ISRADIPINE

ISRADIPINe (is-ra'di-peen) DynaCirc, DynaCirc CR Classifications: calcium channel blocker; antihypertensive; Therapeutic: antihypertensive; calcium channel blocker Prototype: Nifedipine Pregnancy Category: C

Availability

2.5 mg, 5 mg capsules; 5 mg, 10 mg sustained release tablets

Action

Inhibits calcium ion influx into cardiac muscle and smooth muscle without changing calcium concentrations, thus affecting contractility. Isradipine relaxes coronary vascular smooth muscle with little or no negative inotropic effect. It significantly decreases systemic vascular resistance and reduces BP at rest and during isometric and dynamic exercise.

Therapeutic Effect

Reduces BP and has an antianginal effect.

Uses

Mild to moderate hypertension.

Unlabeled Uses

Angina, CHF.

Contraindications

Hypersensitivity to isradipine; pregnancy (category C), lactation.

Cautious Use

CHF, acute MI, severe bradycardia, cardiogenic shock, ventricular dysfunction; older adult; mild renal impairment, hepatic impairment; GERD, hiatal hernia with esophageal reflux. Safety and effectiveness in children are not established.

Route & Dosage

Hypertension Adult: PO 1.25–10 mg b.i.d. (max: 20 mg/d); DynaCirc CR dosed q.d. Angina Adult: PO 2.5–7.5 mg t.i.d. (max: 15 mg/d)

Administration

Oral

• Do not crush sustained release form. It must be swallowed whole.
• Note: After the first 2–4 wk of therapy, dose may be increased for improved BP control in increments of 5 mg/d at 2–4 wk intervals up to a maximum dose of 20 mg/d.
• Store in tight, light-resistant container.

Adverse Effects (≥1%)

CNS: Headache, dizziness, fainting, fatigue, sleep disturbances, vertigo. CV: Flushing, ankle edema, palpitations, tachycardia, hypotension, chest pain, CHF. GI: Nausea, vomiting, abdominal discomfort, constipation, increased liver enzymes. Respiratory: Dyspnea. Skin: Rash, decreased skin sensation.

Interactions

Drug: Adenosine may prolong bradycardia. May increase cyclosporine levels and toxicity.

Pharmacokinetics

Absorption: Rapidly and completely absorbed from GI tract, but only 15–24% reaches systemic circulation because of first-pass metabolism. Onset: 1 h. Peak: 2–3 h. Duration: 12 h. Distribution: Not known if crosses placenta or is distributed into breast milk. Metabolism: Extensive first-pass metabolism in liver. Elimination: 70% in urine as inactive metabolites; 30% in feces. Half-Life: 5–11 h.

Nursing Implications

Assessment & Drug Effects

• Monitor BP throughout course of therapy.
• Monitor patients with a history of CHF carefully, especially with concurrent beta blocker use. Promptly report S&S of worsening heart failure.
• Monitor ambulation, especially with older adult patients, until response to drug is known.

Patient & Family Education

• Notify physician promptly of shortness of breath, palpitations, or other signs of adverse cardiovascular effects.
• Do not drive or engage in other potentially hazardous activities until response to drug is known.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug