BiDil

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BiDil

Treatment option: Heart Failure

Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of BiDil

Quick Facts

Property Description
Active ingredient Hydralazine and Isosorbide Dinitrate (ISDN)
Form Oral tablet (film-coated)
Pharmacological class Vasodilator; Antihypertensive Agent
Common use Adjunct therapy to support heart function
Origin Synthetic (chemically derived)

What Type of Medicine is BiDil?

BiDil is a specialized prescription-only medication structurally defined as a fixed-dose combination product, containing two distinct vasoactive agents within a single tablet. The medication belongs to the primary pharmacological class of vasodilators, which are agents used to widen blood vessels, and is consequently categorized as an antihypertensive agent. This classification is utilized in cardiovascular management. The drug combines isosorbide dinitrate, a nitrate vasodilator, and hydralazine hydrochloride, an arteriolar vasodilator.

Active Ingredients and Dosage Form

The unique formulation of BiDil is a fixed pairing of two separate active ingredients: Hydralazine and Isosorbide Dinitrate (ISDN). The medication is supplied exclusively as an oral tablet for ingestion, which dictates its simple route of administration. Both components are synthetic, chemically derived compounds. This fixed-dose combination has demonstrated efficacy in reducing hospitalization events in certain patient populations, which supports the formulation's clinical use in maintaining circulatory function. The combination is distinct because it targets both the arterial and venous systems simultaneously, which differentiates it from the therapeutic approach of single-agent treatments.

General Purpose of the Dual-Action Formulation

The fundamental purpose of the BiDil fixed combination is to ease the overall strain on the heart by systematically regulating the circulatory system. This dual action is achieved because the two components—one acting predominantly on the arteries and the other on the veins—work together. By relaxing the vessels, one component reduces the pressure the heart must push against, while the other reduces the volume of blood returning to the heart, which provides a comprehensive strategy to support the heart's pumping efficiency.

Regulatory References

  1. FDA DailyMed labeling

What side effects are possible with BiDil?

Possible Side Effects and Safety Information

The medicine's safety profile is formally categorized by regulatory authorities, distinguishing between frequent adverse reactions and serious, clinically important systemic warnings. This classification defines the documented risks associated with the use of the fixed-dose combination of isosorbide dinitrate and hydralazine.


Adverse Reaction Frequencies

Adverse reactions observed in clinical trials are classified by their incidence, with certain effects reported as Very Common (occurring in ge 10% of patients). These most frequently reported effects include Headache, Dizziness, Asthenia (unusual weakness/tiredness), and Nausea. Effects classified as Common (4% to 8% incidence) include Hypotension (low blood pressure), Bronchitis, Sinusitis, and Ventricular tachycardia.

Systemic Regulatory Warnings

The official label highlights several serious adverse reactions. These include the potential for clinically significant Symptomatic Hypotension and the risk of developing a drug-induced syndrome resembling Systemic Lupus Erythematosus (SLE), which is associated with the hydralazine component. Furthermore, there is a warning regarding the potential for Peripheral Neuritis (manifested by paresthesia, numbness, or tingling).

Safety Restrictions and Time-Related Patterns

Use of this medication is Contraindicated in individuals with a known allergy to any component, including nitrates. The label also contains a critical safety restriction: it must not be administered concurrently with Phosphodiesterase-5 (PDE5) Inhibitors or Soluble Guanylate Cyclase (sGC) Stimulators due to the high risk of severe, life-threatening hypotension. Regarding timing, the regulatory data note that effects such as headache and dizziness are reported to be more frequent during the initiation of treatment.

Population-specific notes indicate that older adults may experience reduced clearance of the components, and use during pregnancy requires a benefit-risk assessment.

Overdose and Emergency Response

A BiDil overdose is an officially documented emergency scenario requiring immediate medical attention due to the severe physiological effects of its components, Hydralazine and Isosorbide Dinitrate (ISDN). Overdose manifestations listed in regulatory documents include marked cardiovascular instability such as severe hypotension and compensatory tachycardia, often leading to general symptoms like profound dizziness, severe headache, flushing, and gastrointestinal distress. More severe presentations documented in regulatory labeling involve profound shock, cardiac arrhythmias, and myocardial ischemia. A specific, life-threatening complication associated with the ISDN component is methemoglobinemia.

Seeking Emergency Help

Governmental guidance mandates that any suspected overdose requires the patient to seek immediate medical attention. The documented management involves comprehensive symptomatic and supportive treatment in a monitored clinical setting. While no specific antidote is known for hydralazine, the treatment for methemoglobinemia includes the administration of methylene blue. Management steps to counteract severe hypotension include plasma volume expansion and, if necessary, the controlled use of vasopressor agents. Continuous cardiac monitoring is a required component of observation to assess for severe arrhythmias and other cardiovascular complications following an overdose.

