CLINICAL PHARMACOLOGY
Mechanism Of Action
Tolvaptan is a selective vasopressin V2-receptor antagonist with an affinity for the
V2-receptor that is 1.8 times that of native arginine vasopressin (AVP). Tolvaptan
affinity for the V2-receptor is 29 times that for the V1a-receptor. Decreased binding
of vasopressin to the V2-receptor in the kidney lowers adenylate cyclase activity
resulting in a decrease in intracellular adenosine 3′, 5′-cyclic monophosphate (cAMP)
concentrations. Decreased cAMP concentrations prevent aquaporin 2 containing
vesicles from fusing with the plasma membrane, which in turn causes an increase in
urine water excretion, an increase in free water clearance (aquaresis) and a decrease
in urine osmolality. In human ADPKD cyst epithelial cells, tolvaptan inhibited
AVP-stimulated in vitro cyst growth and chloride-dependent fluid secretion into
cysts. In animal models, decreased cAMP concentrations were associated with
decreases in the rate of growth of total kidney volume and the rate of formation
and enlargement of kidney cysts. Tolvaptan metabolites have no or weak antagonist
activity for human V2-receptors compared with tolvaptan.
Pharmacodynamics
In healthy subjects or patients with eGFRs as low as 10 mL/min/1.73m2 receiving a
single dose of tolvaptan, the onset of the aquaretic effects occurs within 1 to 2 hours
post-dose. In healthy subjects, single doses of 60 mg and 90 mg produce a peak
effect of about a 9 mL/min increase in urine excretion rate is observed between 4 and
8 hours post-dose. Higher doses of tolvaptan do not increase the peak effect in urine
excretion rate but sustain the effect for a longer period of time.
Urine excretion rate returns to baseline within 24 hours following the maximum
recommended 90 mg dose of tolvaptan.
Changes in free water clearance mirror the changes in urine excretion rate. Increased
free water clearance causes an increase in serum sodium concentration unless fluid
intake is increased to match urine output.
Increases in urine excretion rate and free water clearance are positively correlated
with baseline glomerular filtration rate with increases in both values observed in
patients with creatinine clearance as low as 15 mL/min.
With the recommended split-dose regimens, tolvaptan inhibits vasopressin from
binding to the V2-receptor in the kidney for the entire day, as indicated by increased
urine output and decreased urine osmolality. Following a 90/30 mg split-dose
regimen in patients with eGFR >60 mL/min/1.73 m2, the change in mean daily urine
volume was about 4 L for a mean total daily volume of about 7 L. In patients with
eGFR <30 mL/min/1.73 m2, the mean change in daily urine volume was about 2 L for
a total daily urine volume of about 5 L.
Plasma concentrations of native AVP may increase (avg. 2-9 pg/mL) with tolvaptan
treatment and return to baseline levels when treatment is stopped.
During tolvaptan treatment, small changes in renal function are expected and the
changes are independent of baseline renal function. Glomerular filtration rate is
decreased about 6%-10% and uric acid clearance is decreased about 20%-25%.
Percent changes in renal plasma flow are highly correlated to percent changes in
GFR. These changes are reversed upon discontinuation of tolvaptan.
Cardiac Electrophysiology
No prolongation of the QT interval was observed with tolvaptan following multiple
doses of 300 mg/day for 5 days.
Pharmacokinetics
In healthy subjects, the pharmacokinetics of tolvaptan after single doses of up to
480 mg and multiple doses up to 300 mg once daily have been studied. In ADPKD
patients, single doses up to 120 mg and multiple split-doses up to 90/30 mg have
been studied.
Absorption
In healthy subjects, peak concentrations of tolvaptan are observed between 2 and
4 hours post-dose. Peak concentrations increase less than dose proportionally with
doses greater than 240 mg.
The absolute bioavailability of tolvaptan decreases with increasing doses. The absolute
bioavailability of tolvaptan following an oral dose of 30 mg is 56% (range 42-80%).
Co-administration of 90 mg JYNARQUE with a high-fat meal (~1000 calories, of
which 50% are from fat) doubles peak concentrations but has no effect on the AUC
of tolvaptan; tolvaptan may be administered with or without food.
Distribution
Tolvaptan binds to both albumin and α1-acid glycoprotein and the overall protein
binding is >98%; binding is not affected by disease state. The volume of distribution
of tolvaptan is about 3 L/kg. The pharmacokinetic properties of tolvaptan are
stereospecific, with a steady-state ratio of the S-(-) to the R-(+) enantiomer of about
3. When administered as multiple once-daily 300 mg doses to healthy subjects or as
split-dose regimens to patients with ADPKD, tolvaptan’s accumulation factor is <1.2.
