Chemydur

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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 Chemydur

Property Description
Active Ingredient Isosorbide Mononitrate (ISMN)
Form Extended-Release Tablet (Sustained-Release)
Pharmacological Class Organic Nitrate / Vasodilator
General Purpose Prophylactic treatment to reduce cardiac strain
Origin Synthetic

The Identity and Composition of Chemydur

Chemydur is a trade name for a medication that contains the active ingredient Isosorbide Mononitrate (ISMN). This compound is a synthetic chemical entity and functions as a single product agent, belonging to the therapeutic class of antianginal agents. Its core identity is established by its classification as an Organic Nitrate and a Vasodilator. This classification confirms the drug's fundamental design as a compound that affects the musculature of the circulatory system and is clinically recognized for its therapeutic efficacy in this role.

What Type of Medicine is Isosorbide Mononitrate?

The pharmacological class of Isosorbide Mononitrate is the Organic Nitrate group, whose primary function is to promote smooth muscle relaxation within blood vessel walls. The medicine is administered via the oral route and is supplied as an Extended-Release Tablet (XL tablet). This specialized dosage form utilizes solid pharmaceutical excipients to ensure a controlled and sustained-release of the active ingredient over a prolonged period. This long-acting prophylactic treatment is the defining characteristic that distinguishes it from rapid-acting nitrate agents.

The General Purpose of this Antianginal Agent

The general benefit of this long-acting medicine is its role as a prophylactic treatment to reduce the overall cardiac workload on the heart. By promoting vasodilation, the medication effectively decreases both the volume of blood returning to the heart and the resistance it must pump against. This systemic action helps maintain consistent blood flow and adequate oxygenation, thereby providing continuous circulatory support.

What side effects are possible with Chemydur?

Possible Side Effects and Safety Information

The safety profile for Chemydur, containing the active ingredient Isosorbide Mononitrate, is formally documented by government regulatory bodies. Adverse reactions are classified by frequency, establishing the expected risk profile.

Officially Documented Adverse Reactions

The most frequently reported adverse effect is Headache, which is classified as Very Common (occurring in ge 1 in 10 patients) and is generally noted to be more prominent at the initiation of treatment, often diminishing with continued use.

Reactions classified as Common (occurring in ge 1 in 100 to <1 in 10 patients) include Dizziness, Hypotension (low blood pressure), Tachycardia (increased heart rate), Nausea, and Vomiting. These effects are grouped primarily under Nervous System Disorders and Vascular Disorders in regulatory listings.

Less frequent reactions, classified as Uncommon, include Syncope (fainting) and generalized Flushing. Rare reactions documented in official sources include serious events such as Exfoliative Dermatitis and severe Hypersensitivity reactions.

Safety Constraints and Considerations

The medicine is associated with strict safety constraints. Use is contraindicated in conditions involving severe hypotension (systolic BP le 90 mmHg), acute circulatory failure (shock or collapse), marked anemia, and in patients using Phosphodiesterase type 5 (PDE5) inhibitors (such as sildenafil or tadalafil). Safety labeling also notes that older adults may have increased susceptibility to hypotensive effects.

Overdose and Emergency Response

Chemydur (Isosorbide Mononitrate) overdose is officially documented to present with signs of profound vasodilation and circulatory instability. Clinical manifestations described in regulatory labeling include severe hypotension, syncope, and an elevated pulse rate (tachycardia). Central Nervous System symptoms may involve a persistent throbbing headache, confusion, restlessness, and vertigo. Systemic presentations can include flushing, cold perspiration, nausea, vomiting, and, in severe cases, bloody diarrhea.

The most serious outcomes described in official regulatory documents are associated with circulatory collapse and the risk of methaemoglobinaemia, a severe condition that may present with cyanosis and requires specific intervention. Furthermore, overdose may lead to increased intracranial pressure.

Regulatory guidance explicitly mandates that individuals who suspect an overdose must seek emergency medical attention immediately and contact emergency services without delay. Management is symptomatic and supportive, focused primarily on increasing the central fluid volume via measures such as intravenous fluid infusion and passive elevation of the patient's legs. The label identifies Methylene blue as the specific intervention for methaemoglobinaemia. Patients must be held for observation and continuous monitoring of vital signs for a minimum of 12 hours. Regulatory information also notes that volume expansion treatment poses a specific hazard in patients with pre-existing renal disease or congestive heart failure.