Therapeutic Uses of BiDil

What BiDil Treats: Main Uses and Benefits

BiDil is applied in addressing conditions characterized by periods of heightened symptoms related to heart failure, and is relevant for patients in this context. The medication may be part of symptomatic management as an adjunct to standard therapy.

Its use is considered relevant for supporting the patient across situations where symptoms may intensify temporarily, including in the management of heart failure.

This supportive combination is commonly used across conditions presenting with acute episodes. It helps ease the overall symptom burden and contributes to improved comfort during periods of heightened physiological activity. In clinical settings, the use of this medication may assist with maintaining functional stability, which supports the patient during difficult episodes by easing distress and helps improve day-to-day comfort during symptomatic periods.

Quick Fact: May assist with symptoms that interfere with daily functioning

The therapeutic domain of BiDil is commonly used to help with acute or disruptive symptom patterns, and may assist with maintaining a sense of stability when symptoms are more noticeable. As an ancillary therapy, it is intended to supplement existing treatment, contributing to easing the overall symptom load.

“It is a therapeutic option applied across domains where additional symptomatic support is needed for patients experiencing heart failure.”

Eligibility and Restrictions for Use

BiDil's eligibility profile is explicitly defined by regulatory authorities based on population and existing medical conditions. It is formally indicated for the treatment of heart failure as an adjunct to standard therapy only in self-identified Black patients.

The medication is contraindicated in several specific instances. It must not be used in patients with a history of allergy to organic nitrates (such as isosorbide dinitrate). Additionally, use is strictly prohibited in patients concurrently taking Phosphodiesterase-5 (PDE-5) inhibitors (like sildenafil) or the soluble guanylate cyclase (sGC) stimulator riociguat.

Age-related restrictions apply, as the safety and effectiveness in pediatric patients have not been established. For older adults, dose selection should begin at the low end of the range, reflecting the higher frequency of decreased organ function. Use is further restricted in pregnant women, where it is advised only if the potential benefit justifies the potential risk, and there are no available data on its use during lactation or in patients with hepatic impairment. Official labeling also notes little experience with the drug in patients who have NYHA Class IV heart failure.

What should I know about interactions with other medicines?

BiDil's interaction profile is officially documented by regulatory authorities, highlighting critical prohibitions and pharmacokinetic changes when combined with other products. The most severe constraints are defined by Contraindicated Combinations. Co-administration with Phosphodiesterase Type 5 (PDE-5) Inhibitors, such as sildenafil or tadalafil, and Soluble Guanylate Cyclase (sGC) Stimulators, including riociguat, is formally prohibited. This restriction is due to the potentiation of blood pressure lowering, which may lead to severe hypotension. The product is also contraindicated for patients with a known allergy to organic nitrates.

Exposure-Modifying Interactions

The profile details Exposure-Modifying Interactions where the hydralazine component alters the systemic concentrations of certain cardiovascular agents. This pharmacokinetic interaction is documented to increase the plasma exposure (AUC/Cmax) of specific beta-blockers, such as propranolol and metoprolol, and the ACE-inhibitor lisinopril. Hydralazine also increases the clearance rate of the diuretic furosemide. Furthermore, the label notes that consumption of alcohol (ethanol) may result in additive effects that further reduce blood pressure.

Population-Specific Considerations

Official labeling addresses Population-Specific exposure factors. Hydralazine exposure is connected to a patient's genetic acetylator status, which determines its bioavailability. Similarly, concentrations of the isosorbide dinitrate component are officially documented to increase in patients who have hepatic impairment or cirrhosis.

Mechanism of Action

Nitric Oxide Signaling for Preload Modulation

Isosorbide Dinitrate (ISDN) is bioactivated into Nitric Oxide ( NO), a powerful signaling molecule. NO primarily activates the sGC-cGMP cascade within venous smooth muscle , causing these large veins to relax and widen. This physiological change reduces the volume of blood returning to the ventricles, directly decreasing the ventricular filling pressure (Preload) and the resulting mechanical tension on the myocardial wall.


Calcium Modulation for Afterload Reduction

Hydralazine influences arteriolar smooth muscle by interfering with its internal Intracellular Calcium ( Ca^2+) handling. By modulating Ca^2+ mobilization through pathways involving the IP3 receptor, Hydralazine causes the small, high-resistance arteries to relax. This arterial vasodilation lowers the Systemic Vascular Resistance, functionally decreasing the opposing force exerted against the ventricular ejection (Afterload).


