diltiazem

Absorption: Well absorbed, but rapidly metabolized after oral administration.

Distribution: Unknown.

Protein Binding: 70–80%.

Metabolism/Excretion: Primarily metabolized by the liver via the CYP3A4 isoenzyme. Excreted in the urine and feces.

Half-Life: 3.5–9 hr.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
PO	30 min	2–3 hr	6–8 hr
PO–CD, LA, XT	unknown	14 days‡	up to 24 hr
IV	2–5 min	2–4 hr	unknown

‡Maximum antihypertensive effect with chronic therapy.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Sick sinus syndrome;
2nd- or 3rd-degree AV block (unless an artificial pacemaker is in place);
Systolic BP <90 mm Hg;
Recent MI or pulmonary congestion;
Concurrent use of rifampin;
Lactation: Lactation.

Use Cautiously in:

Severe hepatic impairment (↓ dose recommended);
Severe renal impairment;
Serious ventricular arrhythmias or HF;
OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk ;
Pedi: Safety and effectiveness not established in children ;
Geri: dose and slower IV infusion rate recommended in older adults; risk of hypotension; consider age-related decrease in body mass, hepatic/renal/cardiac function, concurrent drug therapy, and other disease states.

Adv. Reactions/Side Effects ⬆ ⬇

CV: peripheral edema, ARRHYTHMIA, bradycardia, chest pain, HF, hypotension, palpitations, syncope, tachycardia

Derm: dermatitis, erythema multiforme, flushing, photosensitivity, pruritus/urticaria, rash, STEVENS-JOHNSON SYNDROME (SJS), sweating

EENT: blurred vision, disturbed equilibrium, epistaxis, tinnitus

Endo: gynecomastia, hyperglycemia

GI: ↑liver enzymes, anorexia, constipation, diarrhea, dry mouth, dyspepsia, nausea, vomiting

GU: dysuria, nocturia, polyuria, sexual dysfunction, urinary frequency

Hemat: anemia, leukopenia, thrombocytopenia

Metab: weight gain

MS: joint stiffness, muscle cramps

Neuro: abnormal dreams, anxiety, confusion, dizziness, drowsiness, dysgeusia, headache, nervousness, paresthesia, psychiatric disturbances, tremor, weakness

Resp: cough, dyspnea

Misc: gingival hyperplasia

Interactions ⬆ ⬇

Drug-drug:

↑hypotension may occur when used with fentanyl, other antihypertensives, nitrates, acute ingestion of alcohol, or quinidine.
Antihypertensive effects may be ↓ by NSAIDs.
May ↑ digoxin levels.
May ↑ levels of and risk of myopathy from simvastatin and lovastatin.
Concurrent use with beta blockers, clonidine, digoxin, disopyramide, ivabradine, or phenytoin may result in bradycardia, conduction defects, or HF; avoid concurrent use with ivabradine.
Phenobarbital and phenytoin may ↑ metabolism and ↓ effectiveness.
May ↓ metabolism of and ↑ risk of toxicity from cyclosporine, quinidine, or carbamazepine.
Cimetidine↑ levels and effects.
May ↑ or ↓ the effects of lithium or theophylline.

Grapefruit juice↑ levels and effect.

Route/Dosage ⬆ ⬇

PO (Adults ): 30–120 mg 3–4 times daily or 180–240 mg once daily as CD or XR capsules or LA tablets (up to 360 mg/day); Concurrent simvastatin therapy: Diltiazem dose should not exceed 240 mg/day and simvastatin dose should not exceed 10 mg/day.
IV (Adults ): 0.25 mg/kg; may repeat in 15 min with a dose of 0.35 mg/kg. May follow with continuous infusion at 10 mg/hr (range 5–15 mg/hr) for up to 24 hr.

