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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Nonsteroidal Anti-inflammatory Drug [EPC]
Dipyridamole is a platelet aggregation inhibitor and vasodilator used to prevent blood clots after heart valve replacement and to reduce the risk of stroke. It belongs to the pharmacological classes of Platelet Aggregation Inhibitors and Nonsteroidal Anti-inflammatory Drugs [EPC].
Name
Dipyridamole
Raw Name
DIPYRIDAMOLE
Category
Nonsteroidal Anti-inflammatory Drug [EPC]
Drug Count
5
Variant Count
24
Last Verified
February 17, 2026
RxCUI
259081, 197622, 309952, 309955, 309953
UNII
R16CO5Y76E, 64ALC7F90C
About Dipyridamole
Dipyridamole is a platelet aggregation inhibitor and vasodilator used to prevent blood clots after heart valve replacement and to reduce the risk of stroke. It belongs to the pharmacological classes of Platelet Aggregation Inhibitors and Nonsteroidal Anti-inflammatory Drugs [EPC].
Detailed information about Dipyridamole
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Dipyridamole.
Dipyridamole is a multi-faceted pharmacological agent primarily recognized as a platelet aggregation inhibitor (a medication that prevents blood cells from sticking together) and a vasodilator (a medication that widens blood vessels). According to the FDA-approved labeling, Dipyridamole belongs to a class of drugs called phosphodiesterase inhibitors, though it is also categorized under the Established Pharmacologic Class (EPC) as a Nonsteroidal Anti-inflammatory Drug [EPC] and a Platelet Aggregation Inhibitor [EPC]. First approved by the U.S. Food and Drug Administration (FDA) in 1961, Dipyridamole has a long clinical history, evolving from its initial use as an anti-anginal medication to its current primary roles in stroke prevention and the management of thromboembolic complications (blood clot risks) following cardiac valve replacement.
In modern clinical practice, Dipyridamole is often utilized in two distinct ways: as a chronic oral therapy for cardiovascular protection and as an intravenous diagnostic tool during cardiac stress testing. When administered orally, it helps maintain blood flow by preventing the formation of dangerous clots that could lead to heart attacks or strokes. When administered intravenously, its potent vasodilatory properties allow healthcare providers to evaluate blood flow through the coronary arteries without the patient needing to perform physical exercise. This versatility makes it a cornerstone in both therapeutic and diagnostic cardiology. Patients should understand that while Dipyridamole is effective at preventing clots, it is not typically used to treat an active, acute blood clot or a heart attack in progress.
The mechanism of action for Dipyridamole is complex and involves several distinct biochemical pathways that ultimately lead to its antiplatelet and vasodilatory effects. At the molecular level, Dipyridamole acts as a phosphodiesterase (PDE) inhibitor. Specifically, it inhibits the enzyme phosphodiesterase, which is responsible for breaking down cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) within platelets and vascular smooth muscle cells. By preventing the breakdown of these molecules, Dipyridamole causes an increase in intraplatelet cAMP levels. High levels of cAMP inhibit platelet activation and aggregation, making the blood less likely to form clots in response to vessel wall damage or prosthetic heart valves.
Furthermore, Dipyridamole functions as an adenosine reuptake inhibitor. It blocks the transport of adenosine into erythrocytes (red blood cells) and endothelial cells. This leads to an accumulation of extracellular adenosine at the site of the A2 receptors on the surface of blood vessels. When adenosine binds to these receptors, it triggers a cascade that results in the relaxation of smooth muscle and subsequent vasodilation (widening of the arteries). This dual action—preventing platelets from clumping while simultaneously keeping blood vessels open—is what provides the drug's therapeutic benefit. In the context of the Cyclooxygenase Inhibitors [MoA] classification, Dipyridamole also exhibits mild inhibitory effects on the formation of thromboxane A2, a potent stimulator of platelet aggregation, thereby complementing its PDE-inhibiting properties.
Understanding how the body processes Dipyridamole is essential for optimizing its therapeutic window and minimizing adverse effects. The pharmacokinetic profile of Dipyridamole is characterized by significant inter-patient variability, which is why healthcare providers must monitor patients closely during the initiation of therapy.
Dipyridamole is FDA-approved for several critical indications, and it is also used off-label in specific clinical scenarios under the guidance of specialists.
Dipyridamole is available in several formulations to accommodate different clinical needs:
> Important: Only your healthcare provider can determine if Dipyridamole is right for your specific condition. The choice of formulation and dosage will depend on your medical history, the condition being treated, and your response to the medication.
The dosage of Dipyridamole is highly specific to the condition being treated and must be individualized by a healthcare professional.
The safety and effectiveness of Dipyridamole in pediatric patients (under the age of 18) have not been established through large-scale clinical trials. While it is occasionally used off-label in children with specific congenital heart conditions or Kawasaki disease, this must only be done under the strict supervision of a pediatric cardiologist. Standardized pediatric dosing ranges are not available, and weight-based calculations are required if deemed necessary by a specialist.
Since Dipyridamole is primarily eliminated through the biliary system (liver/bile), dosage adjustments are generally not required for patients with mild to moderate renal impairment. However, data on patients with severe renal failure or those on dialysis are limited, and these individuals should be monitored closely for signs of toxicity.
