Hydralazine / Isosorbide Dinitrate
Hydralazine / isosorbide dinitrate is a combination of two blood vessel relaxers used to treat heart failure in self-identified Black patients.
🧬 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 6 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 →
📖 Hydralazine / Isosorbide Dinitrate: Patient Information Guide
A plain-language walkthrough of Hydralazine / Isosorbide Dinitrate — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Hydralazine / isosorbide dinitrate is approved for the following use across its supported products:
- Heart failure in self-identified Black patients: BiDil and isosorbide dinitrate and hydralazine hydrochloride tablets are both indicated as add-on therapy to standard heart failure treatment to improve survival, reduce the chance of being hospitalized for heart failure, and improve how patients feel and function day to day.
- There is limited experience in patients with the most severe stage of heart failure (NYHA class IV), so use in this group is not well established.
⚙️How it works▾
This medication pairs two different types of blood vessel relaxers. Isosorbide dinitrate releases nitric oxide, which triggers a chain reaction in blood vessel walls that causes them to relax and widen — reducing the pressure the heart pumps against and allowing blood to flow more easily. Hydralazine specifically relaxes the muscular walls of arteries. Animal studies suggest hydralazine may also slow the development of tolerance to the nitrate component, meaning the nitrate may stay effective longer when both drugs are taken together.
Importantly, the exact reason this combination benefits heart failure patients has not been fully established. A key known issue with nitrates alone is that the body can become tolerant to them quickly — sometimes within 24 hours — making them less effective. A nitrate-free period each day is needed to restore their effect.
💊How it's taken▾
This medication is taken by mouth as a tablet, three times a day. Treatment is typically started at a lower dose and gradually increased — sometimes as quickly as every 3 to 5 days — up to the maximum tolerated dose. If side effects become difficult to manage, the dose can be reduced; the goal is always to work back up to the highest dose you can comfortably take.
- Take exactly as prescribed — do not change your dose without talking to your prescriber
- If you have intolerable side effects, your prescriber may lower your dose temporarily rather than stopping the medication entirely
- There is no current information on whether food affects absorption, so follow the instructions on your prescription label
🤒Side effects — in detail▾
Side effects with this medication are fairly common — here are the ones reported most often:
- Headache — the most common side effect and the top reason patients stop taking the medication
- Dizziness
- Weakness or fatigue
- Nausea or vomiting
- Low blood pressure (hypotension) — especially when standing up quickly
- Tingling or numbness in the hands or feet (paresthesia)
- Sinus congestion (sinusitis)
- Blurred vision (reported after approval)
Call your doctor right away if you faint, have chest pain, notice joint pain or rash (possible lupus-like reaction), or experience a fast or irregular heartbeat. These can be signs of a more serious problem.
⚠️Warnings & precautions▾
- Low blood pressure (hypotension): Even small doses can cause a significant drop in blood pressure, especially if you're dehydrated or on a low-salt diet. Standing up too quickly can make this worse. Your doctor should address dehydration before you start this medication.
- Drug-induced lupus-like syndrome: Hydralazine has been linked to a condition resembling lupus — with joint pain, rash, and fever. Symptoms usually improve when the drug is stopped. Tell your doctor about any new joint pain or skin changes.
- Worsening heart ischemia: Hydralazine can cause a fast heart rate (tachycardia) and low blood pressure, which may reduce blood flow to the heart. This is a particular concern in patients with hypertrophic cardiomyopathy.
- Peripheral neuritis (nerve irritation): Tingling, numbness, or a pins-and-needles feeling in the hands or feet has been reported. If this occurs, your doctor may prescribe vitamin B6 (pyridoxine) alongside this medication.
🔀What it interacts with▾
This medication has serious interactions with certain other drugs — always give your full medication list to every prescriber and pharmacist:
- PDE-5 inhibitors (sildenafil/Viagra, tadalafil/Cialis, vardenafil, avanafil): Combining these with this medication is contraindicated — it can cause a severe, life-threatening drop in blood pressure.
- Riociguat (Adempas): Also contraindicated — this drug works through a similar pathway and the combination causes dangerous hypotension.
