flux and disposition of topically applied drug

– Targeting the pilosebaceous gland

• In vivo study

– Rodents, minipigs and monkeys

– Drug concentrations in skin tissues and systemic exposure

Summary I

• Development of topical products for dermal indications requires additional studies

• Vehicle/formulation effect on development process impacts the process, timeline, and resource of development from early discovery stage to commercialization

• Bridging among animal model and human subjects and understanding formulation BE are critical in each development stage

• There is unmet needs for non-invasive, target-specific quantification methods

Methods explored for the investigation of pilosebaceous gland-targeted drug

products

I. Drug permeation through various skin models

II. Drug permeation through sebum

III. NIR Spectrometry for the qualification of drug in skin

SKIN FLUX STUDY

Apparatus: Franz diffusion cell or alternatives

Membrane: Cadaver Skin or pig skin

Receptor Phase: Appropriate fluid at sink condition

Donor Phase: Saturated solution or formulations

Amount applied

Occlusive or non-occlusive

Temperature: 32°C

Duration: 24 hr or 48 hr

Follicular Transepidermal

Systemic

Topical drug delivery to target site

Franz Cell Flow Cell

Sid-by-side Cell Hanson’s Microette System

Comparison of drug distribution in various skin samples

Compound (0.5%)

Vehicle Apparent Skin Flux (µg/cm²/hr)

Human Minipig Hamster ear

A Ethanol/Water/Propylene glycol/propylene carbonate

70/20/5/5 (% v/v)

0.057 ± 0.018 0.0317 ± 0.0053 0.878 ± 0.149

B Ethanol/Water/Propylene glycol 60/35/5 (% v/v)

0.0074 ± 0.0042 0.0007 ± 0.0032 0.127 ± 0.029

C Ethanol/Water/PEG 400 50/25/25 (% v/v)

0.011 ± 0.006 0.0005 ± 0.0005 0.060 ± 0.030

Comparison of drug distribution in various skin samples

0

5

10

15

20

25

Human Minipig Hamster

Stratum corneum Skin Penetrated

0

5

10

15

20

25

Human Minipig Hamster

Stratum corneum Skin Penetrated

0

5

10

15

20

25

Human Minipig Hamster

Stratum corneum Skin Penetrated

% o

f d

ose

d

% o

f d

ose

d

% o

f d

ose

d

Compound A Compound B

Compound C

Compound A B C

MW 298 388 434

Log P 3.5 4.88 5.74

Dose 0.5% API, 5 -10 µL/cm²

Comparison of drug distribution in skin tissues between female and male hamster

0

10

20

30

40

50

Surface Stratum corneum Skin Penetrated

Female hamster Male hamster

0

10

20

30

40

50

Surface Stratum corneum Skin Penetrated

Female hamster Male hamster

0

10

20

30

40

50

Surface Stratum corneum Skin Penetrated

Female hamster Male hamster

% d

ose

d

% d

ose

d

Compound A Compound B

Compound C

Drug concentration effect on skin permeation, local and systemic exposure, and activity

% A Vehicle Human Skin (single dose) Hamster model (repeated doses)

Flux (µg/cm²/hr)

Derm conc. (µg/g)

SG conc.* (µg/g)

Plasma conc. (ng/mL)

% Reduction of WE**

0.5 EtOH/PG/W/Klu 60/20/20/0.5

0.062 ± 0.017 0.816 ± 0.085 30.1 ± 15.9 1.24 ± 0.55 80

1 EtOH/PG/W/Klu 60/20/20/0.5

0.099 ± 0.075 1.26 ± 0.69 21.0 ± 7.6 1.29 ± 0.43 77

Drug precipitation was observed after dosing 1% formulation

* Drug concentration in the sebaceous glands; ** efficacy model

Formulation effect on skin flux and in vivo activity

Drug Vehicle Skin flux

(µg/cm2/hr) % Reduction of WE

0.5% B EtOH/W/PEG400/PG 50/25/15/10

0.0137 ± 0.0061 78

0.5% B EtOH/W/PEG1000/PG 50/25/15/10

0.0054 ± 0.0010 73

0.5% C EtOH/W/PG 50/30/20

0.0375 ± 0.0171 88

0.5% C EtOH/W 60/40

0.0064 ± 0.0058 86

In vivo follicular drug delivery measurement

• Cyanoacrylate casting and differential stripping

• Follicular blocking techniques

– Microparticles

– Nail varnish

2. Press on to skin, glue spreads across

skin surface and into follicle openings

and dries

1. Drop of ‘Supaglue’ on microscope slide

3. Pull off to harvest stratum corneum

and contents of the follicle where glue

has penetrated

Glue

droplet

Drug

molecule

Dry

glue

Drug

molecules

set in glue

2. Press on to skin, glue spreads across

skin surface and into follicle openings

and dries

1. Drop of ‘Supaglue’ on microscope slide

3. Pull off to harvest stratum corneum

and contents of the follicle where glue

has penetrated

Glue

droplet

Drug

molecule

Dry

glue

Drug

molecules

set in glue

Nonionic lipid effect on the topical delivery of minoxidil to hamster sebaceous glands

Topical delivery systems for active agents S Niemiec et al. US 6419913 B1, Jul 6, 2002

Diffusion properties of model compounds in artificial sebum S Valiveti & G Lu, Int J Pharm 2007, 345: 88-94

