Isradipine
Pronouncation: (iss-RAHD-ih-peen)
Class: Calcium channel blocking agent
Trade Names:
DynaCirc
- Capsules 2.5 mg
- Capsules 5 mg
Trade Names:
DynaCirc CR
- Tablets, controlled-release 5 mg
- Tablets, controlled-release 10 mg
Mechanism of Action
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 (immediately 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.
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