Availability ⬆ ⬇

(Generic available)

Tablets: 30 mg; 60 mg; 90 mg; 120 mg
Extended-release capsules (Cardizem CD, Tiazac, Tiadylt ER, Cartia XT, Taztia XT): 120 mg; 180 mg; 240 mg; 300 mg; 360 mg; 420 mg
Extended-release tablets (Cardizem LA, Matzim LA): 120 mg; 180 mg; 240 mg; 300 mg; 360 mg; 420 mg
Premixed infusion: 125 mg/125 mL D5W; 250 mg/250 mL D5W
Solution for injection: 5 mg/mL

Assessment ⬆ ⬇

Monitor BP and pulse prior to therapy, during dose titration, and periodically during therapy. Monitor ECG periodically during prolonged therapy. May cause prolonged PR interval.
- Monitor intake and output ratios and daily weight. Assess for signs of HF (peripheral edema, rales/crackles, dyspnea, weight gain, jugular venous distention).
- Monitor frequency of prescription refills to determine adherence.
- Patients receiving digoxin concurrently with calcium channel blockers should have routine serum digoxin levels checked and be monitored for signs and symptoms of digoxin toxicity.
Assess for rash periodically during therapy. May cause SJS. Discontinue therapy if severe or if accompanied with fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjunctivitis, hepatitis and/or eosinophilia.
Angina: Assess location, duration, intensity, and precipitating factors of patient’s anginal pain.
Arrhythmias: Monitor ECG continuously during administration. Report bradycardia or prolonged hypotension promptly. Emergency equipment and medication should be available. Monitor BP and pulse before and frequently during administration.

Lab Test Considerations:

Total serum calcium concentrations are not affected by calcium channel blockers.
- Monitor serum potassium periodically. Hypokalemia↑ the risk of arrhythmias and should be corrected.
- Monitor renal and hepatic functions periodically during long-term therapy. May cause ↑ in hepatic enzymes after several days of therapy, which return to normal on discontinuation of therapy.

Implementation ⬆ ⬇

Do not confuse Cardizem with Cardene. Do not confuse Tiazac with Ziac. Do not confuse diltiazem with diazepam.
PO: May be administered without regard to meals. May be administered with meals if GI irritation becomes a problem.
- DNC: Do not open, crush, break, or chew extended-release tablets. Empty tablets that appear in stool are not significant.

IV Administration:

Diluent: Administer bolus dose undiluted.Concentration: 5 mg/mL.
Rate: Administer over 2 min.
Diluent: Dilute 125 mg in 100 mL, 250 mg in 250 mL, or 250 mg in 500 mL of 0.9% NaCl, D5W, or D5/0.45% NaCl. Infusion is stable for 24 hr at room temperature or if refrigerated.Concentration: 125 mg/125 mL (1 mg/mL), 250 mg/300 mL (0.83 mg/mL), 250 mg/550 mL (0.45 mg/mL).
Rate: See Route/Dosage section. Titrate to patient's heart rate and BP response.

Patient/Family Teaching ⬆ ⬇

Advise patient to take medication as directed at the same time each day, even if feeling well. Take missed doses as soon as possible unless almost time for next dose; do not double doses. May need to be discontinued gradually.
- Advise patient to avoid large amounts of grapefruit juice (6–8 glasses/day) during therapy.
- Instruct patient on correct technique for monitoring pulse. Instruct patient to contact health care professional if heart rate is <50 bpm.
- Caution patient to change positions slowly to minimize orthostatic hypotension.
- May cause drowsiness or dizziness. Advise patient to avoid driving or other activities requiring alertness until response to the medication is known.
- Instruct patient on importance of maintaining good dental hygiene and seeing dentist frequently for teeth cleaning to prevent tenderness, bleeding, and gingival hyperplasia (gum enlargement).
- Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to avoid concurrent use of alcohol or OTC medications and herbal products, especially NSAIDs and cold preparations, without consulting health care professional.
- Advise patient to notify health care professional if rash, irregular heartbeat, dyspnea, swelling of hands and feet, pronounced dizziness, nausea, constipation, or hypotension occurs or if headache is severe or persistent.
- Caution patient to wear protective clothing and use sunscreen to prevent photosensitivity reactions.
- Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
Angina: Instruct patient on concurrent nitrate or beta-blocker therapy to continue taking both medications as directed and to use SL nitroglycerin as needed for anginal attacks.
- Advise patient to contact health care professional if chest pain does not improve, worsens after therapy, or occurs with diaphoresis; if shortness of breath occurs; or if severe, persistent headache occurs.
- Caution patient to discuss exercise restrictions with health care professional before exertion.
Hypertension: Encourage patient to comply with other interventions for hypertension (weight reduction, low-sodium diet, smoking cessation, moderation of alcohol consumption, regular exercise, and stress management). Medication controls but does not cure hypertension.
- Instruct patient and family in proper technique for monitoring BP. Advise patient to take BP weekly and to report significant changes to health care professional.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