Because the liver is the primary site of metabolism and the bile is the primary route of excretion, Dipyridamole should be used with extreme caution in patients with hepatic insufficiency. There are no specific sliding-scale dose adjustments, but a lower starting dose or increased monitoring of liver function tests may be warranted.
Clinical studies have shown that plasma concentrations of Dipyridamole can be approximately 40% higher in elderly subjects (over 65 years) compared to younger subjects. While a specific dose reduction is not always mandated, healthcare providers often start at the lower end of the dosing range to minimize the risk of side effects like dizziness or hypotension.
To ensure maximum efficacy and safety, patients should adhere to the following guidelines:
If you miss a dose of Dipyridamole, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Never take two doses at once to make up for a missed one, as this significantly increases the risk of adverse reactions like severe headache or low blood pressure.
An overdose of Dipyridamole can lead to significant peripheral vasodilation and a dangerous drop in blood pressure.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking this medication without medical guidance, as doing so may increase your risk of blood clots.
The most frequently reported side effect of Dipyridamole is headache. This occurs because the drug dilates blood vessels in the brain as well as the body.
> Warning: Stop taking Dipyridamole and call your doctor immediately if you experience any of the following serious symptoms.
With prolonged use, the most significant concern is the potential for chronic gastrointestinal irritation. Additionally, because Dipyridamole affects platelet function, long-term users may notice that minor cuts take longer to stop bleeding. There is no evidence that Dipyridamole causes cumulative organ damage over years of use, provided that liver function remains normal and the patient does not develop hypersensitivity. However, patients on long-term therapy should have regular check-ups to ensure the drug's benefits continue to outweigh any risks, particularly as they age and their cardiovascular profile changes.
No FDA black box warnings for Dipyridamole. While Dipyridamole is a potent medication with significant risks if used improperly, the FDA has not deemed it necessary to include a boxed warning for this agent. This distinguishes it from some other antiplatelet or anticoagulant medications that carry boxed warnings for bleeding risks or specific drug-drug interactions.
Report any unusual symptoms to your healthcare provider. Even mild side effects should be discussed, as they may impact your ability to remain compliant with the medication regimen. Your doctor can often provide strategies to manage common issues like headaches or stomach upset without discontinuing the drug.
Dipyridamole requires careful management, particularly in patients with underlying cardiovascular conditions. The most critical safety consideration is its potential to cause vasodilation, which can lead to significant hypotension (low blood pressure). Patients should be advised to move slowly when transitioning from a sitting or lying position to a standing one to prevent falls and fainting. Additionally, because Dipyridamole affects blood clotting, it must be used with caution in any situation where the risk of bleeding is increased, such as prior to surgery or in patients with active peptic ulcers.
No FDA black box warnings for Dipyridamole. Unlike some newer antiplatelet agents, Dipyridamole does not currently carry any boxed warnings. However, this does not mean the drug is without risk; the precautions regarding coronary artery disease and hypotension are of paramount importance.
Patients taking Dipyridamole long-term may require periodic monitoring to ensure safety:
Dipyridamole may cause dizziness, lightheadedness, or blurred vision, particularly during the first few days of treatment or after a dose increase. Patients should not drive, operate heavy machinery, or engage in potentially dangerous activities until they are certain the medication does not impair their cognitive or motor functions.
Alcohol can enhance the vasodilatory effects of Dipyridamole, leading to a greater risk of severe hypotension and dizziness. It is generally recommended that patients limit or avoid alcohol consumption while taking this medication. Furthermore, chronic heavy alcohol use can impair liver function, which may interfere with the body's ability to process Dipyridamole.
Dipyridamole does not typically require a tapering schedule when discontinued. However, patients must never stop taking the medication abruptly without consulting their doctor, especially if it was prescribed for stroke prevention or heart valve protection. Stopping the drug suddenly can significantly increase the risk of a thromboembolic event (blood clot).
> Important: Discuss all your medical conditions, including any history of heart disease, liver problems, or bleeding disorders, with your healthcare provider before starting Dipyridamole.
There are few absolute contraindications for drug combinations with Dipyridamole, but one stands out as particularly dangerous:
Dipyridamole does not typically interfere with standard laboratory blood tests, such as glucose, electrolytes, or kidney function markers. However, it can interfere with the results of Pharmacologic Stress Tests if the patient has consumed caffeine or theophylline, as these substances block the receptors Dipyridamole needs to act upon, potentially leading to a false-negative result.
For each major interaction, the mechanism usually involves either a pharmacodynamic effect (two drugs having similar or opposing effects on the body) or a pharmacokinetic interference (how the drug is absorbed or transported). Management usually involves dose adjustment, timing changes, or increased monitoring.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Even "natural" products can have significant interactions with Dipyridamole.
