A Study to Assess the Safety, Tolerability and Pharmacokinetics of Viaca (Sildenafil + Cabergoline) Compared With Sildenafil and Cabergoline

July 23, 2026 updated by: Yanping Kong

An Open-Label Single-Ascending Dose Study to Investigate the Safety, Tolerability and Pharmacokinetics of Viaca (Sildenafil + Cabergoline) Compared With Sildenafil and Cabergoline in Healthy Volunteers

This is a Phase 1, open-label, single-ascending-dose study evaluating the safety, tolerability, and pharmacokinetics (PK) of Viaca - a fixed-dose oral combination of sildenafil (a PDE5 inhibitor) and cabergoline (a dopamine D2 agonist) - versus sildenafil monotherapy and cabergoline monotherapy in healthy adult male volunteers. Approximately 30 participants are enrolled across 5 sequential cohorts (6 each). Each participant receives a single oral dose. The combination targets erectile dysfunction through both vascular and neuroendocrine pathways, aiming for efficacy at lower component doses.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Five cohorts of 6 healthy male participants each (n≈30). Viaca dose cohorts: Cohort 1 (25/0.25 mg), Cohort 2 (50/0.5 mg), Cohort 3 (75/0.75 mg). Active-comparator cohorts: Cohort 4 (sildenafil 50 mg) and Cohort 5 (cabergoline 0.5 mg). Cohort 1 runs first; after Safety Review Committee (SRC) review of safety/tolerability/PK through Day 3, Cohorts 2, 4 and 5 may proceed in parallel; Cohort 3 proceeds after SRC review of Cohort 2. Participants fast ≥8 h overnight before dosing and 2 h after. They are confined to a Phase 1 unit and discharged on Day 5 (Cohorts 1-3 and 5) or Day 2 (Cohort 4), with a follow-up visit on Day 8 (±1). Total participation ~33 days including screening. (V2.0 amendment removed the former optional high-dose Viaca cohort.)

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
30

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Australia
    • Queensland
      • Herston, Queensland, Australia, 4006
        • Nucleus Network Brisbane

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Male participants, aged 18 to 65 years (inclusive) at the time of informed consent.
  • In good general health (Investigator judgement) with no significant medical history and no clinically significant abnormalities on physical examination, vital signs, or 12-lead ECG - including systolic blood pressure 110-140 mmHg (inclusive) at Screening and Day -1 - at Screening and/or before first IP administration.
  • BMI ≥ 18.0 and ≤ 32.0 kg/m² and weight ≥ 50 kg.
  • Nonsmoker or casual smoker (< 5 cigarettes/week equivalent) with no tobacco use within 2 months prior to Screening (Investigator discretion).
  • Clinical laboratory values within normal range (or not clinically significant per Investigator).
  • Fertile men agree to acceptable contraception from Screening until 90 days after last IP dose, and no sperm donation from first dose until ≥ 90 days after last dose.
  • Able and willing to attend required study visits.
  • Able and willing to provide written informed consent before any study procedures.

Exclusion Criteria:

