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diltiazem (Cardizem, Dilacor, Tiazac, Cartia, Angiotrofin, Dilcontin)

Tradename: Cardizem, Dilacor*. Indications: 1) hypertension - may be acceptable anti-hypertensive agent in non Q-wave MI - left ventricular diastolic dysfunction 2) angina pectoris - variant angina (Prinzmetal's angina) 3) Raynaud's syndrome 4) supraventricular arrhythmias (SVT) a) atrial fibrillation b) atrial flutter c) paroxysmal supraventricular tachycardia Contraindications: 1) severe hypotension 2) 2nd degree AV block or 3rd degree AV block Dosage: Rapid atrial fibrillation: - Bolus 0.25 mg/kg or 20 mg IV over 2 min. - Rebolus 15 min later (if necessary) 0.35 mg/kg or 25 mg. - Infusion: 5-15 mg/hr. Hypertension: start 30 mg PO QID, max 360 mg/day. Tabs: 30, 60, 90, 120 mg. Cardizem CD & Dilacor XR (sustained release) - start 180 to 240 mg PO QD, max 540 mg/day Tabs: 120, 180, 240, 300 mg. Cardizem SR (twice daily sustained release) - start 60-120 mg PO BID, max 360 mg/day. Tabs: 60, 90, 120 mg. Cardizem LA: QD dosing; QAM or QHS [7,8] Tabs: 120, 180, 240, 300, 360, 420 mg Pharmacokinetics: - metabolized by cyt P450 3A4 (CYP3A4) in the liver Monitor: - electrocardiogram for bradycardia Adverse effects: 1) common (> 10%) - headache 2) less common (1-10%) - dizziness, bradycardia, 1st degree AV block, edema, EKG abnormalities, asthenia 3) uncommon (< 1%) - 2nd degree AV block, angina, dream disturbances, amnesia, depression, gait abnormalities, insomnia, nervousness, paresthesia, tremor, anorexia, constipation, diarrhea, dysgeusia, dyspepsia, urticaria, photosensitivity, amblyopia, alopecia, hemolytic anemia, leukopenia, purpura, retinopathy, thrombocytopenia, pharyngitis, cough, flu-like syndrome, gingival hyperplasia 4) see calcium channel blocker 5) overdose: - tetrad of hypotension, bradycardia, hyperglycemia, metabolic acidosis Drug interactions: 1) diltiazem increases digoxin levels 2) coadministration of beta-adrenergic receptor antagonists intensifies negative inotropic effects 3) diltiazem increases cyclosporine levels 4) concurrent administration of fentanyl may result in severe hypotension 5) cimetidine increases diltiazem levels 6) diltiazem increases carbamazepine, cyclosporine, digoxin levels 7) diltiazem decreases lithium levels 8) pharmacologic effects of theophylline may be enhanced 9) among elderly with atrial fibrillation anticoagulated with apixaban or rivaroxaban, rate control with diltiazem is associated with a higher risk of serious bleeding vs rate control with metoprolol [1] 10) any drug that inhibits CYP3A4 may increase levels of diltiazem 11) any drug that induces CYP3A4 may diminish levels of diltiazem 12) diltiazem inhibits cyt CYP3A4, thus inhibits its own metabolism & metabolism of other CYP3A4 substrates Laboratory: 1) specimen: serum, plasma (EDTA) 2) methods: TLC, GLC, HPLC Mechanism of action: 1) inhibits L-type Ca+2 channels 2) dilates coronary arteries & arterioles & increases myocardial oxygen delivery 3) decreased total peripheral vascular resistance 4) decreases AV node automaticity & AV node conduction 5) negative inotropic agent (less so than verapamil) 6) decreases renal glomerular pressure by efferent arteriolar dilatation, thus diminishing proteinuria [2] * see Brand names for drugs in different countries

Interactions

drug interactions drug adverse effects (more general classes)

Related

Brand names for drugs in different countries cytochrome P450 3A4 (cytochrome P450 C3, nifedipine oxidase, P450-PCN1, NF-25, CYP3A4) L-type Ca+2 channel, long duration or slowly inactivating Ca+2 channel or dihydropyridine receptor (R-type Ca+2 channel)

General

antiarrhythmic agent, Group IV benzazepine calcium channel blocker (CCB)

Properties

MISC-INFO: elimination route LIVER 1/2life 3.2 +/- 1.3 HOURS therapeutic-range 40-200 NG/ML protein-binding 78 +/- 3% pregnancy-category C safety in lactation ?

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  5. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  6. Department of Veterans Affairs, VA National Formulary
  7. Prescriber's Letter 10(4):21 2003
  8. Prescriber's Letter 11(2):suppl 2004
  9. Ray WA, Chung CP, Stein CM et al. Serious bleeding in patients with atrial fibrillation using diltiazem with apixaban or rivaroxaban. JAMA 2024 Apr 15:e243867 [e-pub]. PMID: 38619832 https://jamanetwork.com/journals/jama/fullarticle/2817546

Component-of

enalapril/diltiazem (Teczem)