There is marked inter-subject variation in peak and average exposure to tolvaptan
with a percent coefficient of variation ranging between 30 and 60%.
Metabolism And Elimination
Tolvaptan is metabolized almost exclusively by CYP 3A. Fourteen metabolites have
been identified in plasma, urine and feces; all but one were also metabolized by
CYP 3A and none are pharmacodynamically active. After oral administration of
radiolabeled tolvaptan, tolvaptan was a minor component in plasma representing 3%
of total plasma radioactivity; the oxobutyric acid metabolite was present at 52.5% of
total plasma radioactivity with all other metabolites present at lower concentrations
than tolvaptan. The oxobutyric acid metabolite shows a plasma half-life of ~180 h.
About 40% of radioactivity was recovered in urine (<1% as unchanged tolvaptan)
and 59% in feces (19% as unchanged tolvaptan). Following intravenous infusion,
tolvaptan half-life is approximately 3 hours. Following single oral doses to healthy
subjects, the estimated half-life of tolvaptan increases from 3 hours for a 15 mg
dose to approximately 12 hours for 120 mg and higher doses due to more prolonged
absorption of tolvaptan at higher doses; apparent clearance is approximately
4 mL/min/kg and does not appear to change with increasing dose.
Specific Populations
Age, Gender And Race
Age, gender and race have no effect on tolvaptan pharmacokinetics.
Hepatic Impairment
In studies involving patients with hepatic impairment (Child-Pugh class A-C), but
without ADPKD; moderate (class A, B) or severe (class C) hepatic impairment
decreases the clearance and increases the volume of distribution of tolvaptan.
Renal Impairment
In subjects with creatinine clearances ranging from 10-124 mL/min administered a
single dose of 60 mg tolvaptan, the AUC and Cmax of plasma tolvaptan was increased
90% and 10%, respectively, for subjects with clearances of <30 mL/min compared to
subjects with clearances >60 mL/min [see Use In Special Populations].
In ADPKD patients with estimated creatinine clearance >60 mL/min, pharmacokinetics
were similar to healthy subjects.
Drug Interactions
Impact Of Other Drugs On Tolvaptan
Strong CYP 3A Inhibitors
Tolvaptan’s Cmax and AUC were, respectively, 3.5 times and 5.4 times as high
following ketoconazole 200 mg given one day prior to and concomitantly with
30 mg tolvaptan.
Moderate CYP 3A4 Inhibitors
Fluconazole
Fluconazole 400 mg given one day prior and 200 mg given concomitantly
produced an 80% and 200% increase in tolvaptan Cmax and AUC, respectively.
Grapefruit Juice
When 60 mg tolvaptan was taken with 240 mL regular strength
grapefruit juice, tolvaptan Cmax and AUC increased 90% and 60%, respectively.
CYP 3A Inducers
Rifampin
Rifampin 600 mg once daily for 7 days followed by a single 240 mg dose
of tolvaptan decreased both tolvaptan Cmax and AUC about 85%.
Other Drugs
Co-administration of lovastatin, digoxin, furosemide, and hydrochlorothiazide with
tolvaptan has no clinically relevant impact on the exposure to tolvaptan.
Impact Of Tolvaptan On Other Drugs
CYP 3A Substrates
Co-administration of lovastatin and tolvaptan increases the AUC of lovastatin and its
active metabolite lovastatin-β hydroxy acid by 40% and 30%, respectively. These are
non-clinically significant increases in exposure.
P-gp Substrates
Digoxin
Digoxin 0.25 mg was administered once daily for 12 days. Tolvaptan
60 mg, was co-administered once daily on Days 8 to 12. Digoxin Cmax and AUC were
increased 30% and 20%, respectively.
Transporter Substrates
Tolvaptan is a substrate of P-gp and an inhibitor of P-gp and BCRP. The oxobutyric
acid metabolite of tolvaptan is an inhibitor of OATP1B1/B3 and OAT3; in vitro studies
indicate that tolvaptan or the oxobutyric acid metabolite of tolvaptan may have the
potential to increase exposure of drugs that are substrates of these transporters [see
DRUG INTERACTIONS].
Other Drugs
Co-administration of tolvaptan did not meaningfully alter the pharmacokinetics of
warfarin, furosemide, hydrochlorothiazide, or amiodarone (or its active metabolite,
desethylamiodarone).
Clinical Studies
JYNARQUE was shown to slow the rate of decline in renal function in patients at
risk of rapidly progressing ADPKD in two trials; TEMPO 3:4 in patients at earlier
stages of disease and REPRISE in patients at later stages. The findings from these
trials, when taken together, suggest that JYNARQUE slows the loss of renal function
progressively through the course of the disease.