  • Physical or psychological condition that would impair protocol compliance or study completion (Investigator judgement).
  • History of, or condition that would contraindicate study medication or interfere with study evaluations (Investigator judgement).
  • Previous history of any of: myocardial infarction; cerebrovascular accident; arrhythmia; congestive heart failure; unstable angina; recent (<6 months) need for calcium-channel/beta-blocker/nitrate/anti-epileptic therapy; uncontrolled hypertension (SBP >140 or DBP >100 mmHg); hypotension (SBP <90 or DBP <60 mmHg) incl. syncope/orthostatic/vasovagal; pulmonary/pericardial/retroperitoneal fibrotic disorders; sickle-cell disease or trait; cardiac valve disease; severe psychiatric disorders; Raynaud's/vasospastic disorders; bariatric surgery (cholecystectomy acceptable).
  • Blood/plasma donation or significant blood loss (450 mL) within 30 days prior to first IP dose.
  • Fever (>38°C) or symptomatic viral/bacterial infection within 2 weeks prior to Screening.
  • Infections requiring parenteral antibiotics within 1 month prior to Screening.
  • Concomitant use of an indwelling urethral catheter.
  • Concomitant nitrates/nitric-oxide donors, potent CYP3A4 inhibitors (e.g. ritonavir, indinavir, ketoconazole) or moderate inhibitors (e.g. erythromycin); unwilling to avoid St. John's wort and CYP3A4-active herbals (e.g. grapefruit) within 14 days prior and throughout the study.
  • Medications that significantly affect BP: nitrates (any form), alpha-blockers (e.g. doxazosin, terazosin, tamsulosin), guanylate cyclase stimulators (e.g. riociguat).
  • Positive HCV antibody, HBsAg, or HIV antibody.
  • Live vaccine within 4 weeks prior to first IP dose.
  • Poor pill-swallowing ability or poor venous access.
  • History of severe allergic/anaphylactic reactions or sensitivity to IP or constituents.
  • History of malignancy (except non-melanoma skin cancer excised >5 years prior to Screening).
  • Clinically significant abnormal Screening ECG (e.g. QRS ≥ 120 msec and/or QTcF > 450 msec, per Investigator).
  • History/evidence of renal disease or eGFR < 60 mL/min/1.73 m² at Screening (2021 CKD-EPI creatinine equation).
  • Immunosuppressive drug exposure (incl. experimental therapies) within 4 months or 5 half-lives (whichever longer) prior to Screening.
  • Positive urine toxicology panel (barbiturates, THC, amphetamines/methamphetamines, methadone, MDMA, phencyclidine, tricyclic antidepressants, benzodiazepines, opiates, cocaine) or positive alcohol breath test.
  • Unwilling to abstain from alcohol, caffeine and nicotine from 48 h prior to admission, during confinement, and 48 h prior to follow-up visits.
  • History of substance abuse/dependency or recreational IV drug use in the last 12 months (self-declared).
  • Unwilling to refrain from strenuous exercise (incl. weightlifting) 48 h prior to admission and follow-up visits.
  • Anything the Investigator considers would jeopardize participant safety, prevent full participation, or compromise data interpretation.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cohort 1: Viaca 25/0.25 mg
Single oral dose of Viaca (sildenafil 25 mg / cabergoline 0.25 mg; one low-dose tablet) in 6 healthy male participants.
Drug: Viaca
fixed-dose oral tablet of sildenafil + cabergoline (low-dose 25/0.25 mg; high-dose 50/0.5 mg). Single oral dose.
Experimental: Cohort 2: Viaca 50/0.5 mg
Single oral dose of Viaca (sildenafil 50 mg / cabergoline 0.5 mg; one high-dose tablet
Drug: Viaca
fixed-dose oral tablet of sildenafil + cabergoline (low-dose 25/0.25 mg; high-dose 50/0.5 mg). Single oral dose.
Experimental: Cohort 3: Viaca 75/0.75 mg
Single oral dose of Viaca (sildenafil 75 mg / cabergoline 0.75 mg; one low + one high tablet
Drug: Viaca
fixed-dose oral tablet of sildenafil + cabergoline (low-dose 25/0.25 mg; high-dose 50/0.5 mg). Single oral dose.
Active Comparator: Cohort 4: Sildenafil 50 mg
Single oral dose of sildenafil 50 mg (two 25 mg tablets).
Drug: Sildenafil 50 mg
single oral dose
Active Comparator: Cohort 5: Cabergoline 0.5 mg
Single oral dose of cabergoline 0.5 mg (one 0.5 mg tablet).
Drug: Cabergoline 0.5 MG
single oral dose

