Vasomotor Symptoms and Cardiovascular Control

Visit 1: Screening & Acclimation Visit

The informed consent process for the study will be completed and a signed informed consent
form will be obtained at Spaulding Hospital Cambridge. Subjects will be screened to ensure
they meet preliminary eligibility criteria. All subjects will undergo a clinical interview
to determine the presence of any medical disorders. The following study assessments will be
completed:

- 12-lead EKG

- Resting blood pressure and heart rate

- Height and Weight

Visit 2: VMS Determination and At-Home Assessments Subjects will be interviewed about their
mental health history, and will complete questionnaires about their VMS, related
quality-of-life symptoms (sleep, mood) and quality-of-life. Blood will be drawn to confirm
eligibility and to assess for diabetes and chronic kidney disease (see exclusion criteria).
Subjects will be given a 7-day VMS Diary and a 7-day Sleep Diary at the end of this visit,
to be completed at home during the following week. Participants will also be given an
actigraphic watch to take home to wear for 7 days in order to capture sleep/wake patterns
and activity levels for exploratory analyses. During the 7 days of at-home VMS and sleep
monitoring, subjects will also wear a portable VMS monitor for 24 hours to measure objective
VMS frequency.

Visit 3: Final Eligibility Determination & Lab VMS Monitoring Subjects will return the
objective VMS monitor and the VMS and sleep diaries, and the results of their blood tests
taken during the Visit 2 will be reviewed to ensure eligibility. Eligible subjects will
participate in a 6-hour laboratory objective VMS monitoring session by wearing an objective
VMS monitor while simultaneously subjectively monitoring VMS experienced with a written
diary and an event marker. Objective VMS measures obtained during this visit will be the
primary baseline measure of VMS for investigation. Those who have at least 2 objective VMS
measured during the 6-hour monitoring period will be deemed eligible and referred for
baseline studies and to start medication. Participants will be given additional VMS and
sleep diaries to complete on a daily basis throughout the rest of the study period.

Visit 4: Laboratory Testing Visit & Medication Distribution All studies will be performed
between ~8-10 am and will occur at the same time for the second laboratory testing visit.
All subjects will be instructed to abstain from vigorous exercise for 2 days prior to each
study to avoid autonomic and neuroendocrine effects of exercise. In addition, subjects will
refrain from caffeine and alcohol for the previous 24 hrs, and be studied after a 12 hr
fast.

A. Study Visit: Parameters to be Measured

1. Electrocardiogram.

2. Arterial Pressure.

3. Respiration.

4. Sympathetic Microneurography.

5. Beat-by-Beat Leg Blood Flow. B. Drugs to Study Human Physiology

1) Intravenous bolus injection of 100 ug nitroprusside bolus (a vasodilator which drops
pressure) 2) Intravenous bolus injection 150 ug phenylephrine bolus (a vasoconstrictor which
raises pressure).

These two drugs are used to drop and raise pressure through a range of arterial pressures
within a very short time, approximately 2 minutes.

These medications raise and lower blood pressure by the same amount typically experienced
during the day when performing activities such as climbing stairs or moving from sitting to
standing.

C. Data to be collected/Timing of collection The study visit will take about 4 hours.
Throughout the protocol, subjects will lie supine and will be instrumented for measurement
of the ECG, beat-by-beat arterial pressure, brachial arterial pressure, respiratory
excursions, and popliteal blood flow velocity. After instrumentation and calibration,
instrumentation for measurement of peroneal nerve muscle sympathetic activity will commence,
with the internal search lasting a maximum of 60 minutes.

After either successful or unsuccessful procurement of the nerve recording, the testing
protocol will start:

Testing Protocol

1. Baseline recordings/measurement (~10 minutes): Subjects will rest quietly for 10
minutes.

2. Modified Oxford Baroreflex tests (5 minutes/trial, 2 trials, ~30 minutes total): An
intravenous bolus injection of 100 ug nitroprusside bolus, followed in 1 minute by a
150 ug phenylephrine bolus. After the first trial, a second modified Oxford baroreflex
test will be performed. At least 10-15 minutes will be allowed between the baroreflex
trials to insure that heart rate, blood pressure and nerve activity return to resting
levels. Subjects will be continually assessed for adverse events and symptoms related
to hypotension.

3. Sustained isometric handgrip exercise (~10 minutes): Subjects will be asked to perform
an isometric handgrip exercise at 30% of maximum effort sustained to fatigue.

4. Valsalva's maneuver (~5 minutes): Subjects will be asked to blow into a tube via a
mouthpiece and generate a pressure of ~40 mmHg sustained for 12 seconds. Data will be
collected for one minute prior to the maneuver, one minute after, with two minutes of
recovery between trials. This will be repeated to obtain three successful trials.

