drug distribution & formulation issues · enema + + event/phase microbicide vehicle semen...

Drug Distribution

& Formulation Issues

Craig Hendrix, MD

Acknowledgements

�Human Subjects

�Collaborators

– Edward Fuchs Johns Hopkins

– Lisa Grohskopf CDC

�Funding

– Centers for Disease Control & Prevention

– Johns Hopkins Center for AIDS Research (NIH)

"The findings and conclusions in this presentation have not been formally

disseminated by the Centers for Disease Control and Prevention and should not be

construed to represent any agency determination or policy."

Conceptualization

Assumptions

� The distribution of a microbicide relative to

HIV following sex is likely to be a critical

predictor of microbicide efficacy

� Optimal microbicides will exceed HIV

distribution and duration following sexual

exposure (outdistance and outlast HIV).

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Add Dimension of Time

Success Failure

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HIV Deposition: Area Requiring Coverage

Conceptualization

Formulate to Outdistance & Outlast HIV

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Microbicide & HIV

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Enhanced Adherence

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Enhanced Adherence & Spread

Microbicide

HIV

Conceptualization

Tissue & Cellular DistributionM

icro

bic

ide

Co

nce

ntr

atio

n

Lumen-Blood Distance

Drug

Lumen Mucosa Lamina Propria Blood/Lymph

High

Blood/Colon

Low

Blood/Colon

Drug

Concentration

TH

TH

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TH

Conceptualization

Distribution Unknowns

Location

� Lumen

� Mucosal Tissue

� Mucosal CD4 T cells

Microbicide Type

� Polymers

� Mucosal Entry Inhibitors

� Enzyme inhibitors

Method Development

Quantitative Distribution Methods Needed

� Surrogates for Development– Microbicide gel surrogate

» ARV drug-sized molecule administered in a gel

– Semen Surrogate» Aqueous gel, decreased viscosity with time

– HIV in semen surrogate» Cell-free – HIV-sized particles

» Cell-associated – CD4+ lymphocytes

� Validation Elements– Cell-free HIV

– Cell-associated HIV – CD4+ lymphocytes

– Candidate microbicide (polymer, ARV)

Method Development

Macroscopic Imaging & Simulation

Constituents Microbicide Surrogate Semen Surrogate

Volume 10 mL 5 mL

Gel HEC OTC lubricants HEC OTC lubricants

MRI Gadolinium Gadolinium

Isotope 111In or Tc - DTPA

(490 - 545 MW)

99mTc Sulfur Colloid

(100 nm ~ HIV particle size)

Administration

Vaginal DilatorPlastic tipped syringe Coital Simulator

Method Development

Gel Distribution and Clearance Schema

SPECT/MRISPECT/MRIHour 24




++Remove Dilator

+-Coitus (10 @ 1 cps)

99mTc-labeled simulant-Ejaculate (5ml)

++Coitus (5' @ 1 cps)

-99mTc-labeled vehicleMicrobicide (10ml)

++Enema

Semen SimulantSemen SimulantMicrobicide VehicleMicrobicide VehicleEvent/PhaseEvent/Phase

Colonic Distribution

Effect of Coital Simulation: MRI


HIV/Semen Surrogate: SPECT

5 mL no enema


Quantitative SPECT/CT Imaging

0803 HRS

Counts / Area

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Slic

e #

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80

1139 HRS

Counts / Area

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Slic

e #

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60

80

First Hour Post-Dose (0803 HRS)

SPECT / CT Fusion “Concentration”

Fourth Hour Post-Dose (1139 HRS)

“Concentration” SPECT / CT Fusion

Subject F003: CDS SS 0E

5 mL semen simulant @ 0734 HRS

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510

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35

1.01.5

2.0

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3.5

Con

cen

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CentimetersHou

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Concentration, Distribution, Time

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Dual Isotope Quantitative Imaging

99mTc - HIV/Semen (blue)111In - Microbicide (green) "Concentration"

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Tc - HIV/Semen Hour 0

In - Microbicide Hour 0

11:45 Wednesday Track A Oral Paper 531

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Centimeters from Point Source

Tc-SC (HIV Surrogate)

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In-DTPA (Microbicide ARV Surrogate)99mTc – HIV/Semen Surrogate 111In – Microbicide Surrogate


Tc-SC “HIV” and In-DTPA “Microbicide”


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Dual Isotope Imaging (SMW)

99mTc-SC HIV Surrogate111In-DTPA Microbicide ARV Surrogate

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Application: Simultaneous Imaging

� Validation of Surrogates

– HIV and Tc-sulfur colloid

– Microbicide (ARV) and In-DTPA

� Microbicide Evaluation

– Microbicide candidate vs.