Therapeutic Uses of Chemydur

What Chemydur Treats: Main Uses and Benefits

Chemydur, containing the active ingredient isosorbide mononitrate, is commonly used to assist with the prophylactic management of angina pectoris in patients with coronary artery disease (CAD). This medication may be part of the long-term management of conditions associated with acute or disruptive episodes.


The medicine's key therapeutic benefit may be part of providing supportive relief for symptoms related to stable ischemic heart disease. It is relevant for managing symptoms that become more disruptive during flare-ups and may assist with maintaining a sense of stability when symptoms are more noticeable. The key indications where this support is considered relevant include the prevention of recurrent anginal chest pain, support for chronic stable angina, and the management of symptoms associated with coronary artery disease.


“The medicine helps address symptom clusters that may become intense or disruptive, contributing to easing the overall symptom load.”


By addressing the symptoms related to organ-specific functional stress, Chemydur supports general well-being and assists with maintaining functional stability during symptomatic periods associated with physical activity. The medication may assist with maintaining a sense of stability when symptoms are more noticeable.

Quick Fact: Relief for Recurrent Anginal Chest Pain

Regulatory References

  1. NIH DailyMed information for Isosorbide Mononitrate Tablets

Eligibility and Restrictions for Use

Eligibility Map: Who Can and Cannot Use Chemydur (Isosorbide Mononitrate)

The official population eligibility for Chemydur is defined by regulatory labels across several domains, establishing absolute exclusions and necessary cautions.


Eligibility Scope

Classification Regulatory Status Details
Populations Allowed Approved Adults aged 18 years and over.
Populations Contraindicated Absolute Prohibition Concurrent use with Phosphodiesterase Type-5 (PDE5) Inhibitors (e.g., sildenafil) or sGC Stimulators (e.g., riociguat) [1.1, 1.3].
Conditions Contraindicated Absolute Prohibition Acute Circulatory Failure, Cardiogenic Shock, Severe Anemia, Marked Low Blood Pressure (Systolic leq 90 mmHg), or specific conditions causing low cardiac filling pressures [1.1, 2.4].

Age and Condition-Based Rules

Population Group Eligibility Rule Restriction Type
Pediatric Population Not Established Safety and efficacy have not been established for children or adolescents [2.3].
Pregnancy/Lactation Not Recommended Use is conditional; safety has not been established in humans [1.1, 3.2].
Organ Function Caution Required Severe Hepatic Impairment or Severe Renal Impairment necessitates cautious use [1.1, 2.3].
Special Caution Groups Caution Required Patients with pre-existing hypotension, volume depletion, Hypothyroidism, or Hypertrophic Obstructive Cardiomyopathy [1.1, 1.2, 4.3].

Connection to the Overall Eligibility Profile

Official regulatory documents strictly define who can and cannot use Chemydur based on absolute contraindications, primarily concerning co-medication and critical heart status. Eligibility is further structured by specific conditional restrictions concerning age, reproductive status, and severe organ impairment, all of which mandate caution according to the labeled prescribing information. This framework ensures the medicine is used only within the officially established and restricted adult patient categories.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Regulatory documents define specific interaction patterns for Chemydur (Isosorbide Mononitrate), primarily involving pharmacodynamic synergism and additive vasodilating effects.

Contraindicated Combinations

Co-administration with certain medicinal products is strictly prohibited due to the risk of severe, life-threatening hypotension and circulatory collapse. This prohibition is based on a potent pharmacodynamic synergism documented in official labeling.

Substance Category Examples Interaction Outcome Restriction
Phosphodiesterase Type 5 (PDE-5) Inhibitors Sildenafil, Tadalafil, Vardenafil Severe Hypotension, Syncope Strictly Prohibited
Soluble Guanylate Cyclase (sGC) Stimulators Riociguat Profound Hypotension Strictly Prohibited

Other Documented Interactions

Co-administration with other blood pressure-lowering agents and vasodilators (such as beta-blockers or calcium channel blockers) may result in additive vasodilating effects, increasing the risk of enhanced symptomatic hypotension. This is categorized as a use-with-caution interaction.

Separately, the concomitant use of alcohol (ethanol) may also exhibit additive vasodilating effects, which can enhance the risk of orthostatic hypotension and light-headedness. Furthermore, co-administration may increase the blood level and hypertensive effect of dihydroergotamine. The official label includes notes regarding caution in patients with conditions predisposing to labile circulation, such as volume depletion or pre-existing hypotension.

Mechanism of Action

Chemydur (Isosorbide Mononitrate) acts through a defined mechanism focused on modulating vascular smooth muscle tone to reduce the heart's workload.


Molecular Action: Activating the Nitric Oxide-cGMP Cascade

The mechanism is initiated when the drug acts as a prodrug, releasing Nitric Oxide (NO), an endogenous signaling molecule. NO activates the intracellular enzyme soluble Guanylyl Cyclase (sGC), which significantly raises the levels of the chemical messenger cyclic GMP (cGMP) within the smooth muscle cells. This cascade modulates systems through targeted pathway adjustment, culminating in the generalized relaxation of blood vessel walls.


Hemodynamic Effect: Reducing Cardiac Preload and Afterload

The resulting vasodilation is not uniform; it preferentially affects the venous capacitance vessels (veins). This major venodilation reduces the volume of blood returning to the heart (preload), while minor dilation of the arteries reduces the resistance the heart pumps against (afterload). This dual hemodynamic adjustment leads to a profound decrease in the heart's overall physical workload, resulting in a decreased myocardial oxygen demand.


Mechanistic Constraint: Understanding Nitrate Tolerance

A key constraint of this mechanism is the potential for nitrate tolerance (tachyphylaxis) upon continuous exposure. This attenuation of effect arises from the pathway's reliance on specific cellular cofactors and the body's compensatory mechanisms (like the activation of vasoconstrictor systems). The mechanism's susceptibility to attenuation necessitates the intermittent presence of the drug to sustain the physiological response.

Dosage and Administration Information

How to Use Chemydur

Chemydur, which contains the active substance isosorbide mononitrate, is an extended-release tablet intended solely for oral administration. Its usage follows a specific protocol designed to maximize its prophylactic efficacy while preventing the development of tolerance, a common characteristic of organic nitrates.


Official Dosing and Scheduling Protocol

The established regimen requires that the medication be administered once daily in the morning. This fixed timing is crucial for creating a mandatory nitrate-free interval overnight, which is essential to maintain the drug’s long-term effectiveness.

Treatment typically begins at a starting dose of 30 mg or 60 mg, taken once daily. The maintenance dose usually falls within the range of 30 mg to 120 mg once per day. The official maximum labeled dose is 240 mg once daily.


Administration Requirements

Instruction Requirement Contextual Note
Tablet Handling The extended-release tablet must be swallowed whole with a half-glass of fluid. It must not be chewed, crushed, or divided. This ensures the sustained-release mechanism remains intact, preventing rapid drug exposure.
Food Relationship May be taken with or without food. Food intake does not significantly impact the absorption of the tablet.
Discontinuation The medication should not be stopped abruptly. The dosage should be tapered gradually over several days as specified in the official instructions. This procedure manages the transition off long-term use.

Population-Specific Use

For older adults, official labeling advises beginning treatment at the lower end of the dosing range. For pediatric patients (under 18 years of age), the safety and efficacy of this medicine have not been established.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Chemydur


Evidence for use in Chronic Stable Angina Prophylaxis

The research base for Chemydur, which contains Isosorbide Mononitrate (ISMN), was studied for the prophylaxis (prevention) of episodes of angina pectoris in adults with Coronary Artery Disease (CAD). This evaluation relied on Randomized Controlled Trials (RCTs) and Systematic Reviews that utilized short-term and medium-term study designs to investigate measured changes in functional axes over defined time intervals.

In these studies, research examined various outcomes related to physical discomfort and functional limitations. Primary measures included functional axes such as Total Exercise Duration on a treadmill and the Time to Angina Onset, which are measures used to monitor physiological strain. Studies also focused on patient-reported outcomes, where researchers monitored the weekly Frequency of Angina Attacks and the amount of Short-Acting Nitrates (rescue medication) consumed. The findings describe patterns observed in the studies, where the observed populations reported experiences regarding measured outcomes related to daily functioning.

The research also documents an observed pattern of measured changes in functional axes during the study period. This pattern was observed in some studies, particularly in trials of chronic dosing when a nitrate-free period was not incorporated.


The Landscape of Follow-up and Long-term Data

Clinical trials for this medicine typically focused on acute dosing (observing responses within 12 hours) and medium-term chronic dosing periods, where follow-up durations were limited to approximately 6 weeks (42 days). These short-term studies provide context but do not offer individual predictions about long-term use. Research exploring extended outcomes, such as those related to major health events, is limited.


Research Evidence in Specific Populations

Specific research exploring pharmacokinetics, or how the medicine is absorbed and cleared by the body, was observed in trials that included Older Adults (aged 65 years and over). However, data for certain groups remain insufficient. The results apply only to the populations studied and may not reflect outcomes in other groups.


What the Research Describes as Study Limitations

In the regulatory reviews, a key limitation described relates to the potential for the development of tolerance with continuous use. This suggests that the development of tolerance may involve the need for a structured nitrate-free interval. Furthermore, the evidence quality varies across studies when analyzing certain subgroups or comparing different formulations.

Key Studies & References

  1. Isosorbide Mononitrate Extended-Release Tablets, USP Rx only (Full Prescribing Information/Package Insert)
  2. Label: ISOSORBIDE MONONITRATE tablet (Detailed FDA Labeling Information)
  3. Clinical Profile: Isosorbide Mononitrate 30mg Extended-Release Tablets - GlobalRx (Summary of indications and clinical efficacy)

Frequently Asked Questions (FAQ)

Common questions about Chemydur (FAQ)

Q: How quickly is Chemydur expected to start working?

According to official product information, Chemydur is an extended-release medicine used for prophylactic (preventive) treatment over time. Its anti-anginal effect is generally observed about one hour after the tablet is taken. The peak effect is typically noted between one to four hours after dosing.

Q: What happens if a dose of Chemydur is missed?

If a dose is missed, official patient instructions advise taking it as soon as it is remembered. However, if it is close to the time for the next scheduled dose (for example, more than eight hours later), the recommended procedure is to skip the dose. Regulatory guidance indicates that patients should not take a double dose to make up for the one that was missed.

Q: Are there any common supplements or vitamins that should not be taken with Chemydur?

Regulatory documents strictly prohibit using Chemydur with certain prescription drugs, such as PDE-5 inhibitors and sGC stimulators. Regarding other products, patients are advised to inform their healthcare professional about all medications, vitamins, supplements, and herbal products taken. This step is described as important for assessing potential interactions.

Q: Is it true that Chemydur is absorbed better at certain times of day?

The drug's absorption profile is described in official pharmacokinetic studies as being consistent and highly reproducible. The required once-daily, morning dosing schedule is a necessary step to create a daily nitrate-free interval. This specific timing is to maintain the drug's effectiveness over time, not because of differences in absorption based on the time of day.

Q: How does Chemydur affect the liver or kidney function based on official documents?

Isosorbide mononitrate is predominantly cleared from the body through metabolism in the liver. Official pharmacokinetic data indicate that routine dose adjustment is generally not required in patients with mild kidney or liver impairment. However, caution is advised by regulatory bodies when the medicine is used in patients with severe liver or kidney impairment.

Q: How is Chemydur generally cleared from the body?

The medicine is cleared from the body mainly by a process called metabolism, which primarily takes place in the liver. During this process, the drug is converted into inactive substances (metabolites) before being eliminated. Only a small portion of the drug (around 1–5%) is excreted unchanged.

Q: What type of monitoring is required when someone is taking Chemydur?

No routine laboratory monitoring, such as blood tests, is typically specified in official guidance for dose adjustment. The necessary monitoring is clinical, focusing on assessing blood pressure (especially during initial dose changes), heart rate, and any new or persistent symptoms like headaches, lightheadedness, or dizziness.

Q: Is Chemydur the same kind of medicine as [similar drug name]? What's the difference?

Chemydur is the trade name for the active ingredient Isosorbide Mononitrate, which is classified as an Organic Nitrate and a Vasodilator. The key characteristic that sets this formulation apart is that it is designed to be long-acting and extended-release, requiring a once-daily dosing schedule to maintain therapeutic benefit.

Q: Is Chemydur known to cause weight gain?

According to the official regulatory safety documents, neither weight gain nor weight loss is listed as a very common, common, or less common adverse reaction reported with this medication.

Q: Can older adults typically use Chemydur?

Chemydur is approved for use in adults. While official clinical experience has not identified differences in response compared to younger patients, caution is noted in regulatory documents. Older adults may have an increased susceptibility to hypotensive (low blood pressure) effects, and official labeling notes that treatment for older adults may begin at the lower end of the dose range.

Q: Does Chemydur show up on standard drug tests?

Chemydur is an antianginal medicine that is not classified as a controlled substance by regulatory bodies. For this reason, the active ingredient is not typically included in standard, non-medical drug-screening panels.

Q: Can Chemydur affect sleep patterns?

Official safety documentation notes that some less common adverse reactions related to the nervous system have been reported. These reactions include reports of insomnia (difficulty sleeping) and nightmares.

Q: Is there any research about Chemydur use in children or teenagers?

The official labeling states that the safety and efficacy of Chemydur have not been established in pediatric patients, which includes children and adolescents.

Q: What if I'm taking herbal products? Could they interact with Chemydur?

Regulatory guidance suggests that herbal products are generally not tested for safety and effectiveness with this medicine in the same manner as prescription drugs. The guidance provided by regulatory bodies is to inform the healthcare professional about all herbal remedies or supplements being taken.

Q: Is Chemydur available as a generic version?

Yes, regulatory bodies such as the FDA have approved a generic version of the extended-release tablet containing the active ingredient Isosorbide Mononitrate.

Q: Are there specific food types that are noted to interact with Chemydur?

The official administration instructions state that the medication may be taken with or without food, as food intake does not significantly impact absorption. Specific food types are not listed as restrictions in the official prescribing information.

Q: Is Chemydur a habit-forming or controlled substance?

Chemydur is not classified as a controlled substance by regulatory bodies. While physical dependence has been noted in industrial workers exposed to high, continuous doses of nitrates, the clinical importance of this observation to routine oral use is not known.

Q: Do official documents mention any potential for withdrawal symptoms if Chemydur is stopped suddenly?

Abrupt discontinuation is known to potentially cause a rebound worsening of angina (chest pain) in some patients. Regulatory documents indicate the need for a gradual tapering of the dose when stopping therapy.

Q: Is there a maximum length of time someone can be prescribed Chemydur?

The official label and prescribing information do not specify a maximum length of time for which Chemydur can be prescribed. The duration of this prophylactic treatment is not specified and is managed based on the patient's condition.

Q: Is Chemydur known to cause any issues related to vision?

Official safety data notes that blurred vision is an adverse reaction that has been reported. The product information describes blurred vision as an adverse reaction that has been reported.

Q: Can Chemydur affect blood sugar levels?

Clinical studies examining the use of isosorbide mononitrate in individuals with coronary artery disease found no effect on insulin sensitivity or glucose levels over a six-month period.

How should Chemydur be stored and disposed of?

How to Store and Dispose of Chemydur

The storage and disposal of Chemydur (Isosorbide Mononitrate) must adhere strictly to the conditions specified on the regulatory label to maintain its stability and ensure safety.

Official Storage and Handling Requirements

Condition Regulatory Requirement
Temperature Store below 25 C.
Protection Protect from light.
Packaging Keep in the original container and keep tightly closed.
Child Safety Keep out of the sight and reach of children.

Disposal Instructions

Unused or expired Chemydur must not be disposed of via household waste or wastewater, as mandated by environmental protection rules. The official instruction requires returning the product to a pharmacist who will manage its proper pharmaceutical waste disposal.

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

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