5. Paced breathing (~15 minutes total): Subjects will be asked to maintain a constant
breathing frequency of 15 breaths/min (0.25 Hz) following an audio signal (i.e., "in,
two, out, two") for 5 minutes after a short period of acclimation.

Distribution of Study Medication: After all baseline measures are complete, study medication
(gabapentin) will be distributed to all study participants and participants will be
instructed as to how to take and titrate the medication dose.

Visit 5a: Medication Dosage & Adverse Event Monitoring (Telephone) Study staff will check in
with study participants over the telephone after they have been on gabapentin for
approximately one week to monitor any side effects or adverse events of the medication. If
subjects are experiencing intolerable side effects, they will be taken off of the medication
while completing the remaining study procedures. In order to track potential after effects
of microneurography, subjects who had the electrode placed beneath the surface of their skin
will be given the Microneurography Questionnaire (MSNA). Over the last 18 years of
performing the technique, roughly 5% of participants have after effects, and of these the
most often reported effect (>90%) is slight bruising at the site of insertion.

Visit 5b: Medication Dosage & Adverse Event Monitoring (Telephone) Study staff will check in
with study participants over the telephone after they have been on gabapentin for
approximately three weeks to monitor any side effects or adverse events of the medication.
If subjects are experiencing intolerable side effects, they will be taken off of the
medication while completing the remaining study procedures.

Visit 6: Objective VMS Monitoring All subjects will repeat the 6-hour laboratory objective
VMS monitoring session on gabapentin for post-treatment measures of VMS, as described above
for Visit 3. Participants will also complete the same set of pre-treatment questionnaires
about their VMS, related quality-of-life symptoms (sleep, mood) and quality-of-life. All
subjects will be given the ambulatory VMS monitor to wear for 24 hours at home, to capture
the frequency of VMS in the ambulatory setting as well as the actigraphic watch to wear for
a one-week period. Participants will be reminded to continue to complete their VMS and sleep
diaries.

Visit 7: Laboratory Testing Visit & Medication Collection Procedures performed during Visit
4 will be repeated at Visit 7, to collect data on cardiovascular measures after participants
have been on gabapentin for at least 4 weeks at the full dose. All VMS and sleep diaries, as
well as unused study medication, actigraphic watch, and the objective VMS monitor, will be
returned and collected at this visit.

Inclusion Criteria:

1. Women aged 45 to 58 years,

2. Early postmenopausal, defined as a minimum of one year and up to 6 years from final
menstrual period (FMP)

3. Vasomotor symptoms for at least 6 months

- At least 4/day or 28/week by retrospective report and confirmed on prospective
monitoring over 2-week period.

- At least 2 VMS measured objectively on the VMS monitor during the 6-hour VMS
laboratory monitoring session.

4. Normal to overweight (18.5≤BMI≤35 kg/m2)

5. Sedentary to normally physically active (performing regular aerobic exercise <60
min/week)

Exclusion Criteria:

1. Hypertension (resting pressures ≥140/90 mmHg)

2. Diabetes (verified by plasma hemoglobin A1C level ≥6.5)

3. Cardiovascular disease, including any stenotic valvular heart disease

4. Neurological disease

5. Current depression (per screening procedures)

6. Current or history of suicidal ideation or attempts (within 3 years prior to
enrollment)

7. Lifetime history of bipolar disorder

8. Active cancer (non-melanoma skin cancer allowed)

9. Abnormal resting ECG

10. Recent weight change (>10 lb weight change in last 6 months)

11. Regular tobacco use/current smoking

12. Current use of anti-hypertensives or other medications that could influence any of
the dependent variables

13. Current or previous use (past 2 months) of anti-anxiety, anti-depressant or
antipsychotic medications

14. Current use of vasodilators

15. Current use of stimulants or stimulant-like medications

16. Current use of systemic hormone therapies/medications

17. Current use of non-hormonal treatments for VMS

18. Current use of gabapentin or medications contraindicated to be used in combination
with gabapentin

19. Past intolerance or hypersensitivity to gabapentin

20. History of syncope or vasovagal/carotid sensitivity

21. History of sickle cell anemia

22. Abnormal kidney function: CrCl or GFR <60 ml/min (Cockcroft and Gault equation)

23. Ventricular tachycardia

24. Hyperthyroidism

25. Hypersensitivity to phenylephrine

26. Compensatory hypertension, where the primary hemodynamic lesion is aortic coarctation
or arteriovenous shunting

27. Congenital (Leber's) optic atrophy or tobacco amblyopia

28. Hypersensitivity to nitroprusside