Isradipine
Isradipine is a calcium channel blocker used to treat high blood pressure (hypertension).
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 3 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Isradipine (DynaCirc) is a calcium channel blocker for high blood pressure, alone or with a water pill, that blocks calcium from entering blood vessel walls so they relax and widen; on the market since about 1990 and available as a generic, it is now used far less than amlodipine. Most people tolerate it well, and headache, flushing, ankle swelling and a pounding heartbeat come from that same vessel widening and often ease with time. It carries no boxed warning, but feeling faint, chest pain or a very fast or irregular heartbeat needs medical help right away. Give it a few weeks to reach full effect.
Clinical pearls
- Isradipine can raise propranolol levels in the blood, so make sure the prescriber knows if you take both.
- Food slows absorption but not the total amount absorbed, so take it with or without food, just consistently.
- Nitroglycerin can be used with it, but expect extra blood pressure lowering, so stand up slowly at first.
- If you are over 65 or have liver or kidney problems, more drug reaches your bloodstream, so expect closer monitoring.
Patient information guide A plain-language walkthrough of Isradipine, written from its FDA label.
What Isradipine is used for
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Isradipine is a calcium channel blocker approved for one main use:
- High blood pressure (hypertension): Isradipine capsules are indicated for the management of hypertension. They can be used on their own or together with a thiazide-type diuretic (a water pill) for additional blood pressure lowering.
How Isradipine works
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Isradipine is a dihydropyridine calcium channel blocker. It binds tightly and specifically to calcium channels in the walls of blood vessels, blocking calcium from flowing in. Without that calcium signal, the vessels relax and widen — a process called vasodilation. Wider vessels mean the heart faces less resistance when pumping blood, which brings blood pressure down. At the doses used clinically, this effect on blood vessels happens before any significant effect on the heart muscle itself.
In people with normal heart function, the reduced workload on the heart (lower afterload) actually allows the heart to pump a little more blood per beat, slightly increasing cardiac output.
Isradipine dosage
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Isradipine capsules are taken by mouth twice a day. Food can slow the time it takes for the medicine to peak in your bloodstream by about an hour, but the total amount absorbed remains the same — so you can take it with or without food, whichever is easiest for you to keep consistent.
- Blood pressure starts to respond within 2 to 3 hours of a dose
- The full, steady benefit may take 2 to 4 weeks of regular use
- Most patients do not get extra benefit at higher doses, and side effects increase above a certain daily threshold — your doctor will find the right amount for you
Always follow your prescriber's instructions and do not change your dose without talking to them first.
Dosing details from the FDA-approved label
From the Isradipine prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Hypertension (general; initial dose, alone or in combination with a thiazide diuretic)
- Initial dose 2.5 mg b.i.d. alone or in combination with a thiazide diuretic
- If blood pressure reduction is not satisfactory after 2 to 4 weeks, the dose may be adjusted in increments of 5 mg/day at 2 to 4 week intervals
- Maximum: 20 mg/day
- Most patients show no additional response above 10 mg/day, and adverse effects are increased in frequency above 10 mg/day
- Elderly patients (above 65 years), patients with hepatic functional impairment, and patients with mild renal impairment
- Ordinarily, the starting dose should still be 2.5 mg b.i.d
- Bioavailability (increased AUC) is increased in these patients
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION The dosage of isradipine should be individualized. The recommended initial dose of isradipine is 2.5 mg b.i.d. alone or in combination with a thiazide diuretic. An antihypertensive response usually occurs within 2 to 3 hours. Maximal response may require 2 to 4 weeks. If a satisfactory reduction in blood pressure does not occur after this period, the dose may be adjusted in increments of 5 mg/day at 2 to 4 week intervals up to a maximum of 20 mg/day. Most patients, however, show no additional response to doses above 10 mg/day, and adverse effects are increased in frequency above 10 mg/day. The bioavailability of isradipine (increased AUC) is increased in elderly patients (above 65 years of age), patients with hepatic functional impairment, and patients with mild renal impairment. Ordinarily, the starting dose should still be 2.5 mg b.i.d. in these patients.
Read the full Dosage and Administration section on DailyMed →
Isradipine side effects
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Most side effects of isradipine are mild and linked to its blood vessel-widening action. Common ones include:
Common side effects
- Headache
- Dizziness
- Swelling (edema), especially in the feet or ankles
- Palpitations (feeling your heartbeat)
- Flushing (feeling warm or looking red)
- Fatigue or weakness
- Nausea
- Faster heart rate (tachycardia)
- Nausea or stomach discomfort
When to get medical help
- Call your doctor if swelling, dizziness, or palpitations are severe or don't go away
- Seek medical help right away if you feel faint, have chest pain, or notice a very fast or irregular heartbeat
- Tell your doctor if you develop shortness of breath that is new or getting worse
Many of these are transient (temporary) and improve as your body adjusts. However, if you experience severe swelling, chest pain, a very fast or irregular heartbeat, or shortness of breath, contact your doctor or seek medical care promptly.