– HIV - Cell-free or Cell-associated (CD4+)

Distance (cm)

0 10 20 30 40 50 60 70

Fra

ction

of In

itia

l C

once

ntr

ation

10-5

10-4

10-3

10-2

10-1

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Colonic – Tissue Distribution

Direct Endoscopic Sampling

Sheathed Brush

Biopsy Forceps

Fractional change from administered concentration of 99mTc-SC, 4

hours after dosing, along the length of the distal colon beginning

at the anus (0 cm), extending up toward the splenic flexure (60 cm).

Brush

Biopsy

[Vaginal]/[Blood]

70-145%

80-130%

50%

6-48%

8-12%

0-4%

Tissue Distribution

Vaginal Fluid Level with Oral Dosing

Antiretroviral

Indinavir

Nevirapine

Amprenavir

Delavirdine

Lopinavir

Ritonavir

Compiled by Angela Kashuba, UNC

Hours

0 4 8 12 16 20 24

PM

PA

ng/m

L

1

10

100

1000

LLOQ

Tissue Distribution

Blood Concentration with Vaginal Dosing

Figure Legend

270 mg PMPA QD PO135 mg PMPA QD PO68 mg PMPA QD PO34 mg PMPA QD PO

[Barditch-Crovo AAC 2001]

40 mg PMPA BID vaginal[Mayer AIDS 2006 (HPTN 050)

6/25 Subjects w/ 3+ blood levels]

6%1.35340Vaginal

21.2717 34

23.91,613 68

21.82,937 135100%

22.56,073 270

Oral

Relative

F

AUC per

100 mgAUC

(ng*hr/mL)

Dose (mg)Route

Tissue Distribution

Quantitative Tissue Assays Needed

�CD4 intracellular ARV concentration

– Drug concentration at site of action

�HIV & CD4 distinguishable from native

– Potential for microbicide HIV challenge test

Summary Points

� Methods– Simulated intercourse feasible (and informative)

– Microbicide/semen surrogate distribution-time quantitative

– Dual isotope imaging feasible

� Findings– Semen surrogate to splenic flexure in some

– Rectal ampulla largely devoid of gel after simulated RAI

– HIV and ARV distribute similarly (5 minute dosing separation)

� Future– Validate surrogates with real HIV and drugs in lumen

– Test candidate microbicide against HIV distribution

– Define variables affecting drug distribution to aid formulation

– Quantitative tissue methods need development

– HIV challenge test needed to fill Phase II proof-of-concept gap

Thank You

Collaborators – School of MedicineEdward Fuchs Medicine – ClinPharm Drug Development Unit

Anita Guidos Medicine – ClinPharm Drug Development Unit

Ying-Jun Cao Medicine – ClinPharm Post-Doctoral Fellow

Sridhar Nimmagadda Medicine – ClinPharm Post-Doctoral Fellow

Teri Parsons Medicine – ClinPharm Analytical Pharmacology

Rahul Bakshi Medicine – ClinPharm Analytical Pharmacology

Linda Lee Medicine – Gastroenterology

Kasia Macura Radiology – Magnetic Resonance Imaging

Richard Wahl Radiology – Nuclear Medicine

Jeff Leal Radiology – Nuclear Medicine

David Clough Radiology – Nuclear Medicine

Mike Torbenson Pathology

James Hildreth Pharmacology

Jean Anderson Obstetrics and Gynecology

Microbicide Development

HIV Distribution

� Objectives– Validation of HIV surrogate (99mTc-SC)

