Diltiazem
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Calcium channel blocker (non-dihydropyridine), Antianginal, Antiarrhythmic (class IV), Antihypertensive
Diltiazem
Cardizem, Tiazac, Cartia XT, Dilacor XR, Taztia XT, Matzim LA
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Summary
Pharmacy
Starting dose
ER 180-240 mg PO once daily; IR 30 mg PO QID; IV 0.25 mg/kg over 2 min for acute rate control, then 5-15 mg/h infusion
Preparations
IR 30, 60, 90, 120 mg tablets; multiple ER capsules and tablets 60-420 mg; IV 5 mg/mL
US FDA Max
~480 mg/d (oral); IV per protocol
Pharmacology
Routes
Oral (IR, multiple ER formulations), IV
Onset
IV: 3-7 minutes (rate control); PO IR: 30-60 minutes; ER: hours
Duration
IR: 4-8 hours; ER: 24 hours
Half-life
3-4.5 hours (IR); 5-7 hours (ER; effective duration 24 hours via formulation)[1]
Bioavailability
~40% (oral; extensive first-pass via CYP3A4)[1]
Pregnancy
Limited data; labetalol/nifedipine generally preferred. Crosses placenta.[citation needed]
Legal status
Rx-only in US
Purported mechanism
Diltiazem is a benzothiazepine non-dihydropyridine calcium channel blocker; unlike amlodipine and nifedipine, it has substantial AV nodal and cardiac myocyte L-type channel blockade in addition to vascular smooth muscle effects, producing rate control plus modest vasodilation.0 Avoid in HFrEF (negative inotropy). CYP3A4 substrate AND moderate inhibitor — interacts substantially with statins (especially simvastatin), tacrolimus, cyclosporine, and many other CYP3A4 substrates[1].
References
- ↑ 1.0 1.1 1.2 FDA Prescribing Information, Cardizem (diltiazem HCl), Sun Pharma, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/018602s055lbl.pdf