TEMPO 3:4-NCT00428948: A Phase 3, Double-Blind, Placebo-Controlled, Randomized
Trial In Early, Rapidly-Progressing ADPKD
In TEMPO 3:4, 1445 adult patients (age >18 years) with early (estimated creatinine
clearance [eCrCl] ≥60 mL/min), rapidly-progressing (total kidney volume [TKV]
≥750 mL and age <51 years) ADPKD (diagnosed by modified Ravine criteria) were
randomized 2:1 to treatment with tolvaptan or placebo. Patients were treated for up
to 3 years; patients who discontinued medication prematurely were only required
to attend clinic visits to assess renal function for up to 42 days after treatment
withdrawal and to attend telephone visits at all scheduled visits for up to 36 months.
Patients who completed treatment at the 3-year visit had treatment interrupted for
2-6 weeks to assess renal function post treatment. Patients received treatment twice
a day (first dose on waking, second dose approximately 9 hours later). Patients
were initiated on 45 mg/15 mg, and up-titrated weekly to 60 mg/30 mg and then
to 90 mg/30 mg as tolerated. Patients were to maintain the highest tolerated dose
for 3 years, but could interrupt, decrease and/or increase as clinical circumstances
warranted within the range of titrated doses. All patients were encouraged to drink
adequate water to avoid thirst or dehydration and before bedtime.
The primary endpoint was the intergroup difference for rate of change of TKV
normalized as a percentage. The key secondary composite endpoint (ADPKD
progression) was time to multiple clinical progression events of: 1) worsening kidney
function (defined as a persistent 25% reduction in reciprocal serum creatinine during
treatment from end of titration to last on-drug visit); 2) medically significant kidney
pain (defined as requiring prescribed leave, last-resort analgesics, narcotic and
anti-nociceptive, radiologic or surgical interventions); 3) worsening hypertension
(defined as a persistent increase in blood pressure category or an increased
anti-hypertensive prescription); 4) worsening albuminuria (defined as a persistent
increase in albumin/creatinine ratio category).
At baseline, average estimated glomerular filtration rate (eGFR) was
82 mL/min/1.73 m2 (CKD-Epidemiology formula) and mean TKV was 1692 mL
(height adjusted 972 mL/m). Approximately 35% had an eGFR of 90 mL/min/1.73 m2
or greater, 48% had an eGFR between 60-89 mL/min/1.73 m2, 14% had an eGFR of
45-60 mL/min/1.73 m2, and 3% had an eGFR of <45 mL/min/1.73 m2. The subjects’
mean age was 39 years, 48% were female, 84% were Caucasian, 13% were Asian,
and 1.7% were Black or African-American. Approximately 80% had hypertension and
approximately 71% were taking an agent that acts on the renin-angiotensin system.
Of the 770 subjects who submitted to genetic analysis in TEMPO 3:4’s open-label
extension, 749 (97%) had an identifiable mutation in the PKD1 (656 or 88%), or
PKD2 (93 or 12%) gene.
The trial met its prespecified primary endpoint of 3-year change in TKV (p<0.0001).
The difference in TKV between treatment groups mostly developed within the first
year, the earliest assessment, with little further difference in years two and three. In
years 4 and 5 during the TEMPO 3:4 extension trial, both groups received JYNARQUE
and the difference between the groups in TKV was not maintained. Tolvaptan has little
effect on kidney size beyond what accrues during the first year of treatment.
The relative rate of ADPKD-related events was decreased by 13.5% in tolvaptantreated
patients, (44 vs. 50 events per 100 person-years; hazard ratio, 0.87; 95% CI,
0.78 to 0.97; p=0.0095). As shown in the table below, the result of the key secondary
composite endpoint was driven by effects on worsening kidney function and kidney
pain events. In contrast, there was no effect of tolvaptan on either progression of
hypertension or albuminuria. Few subjects in either arm required a radiologic or
surgical intervention for kidney pain. Most kidney pain events reflected use of a
medication to treat pain such as use of paracetamol, tricyclic antidepressants,
narcotics and other non-narcotic agents.