Complementary Vasodilation and Mechanistic Constraints

The mechanism involves a dual-site action on the vasculature, resulting in the simultaneous modulation of Preload (via venous activity) and Afterload (via arterial activity). However, the drop in arterial pressure can stimulate the Baroreceptor Reflex, a feedback loop that results in a reflex increase in heart rate. Hydralazine's proposed antioxidant properties may mechanistically influence NO bioavailability, potentially modulating the biological process of nitrate tolerance which is a known constraint of NO signaling.

Dosage and Administration Information

How BiDil is Used

BiDil is administered as an oral tablet and is used as an adjunct therapy within a long-term management plan for heart failure. The usage pattern involves specific requirements concerning the route, frequency, and dose ranges, adhering to a consistent schedule throughout treatment.


Standard Dosing Regimen

The dosage regimen is characterized by a three-times-daily frequency. The medication is available as a fixed-dose combination tablet containing 20 mg of isosorbide dinitrate and 37.5 mg of hydralazine hydrochloride. Administration begins with a low starting dose that is subsequently titrated based on patient tolerance.

Instruction Entity Detail
Route of Administration Oral (by mouth)
Standard Frequency Three times a day
Initial Dose One tablet of the 20 mg/37.5 mg strength
Maximum Dose Should not exceed two tablets three times a day

Dose Adjustment and Titration

The goal of the regimen is to achieve the maximum tolerated dose. The initial dose is subject to upward titration, a process that can be accomplished relatively quickly in a matter of a few days. The tablets are scored, which is a feature that permits the dose to be reduced to as little as one-half tablet three times a day if intolerance prevents escalation to the target dose. There are no explicit instructions regarding missed doses, nor is it mandated that the drug be taken with food. Regarding specific populations, the drug's components may be eliminated more slowly in older patients.

Recent Clinical Evidence

BiDil: Recent Clinical Evidence

The fixed-dose combination of isosorbide dinitrate and hydralazine (BiDil) was the primary focus of the African-American Heart Failure Trial (A-HeFT). This landmark Phase III randomized, placebo-controlled trial enrolled self-identified Black patients with New York Heart Association (NYHA) functional class III or IV heart failure with reduced ejection fraction (HFrEF).

Key Findings from A-HeFT

Patients in the trial were already receiving standard therapy (such as ACE inhibitors or ARBs, and beta-blockers) before being randomized to receive either the fixed-dose combination or a placebo. The trial was halted early due to a demonstrated benefit in the active treatment group.

  • Mortality: Treatment was associated with a statistically significant 43% reduction in the risk of all-cause mortality compared to placebo. The survival difference began to emerge approximately six months after randomization.
  • Hospitalization: There was a statistically significant reduction in the risk of first hospitalization for heart failure.
  • Functional Status: Patients receiving the combination reported statistically significant improvement in self-reported quality of life (measured by the Minnesota Living with Heart Failure Questionnaire) compared to the placebo group.

Mechanism of Action Studied

Research suggests that the benefit may be related to the drug's components potentially enhancing the effect of nitric oxide (NO) and reducing oxidative stress. The components are believed to work by reducing both preload (isosorbide dinitrate) and afterload (hydralazine) on the heart.

Safety Observation

Side effects in the A-HeFT trial, particularly headache and dizziness, were reported more frequently in the fixed-dose combination group compared to placebo, leading to a higher rate of discontinuation in the treatment arm.

Frequently Asked Questions (FAQ)

Common questions about BiDil (FAQ)

Q: How does BiDil differ from standard heart failure medicine?

Official product information describes BiDil as a fixed-dose combination containing two separate vasodilating medicines, isosorbide dinitrate and hydralazine. It is prescribed as an adjunct therapy, meaning it is added on to other standard heart failure treatments the patient is already taking. The medicine has a specific indication for use in self-identified Black patients with heart failure.

Q: Is it okay to drink alcohol while taking BiDil?

Regulatory sources warn that drinking alcohol while taking this medicine can increase the risk of side effects. Alcohol may cause a drop in blood pressure, making a patient more likely to experience dizziness, lightheadedness, or fainting. For specific guidance on alcohol consumption, patients should consult their healthcare provider.

Q: Is BiDil safe for older adults over 65?

Regulatory documents note that the medicine may be eliminated more slowly in older patients. Official prescribing information indicates that dose selection for this population should generally begin at the low end of the dosing range.

Q: What is the difference between BiDil and its generic components?

BiDil is defined as a specific fixed-dose combination tablet containing two active ingredients, isosorbide dinitrate and hydralazine hydrochloride. While these components are available separately, the BiDil tablet is the unique fixed combination product that was studied and approved for use as an adjunct therapy in a specific patient population.