– Determination of HIV distribution and clearance

� Methods– Lymphocyte, HIV Labeling

– Distribution SPECT/CT

– Biopsy for quantitative assessment

� Future Application– Microbicide distribution with validated HIV surrogate

– HIV Challenge Study

Microbicide Toxicity

Osmolality Study

24 hrs24 hrsComplete Permeability Testing

2.25 hrs2.25 hrsRectal Lavage

2 hrs2 hrsEndoscopy

0 hrs0 hrsPermeability testing

0 hrs0 hrs99mTc-labeled vehicle

-8 hrs-8 hrsEnema

HyperosmolarHyperosmolarIsoIso--osmolarosmolarEvent/PhaseEvent/Phase

Hypothesis:

Hyperosmolar gels cause epithelial damage to colonic mucosa

Rectal Microbicide PK

Hyperosmolar Gel Effect on Mucosa

Same subject, 10 cm beyond anus, 1 hour after rectal application of gel

Panel A: Grade 1/3 toxicity, epithelial cell layer mostly intact, mucin-depleted epithelial cells

lifting off the basement membrane and separating from lamina propria (short arrows).

Panel B: Grade 3/3 toxicity, absence of epithelium and an exposed lamina propria (long arrows)

EPI - epithelial cells. LP - lamina propria. C – goblet cells.

Iso-Osmolar Gel Hyper-Osmolar Gel

Collaborators – Hopkins Outside SOM

School of Public Health

David Celentano Epidemiology - BehaviorJohn Hylton Epidemiology - Behavior

Richard Markham Mol Micro & Immunology – Animal Models

Brian Caffo Biostatistics

School of Arts and Sciences

Richard Cone Biophysics

Tom Moench Biophysics

HIV Chemoprevention

Microbicide Development Program

CDCPermeability

CDCSurrogate Gels PK

IPMTMC 120CDCCAPPhase I/II

IPMHIV distributionP30 CFARHIV distributionViral Behavior

U01 (HPTN)TenofovirCDCCAPPhase I

U01 (MTN)PermeabilityP30 CFAROsmolalityDrug toxicity

U19 (UCLA)Bhvr & Anal Health

FundingStudyFundingStudy

U19 (Biosyn)Cyanovirin

U01 (MTN)Mucosal ImagingK24 GCRCPK FeasibilityPK Methods

CDCMSM Focus GroupsHuman Behavior

Female Genital TractDistal GI TractDevelopment

Phase

Funded; Proposed

Cohen MS and Pilcher CD JID 2005 (based on Wawer, et al. JID 2005)

Phase III Challenges

� High incidence (>2%) if size to be feasible

� Confounding by anal (if vaginal), and IDU routes

� Time-limited to diminish likely reduction in adherence over time (not unique)

� Community involvement – killed at least 3 trials already

� Costs ~ US$ 50 M depending on size

Microbicide Clinical Trials

Consequences of more complex clinical trial designs. Longer trials result from the time for enrolling

additional volunteers. Trial costs are based on an estimated $30 million cost for two-arm

phase III trials and linear increases with additional volunteers.We assume 5 million new HIV infections

annually (2003 UNAIDS estimates) .

Microbicide Efficacy

Smith RJ, et al. AIDS 2005;19(4): 413–421 Figure 2.

Female sex workers who never use condoms with their clients (FSW-NCs). Bands

represent percentage reduction in daily risk of acquisition of HIV

00––10%10%

1010––20%20%

2020––30%30%

3030––40%,40%,

4040––50%,50%,5050––60%60%

6060––70%,70%,

7070––80%80%

Changing HIV Demographic

Mack, et al. JAIDS 2003

Shattock RJ and Moore JP Nat Rev Microbiol 2003

ARV effect on AIDS

Nonoxynol-9 COL-1492

� Nonoxynol-9 first reported with in vitro activity against HIV 1985 (Hicks DR, et al. Lancet 1985)

� Nonoxynol-9 recommendations for use begin appearing in medical literature at least as early as 1987

� Prevents prevents SIV in macaques (Miller CJ, et al. Fertil Steril 1992)

� Phase I short term studies – some with inflammation

� Phase II mixed results across studies some with vaginal epithelial disruptions with prolonged use