Event |
Tolvaptan |
Placebo |
Hazard Ratio, 95% CI |
Total Number of Events (Events per 100 personyears) |
Number of Subjects with an Event (percentage) |
Total Number of Events (Events per 100 personyears) |
Number of Subjects with an Event (percentage) |
Composite |
1049 (43.9) |
572 (59.5) |
665 (50.0) |
341 (70.6) |
0.87
(0.78,0.97) |
Worsening
Kidney
Function |
44 (1.9) |
42 (4.6) |
64 (4.8) |
61 (12.8) |
0.39
(0.26,0.57) |
Kidney
Pain |
113 (4.7) |
95 (9.9) |
97 (7.3) |
78 (16.2) |
0.64
(0.47,0.89) |
Onset or
progression of
hypertension |
734 (30.7) |
426 (44.3) |
426 (32.1) |
244 (50.5) |
0.94
(0.81,1.09) |
Worsening
Albuminuria |
195 (8.2) |
195 (20.3) |
103 (7.8) |
101 (20.9) |
1.04
(0.84,1.28) |
The third endpoint (kidney function slope) was assessed as slope of eGFR during
treatment (from end of titration to last on-drug visit). The estimated difference
in the annual rate of change in those who contributed to the analysis was
1.0 mL/min/1.73m2/year with a 95% confidence interval of (0.6, 1.4). Of the subjects
enrolled in the trial, 5 % of subjects in the tolvaptan arm and 2% in the placebo arm
either had missing baseline data or discontinued from treatment prior to the end of
the titration visit and hence were excluded from the analysis. In the extension trial,
eGFR differences produced by the third year of the TEMPO 3:4 trial were maintained
over the next 2 years of JYNARQUE treatment.
The efficacy profile was generally consistent across subgroups of interest for this
indication; few Black or African-American patients were enrolled in the trial.
REPRISE-NCT02160145: A Phase 3, Double-Blind, Placebo-Controlled, Randomized
Withdrawal Trial In Later-Stage ADPKD
REPRISE was a double-blind, placebo-controlled randomized withdrawal trial in
adult patients (age 18-65) with chronic kidney disease (CKD) with an eGFR
between 25 and 65 mL/min/1.73m2 if younger than age 56; or eGFR between 25
and 44 mL/min/1.73m2, plus eGFR decline >2.0 mL/min/1.73m2/year if between age
56-65. Subjects were to be treated for 12 months; after completion of treatment,
patients entered a 3-week follow-up period to assess renal function. The primary
endpoint was the treatment difference in the change of eGFR from pre-treatment
baseline to post-treatment follow-up, annualized by dividing by each subject’s
treatment duration.
Prior to randomization, patients were required to complete sequential single-blind
run-in periods during which they received placebo for 1 week, followed by tolvaptan
titration for 2 weeks, and then treatment with tolvaptan at the highest tolerated dose
achieved during titration for 3 weeks. During the titration period, tolvaptan was
up-titrated every 3-4 days from a daily oral dose of 30 mg/15 mg to 45 mg/15 mg,
60 mg/30 mg and up to a maximum dose of 90 mg/30 mg. Only patients who could
tolerate the two highest doses of tolvaptan (60 mg/30 mg or 90 mg/30 mg) for the
subsequent 3 weeks were randomized 1:1 to treatment with tolvaptan or placebo.
Patients were maintained on their highest tolerated dose for a period of 12 months
but could interrupt, decrease and/or increase as clinical circumstances warranted
within the range of titrated doses. All patients were encouraged to start drinking an
adequate amount of water at screening and continuing through the end of the trial to
avoid thirst or dehydration.
A total of 1519 subjects were enrolled in the study. Of these, 1370 subjects
successfully completed the pre-randomization period and were randomized and
treated during the 12-month double-blind period. Because 57 subjects did not
complete the off-treatment follow-up period, 1313 subjects were included in the
primary efficacy analysis.
For subjects randomized, the baseline, average estimated glomerular filtration rate
(eGFR) was 41 mL/min/1.73 m2 (CKD-Epidemiology formula) and historical TKV,
available in 318 (23%) of subjects, averaged 2026 mL. Approximately 5%, 75% and
20% had an eGFR 60 mL/min/1.73 m2 or greater, between 30-59 mL/min/1.73 m2,
and between 25 and 29 mL/min/1.73 m2, respectively. The subjects’ mean age was
47 years, 50% were female, 92% were Caucasian, 4% Black or African-American
and 3% were Asian, 93% had hypertension, and 87% of subjects were taking
antihypertensive agents affecting the angiotensin converting enzyme or receptor. Of
the 115 (8%) of subjects who had prior genetic tests, only 54 (47%) knew their
results with 48 (89%) of these having PKD1 and 6 (11%) having PKD2 mutations.
In the randomized period, the change of eGFR from pretreatment baseline to
post-treatment follow-up was −2.3 mL/min/1.73 m2/year with tolvaptan as compared
with −3.6 mL/min/1.73 m2/year with placebo, corresponding to a treatment effect of
1.3 mL/min/1.73 m2/year (p <0.0001). The key secondary endpoint (eGFR slope in
ml/min/1.73 m2/year assessed using a linear mixed effect model of annualized eGFR
(CKD-EPI)) showed a difference between treatment groups of 1.0 ml/min/ m2/year
that was also statistically significant (p < 0.0001).
The efficacy profile was generally consistent across subgroups of interest for this
indication; few Black or African-American patients were enrolled in the trial.