Q: What foods or drinks should be limited while on BiDil?

Official patient information notes that patients should be aware of the need to limit alcohol intake due to the risk of additive blood pressure lowering effects. There are no specific limitations for any particular foods noted in the regulatory documents.

Q: Can BiDil be crushed or split in half?

The tablets are manufactured as scored tablets, which means they are designed to be split. The scored feature of the tablet indicates that a dose may be reduced to one-half tablet if a lower dose is required for titration or to manage side effects.

Q: What if I have an allergic reaction to BiDil?

Use of BiDil is contraindicated, or strictly prohibited, if a person has a known allergy to organic nitrates, one of the medicine’s components. If a patient experiences signs of a serious allergic reaction, such as a rash, fever, or joint pain, official patient counseling states that the medication must be discontinued immediately and a healthcare provider should be consulted.

Q: Can BiDil be taken if I am already on blood pressure medication?

BiDil is indicated for use as an adjunct to standard heart failure therapies, which commonly include other medications that lower blood pressure. Official labeling cautions that combining these medicines may cause blood pressure to become too low, leading to dizziness or fainting. It is important that a healthcare provider is aware of all blood pressure medicines a patient is taking.

Q: Are there any specific lifestyle changes needed while on BiDil?

To minimize the risk of low blood pressure (hypotension), official patient information indicates that patients should take precautions during exercise or hot weather, or when they must stand for long periods of time.

Q: Can BiDil be used for high blood pressure alone?

No, official regulatory labeling indicates BiDil only for the treatment of heart failure as an adjunct to standard therapy. It is not indicated for the treatment of high blood pressure when used alone.

Q: Does BiDil interact with common pain relievers like ibuprofen?

Regulatory and pharmaceutical references suggest that some non-steroidal anti-inflammatory drugs (NSAIDs), which include common pain relievers, may interfere with the effectiveness of the hydralazine component. This potential interaction may reduce the medicine's blood pressure lowering effects.

Q: Does BiDil interact with any herbal supplements?

Official patient counseling states that a healthcare provider should be informed about all substances being taken. This includes prescription and over-the-counter medicines, vitamins, and herbal supplements, as these products may affect BiDil or be affected by it.

Q: How quickly does BiDil start to work after I begin taking it?

The precise mechanism by which BiDil achieves its full beneficial effects has not been established in regulatory documents. In the primary clinical trial, the study found that the beneficial effect on survival began to emerge approximately six months after patients started treatment.

Q: Is BiDil a cure for heart failure?

No. Regulatory labeling specifies that BiDil is an adjunct therapy for the treatment and management of heart failure. It is intended to ease the overall strain on the heart and improve outcomes when used alongside other standard heart failure medications.

Q: Does BiDil affect kidney function?

Regulatory information regarding the hydralazine component notes that studies suggested the effect of renal impairment on the drug’s pharmacokinetics (how the body handles the drug) does not necessarily require a dose change. Regulatory information notes that patients with kidney issues are subject to monitoring when using this medication.

Q: Can BiDil be taken if I have mild kidney problems?

Studies on the hydralazine component suggested that a dose adjustment was not needed even for severely impaired renal function. The official information does not state that mild kidney problems are a contraindication, but monitoring for patients with any degree of renal impairment is noted.

Q: Does BiDil cause problems with vision?

Yes, regulatory documentation lists blurred vision as a potential adverse reaction. Other less common adverse reactions related to the eye that have been reported include lacrimation (tearing) and conjunctivitis.

Q: Does BiDil help improve exercise tolerance?

While studies do not specifically measure exercise tolerance, the main clinical trial found that BiDil significantly improved patient-reported functional status. This improvement relates to the patient's ability to perform and feel better during daily physical activities.

Q: How does BiDil affect the heart muscle over time?

Official indications and study findings suggest BiDil has a beneficial long-term effect on the progression of heart failure. Regulatory data shows it can improve survival and prolong the time until a patient requires hospitalization for heart failure.

How should BiDil be stored and disposed of?

How to Store and Dispose of BiDil

BiDil tablets must be stored at controlled room temperature, specifically 25°C (77°F), with permitted variations between 15°C and 30°C (59°F and 86°F).

Storage Requirements

Condition Requirement
Temperature 25°C (77°F); excursions allowed 15°C–30°C
Container Dispense in a tight, light-resistant container
Protection Must be protected from light and stored away from moisture and heat
Child Safety Keep tablets out of the reach of children

Disposal

Unused or expired BiDil should be disposed of properly according to official guidance. Patients should consult a pharmacist or other healthcare professional for instructions on how to discard the medicine. This product is not recommended for disposal by flushing down a toilet.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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