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Participants with AEs/SAEs
Time Frame: Day 1 (dosing) through Day 8
Number of participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs). Unit: participants (summarised by severity and relatedness).
Day 1 (dosing) through Day 8
Blood pressure
Time Frame: Baseline through Day 8.
Change from Baseline in systolic and diastolic blood pressure. Unit: mmHg.
Baseline through Day 8.
Pulse rate
Time Frame: Baseline through Day 8.
Change from Baseline in pulse rate. Unit: beats/min.
Baseline through Day 8.
Respiratory rate
Time Frame: Baseline through Day 8.
Change from Baseline in respiratory rate. Unit: breaths/min.
Baseline through Day 8.
Body temperature
Time Frame: Baseline through Day 8.
Change from Baseline in body temperature. Unit: °C.
Baseline through Day 8.
ECG heart rate
Time Frame: Baseline through Day 8.
Change from Baseline in 12-lead ECG heart rate. Unit: beats/min.
Baseline through Day 8.
ECG intervals
Time Frame: Baseline through Day 8.
Change from Baseline in 12-lead ECG intervals (QTcF, PR, QRS). Unit: milliseconds.
Baseline through Day 8.
Laboratory tests
Time Frame: Baseline through Day 8.
Number of participants with clinically significant safety laboratory abnormalities. Unit: participants.
Baseline through Day 8.
Physical examination
Time Frame: Baseline through Day 8.
Number of participants with clinically significant physical examination findings. Unit: participants.
Baseline through Day 8.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Cmax
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Maximum observed plasma concentration (Cmax). Unit: e.g. ng/mL.
Predose (Day 1) through 168 hours post-dose (Day 8).
Tmax
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Time to maximum plasma concentration (Tmax). Unit: hours.
Predose (Day 1) through 168 hours post-dose (Day 8).
AUC0-t
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8)
Area under the plasma concentration-time curve from time 0 to the last measurable concentration (AUC0-t). Unit: e.g. ng·h/mL.
Predose (Day 1) through 168 hours post-dose (Day 8)
AUC0-24
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
AUC from time 0 to 24 hours (AUC0-24). Unit: e.g. ng·h/mL.
Predose (Day 1) through 168 hours post-dose (Day 8).
AUC0-inf
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
AUC from time 0 extrapolated to infinity (AUC0-inf). Unit: e.g. ng·h/mL.
Predose (Day 1) through 168 hours post-dose (Day 8).
%AUCextrap
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Percentage of AUC0-inf obtained by extrapolation (%AUCextrap). Unit: percentage.
Predose (Day 1) through 168 hours post-dose (Day 8).
t½
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Apparent terminal elimination half-life (t½). Unit: hours.
Predose (Day 1) through 168 hours post-dose (Day 8).
kel
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Terminal elimination rate constant (kel). Unit: 1/hour.
Predose (Day 1) through 168 hours post-dose (Day 8).
CL/F
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Apparent total clearance after oral dosing (CL/F). Unit: e.g. L/h.
Predose (Day 1) through 168 hours post-dose (Day 8).
Vz/F
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Apparent volume of distribution during the terminal phase after oral dosing (Vz/F). Unit: e.g. L.
Predose (Day 1) through 168 hours post-dose (Day 8).
Cmax/D
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Dose-normalised maximum plasma concentration (Cmax/D). Unit: e.g. ng/mL per mg.
Predose (Day 1) through 168 hours post-dose (Day 8).
AUC0-inf/D
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Dose-normalised AUC0-inf (AUC0-inf/D). Unit: e.g. ng·h/mL per mg.
Predose (Day 1) through 168 hours post-dose (Day 8).
AUC0-t/D
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Dose-normalised AUC0-t (AUC0-t/D). Unit: e.g. ng·h/mL per mg.
Predose (Day 1) through 168 hours post-dose (Day 8).
Dose proportionality
Time Frame: Predose (Day 1) through 168 hours post-dose (Day 8).
Dose proportionality of Cmax and AUC across Viaca dose levels. Unit: e.g. slope (power-model estimate).
Predose (Day 1) through 168 hours post-dose (Day 8).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Yanping Kong

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Novotech (Australia) Pty Limited

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Emma Trowbridge, MD, Nucleus Network Brisbane

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 19, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 19, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 13, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 23, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 28, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • CR-067-001
  • EC00372 (Other Identifier: Bellberry HREC code)
  • 462/26 (Other Identifier: Alfred governance)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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