Drug Diffusion through artificial sebum

TransWell Insert

Donor solution or suspension (150 L)

Artificial sebum (5 L)

Receptor fluid (10% HP--CD in CPB, pH 5.5)

0.4 m membrane

In vitro diffusion through the artificial sebum

A 24 well Transwell® plate (polycarbonate, 0.33 cm2 area, 0.44 μm pore size)

A 5 μL of artificial sebum was loaded on to the each well

A 150 μL of drug suspension (10 mg/ml) was loaded on to the each well, citrate-phosphate buffer pH 5.5 used as receiver solution

Samples were withdrawn at 10 min interval for 2h

At each time point entire receiver solution was replaced with fresh buffer

Influence of receiver solution on lidocaine diffusion through the artificial sebum from water

0.00

10.00

20.00

30.00

40.00

50.00

0 20 40 60 80 100 120

cum

ula

tive a

mount

transp

ort

ed

(ug/c

m2)

Time (min)

pH 5.5 CPB buffer

5% HP-CD in CPB buffer pH 5.5

10% HP-CD in CPB buffer pH 5.5

Lidocaine and minoxidil diffusion through the artificial sebum from water

lidocaine Flux = 34.89 mcg/cm2/min

Minoxidil Flux = 1.51 mcg/cm2/min

0

500

1000

1500

2000

2500

3000

3500

4000

0 20 40 60 80 100 120

cu

mu

lati

ve

am

ou

nt

tra

ns

po

rte

d (

mc

g/c

m2)

Time (min)

Drug transport profiles through artificial sebum from water

Lidocaine suspension in water

Minoxidil suspension in water

Effect of solvent system on the minoxidil diffusion through the artificial sebum

Minoxidil Flux = 3.60 mcg/cm2/min

Minoxidil Flux = 1.51 mcg/cm2/min

0

200

400

600

0 20 40 60 80 100 120

Time (min)

cu

mu

lati

ve

am

ou

nt

tra

ns

po

rte

d (

mc

g/c

m2)

5% Minoxidil in ethanol:water:PG (60:20:20:)

5% Minoxidil in Water

Effect of the solvent system on the lidocaine diffusion through the artificial sebum

Liodocaine permeation profiles through artificial sebum

Lidocaine Flux = 149.60 mcg/cm2/min

Lidocaine Flux = 34.89 mcg/cm2/min.

0

5000

10000

15000

0 20 40 60 80 100 120

Time (min)

cu

mu

lati

ve a

mo

un

t tr

an

sp

ort

ed

(m

cg

/cm

2)

Saturated solution of lidocaine in

ethanol:water:PG (60:20:20:)

Suspension of lidocaine in water

Influence of volume of donor solution on the minoxidil flux through artificial sebum

Flux from 10 uL = 3.77 mcg/cm2/min

Flux from 15 uL = 4.388 mcg/cm2/min

Flux from 20 uL = 5.1235 mcg/cm2/min

Flux from 25 uL = 6.0152 mcg/cm2/min

0

200

400

600

0 20 40 60 80 100 120

Time (min)

cum

ulat

ive

amou

nt t

rans

port

ed (

ug/c

m2)

10 uL 15 uL

20 uL 25 uL

NIR Spectrometry Method

• J Medendorp et al. Pharm Res. 23: 835-843 (2006)

• Econazole nitrate (EN) and 4-cyanophernol (4-CP) exhibit strong NIR chromophores. The NIR spectrum at 1470-1870 nm for 4-CP, and at 1936-2336 nm for EN were selected for quantification .

• Hairless guinea pig skin, MatTek permeation device and Technicon InfraAlyzer 500 were used for the study.

• Scattering data were analyzed using principle component regression (PCR), interval PCR and PCR-uninformative variable elimination models

Estradiol distribution in skin tissues after application of topical formulations using NIR spectra method

• J Medendorp et al. AAPS AM posters, 2007

• Estradiol was formulated in gel, suspension and nanosuspension

• Estradiol distribution in hairless guinea pig skin was investigated using NIR method

• Scattering data were analyzed using principle component method

Principal component ellipses calculated from multiplicative scatter corrected data in the mid-IR region (4,000 – 2,000 cm-1) demonstrating the tendency of like-data to cluster in the same region of multidimensional hyperspace. These clusters included those spectra of tissues harvested from the left side of the guinea pig.

2% Estradiol Gel

0

20

40

60

80

100

120

140

160

0 5 10 15 20 25

ng

/mL

Time (h)

Hartley (shaved)

IAF Hairless

Hartley (hair removed)

Hairy Guinea Pigs

0

20

40

60

80

100

120

140

160

0 5 10 15 20 25Time (h)

ng

/mL

Milled

Gel

Large Particle

Baseline

D.C. Hammell et al. AAPS AM poster, 2007

Summary II

• Skin permeation and disposition studies in various models are commonly used for the development of dermal drug products.

• Sebum model provides a complementary tool for molecule and formulation screening, particularly for those targeting pilosebaceous glands.

• The correlation among rodent models for efficacy and irritation, minipig model for tolerance, and human subjects in clinical trials needs to be carefully assessed at discovery and early development stages.

• The MIR/NIR instrumentation presented in this research have proven to be effective means for visualizing estradiol distribution in human tissue, and demonstrated the formulation effect on the distribution. Further investigation for the application is needed.

• Hairy and hairless guinea pigs were used as the animal models for the investigation of hair follicular drug delivery.