Ivabradine

證據等級: L5

預測適應症: 10 個

Ivabradine: From Chronic Heart Failure to Pulmonary Hypertension

One-Sentence Summary

Ivabradine is a selective HCN4 channel inhibitor originally indicated for chronic heart failure with reduced ejection fraction and stable angina, reducing heart rate through sinoatrial If current blockade without suppressing cardiac contractility. Among the TxGNN model's top 10 predictions, Pulmonary Hypertension (rank 7, score 98.50%) stands out as the most clinically relevant candidate, supported by 3 clinical trial registrations and 20 publications — including direct animal and clinical observational evidence for right ventricular function improvement. Notably, the top 6 TxGNN computational predictions (ranks 1–6, largely hair and dental malformation syndromes) are assessed as mechanistic false positives due to absent pathophysiological links to the If channel; the pulmonary hypertension signal is the most actionable finding in this evidence pack.

Quick Overview

Item	Content
Original Indication	Chronic heart failure with reduced ejection fraction (HFrEF); stable angina
Predicted New Indication	Pulmonary Hypertension
TxGNN Prediction Score	98.50% (Rank 7 of 17,080 diseases)
Evidence Level	L3
Singapore Market Status	✗ Not marketed
Number of Registrations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Ivabradine selectively inhibits the If ("funny current") channel — encoded by the HCN4 subunit — in the sinoatrial node. This reduces spontaneous pacemaker depolarisation, lowering heart rate in a dose-dependent manner without any negative inotropic effect. Unlike beta-blockers, ivabradine does not reduce cardiac contractility or blood pressure, making it theoretically attractive in conditions where heart rate reduction is beneficial but further haemodynamic depression must be avoided.

In pulmonary hypertension (PH), the right ventricle faces chronically elevated afterload from increased pulmonary vascular resistance. The compensatory tachycardia that develops shortens diastolic filling time and amplifies right ventricular oxygen demand, creating a vicious cycle of worsening right heart function. Ivabradine's selective heart rate reduction would theoretically restore diastolic filling time, reduce right ventricular wall tension and myocardial oxygen demand, and slow the progression of right ventricular remodelling — without the cardiac output penalties that make beta-blockers poorly tolerated in advanced PH.

Two independent rat model studies (monocrotaline-induced PH and SU5416/hypoxia-induced PH) confirm that ivabradine reduces right ventricular fibrosis and improves biventricular function, with mechanistic evidence pointing to downregulation of the TGF-β/Smad fibrotic pathway. Multiple small clinical studies and case series in humans — including patients with systemic sclerosis–associated PAH and COPD-associated pulmonary hypertension — report functional improvements with ivabradine therapy. The presence of HCN channel expression in pulmonary vascular smooth muscle cells further raises the hypothesis of direct vasodilatory effects, though this remains unconfirmed in humans.

Clinical Trial Evidence

Two of the three identified trials directly involve ivabradine; the third (NCT04735354, studying sacubitril/valsartan in HFrEF) provides only indirect background context and is excluded below.

Trial Number	Phase	Status	Enrollment	Key Findings
NCT03650205	N/A	Unknown	160	Ivabradine to prevent anthracycline-induced cardiotoxicity — assesses cardiac-protective effects via If channel inhibition; provides indirect safety and cardioprotection data for ivabradine under cardiac stress conditions
NCT00757055	Phase 2	Withdrawn	0	Ivabradine in diastolic heart failure — withdrawn before enrolment (reason unknown); the stated rationale addresses heart rate reduction to improve impaired ventricular filling, mechanistically overlapping with the right heart failure pathophysiology seen in PH

Evidence gap: No dedicated clinical trial targeting ivabradine specifically for pulmonary hypertension has been registered on ClinicalTrials.gov or ICTRP. This is a critical gap for advancing this repurposing candidate.

Literature Evidence

The following 10 publications are most directly relevant to ivabradine and pulmonary hypertension, prioritised by study type and direct drug–disease relevance:

