Diltiazem

證據等級: L5

預測適應症: 10 個

Diltiazem: From Cardiac Arrhythmia & Hypertension to Cerebrovascular Disorder

One-Sentence Summary

Diltiazem is a non-dihydropyridine calcium channel blocker (CCB) widely used for rate control in atrial fibrillation, hypertension, and angina pectoris. The TxGNN model's top-ranked prediction uses obsolete ontology terminology; the highest-ranked clinically meaningful indication is Cerebrovascular Disorder (rank #4, TxGNN score 97.63%), supported by 6 clinical trials and 20 publications. However, most evidence is indirect — primarily through Diltiazem's role in atrial fibrillation management and its pharmacokinetic interactions with anticoagulants — and targeted direct evidence for cerebrovascular treatment remains limited.

Quick Overview

Item	Content
Original Indication	Atrial fibrillation (rate control), hypertension, angina pectoris
Predicted New Indication	Cerebrovascular Disorder
TxGNN Prediction Score	97.63%
Evidence Level	L3
Singapore Market Status	Not Marketed
Number of Registrations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, formal mechanism of action data was not retrieved from the database. Based on well-established pharmacological knowledge, Diltiazem belongs to the non-dihydropyridine CCB class. It blocks L-type voltage-gated calcium channels in cardiac and vascular smooth muscle cells, producing vasodilation, heart rate reduction, decreased myocardial contractility, and slowed atrioventricular conduction. These properties underpin its primary clinical uses: rate control in atrial fibrillation, management of hypertension, and treatment of chronic stable angina.

The mechanistic case for cerebrovascular applications is built on multiple indirect pathways. Atrial fibrillation is the leading cause of cardioembolic stroke, and Diltiazem's heart rate control function indirectly reduces cardioembolic risk. Beyond that, L-type calcium channel blockade in cerebrovascular smooth muscle can relieve vasospasm and improve cerebral perfusion — a mechanism directly examined in a 1985 primate model of chronic cerebrovascular spasm (PMID: 2416213) and in a cat middle cerebral artery occlusion model (PMID: 4056906). The landmark NORDIL trial (Lancet 2000; PMID: 10972367), a Phase 3 RCT in 10,881 hypertensive patients, provided the broadest population-level data, showing numerically lower fatal and non-fatal stroke rates in the Diltiazem arm compared to diuretics and beta-blockers.

A critical caveat tempers this picture: Diltiazem is a moderate inhibitor of both CYP3A4 and P-glycoprotein. In patients who require concurrent anticoagulation for AF-related stroke prevention — using DOACs such as rivaroxaban or apixaban — Diltiazem significantly elevates DOAC plasma concentrations and may increase major bleeding risk. This pharmacokinetic interaction is well-documented across multiple 2022–2026 cohort studies and a 2026 meta-analysis (PMID: 40326046), creating a complex risk-benefit trade-off that makes Diltiazem a double-edged agent in the cerebrovascular disease setting.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT05838664	N/A	Completed	2,140,403	Large retrospective French registry (2016–2020) comparing stroke, major bleeding, and mortality in AF patients on vs. off oral anticoagulants; provides real-world context for cerebrovascular risk in the AF–Diltiazem population
NCT01176565	Phase 3	Terminated	1,000	ATACH-II: intensive BP reduction in acute intracerebral hemorrhage primarily using nicardipine; provides CCB-class context for acute cerebrovascular event management; terminated early due to futility
NCT03529149	Phase 4	Unknown	90	TCD-guided blood pressure control after endovascular thrombectomy for ischemic stroke; Diltiazem may be a candidate antihypertensive; evaluates cerebral blood flow optimisation in post-stroke care
NCT06175663	N/A	Unknown	130	Observational MRI study assessing early brain structural changes in midlife hypertension; relevant to understanding Diltiazem's antihypertensive role in cerebral small vessel disease prevention
NCT02922452	Phase 1	Completed	16	PK/DDI study evaluating Diltiazem's effect on BMS-986141 pharmacokinetics; provides quantitative data on CYP3A4-mediated drug level elevation relevant to DOAC co-prescription safety
NCT06783868	N/A	Not Yet Recruiting	100	SAVE STROKE Phase II: AF catheter ablation vs. rate-control medication in patients with new-onset AF at time of stroke; Diltiazem likely included as rate-control comparator; no data yet available

