calcium channel blockers
Inhibits transport of calcium into myocardial and vascular smooth muscle cells, resulting in inhibition of excitation-contraction coupling and subsequent contraction.
Absorption: Well absorbed, but rapidly metabolized after oral administration.
Protein Binding: 70–80%.
Metabolism and Excretion: Mostly metabolized by the liver (CYP3A4 enzyme system).
Half-life: 3.5–9 hr.
|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|
Use Cautiously in:
EENT: blurred vision, disturbed equilibrium, epistaxis, tinnitus
Resp: cough, dyspnea
CV: ARRHYTHMIAS, HF, peripheral edema, bradycardia, chest pain, hypotension, palpitations, syncope, tachycardia
GI: ↑ liver enzymes, anorexia, constipation, diarrhea, dry mouth, dysgeusia, dyspepsia, nausea, vomiting
GU: dysuria, nocturia, polyuria, sexual dysfunction, urinary frequency
Derm: STEVENS-JOHNSON SYNDROME, dermatitis, erythema multiforme, flushing, sweating, photosensitivity, pruritus/urticaria, rash
Endo: gynecomastia, hyperglycemia
Hemat: anemia, leukopenia, thrombocytopenia
Metabolic: weight gain
MS: joint stiffness, muscle cramps
Neuro: paresthesia, tremor, abnormal dreams, anxiety, confusion, dizziness, drowsiness, headache, nervousness, psychiatric disturbances, weakness.
Misc: gingival hyperplasia
* CAPITALS indicate life-threatening.
Underline indicate most frequent.
Grapefruit juice ↑ levels and effect.
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.
Tablets: 30 mg, 60 mg, 90 mg, 120 mg
Generic: 30 mg $10.44/100, 60 mg $22.25/100, 90 mg $26.89/100
Extended-release capsules (Cardizem CD, Tiazac, Cartia XT, Taztia XT): 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, 420 mg
Generic: 180 mg $58.19/100, 240 mg $63.54/100, 420 mg $171.49/100
Extended-release tablets (Cardizem LA): 120 mg, 180 mg, 240 mg, 300 mg, 360 mg, 420 mg
Solution for injection: 5 mg/mL
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.
Lab Test Considerations:
Total serum calcium concentrations are not affected by calcium channel blockers.
May be administered without regard to meals. May be administered with meals if GI irritation becomes a problem.
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.
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.
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.
Decrease in frequency and severity of anginal attacks.
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