Isradipine warnings and precautions
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- Allergy: Do not take isradipine if you have had a hypersensitivity (allergic) reaction to it or any of its ingredients in the past.
- Older adults (65+): The body absorbs more isradipine with age, so this group should be monitored carefully — though the usual starting dose applies.
- Liver impairment: Reduced liver function increases how much of the drug reaches the bloodstream. Tell your doctor about any liver condition.
- Kidney impairment: Mild kidney disease raises drug levels; effects in severe kidney failure differ. Share your kidney health history with your prescriber.
- Higher doses: Side effects become more frequent above the common effective daily range, without proportionally greater blood pressure benefit.
Isradipine interactions
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Isradipine can interact with several medicines. Let your doctor and pharmacist know about everything you take:
- Propranolol (beta-blocker): A single-dose study found isradipine raised propranolol blood levels noticeably; steady-state effects were less significant, but the combination should be monitored.
- Hydrochlorothiazide (diuretic/water pill): The two drugs do not significantly affect each other's absorption, and combining them can provide additional blood pressure lowering.
- Nitroglycerin: Can be taken together; both lower blood pressure, so monitor for additive effects.
- Cimetidine (heartburn medicine): In overdose situations, cimetidine can raise isradipine levels further and should be withheld — flag this to emergency providers if needed.
Interactions listed in the FDA-approved label
From the Isradipine prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Nitroglycerin: Isradipine has been safely coadministered with nitroglycerin.
- Hydrochlorothiazide: Concomitant administration did not alter the pharmacokinetics of either drug in healthy volunteers; in hypertensive patients, adding isradipine to existing hydrochlorothiazide therapy caused no unexpected adverse effects and gave an additional antihypertensive effect.
- Propranolol: In a single dose study, propranolol had a small effect on the rate but no effect on the extent of isradipine bioavailability, with increases in propranolol AUC (27%) and C max (58%) and decreases in t max (23%); at steady state with 5 mg b.i.d. isradipine and 40 mg b.i.d. propranolol there was no relevant effect on either drug's bioavailability.
Read the label’s full interactions text
Drug Interactions Nitroglycerin: Isradipine has been safely coadministered with nitroglycerin. Hydrochlorothiazide: A study in normal healthy volunteers has shown that concomitant administration of isradipine and hydrochlorothiazide does not result in altered pharmacokinetics of either drug. In a study in hypertensive patients, addition of isradipine to existing hydrochlorothiazide therapy did not result in any unexpected adverse effects, and isradipine had an additional antihypertensive effect. Propranolol: In a single dose study in normal volunteers, co-administration of propranolol had a small effect on the rate but no effect on the extent of isradipine bioavailability. Significant increases in AUC (27%) and C max (58%) and decreases in t max (23%) of propranolol were noted in this study. However, concomitant administration of 5 mg b.i.d. isradipine and 40 mg b.i.d. propranolol to healthy volunteers under steady-state conditions had no relevant effect on either drug's bioavailability. AUC and C max differences were <20% between isradipine given singly and in combination with propranolol, and between propranolol given singly and in combination with isradipine. Cimetidine: In a study in healthy volunteers, a one-week course of cimetidine at 400 mg b.i.d. with a single 5 mg dose of isradipine on the sixth day showed an increase in isradipine mean peak plasma concentrations (36%) and significant increase in area under the curve (50%). If isradipine therapy is initiated in a patient currently receiving cimetidine, careful monitoring for adverse reactions is advised and downward dose adjustment may be required. Rifampicin: In a study in healthy volunteers, a six-day course of rifampicin at 600 mg/day followed by a single 5 mg dose of isradipine resulted in a reduction in isradipine levels to below detectable limits.
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Isradipine
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- Do not take isradipine if you are allergic to it or any ingredient in the formulation.
- Tell your doctor if you are over 65 — drug levels run higher in older adults.
- Tell your doctor about any liver disease — impaired liver function increases how much drug your body is exposed to.
- Tell your doctor about any kidney problems — mild kidney impairment raises drug exposure; severe kidney failure may change this in a different direction.
- Share a complete list of all medications (prescription, over-the-counter, and supplements) with your doctor and pharmacist, especially other blood pressure medicines or heart medications like beta-blockers.
Isradipine overdose
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Taking too much isradipine can cause a significant drop in blood pressure (hypotension), a faster-than-normal heart rate (tachycardia), and lethargy. If you suspect an overdose, call emergency services or Poison Control right away — do not wait for symptoms to worsen. Isradipine is tightly bound to proteins in the blood and cannot be removed by dialysis, so medical treatment focuses on supporting blood pressure and heart function.
What Isradipine does in the body
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Isradipine produces measurable, dose-related reductions in both sitting and standing blood pressure within 2 to 3 hours of an oral dose. It also causes a small increase in resting heart rate — averaging about 3 to 5 beats per minute with ongoing use — though this is not closely tied to dose. By widening peripheral blood vessels, it reduces the resistance the heart pumps against (systemic vascular resistance) and, in people with normal heart function, modestly increases the amount of blood the heart pumps per minute (cardiac output).
