non-invasive telemetry what else but ecg ? pierre lainee claire grant – emily bailey

Non-invasive telemetryWhat else but ECG ?

Pierre Lainee

Claire Grant – Emily Bailey

Non invasive telemetry BP

Why would we use it in Tox studies ?

Because they give access to repeated dosing Because exposures are higher, potentially improving safety margins Because Phase 1 trials also include repeated administration Because small changes over long periods need attention If ECG is already collected with this method, limiting the need for

additional jacket training Because incidence of BP effects in preclinical studies is significant

2 EMKA Presentation– 21 September 2011

0%

20%

40%

60%

80%

100%

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

No Effect Effect at High Dose Effect at Mid Dose Effect at Low Dose

Impact of repeated dosing

Comparison of ECG findings beginning vs. end of studies


Identical69%

Increase13%

Decrease18%

Different0%

Identical70%

Increase17%

Decrease13%

Different0%

Dog DRF studies (n=150) Dog 1-month studies (n=160)

Isn’t it likely to be similar for BP effects ?

Current Methods


Blood Pressure

Invasive telemetry Not suitable for tox studies

Minimally invasive telemetry Growing interest and rational But still demanding and expensive

Invasive ear catheter Restraint/Stress 30s/twice a week

Respiration

Rodent WBPThis is an indirect measure of respiratory functionLimited in duration due to animal welfare constraints

Non-invasive Blood Pressure (NIBP)


Utilises tail cuff Detects changes in oscillations Extended recording periods Freely moving animals Programmed to inflate/deflate every 4 min Cuff inflated to 240 mmHg Deflation takes ~ 30 s Reported as an average of 5 inflations (time point ±10 min) On average replace tail cuff ~ 1 per session From our experience, we feel that the difficulty of keeping the cuff on

is strongly related to the tail shape, e.g. some have very thick bases and the tail gets progressively thinner (cone- shaped)

Non-invasive Blood Pressure (NIBP)

• Tail is shaved (~ 10 cm)

• Animals are habituated to tail cuff (at the same time as jacket

training). First training session just jacket, second session

with tail cuff, third session with cuff inflating/deflating. Each

session gets progressively longer.

• Wrap the tail cuff round the tail, approximately 3 cm from the

base of the tail.

• Vetwrap is wrapped round the tail below the cuff to prevent the

cuff from slipping (a ‘stopper’).

• Another layer of vetwrap is placed round the cuff and the

‘stopper’.

• Do not wrap too tightly as this will impair blood flow. The tubes

coming out of the cuff are cut to correct length to and are

attached to the transmitter.


Animal preparation

Respiratory Inductive Plethysmography (RIP)

RIP utilizes specialized belts containing inductive wires

placed around the thorax and abdomen.

Measures changes in inductance, which are

proportional to cross sectional area and then indirectly

to lung volume.

Enables calculation of breathing frequency (f), tidal

volume (TV) and minute volume (MV).

To get volume values, a face mask calibration is

required (approx. 30 sec measurement).

Good calibration performed pre-study and that

calibration coefficient used for subsequent recordings

for that dog.

Animal posture does not impact on calibration (let the

dog be in a relaxed position).


Analysis


Blood Pressure

Pulse amplitude vs. Cuff pressure plotted

SBP and DBP derived from curve

Respiration

Respiratory trace recording

Continuous acquisition and on-line analysis of ach breath(up to ~30,000 during a 24 hour recording)

Noisy data can easily be excluded

Analysis

Signals are acquired and analysed by the EMKA analysis system.

Methods


4 reference compounds tested

Theophylline: 0, 5, 10 and 20 mg/kg

Clonidine: 0, 0.03, 0.1 and 0.3 mg/kg

Verapamil: 5, 10 and 15 mg/kg

L-NAME: 0 and 10 mg/kg

Single dose of vehicle followed by single dose of compound in ascending

concentrations at intervals of 2-5 days

Dogs are part of the invasive telemetry colony, naïve to jacket training

SBP, DBP and ECG recorded by invasive telemetry (INV)

SBP, DBP, ECG, f, TV, MV recorded by NIBP and RIP

Blood Samples taken at pre-dose, 1, 3 and 24 hours

All animals observed via CCTV for abnormal clinical signs and vomiting

NIBP vs. INV


Values for both SBP (-14%) and DBP(-10%) are lower with the NIBP system than the INV.

NIBP system measures pressure in the medial coccygeal artery

INV measures pressure directly in the descending aorta

Reference (i.e. zero) value not undefined for INV

Sensitivity of NIBP systemTheophylline

11 EMKA Presentation– 21 September 2011Graphs only display high dose, mean ± SEM

• System detected increase in BP• Duration and magnitude similar to

invasive telemetry.

