Diltiazem (Cardizem) and Ketamine Therapy | Tovani Health
Cardizem (Diltiazem) (also: Tiazac) — Non-dihydropyridine calcium channel blocker (CYP3A4 inhibitor)
Verdict at Tovani Health
Compatible; moderate CYP3A4 inhibition can modestly raise ketamine levels.
Diltiazem and ketamine are compatible with awareness. Diltiazem is a moderate CYP3A4 inhibitor — distinct from amlodipine which has no meaningful CYP effect — and can modestly raise ketamine plasma levels. Patients on stable diltiazem for atrial fibrillation rate control or hypertension can proceed with KAP without medication changes.
If you take Cardizem regularly and are considering at-home ketamine therapy, the combination is safe with monitoring or dose adjustment. This page covers the brief pharmacologic context and what we do at intake.
How Cardizem interacts with ketamine
Diltiazem inhibits L-type calcium channels (BP/HR reduction) and moderately inhibits CYP3A4 (slowing metabolism of CYP3A4 substrates including ketamine). The CYP effect is real but smaller than potent inhibitors like clarithromycin or ritonavir.
What we do at intake
Disclose dose and formulation (immediate vs extended release). Continue as normal. Tell us about any other CYP3A4 modulators you take.
Bottom line
Diltiazem and ketamine are compatible with awareness. Diltiazem is a moderate CYP3A4 inhibitor — distinct from amlodipine which has no meaningful CYP effect — and can modestly raise ketamine plasma levels. Patients on stable diltiazem for atrial fibrillation rate control or hypertension can proceed with KAP without medication changes.
Ready to find out if at-home ketamine fits your situation?
We’ll note that you’re on Cardizem (Diltiazem) at intake. The eligibility check takes 5 minutes and gives you an honest answer about whether at-home ketamine fits your specific situation.
FL and NJ residents only. Benjamin Soffer, DO — Tovani Health.
Sources
The verdict and clinical guidance on this page are based on the following peer-reviewed literature and FDA prescribing information.
- Ketamine: A Review of Clinical Pharmacokinetics and Pharmacodynamics in Anesthetic and Pain Therapy. Peltoniemi MA, Hagelberg NM, Olkkola KT, Saari TI. Clinical Pharmacokinetics. 2016. PMID: 27028535
Reviews CYP3A4 inhibitors affecting ketamine clearance.
Clinically reviewed
Reviewed by Benjamin Soffer, DO on May 17, 2026. Dr. Soffer is a board-certified physician (American Board of Internal Medicine) licensed in Florida and New Jersey, prescribing at-home ketamine therapy through Tovani Health.
This page is general information about how this medication interacts with at-home ketamine therapy at Tovani Health. It is not a substitute for medical advice from your prescribing physician about your specific situation. Always discuss medication changes with the doctor who prescribed them.