Literature Evidence

PMID	Year	Type	Journal	Key Findings
10972367	2000	RCT	Lancet	NORDIL trial: Diltiazem vs. diuretics/beta-blockers in hypertension; comparable combined cardiovascular endpoints; fatal and non-fatal stroke numerically favoured Diltiazem arm
40326046	2026	Meta-analysis	Ann Pharmacother	Diltiazem/verapamil co-prescribed with DOACs: contradictory findings across real-world studies; overall signal toward increased bleeding risk requiring clinical vigilance
41152878	2025	Retrospective Cohort	BMC Medicine	Multinational cohort in non-valvular AF: antiarrhythmic drugs including diltiazem co-administered with DOACs; quantified stroke prevention vs. bleeding risk trade-off across healthcare systems
37791408	2023	Retrospective Cohort	Eur Heart J CVP	Nationwide cohort: P-gp/CYP3A4 inhibitors including diltiazem with NOACs in AF; clinically relevant pharmacokinetic interactions affecting stroke and bleeding outcomes
36149579	2023	Retrospective Cohort	J Interv Card Electrophysiol	Diltiazem + DOAC co-prescription in AF: characterised major bleeding risk arising from CYP3A4/P-gp-mediated DDI
35861836	2022	Retrospective Cohort	J Am Heart Assoc	Diltiazem with DOACs in 4,544 AF patients: bleeding risk stratified by kidney function; moderate CYP3A4 inhibition increases DOAC exposure, particularly in impaired renal function
2416213	1985	Animal Study	Am J Cardiol	Primate model of chronic cerebrovascular spasm (5 days post-haemorrhage): Diltiazem assessed for protection of cerebral arterial structure and function; provides direct mechanistic evidence for cerebrovascular vasodilation
4056906	1985	Animal Study	J Neurosurg	Cat MCA occlusion model: IV Diltiazem infusion (0.1–1.0 µg/kg/min) initiated 2 hours before stroke onset; evaluated neuroprotective potential compared to verapamil in acute ischemic stroke
8204245	1994	Clinical Study	J Clin Anesthesia	Diltiazem 5 mg bolus vs. nicardipine 1 mg during cerebral aneurysm surgery for subarachnoid haemorrhage: compared effects on internal carotid artery flow velocity and local cerebral blood flow under isoflurane anaesthesia
17309423	2007	Review	Med J Australia	Atrial fibrillation management: Diltiazem and verapamil cited as superior to digoxin for exercise heart rate control; supports AF rate-control strategy for reducing cardioembolic cerebrovascular events

Singapore Market Information

Diltiazem currently has no active product registrations with the Singapore Health Sciences Authority (HSA). No license entries are available in the Singapore regulatory database.

Safety Considerations

Drug Interactions (from literature): Diltiazem is a moderate CYP3A4 and P-glycoprotein inhibitor. Co-administration with DOACs (rivaroxaban, apixaban) significantly increases DOAC plasma concentrations and elevates major bleeding risk — particularly critical in AF patients using anticoagulation for stroke prevention. Multiple large real-world studies (2022–2026) and a meta-analysis have confirmed this DDI as clinically significant. Co-prescription with simvastatin may increase myopathy and rhabdomyolysis risk via CYP3A4 inhibition (PMID: 17304269); a case of fatal intracranial haemorrhage with supratherapeutic INR was reported following a statin switch in a patient on both diltiazem and warfarin.

For complete warnings and contraindications, please refer to the relevant product package insert.

Conclusion and Next Steps

Decision: Hold

Rationale: Diltiazem's mechanistic plausibility for cerebrovascular protection is supported by its established AF rate-control function, antihypertensive effects, and preclinical evidence of direct cerebrovascular vasodilation — but no dedicated clinical trial has evaluated Diltiazem as a primary treatment for cerebrovascular disorder. The available evidence is predominantly indirect (AF management, antihypertensive cohorts), evidence level is L3, and the drug's significant DDI risk with DOACs — the mainstay of stroke prevention in AF — creates a complex and potentially hazardous co-prescription scenario. Its absence from the Singapore market further limits immediate clinical deployment.

To proceed, the following is needed:

Retrieval of the full DrugBank MOA record and package insert (complete warnings, contraindications, and DDI profile)
Singapore HSA regulatory pathway assessment for new registration or research use authorisation
A prospective clinical trial specifically designed to evaluate Diltiazem's direct effects on cerebrovascular outcomes, independent of AF or hypertension endpoints
Quantitative DDI risk modelling for Diltiazem + DOAC co-administration in cerebrovascular patients, stratified by renal function
Alignment with current clinical practice guidelines (ACC/AHA, ESC, Singapore MOH) on CCB use in cerebrovascular disease management before any protocol development
Disclaimer

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