NIBP

INV

Sensitivity of NIBP system

L-NAME


NIBP

INV

• System detected increase in BP• Duration and magnitude similar to

invasive telemetry.

Graphs only display high dose , mean ± SEM


Clonidine


• NIBP is less sensitive than INV for this decrease in BP

Graphs only display high dose , mean ± SEM

NIBP

INV

Verapamil

14 EMKA Presentation – 21 September 2011 Graphs only display high dose , mean ± SEM

• System detected decrease in BP• Duration and magnitude similar

to invasive telemetry• Effects on DBP are less marked

NIBP

INV


NIBP variability

Using 4 animals the statistical power of NIBP and INV to detect significant changes in blood pressure are comparable.

Using the NIBP system with 4 dogs a change of 24 (SBP) and 18 (DBP) mmHg is significant (vs. 29 and 18 for INV)

Most of the difference in sensitivity comes from the ability to select the best periods with invasive telemetry (i.e. continuous vs. repeated timepoints)

15 EMKA Presentation – 21 September 2011

Baseline values(mmHg)

Significant Delta%(80% power, n=4)

Duration of recording

• Recording of NIBP has been limited to 6 h post-dose for welfare reasons and

better protection of the equipment.

• A review of AstraZeneca INV telemetry studies from 2000 (~300 studies) was

performed.

• 36 studies showed clear blood pressure related effects.

- T max ≤ 6h 35 studies

- Time of onset all below 4 h

- Return to baseline ≤ 6h 16 studies

• If recording for 6 h post-dose an effect would have been detected in all studies.


Sensitivity of RIP system

17

5 mg/kg 10 mg/kg 20 mg/kg

BF +22% +18% +45%

TV +18% +21% +25%

MV +25% +41% +78%

0.03 mg/kg 0.01 mg/kg 0.3 mg/kg

BF -21% -16% -28%

Theophylline

Clonidine

EMKA Presentation – 21 September 2011

Graphs only display high dose

Sensitivity of RIP system


10 mg/kg

BF +32%

TV -26%

MV -28%

L-NAME

Graphs only display high dose.% change is max effect compared to time matched vehicle.

NIBP Practical considerations

Pros and Cons

Although HDO offers a better outcome, it

seems that SBP effects are still better

detected than DBP ones Long term recording but not continuous,

which limits the selection of optimal period,

and secondarily decreases sensitivity Limitations in early studies due to small

groups Additional time for data analysis (but very

valuable data) Additional investment (but value for money)

Access to effects after repeated dosing with

no need for additional study and no surgery Easy to use with staff trained to external

telemetry Training is not a limitation as it takes place

along jacket training In a context where external telemetry is

used routinely, NIBP and RIP definitely add

value In the hands of a SP group, reference

compounds do show the expected effects Sensitivity can be compensated by larger

size groups in 1-month studies


This validation work was convincingand NIBP will find a place in our CVS strategy

Testing Strategy

Include NIBP in repeat dose phase of dose range finding dog toxicology

study when blood pressure liability is identified from Project knowledge Earlier CVS studies (anesthetised GP or rat telemetry)

3Rs incentive of more data without increasing animal numbers

Include RIP in GLP invasive telemetry study (need more data first). Replace rodent whole body plethysmography study. 3Rs incentive of reduction of ~40 rodents per compound. Assess multiple organ systems simultaneously in large animals to explore the

pharmacological interaction in response to a drug.


Conclusions


10 minutes to jacket animal and perform 30 second calibration BP – 6 hours, Respiration and ECG 24 hours Detected changes in response to reference compounds Ease of analysis – eliminates noisy data No effect on quality of ECG measurements

Future Work and Perspectives

Now being used in repeat-dose tox studies Incorporation into ToE ?

Use of activity and video for clinical monitoring Improves vomiting detection

Possible replacement of WBP with RIP Bronchoconstriction – Carbachol

use of the shift between abdominal and thoracic signals)

Thanks

To all staff involved in testing over the last year

- Emily for her dedication along a placement year

- Claire for supervising the work and organising the

studies

- Jackie for helping with the invasive telemetry

acquisition and analysis

- Clare and Kate for bringing the expertise and patience

acquired from ECG recordings into this new method

To the EMKA team which provided

- the appropriate conditions and support for the required

adjustments to be made

- the training to facilitate data analysis optimisation


non-invasive telemetry what else but ecg ? pierre lainee claire grant – emily bailey

Documents

tail cuff

cuff inflatingdeflating

emka presentation

tail shape

animal preparation slide

tox studies

training session

invasive telemetry bp