How your body processes Isradipine
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Isradipine is almost completely absorbed from the gut (90–95%), but a large portion is broken down by the liver before it reaches the bloodstream — a process called first-pass metabolism — leaving about 15–24% of the dose active in the body. It begins appearing in the blood within 20 minutes and reaches peak levels around 1.5 hours after a dose; food delays that peak by roughly an hour but does not reduce the total amount absorbed. The drug is cleared in two phases, with a final half-life (the time for half the drug to leave the body) of about 8 hours. It is completely broken down by the body — none is excreted unchanged — with most leaving through the urine and the rest through the stool.
How to store Isradipine
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Store 20°- 25°C (68°- 77°F) .
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Isradipine
239 supplements and herbal products have documented interactions with Isradipine in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 11
- Moderate · 187
- Minor · 41
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Nutrient depletion considerations
Isradipine has been associated with lower levels of 2 nutrients in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
Isradipine: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Isradipine — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is isradipine supposed to do for me?
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Should I take it with food or on an empty stomach?
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How long will it take before my blood pressure actually improves?
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What side effects should I actually expect, and which ones should make me call someone?
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I take propranolol for my heart — is it safe to use both?
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I'm over 65 — is there anything special I need to know?
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Is Isradipine available over the counter?
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When was Isradipine first available?
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Who makes Isradipine?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Isradipine on HelloPharmacist
Isradipine forms and strengths (how it comes)
Isradipine is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Capsule
How this form is used
- Isradipine capsules are used to treat high blood pressure (hypertension)
- Isradipine capsules may be used alone or combined with a thiazide diuretic (water pill) for blood pressure control
- Isradipine capsules are taken by mouth twice daily
- Food slows absorption slightly but does not reduce the total amount absorbed — take with or without food
- It can take 2 to 4 weeks for the full blood pressure-lowering effect to appear
- Follow your prescriber's dosing instructions carefully; do not adjust the dose on your own
Isradipine on the U.S. market: products, makers and brands
How Isradipine appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
3 companies list 5 Isradipine product records with the FDA, mostly as capsule; the earliest marketing or approval year on record is 1990. Brand names on the directory include DynaCirc, DynaCirc CR; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (4) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
How widely Isradipine is used (Medicaid data)
A general measure of how commonly Isradipine is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Isradipine is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Isradipine prescribed? Of the 1,601 medications we measure, Isradipine ranks #1,321 by Medicaid prescriptions — more than 17% of them.
Utilization by Isradipine product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
isradipine 5 MG Oral Capsule Most dispensed
Summed across the 2 of 7 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197849
isradipine 2.5 MG Oral Capsule
Summed across the 2 of 8 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197848
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Isradipine, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 4 of 15 listed Isradipine NDCs with Medicaid activity.
Compare Isradipine products
A representative set of FDA-listed product records for Isradipine — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Capsule | ||||
| 2.5 mg | Oral | AvKARE | ANDA | View NDC → |
| 2.5 mg | Oral | Elite Laboratories, Inc. | ANDA | View NDC → |
| 5 mg | Oral | Elite Laboratories, Inc. | ANDA | View NDC → |
| 2.5 mg | Oral | Teva Pharmaceuticals USA, Inc. | ANDA | View NDC → |
| 5 mg | Oral | Teva Pharmaceuticals USA, Inc. | ANDA | View NDC → |
Showing 5 of 5 products — FDA National Drug Code Directory. See every product, package size and price: browse all 5 Isradipine NDCs →
Isradipine side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Isradipine — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Isradipine in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Isradipine FDA approval history
How Isradipine went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Isradipine recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Isradipine recalls since July 2021.
✅No Isradipine recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 33910 3 dose forms · 5 strengths
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Dose form (SCDF) Extended Release Oral Tablet RxCUI 370723No current FDA listingClinical drug / strength (SCD) 24 HR isradipine 10 MGRxCUI 56251824 HR isradipine 5 MGRxCUI 562520 -
Dose form (SCDF) Oral Capsule RxCUI 370724In current FDA listings -
Dose form (SCDF) Oral Tablet RxCUI 376248No current FDA listingClinical drug / strength (SCD) 2.5 MGRxCUI 199757
Look up RxCUI 33910 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Isradipine supply and shortage status
Whether Isradipine is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
💵 What Isradipine costs pharmacies (NADAC benchmark)
The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.
| Form | Strength | Pharmacy acquisition benchmark | |
|---|---|---|---|
| Capsule · Oral | 2.5 mg | $1.14 per capsule | NDC details & price history |
| Capsule · Oral | 5 mg | $1.70 per capsule | NDC details & price history |
Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.
Isradipine brand names
Isradipine is sold under 2 brand names in the FDA directory — DynaCirc, DynaCirc CR. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Isradipine: manufacturers and labelers
3 companies list Isradipine products with the FDA. By number of product records, the largest are Elite Laboratories, Inc., Teva Pharmaceuticals USA, Inc., AvKARE. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Isradipine drug class (RxNorm)
Isradipine belongs to the Dihydropyridine Calcium Channel Blocker class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Isradipine page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Elite Laboratories, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →