Cardiovascular effects of apelin infusion in healthy male subjects

Apelin is a protein that is made in the blood vessels of many parts of the
body. Apelin increases the contraction of the heart, lowers blood pressure, and
promotes the formation of new blood vessels. Apelin is not registered as a drug
but has been given to humans before.

The purpose of the study is to compare the hemodynamic effects (study of blood
flow or circulation, such as blood pressure, heart rate, cardiac output (the
volume of blood being pumped by the heart) and glomerular filtration rate (flow
rate of filtered fluid through the kidney) of apelin to those of the registered
sodium nitroprusside (SNP; a drug that is used to lower blood pressure in
people with severe hypertension) and control (placebo).
This study is not intended to improve the health of the subjects, but may help
the further development of apelin. Furthermore, this study is being conducted
to see if medications that are similar to apelin may be useful in people with
heart or blood vessel diseases.

This is a six-period infusion study in fifteen healthy male subjects. In
periods 1 and 2 the optimal dose, safety, and tolerability of apelin (APL)
and sodium nitroprusside (SNP) infusions will be assessed.

Procedures and assessments:

Screening and follow-up: clinical laboratory, vital signs, weight, physical
examination, ECG
At eligibility screening: medical history, height, drug screen, HBsAg, anti
HCV, anti-HIV 1/2;
Drug screen to be repeated upon first admission

Observation period: 2 periods, first period in clinic from -17 h up to 24 h
after start of APL infusion on Day 1 up to 4 h after start of APL infusion on
Day 2 and second period in clinic from Day 8 for start of sodium stabilization
up to 4 h after start of APL/SNP/placebo infusion on Day 12

Blood sampling:
For pharmacokinetics of APL in plasma: 5 minutes prior to the start of infusion
on Day 1 of period 1, and 25, 55, 90, 95, 105 and 115 minutes after the start
of infusion on Day 1 of period 1
5 minutes prior to the start of infusion on Day 2 of period 1, and 5, 10, 15,
25, 55, 115, 175, 235, 245, 255 and 270 minutes after the start of infusion on
Day 2 of period 1
5 min prior to start of infusion in period 2, and 25, 55, 120, 180 and 240
minutes after the start of infusion in period 2
5 minutes prior to the start of infusion on Day 1 of period 7, and 5, 10, 15,
25, 55, 115, 175, 235, 245, 255 and 270 minutes after the start of infusion on
Day 1 of period 3 (period 7 study protocol)

For pharmacokinetics of iohexol in plasma: 5 min prior to start of infusion in
period 2, and 25, 55, 120, 180, 240 and 265 minutes after the start of infusion
in period 2

Hemodynamic Assessments:
Upright blood pressure, heart rate and cardiac output: 5 minutes prior to the
start of APL and SNP infusion on Day 1 of period 1, and 25, 55, 85 and 115
minutes after the start of APL and SNP infusion on Day 1 of period 1, and 5
minutes prior to the start of APL infusion on Day 2 of period 1, and 25, 145,
270 and 300 minutes after the start of APL infusion on Day 2 of period 1, and 5
minutes prior to the start of APL, SNP and placebo infusion in period 2, and
25, 145, 270 and 300 minutes after the start of APL, SNP and placebo infusion
in period 2.
Supine blood pressure, heart rate and cardiac output: 55, 85, 115, 175, 210 and
235 minutes after the start of APL, SNP and placebo infusion in period 1 and 2.

ATII pressor test: 60 and 90 minutes after start of APL, SNP and placebo
infusion in period 2

NE pressor test: 180 and 210 minutes after start of APL, SNP and placebo
infusion in period 2

Glomerular Filtration Rate (GFR): 30 minutes prior to start of APL, SNP and
placebo infusion in period 2

Safety assessments: adverse events and concomitant medications: throughout the
study; ECG: 15 minutes prior to and 115 minutes after the start of APL infusion
on Day 1 of period 1, and 15 minutes prior to and 300 minutes after the start
of APL infusion on Day 2 of period 1.

In the first period the subjects will receive 3 different infusions:
- Apelin will be administrated by infusion at 3 dose levels (0.3, 3.0 and 30
nmol/min) for 30 minutes each.
- SNP will be administrated by infusion at 3 dose levels (0.25, 0.625 and 1.5
ug/kg/min) for 30 minutes each.
- Apelin will be administrated by infusion at the maximum dose level for 4
hours.

In the second period the subjects will receive apelin, SNP and placebo
infusions for 4 hours in a randomized (by chance) sequence.

In the third period (period 7 study protocol) the volunteers will receive a 4
hour infusion of apelin.

Registration of adverse effects: During the entire investigation all adverse
effects will be documented.

Blood draw, indwelling cannula: During this study less than 500 ml of blood
will be drawn. It is anticipated that for the blood draws at Day 1 and 2 of
each period an indwelling cannula will be used as there are several blood
samples taken over these days. On the other days blood will be drawn by direct
puncture of the vein.

IV dosing: For the iv administration an indwelling cannula will be inserted
specifically for this purpose in addition to the indwelling cannula used for
blood sampling.

Heart trace (ECG*s): ECG*s will be made regularly.

Systolic and diastolic blood pressure, and heart rate: Systolic and diastolic
blood pressure and heart rate will be recorded twice over approximately 2
minutes at several time points during the study. Thereafter blood pressure and
heart rate will be measured in upright position after 3 and 5 minutes.

Cardiac output: Electrodes will be placed on the chest to measure the volume of
blood being pumped by the heart. This will be measured noninvasive with the
Physioflow at many time points during each infusion.

Angiotensin II Pressor Test: Blood pressure and heart rate will be recorded
twice over 2 minutes during the infusion of 2 and 6 ng/kg/min of intravenous
angiotensin II (AT II), a naturally occurring hormone that increases blood
pressure. Each dose will be infused for approximately 30 minutes in supine
position. This test will be performed to study the effect of apelin on AT
II-induced contraction of the blood vessels.

Noradrenaline Pressor Test: Blood pressure and heart rate will be recorded
twice over 2 minutes during the infusion of 0.03 and 0.1 ug/kg/min of
intravenous noradrenaline (NE), a naturally occurring hormone that increases
blood pressure. Each dose will be infused for approximately 30 minutes each in
supine position. This test will be performed to study the effect of apelin on
noradrenaline-induced contraction of the blood vessels.

Glomerular filtration rate: Intravenous iohexol (an indicator of the blood flow
in the kidney) will be administrated prior to the start of apelin infusion to
calculate the flow rate of filtered fluid through the kidney. Blood samples to
measure iohexol will be taken at several time points during the infusions.