� Phase II/III Kenya and Cameroon trial suggest no protection or decreased protection (Kreis JAMA 1992 challenged for methodology; Roddy NEJM 1998)

� 2 Cohort studies show protective effect in consistent high risk users (ZekengAIDS 1993; Hira Int J STD AIDS 1997)

� Phase III Thailand/South Africa July 2000 increased HIV transmission risk, frequency dependent (Van Damme Lancet 2003)

PrEP and Condom Migration

HAART Effect on Risk Behavior

� Increased Risky Behaviors– Miller M. AIDS. 2000

– Ostrow DE. AIDS. 2002

– Kartz MH. Am J Public Health. 2002

– Desquilbet L. AIDS. 2002

– Stolte G. Euro Surveill 2002

� No change in Risky Behaviors– Van der Straten A. AIDS 2000

– Wolf K. JAIDS 2003

� Decrease in Risky Behaviors– Bouhnik AD. J Epidemiol Community Health. 2002

Pre-Exposure Prophylaxis

� Current clinical trials

� PK-PD model to inform future trials – our model

plan

� Does the route of administration make sense

– Reduced dose?

– Adequate tissue levels?

– Reduced toxicity?

– Resistance risk?

PrEP and Resistance

� High transmissibility in early infection also

suggests most effective ARV would be PrEP in

order to catch high VL, otherwise less impact

� BUT, this is riskiest for resistance since load high

and may increase risk of resistance if single agnet

� In the end, it depends largely on balance between

degree of efficacy and likelihood of resistance

with failure for given ARV

Wawer, et al. JID 2005 Figure 1

Vaginal Microbicide PK

Imaging Gel Distribution: MRI

� Gadolinium labeled gel

� Resolution - 1 mm

� Measurable Variables– Anatomic distribution

– Spread over time

– Ambulation effects

– Simulated Intercourse

– Surface area coverage

6 hours after Gadolinium-labeled

Nonoxynol-9 Gel Insertion into the VaginaCourtesy: Kurt Barnhart, U Penn

SP

Introitus

Vagina

Uterus

RectalAmpulla

Bladder

Condom-to-Microbicide Migration

Smith RJ, et al. AIDS 2005;19(4): 413–421 Figure 3.

Change in transmission risk with addition of microbicides is more sensitive to use than efficacy

30% Microbicide Efficacy 50% Microbicide Efficacy 80% Microbicide Efficacy

Prevention and Treatment

Interactions

R0 = β · c · D

R0 reproductive rate of infection

(>1 = epidemic)

β transmissibility per contactc rate at which contact made

D duration of infectiousness

Limit

partners

ARV Rx↑

↓

ARV Rx

Condoms

PEP

PrEP?

Microbicides?

Rationale

Evolution of HIV Chemoprevention

� Vertical Transmission (RCT Connor E NEJM 1994)

� Post-Exposure Prophylaxis (PEP) (Case-Control Cardo NEJM 1997)

� Antiretroviral Therapy– 0.5 RR hetero ZDV partners (Musicco Arch Intern Med 1994)

– 0.4 RR MSM HAART community (Porco AIDS 2004)

– 0% infection heterosexual HAART couples (Castilla JAIDS 2005)

� Sexual Post-Exposure Prophylaxis (nPEP or PEPSE)– Observational study, no efficacy, ? power (Schechter JAIDS 2004)

– Recommendations - animal models (Tsai CC. Science 1995, J Virol 1998)

� Pre-Exposure Prophylaxis (PrEP) (RCTs begin 2005)

� Topical Microbicides (RCTs begin 2005)

Development

CDC PrEP Study PK-PD Modeling� Intracellular pharmacokinetics in clinical study

� Model IC PK based on extracellular (EC) plasma PK

� Model prevention efficacy (PD) with IC-EC levels

� Determine target drug levels

Development

PrEP and HIV Resistance

� Failure of PrEP results in monotherapy during highest viral load possibly selecting for resistance

� Relevant only in failures

� High efficacy diminishes impact

� ARV slow to develop resistance favored

� Increases importance of HIV testing (shorten duration of ineffective ARV)

� Balance cost/adherence/safety v. resistance concern

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