DYNACIRC

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DYNACIRC (DYNACIRC).

How it works

Dynacirc (isradipine) is a dihydropyridine calcium channel blocker that inhibits the influx of calcium ions through L-type calcium channels in vascular smooth muscle and cardiac muscle, leading to vasodilation and reduced peripheral vascular resistance, thereby lowering blood pressure.

What the body does with it

Metabolism	Primarily hepatic via CYP3A4 isoenzyme; undergoes extensive first-pass metabolism.
Excretion	Primarily hepatic metabolism (CYP3A4) with <1% excreted unchanged in urine; approximately 60% of metabolites are excreted in feces via bile, and 35% in urine.
Half-life	Terminal elimination half-life is 7-8 hours. In elderly patients or those with hepatic impairment, half-life may be prolonged up to 14 hours, necessitating dose adjustment.
Protein binding	Approximately 95% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Volume of distribution is 3-5 L/kg, indicating extensive tissue distribution beyond the vascular compartment.
Bioavailability	Oral bioavailability is approximately 30-40% due to extensive first-pass metabolism by CYP3A4 in the liver and gut wall.
Onset of Action	Oral administration: onset of antihypertensive effect occurs within 1-2 hours with peak effect at 2-4 hours.
Duration of Action	Duration of antihypertensive effect is approximately 24 hours with once-daily dosing, allowing sustained blood pressure control over the dosing interval.

Classification & Brands

Dosing & administration

2.5-10 mg orally once daily; titrate based on response. Maximum 20 mg/day.

Dosage form	CAPSULE
Renal impairment	CrCl <30 mL/min: 2.5 mg once daily; increase cautiously. CrCl ≥30 mL/min: no adjustment needed.
Liver impairment	Child-Pugh A: use with caution, start at 2.5 mg daily. Child-Pugh B or C: not recommended due to extensive hepatic metabolism.
Pediatric use	Safety and efficacy not established; no standard pediatric dosing.
Geriatric use	Initiate at 2.5 mg once daily; increase slowly due to increased systemic exposure and risk of hypotension.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DYNACIRC (DYNACIRC).

Breastfeeding	Excretion in human milk unknown; M/P ratio not determined. Risk of hypotension in neonate. Use with caution, monitor infant for signs of hypotension.
Teratogenic Risk	First trimester: No adequate studies; animal reproduction studies not available. Second trimester: Possible fetal bradycardia, hypotension, hypoxia if used after 20 weeks due to calcium channel blocker effects. Third trimester: Increased risk of fetal hypoxia, oligohydramnios, and neonatal complications. Avoid use in pregnancy unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to isradipine or any of its components.","Concurrent use with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin) is contraindicated."]

Clinical Precautions

Precautions	["Use with caution in patients with heart failure, aortic stenosis, or severe left ventricular dysfunction.","May cause hypotension, especially with concurrent beta-blocker use.","Avoid abrupt withdrawal; taper gradually.","Monitor for peripheral edema, particularly in the lower extremities."]
Food/Dietary	Grapefruit juice increases isradipine bioavailability; avoid concurrent use. No other significant food interactions. Maintain consistent salt intake to avoid blood pressure fluctuations.

Clinical Tips & Counseling

Drug interactions

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DYNACIRC

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DYNACIRC (DYNACIRC).

How it works

What the body does with it

Metabolism	Primarily hepatic via CYP3A4 isoenzyme; undergoes extensive first-pass metabolism.
Excretion	Primarily hepatic metabolism (CYP3A4) with <1% excreted unchanged in urine; approximately 60% of metabolites are excreted in feces via bile, and 35% in urine.
Half-life	Terminal elimination half-life is 7-8 hours. In elderly patients or those with hepatic impairment, half-life may be prolonged up to 14 hours, necessitating dose adjustment.
Protein binding	Approximately 95% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
Volume of Distribution	Volume of distribution is 3-5 L/kg, indicating extensive tissue distribution beyond the vascular compartment.
Bioavailability	Oral bioavailability is approximately 30-40% due to extensive first-pass metabolism by CYP3A4 in the liver and gut wall.
Onset of Action	Oral administration: onset of antihypertensive effect occurs within 1-2 hours with peak effect at 2-4 hours.
Duration of Action	Duration of antihypertensive effect is approximately 24 hours with once-daily dosing, allowing sustained blood pressure control over the dosing interval.

Classification & Brands

Dosing & administration

2.5-10 mg orally once daily; titrate based on response. Maximum 20 mg/day.

Dosage form	CAPSULE
Renal impairment	CrCl <30 mL/min: 2.5 mg once daily; increase cautiously. CrCl ≥30 mL/min: no adjustment needed.
Liver impairment	Child-Pugh A: use with caution, start at 2.5 mg daily. Child-Pugh B or C: not recommended due to extensive hepatic metabolism.
Pediatric use	Safety and efficacy not established; no standard pediatric dosing.
Geriatric use	Initiate at 2.5 mg once daily; increase slowly due to increased systemic exposure and risk of hypotension.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DYNACIRC (DYNACIRC).

Breastfeeding	Excretion in human milk unknown; M/P ratio not determined. Risk of hypotension in neonate. Use with caution, monitor infant for signs of hypotension.
Teratogenic Risk	First trimester: No adequate studies; animal reproduction studies not available. Second trimester: Possible fetal bradycardia, hypotension, hypoxia if used after 20 weeks due to calcium channel blocker effects. Third trimester: Increased risk of fetal hypoxia, oligohydramnios, and neonatal complications. Avoid use in pregnancy unless benefit outweighs risk.

Warnings & precautions

■ FDA Black Box Warning

None

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to isradipine or any of its components.","Concurrent use with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin) is contraindicated."]

Clinical Precautions

Precautions	["Use with caution in patients with heart failure, aortic stenosis, or severe left ventricular dysfunction.","May cause hypotension, especially with concurrent beta-blocker use.","Avoid abrupt withdrawal; taper gradually.","Monitor for peripheral edema, particularly in the lower extremities."]
Food/Dietary	Grapefruit juice increases isradipine bioavailability; avoid concurrent use. No other significant food interactions. Maintain consistent salt intake to avoid blood pressure fluctuations.

Clinical Tips & Counseling

Drug interactions

Loading safety data…