Isradipine

Pronunciation: (iss-RAHD-ih-peen)
Class: Calcium channel blocking agent

Trade Names

DynaCirc CR
- Tablets, controlled-release 5 mg
- Tablets, controlled-release 10 mg

Isradipine
- Capsules 2.5 mg
- Capsules 5 mg

Pharmacology

Reduces systemic vascular resistance and BP by inhibiting movement of calcium ions across cell membrane in systemic and coronary vascular smooth muscle and myocardium.

Pharmacokinetics

Absorption

The bioavailability is 15% to 24%. The C _max is approximately 1 ng/mL/mg (immediate release); 3 to 4 ng/mL (controlled release). The T _max is 1.5 h (immediate release); 7 to 18 h (controlled release). Increased bioavailability up to 25% with food.

Distribution

95% is protein bound.

Metabolism

Completely metabolized by ring oxidation and ester cleavage primarily via CYP-450 3A4. Metabolites are inactive.

Elimination

The t _1/2 is approximately 8 h. 60% to 65% is excreted in the urine, 25% to 30 % in the feces.

Special Populations

Renal Function Impairment
Mild (CrCl 30 to 80 mL/min)

The AUC increases by 45%.

Severe (CrCl is less than 10 mL/min, hemodialysis)

The AUC decreases by 20 to 50%.

Hepatic Function Impairment

The C _max increases by 32% and AUC increases by 52%.

Elderly

The AUC and C _max increases.

Indications and Usage

Treatment of hypertension.

Contraindications

Standard considerations.

Dosage and Administration

Adults

PO 2.5 to 10 mg/day in 2 divided doses (max dose 20 mg/day).

Storage/Stability

Store in tightly closed container at room temperature. Protect from light.

Drug Interactions

None well documented.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Peripheral edema; flushing; palpitations; angina; tachycardia; hypotension; syncope; CHF; MI; atrial or ventricular fibrillation.

CNS

Dizziness; lightheadedness; headache; fatigue; lethargy; weakness; shakiness; psychiatric disturbances.

Dermatologic

Rash.

GI

Nausea; diarrhea; constipation; abdominal discomfort; cramps; dyspepsia; vomiting.

Genitourinary

Urinary frequency; micturition disorders; sexual difficulties.

Respiratory

Shortness of breath; dyspnea; wheezing.

Miscellaneous

Transient ischemic attack; stroke.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

CHF

Use with caution in patients with CHF.

Overdosage

Symptoms

Hypotension, dizziness, slurred speech, nausea, weakness, drowsiness, confusion.

Patient Information

• Explain that dosage will be tapered slowly before stopping to avoid withdrawal symptoms. Warn patient that sudden discontinuation may cause serious chest pain.
• Tell patient to brush and floss teeth regularly to minimize gum changes (eg, overgrowth of gums).
• Instruct patient to report the following symptoms to health care provider: irregular heart beat, shortness of breath, swelling of hands or feet, pronounced dizziness, constipation, nausea, or hypotension.
• Advise patient that drug may cause dizziness and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.