PMID	Year	Type	Journal	Key Findings
37742537	2023	Clinical Observational	Am J Cardiology	Prospective study (n not stated); ivabradine selectively lowers heart rate and significantly improves right ventricular systolic function in COPD patients with cor pulmonale and PH
24556029	2014	Case Series	J Cardiac Failure	Functional improvements (6MWT, NYHA class) reported in PAH patients treated with ivabradine; early proof-of-concept signal in humans
32915674	2020	Animal Study	Am J Resp Cell Mol Biol	Ivabradine (10 mg/kg/d) reduces RV fibrosis and improves RV function in MCT and SUHX rat PH models; anti-fibrotic mechanism via TGF-β/Smad pathway confirmed
29146614	2018	Animal Study	Am J Physiol Heart Circ	HR reduction with ivabradine (vs carvedilol) improves biventricular mechanics, cardiac cycle timing, and interventricular interactions in monocrotaline-PAH rats
22792738	2012	Small Clinical Study	Kardiologiia	Ivabradine (10 mg/day, 2 weeks) produces statistically significant reduction in pulmonary hypertension severity in COPD patients (n=60, controlled)
23021874	2012	Case Series	Eur J Int Med	Ivabradine in systemic sclerosis–related PAH — reports clinical improvement in this high-risk subgroup
22383181	2012	Case Series	Clin Res Cardiol	Ivabradine safe and well-tolerated in systemic sclerosis patients with PH; supports the feasibility of use alongside PH-specific therapies
23389056	2013	Case Series	Clin Res Cardiol	Ivabradine in PAH — preliminary data suggesting potential to delay escalation to parenteral prostanoid therapy
28701278	2017	Review	Eur J Int Med	Narrative review covering ACEi, ARB, beta-blockers, and ivabradine as supportive therapies in PH; discusses drug safety, tolerability, and interaction considerations
32248556	2020	Scoping Review	Pharmacotherapy	Systematic scoping review of novel ivabradine uses beyond approved indications; pulmonary hypertension identified as one of the most evidence-supported off-label applications

Singapore Market Information

Ivabradine is currently not registered in Singapore. The HSA product license database returns zero registrations for this drug. There are no approved brand-name products, dosage forms, or indication-specific approvals on record.

This means any clinical use of ivabradine in Singapore would require special access (e.g., Special Access Route / Investigational New Drug pathway) and there is no locally available reference product or approved label to draw upon for safety benchmarking.

Safety Considerations

Formal Singapore HSA package insert data are not available (drug is unregistered). Based on the international clinical literature present in this evidence pack and known pharmacology:

Key mechanism-based risk: Dose-dependent bradycardia — the primary adverse effect; risk is amplified in patients with baseline low heart rate or those on concomitant rate-lowering agents
Visual disturbances: Transient luminous phenomena (phosphenes) due to HCN1 channel expression in retinal photoreceptors; generally mild and reversible
CYP3A4 interactions: Ivabradine is metabolised by CYP3A4; concomitant use with potent inhibitors (e.g., azole antifungals, macrolides) markedly increases plasma levels and bradycardia risk
Atrial fibrillation risk: Noted in the SHIFT trial; ivabradine should be used with caution in patients at risk of AF
Contraindicated in: Resting heart rate <60 bpm, severe hepatic impairment, sick sinus syndrome, sinoatrial block, and use with strong CYP3A4 inhibitors

For the specific PH patient population, drug interactions with ERA (endothelin receptor antagonists), PDE5 inhibitors, and prostanoids — the standard of care in PAH — require formal review before clinical use.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: The mechanistic basis for ivabradine in pulmonary hypertension is well-grounded: selective heart rate reduction without negative inotropy addresses a key pathophysiological driver of right ventricular deterioration in PH. This rationale is reinforced by convergent evidence from two independent animal models and multiple small clinical studies, establishing ivabradine as a scientifically credible repurposing candidate at the observational/hypothesis-generating stage (L3). The absence of a completed Phase 2/3 RCT is the key evidence gap preventing a "Go" determination.

To proceed, the following is needed:

Regulatory: Assess Singapore HSA Special Access Route eligibility; obtain international reference label (EMA/FDA) for full contraindication and safety profiling
Safety review: Formal drug interaction assessment with standard PAH therapies (endothelin antagonists, PDE5 inhibitors, prostanoids)
MOA documentation: Retrieve and document full HCN4 pharmacology from DrugBank (DG002 remediation) to support mechanistic narrative in any future IND submission
Clinical trial design: Design a prospective RCT — recommended target population: PAH (Group 1) or COPD-associated PH (Group 3) with baseline HR ≥75 bpm; primary endpoint: right ventricular function (echocardiographic) or 6-minute walk distance
Local KOL consultation: Engage Singapore pulmonary hypertension specialists to assess feasibility and patient availability for an investigator-initiated trial
Heart rate phenotyping: Identify the PH patient subgroup most likely to benefit (tachycardic patients at rest, inadequately controlled with existing therapies)
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.