- Other blood pressure-lowering medications: These may add to the blood pressure-lowering effect of this medication, increasing the risk of hypotension.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Do not take if you are allergic to organic nitrates (a class of medications that includes isosorbide dinitrate)
- Do not take if you currently use a PDE-5 inhibitor (sildenafil, tadalafil, vardenafil, avanafil) or riociguat
- Tell your doctor if you are dehydrated or eating a very low-sodium (salt) diet — you face a higher risk of low blood pressure
- Tell your doctor if you have hypertrophic cardiomyopathy (a thickened heart muscle condition) — this medication may reduce blood flow to the heart in these patients
- Older adults: This medication may be cleared from the body more slowly; starting at the lowest dose is recommended
- Children: Safety and effectiveness have not been established in patients under 18
- Pregnancy: No human data on the combination product exists; animal studies showed potential harm at high doses. Pregnant women with heart failure face added risks. Discuss with your doctor.
- Breastfeeding: It is unknown whether this drug passes into breast milk; discuss with your doctor before breastfeeding
- Liver impairment: Isosorbide dinitrate levels may be higher in patients with cirrhosis (severe liver scarring); inform your prescriber of any liver conditions
🚑If you take too much▾
Taking too much of this medication can cause a dangerous drop in blood pressure, rapid heart rate, severe headache, flushing, confusion, and fainting. In severe cases, it can lead to reduced blood flow to the heart, dangerous heart rhythms, shock, coma, or death. There is no specific antidote — if you suspect an overdose, call 911 or go to the nearest emergency room immediately.
📡Pharmacodynamics — effects in the body▾
In a study of patients with chronic heart failure, the combination of hydralazine and isosorbide dinitrate produced a significant decrease in pulmonary capillary wedge pressure (the back-pressure of fluid in the lungs) compared to hydralazine alone — meaning the combination more effectively reduced fluid backup in the lungs. Increases in cardiac output (the amount of blood the heart pumps) and blood flow to the kidneys and limbs were seen with the combination but were not greater than with hydralazine alone. The exact basis for the clinical benefits seen in heart failure trials is not fully understood.
🔬Pharmacokinetics — how your body processes it▾
After taking a dose by mouth, both hydralazine and isosorbide dinitrate reach peak blood levels within about one hour. Hydralazine has a half-life of roughly 4 hours, while isosorbide dinitrate itself clears faster — about 1 to 2 hours — though its active breakdown products (metabolites) last longer, especially isosorbide-5-mononitrate, which has a half-life of about 5 hours. Both drugs undergo significant first-pass metabolism in the liver, meaning a large portion is broken down before reaching the bloodstream; how much gets through varies considerably from person to person. Hydralazine is primarily eliminated through metabolism; isosorbide dinitrate and its metabolites are cleared mainly through the kidneys. Older adults may clear both drugs more slowly.
📦How to store it▾
Store at 25°C (77°F), excursions permitted to 15-30°C (59-86°F). Protect from light. Dispense in a light-resistant, tight container.
📄 Written from Hydralazine / Isosorbide Dinitrate’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Hydralazine / Isosorbide Dinitrate — the kind of thing our pharmacy team would talk through with you at the counter.
Why is this medication specifically for Black patients? Can anyone else take it? ▾
I get terrible headaches — is that from this medication, and will they go away? ▾
I take sildenafil (Viagra) for another reason — is that okay with this medication? ▾
I sometimes feel dizzy when I stand up — what should I do? ▾
What warning signs should make me call my doctor or go to the ER right away? ▾
Is it safe to take this medication if I'm pregnant or trying to get pregnant? ▾
Is Hydralazine / Isosorbide Dinitrate available over the counter? ▾
When was Hydralazine / Isosorbide Dinitrate first available? ▾
Who makes Hydralazine / Isosorbide Dinitrate? ▾
💬 Answers drafted from Hydralazine / Isosorbide Dinitrate’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Hydralazine / Isosorbide Dinitrate comes
Hydralazine / Isosorbide Dinitrate 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.
