Cilostazol for Stroke Prevention

(Clarity Trial)

Age: 18+

Sex: Any

Trial Phase: Phase 3

Sponsor: Stanford University

Must be taking: Aspirin, Clopidogrel

Disqualifiers: Brain bleed, Heart failure, others

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: Unknown

Duration: Up to 4 years

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests whether adding cilostazol to either aspirin or clopidogrel can help prevent strokes and heart attacks in individuals who have experienced a stroke or mini-stroke. Participants will take either cilostazol or a placebo for up to four years. The trial seeks individuals who have had a stroke or mini-stroke within the last 180 days and are currently taking either aspirin or clopidogrel. As a Phase 3 trial, this study represents the final step before FDA approval, offering participants an opportunity to contribute to potentially groundbreaking treatment advancements.

Will I have to stop taking my current medications?

The trial requires you to continue taking either aspirin or clopidogrel, but not both, as part of the study.

Is there any evidence suggesting that cilostazol is likely to be safe for humans?

Studies have shown that cilostazol is generally safe for people who have had a stroke. Research indicates that cilostazol is both safe and effective, significantly reducing the risk of serious bleeding in the brain compared to other treatments. This means it is less likely to cause dangerous side effects like bleeding inside the skull.

While cilostazol helps prevent strokes, some people may still experience minor side effects, such as headaches or stomach issues. However, serious side effects are rare. Overall, cilostazol is well-tolerated and has been used safely for other conditions. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising?

Cilostazol is unique because it works by inhibiting an enzyme called phosphodiesterase III, which leads to increased blood flow and reduced clot formation. Unlike traditional stroke prevention treatments like aspirin and clopidogrel, which primarily focus on antiplatelet effects, cilostazol offers a dual action by also improving blood vessel health. Researchers are excited about cilostazol because it offers a promising alternative that targets multiple pathways, potentially providing enhanced protection against strokes.

What evidence suggests that cilostazol might be an effective treatment for stroke prevention?

Studies have shown that cilostazol can help prevent strokes. One study found that people taking cilostazol had a lower chance of another stroke compared to those taking aspirin, with yearly recurrence rates of 2.76% for cilostazol and 3.71% for aspirin. Research also shows that cilostazol is generally safe and significantly reduces the risk of bleeding in the brain. Additionally, using cilostazol with other medications like aspirin can further lower the chance of another stroke. Overall, these findings suggest cilostazol is a promising option for reducing stroke risk after an initial stroke. Participants in this trial will receive either cilostazol or a placebo to evaluate its effectiveness in stroke prevention. ^{4 6 7 8 9}

Who Is on the Research Team?

Maarten Lansberg, MD, PhD

Principal Investigator

Stanford University

Are You a Good Fit for This Trial?

This trial is for individuals who've had a stroke or mini-stroke (TIA) within the past 6 months and are currently taking aspirin or clopidogrel. It's not suitable for those with a life expectancy under 6 months, recent spontaneous brain bleed, or moderate to severe heart failure.

Inclusion Criteria

I had a stroke or mini-stroke in the last 6 months.

I am currently taking aspirin or clopidogrel to prevent another stroke.

Exclusion Criteria

Life expectancy is less than 6 months

I had a brain bleed without injury in the last 2 years.

I have moderate to severe heart failure.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants take oral cilostazol or placebo until a study endpoint occurs, they reach maximum follow-up duration, withdraw, or the study ends

Up to 4 years

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Cilostazol

Trial Overview The study is testing if cilostazol added to either aspirin or clopidogrel can prevent further strokes and heart attacks in patients who have previously experienced these conditions.

How Is the Trial Designed?

Group I: Cilostazol 100mg Experimental Treatment 1 Intervention

Participants take oral cilostazol until a study endpoint occurs, they reach maximum follow up duration (4 years), the participant withdraws, or the study ends.

Group II: Placebo Placebo Group 1 Intervention

Participants take oral placebo until a study endpoint occurs, they reach maximum follow up duration (4 years), the participant withdraws, or the study ends.

Who Is Running the Clinical Trial?

Stanford University

Lead Sponsor

Trials

2,527

Recruited

17,430,000+

National Institute of Neurological Disorders and Stroke (NINDS)

Collaborator

Trials

1,403

Recruited

655,000+

Yale University

Collaborator

Trials

1,963

Recruited

3,046,000+

University of Cincinnati

Collaborator

Trials

442

Recruited

639,000+

Medical University of South Carolina

Collaborator

Trials

994

Recruited

7,408,000+

Citations

1. ahajournals.org ahajournals.org/doi/10.1161/STROKEAHA.120.029454

Cilostazol for Secondary Prevention of Stroke and ... Cilostazol reduced recurrent ischemic stroke more when given long (>6 months) versus short term without increasing hemorrhage, and in trials ...

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8885726/

The Efficacy and Safety of Cilostazol vs. Aspirin for ... (4) reported that the primary endpoint for prevention of secondary stroke occurred at yearly rates of 2.76% in the cilostazol group and 3.71% in ...

3. medrxiv.org medrxiv.org/content/10.1101/2023.02.05.23285505v1.full-text

Long-Term Comparison of Cilostazol versus Clopidogrel in ... This real-world, comparative effectiveness research study suggests that cilostazol is effective and safe for noncardioembolic ischemic stroke.

4. svn.bmj.com svn.bmj.com/content/6/3/410

Cilostazol for secondary stroke prevention: systematic ... Cilostazol demonstrated favourable safety profile, significantly reducing the risk of intracranial haemorrhage (RR=0.46, 95% CI 0.31 to 0.68) ...

5. frontiersin.org frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1533674/full

New options for cilostazol-based dual antiplatelet therapy ... The results showed that cilostazol-based DAPT significantly reduced ischaemic stroke recurrence compared with SAPT (RR = 0.54; 95% CI 0.38–0.75; ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC4301843/

an updated meta-analysis - PMC - PubMed Central In the secondary prevention of ischemic stroke in acute phase, cilostazol did not show any effect in the ROCI, HSSH, ACD and mRS compared to placebo or aspirin.

7. ahajournals.org ahajournals.org/doi/10.1161/STROKEAHA.121.035002

Cilostazol for Secondary Stroke Prevention The primary outcome was ischemic stroke, which occurred less frequently in the cilostazol versus placebo arm (3.37% versus 5.78% annually; ...

8. frontiersin.org frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.814654/full

The Efficacy and Safety of Cilostazol vs. Aspirin for ... (4) reported that the primary endpoint for prevention of secondary stroke occurred at yearly rates of 2.76% in the cilostazol group and 3.71% in ...

9. ejnpn.springeropen.com ejnpn.springeropen.com/articles/10.1186/s41983-025-01033-9

Cilostazol plus aspirin for secondary prevention of non ... Pooled analysis showed no significant reduction in stroke recurrence with the aspirin–cilostazol combination (AC) compared with aspirin alone at ...