Isradipine

Isradipine (tradenames DynaCirc, Prescal) is a calcium channel blocker of the dihydropyridine class. It is usually prescribed for the treatment of high blood pressure in order to reduce the risk of stroke and heart attack.

Isradipine

Clinical data
Trade names	DynaCirc
AHFS/Drugs.com	Monograph
MedlinePlus	a693048
Pregnancy category	C
Routes of administration	Oral
ATC code	C08CA03 (WHO)
Legal status
Legal status	UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	15-24%
Protein binding	95%
Metabolism	100% Hepatic
Elimination half-life	8 hours
Excretion	70% Renal, 30% Fecal
Identifiers
IUPAC name 3-Methyl 5-propan-2-yl 4-(2,1,3-benzoxadiazol-4-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate
CAS Number	75695-93-1 Y
PubChem CID	3784
DrugBank	DB00270 Y
ChemSpider	3652 Y
UNII	YO1UK1S598
KEGG	D00349 Y
ChEMBL	ChEMBL1648 Y
CompTox Dashboard (EPA)	DTXSID4023179
ECHA InfoCard	100.158.721
Chemical and physical data
Formula	C19H21N3O5
Molar mass	371.393 g·mol−1
3D model (JSmol)	Interactive image
SMILES O=C(OC)\C3=C(\N\C(=C(\C(=O)OC(C)C)C3c1cccc2nonc12)C)C
InChI InChI=1S/C19H21N3O5/c1-9(2)26-19(24)15-11(4)20-10(3)14(18(23)25-5)16(15)12-7-6-8-13-17(12)22-27-21-13/h6-9,16,20H,1-5H3 Y Key:HMJIYCCIJYRONP-UHFFFAOYSA-N Y
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It was patented in 1978 and approved for medical use in 1989.^[1]

Medical uses

Isradipine is given as either a 2.5 mg or 5 mg capsule.^[2]

Side effects

Common side effects include:^[3]

• Dizziness
• Warmth, redness, or tingly feeling under your skin
• Headache
• Weakness, tired feeling
• Nausea, vomiting, diarrhea, upset stomach
• Skin rash or itching

Serious side effects include:^[3]

• Lightheadedness or fainting
• Shortness of breath, especially from minimal physical activity
• Swelling in the hands and feet
• Rapid and/or heavy heartbeat
• Chest pain

Drug interactions

It is advised that those using isradipine not take dolasetron (Anzemet), as both agents can cause a dose-dependent PR interval and QRS complex prolongation.^[4]

Itraconazole (Onmel/Sporanox) exhibits a negative inotropic effect on the heart and thus could spur an additive effect when used concomitantly with isradipine. Itraconazole also inhibits an important cytochrome liver enzyme (CYP 450 3A4) which is needed to metabolize isradipine and other calcium channel blockers. This will increase plasma levels of isradipine and could cause an unintentional overdose of the medication. Caution is advised when administering both agents together.^[5]

Tizanidine demonstrates anti-hypertensive effects and should be avoided in patients taking isradipine due to the possibility of synergism between both medications.^[6]

The antibiotic rifampin lowered plasma concentrations of isradipine to below detectable limits.^[2]

Cimetidine increased isradipine mean peak plasma levels. A downward dose adjustment may be necessary with this particular instance of polypharmacy.^[2]

Severe hypotension was reported with fentanyl anesthesia when it was combined with other calcium channel blockers. Even though isradipine, another calcium channel blocker, has not been used in conjunction with fentanyl anesthesia in any studies, caution is advised.^[2]

Overdose

Symptoms of an isradipine overdose include:^[2]

• Lethargy
• Sinus tachycardia
• Transient hypotension

Stereochemistry

Isradipine contains a stereocenter and consists of two enantiomers, more precisely atropisomers. This is a racemate, i.e. a 1: 1 mixture of (R)- and the (S)-forms:^[7]

Enantiomers of Isradipine
CAS-Nummer: 84260-63-9	CAS-Nummer: 84260-64-0