Tablet
How this form is used
- BiDil is used to treat heart failure as an add-on to standard therapy in self-identified Black patients, to improve survival and reduce hospitalizations
- Isosorbide dinitrate and hydralazine hydrochloride tablets are used to treat heart failure as an add-on to standard therapy in self-identified Black patients, to improve survival, reduce hospitalizations, and improve functional status
- BiDil: start with one tablet three times a day; your doctor may increase to a maximum of two tablets three times a day as tolerated
- Isosorbide dinitrate and hydralazine hydrochloride tablets: start with one tablet three times a day, titrated up to two tablets three times a day if tolerated
- If side effects are intolerable, the dose may be reduced to as little as one-half tablet three times a day — work with your prescriber to increase the dose again as soon as symptoms allow
- Dose increases can happen as quickly as every 3 to 5 days, but may take longer depending on how well you tolerate the medication
📊 Hydralazine / Isosorbide Dinitrate across the U.S. market
How Hydralazine / Isosorbide Dinitrate 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.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Hydralazine / Isosorbide Dinitrate is used
A general measure of how commonly Hydralazine / Isosorbide Dinitrate 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 Hydralazine / Isosorbide Dinitrate 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 Hydralazine / Isosorbide Dinitrate prescribed? Of the 1,596 medications we measure, Hydralazine / Isosorbide Dinitrate ranks #1,051 by Medicaid prescriptions — more than 34% of them.
Utilization by Hydralazine / Isosorbide Dinitrate 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.
hydralazine hydrochloride 37.5 MG / isosorbide dinitrate 20 MG Oral Tablet
Summed across the 4 of 11 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 905377
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 Hydralazine / Isosorbide Dinitrate, 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 11 listed Hydralazine / Isosorbide Dinitrate NDCs with Medicaid activity.
🔍 Compare Hydralazine / Isosorbide Dinitrate products
A representative set of FDA-listed product records for Hydralazine / Isosorbide Dinitrate — 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 |
|---|---|---|---|---|
| 💊Tablet | ||||
| ISOSORBIDE DINITRATE 20 mg/1; HYDRALAZINE HYDROCHLORIDE 37.5 mg | Oral | A2A Integrated Pharmaceuticals | ANDA | View NDC → |
| 37.5; 20 mg/1; mg | Oral | Azurity | NDA | View NDC → |
| HYDRALAZINE HYDROCHLORIDE 37.5 mg/1; ISOSORBIDE DINITRATE 20 mg | Oral | Azurity Pharmaceuticals, Inc. | NDA | View NDC → |
| HYDRALAZINE HYDROCHLORIDE 37.5 mg/1; ISOSORBIDE DINITRATE 20 mg | Oral | Bryant Ranch Prepack | NDA AUTHORIZED GENERIC | View NDC → |
| ISOSORBIDE DINITRATE 20 mg/1; HYDRALAZINE HYDROCHLORIDE 37.5 mg | Oral | i3 Pharmaceuticals, LLC | ANDA | View NDC → |
| HYDRALAZINE HYDROCHLORIDE 37.5 mg/1; ISOSORBIDE DINITRATE 20 mg | Oral | Ingenus Pharmaceuticals, LLC | ANDA | View NDC → |
| 37.5; 20 mg/1; mg | Oral | Ingenus Pharmaceuticals, LLC × 2 listings | ANDA | View NDC → |
| HYDRALAZINE HYDROCHLORIDE 37.5 mg/1; ISOSORBIDE DINITRATE 20 mg | Oral | Wilshire Pharmaceuticals | NDA AUTHORIZED GENERIC | View NDC → |
Showing 9 of 9 products — FDA National Drug Code Directory. See every product, package size and price: browse all 9 Hydralazine / Isosorbide Dinitrate NDCs →
📈 What people report — real-world data (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 Hydralazine / Isosorbide Dinitrate — 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 Hydralazine / Isosorbide Dinitrate 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.
🏛️ The road to your pharmacy
How Hydralazine / Isosorbide Dinitrate went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 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.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one exact multiple-ingredient concept (MIN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). A product with a different ingredient combination belongs on a different page.
RxCUI 608424 1 dose form · 1 strength
-
Dose form (SCDF) Oral Tablet RxCUI 721832In current FDA listingsClinical drug / strength (SCD) hydralazine hydrochloride 37.5 MG / isosorbide dinitrate 20 MGRxCUI 905377
Look up RxCUI 608424 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.
📦 Supply & shortage status
Whether Hydralazine / Isosorbide Dinitrate 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.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Hydralazine / Isosorbide Dinitrate belongs to the Arteriolar Vasodilator 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.
🔬 Where this comes from
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 we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 6 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Wilshire Pharmaceuticals is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.