There are specific clinical scenarios where the use of Dipyridamole is strictly prohibited due to the high risk of harm:
These are conditions where the drug should be used only if the potential benefits clearly outweigh the risks, and with extreme caution:
There is no significant evidence of cross-sensitivity between Dipyridamole and other classes of antiplatelet drugs like P2Y12 inhibitors (clopidogrel) or traditional NSAIDs. However, because Dipyridamole is often formulated with aspirin (as in Aggrenox), patients with an Aspirin Allergy or NSAID-induced Asthma must be extremely careful to check which formulation they have been prescribed. A patient allergic to aspirin can safely take pure Dipyridamole but would have a severe reaction to the combination product.
> Important: Your healthcare provider will evaluate your complete medical history, including any previous drug reactions, before prescribing Dipyridamole. Always ensure your provider knows about all your allergies.
Dipyridamole is classified as FDA Pregnancy Category B. This means that animal reproduction studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women.
Dipyridamole is known to be excreted in human breast milk, though the amounts are typically very small. The American Academy of Pediatrics considers Dipyridamole to be generally compatible with breastfeeding. However, because the effects on a nursing infant's platelet function are not fully understood, healthcare providers usually recommend monitoring the infant for any unusual bruising or bleeding. The decision to breastfeed while taking Dipyridamole should involve a risk-benefit analysis between the mother and her pediatrician.
As previously noted, the safety and efficacy of Dipyridamole in children under 18 have not been established. Its use in the pediatric population is limited to specialized cases, such as managing children with prosthetic heart valves or treating Kawasaki disease (an inflammation of the blood vessels). In these cases, the dose is strictly calculated based on the child's weight and body surface area. There is no evidence that Dipyridamole affects growth or development in children when used for short periods under specialist care.
Elderly patients are at a higher risk for adverse reactions to Dipyridamole.
For patients with renal impairment, Dipyridamole is generally considered safer than many other medications because it does not rely on the kidneys for elimination. No dose adjustment is required for mild to moderate kidney disease. For patients with end-stage renal disease (ESRD), clinical data are sparse, and these patients should be monitored for any signs of increased drug effect or toxicity.
Because Dipyridamole is metabolized by the liver and excreted through the bile, hepatic impairment is a major concern. Patients with significant liver disease (Child-Pugh Class B or C) may experience a dramatic increase in the half-life of the drug. This can lead to accumulation and toxic effects. Dose reductions or longer intervals between doses may be necessary, and regular monitoring of liver enzymes is mandatory.
> Important: Special populations require individualized medical assessment. Always inform your doctor if you are pregnant, planning to become pregnant, or are breastfeeding before starting this medication.
Dipyridamole exerts its therapeutic effect through two primary molecular mechanisms. First, it is a potent inhibitor of the enzyme phosphodiesterase (PDE), specifically PDE3 and PDE5. By inhibiting PDE, Dipyridamole prevents the degradation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). In platelets, increased cAMP levels inhibit the release of calcium ions, which are necessary for platelet activation and the subsequent "clumping" process. Second, Dipyridamole inhibits the equilibrative nucleoside transporter 1 (ENT1). This transporter is responsible for moving adenosine from the extracellular space into cells. By blocking this transporter, Dipyridamole increases the local concentration of adenosine at the vascular A2 receptors, leading to potent vasodilation and further inhibition of platelet aggregation.
The pharmacodynamic effects of Dipyridamole are dose-dependent. Following an oral dose, the antiplatelet effect typically begins within 1 to 2 hours. The duration of the effect is linked to the plasma concentration, which is why multiple daily doses (or an extended-release formulation) are required for continuous protection. Unlike aspirin, which irreversibly inhibits platelets for their entire 7-10 day lifespan, the effect of Dipyridamole is reversible. Once the drug is cleared from the system, platelet function returns to normal within approximately 24 hours. Tolerance to the vasodilatory effects (such as headache) often develops within the first two weeks of therapy, but the antiplatelet effects remain consistent over long-term use.
| Parameter | Value |
|---|---|
| Bioavailability | 37% to 66% (pH-dependent) |
| Protein Binding | >99% (primarily to albumin) |
| Half-life (Terminal) | 10 to 12 hours |
| Tmax (Peak Time) | 2 to 3 hours (oral tablets) |
| Metabolism | Hepatic (Glucuronidation via UGT1A1) |
| Excretion | Fecal (>95%), Renal (<5%) |
Dipyridamole is classified therapeutically as an Antiplatelet Agent and a Vasodilator. Within the EPC system, it is categorized as a Platelet Aggregation Inhibitor [EPC] and a Nonsteroidal Anti-inflammatory Drug [EPC]. It is distinct from other antiplatelet classes such as the thienopyridines (clopidogrel) and the direct-acting P2Y12 inhibitors (ticagrelor) due to its unique PDE-mediated mechanism of action.
Medications containing this ingredient
Common questions about Dipyridamole
Dipyridamole is primarily used to prevent blood clots in patients who have had heart valve replacement surgery. It is also frequently prescribed in combination with aspirin to reduce the risk of a second stroke in people who have already had a stroke or a 'mini-stroke' (TIA). Additionally, an intravenous form of the drug is used by doctors during a cardiac stress test to help see how well blood is flowing to the heart. It works by keeping platelets in the blood from sticking together and by widening the blood vessels to improve circulation. Your doctor will determine the best use for your specific cardiovascular needs.
The most common side effect reported by patients taking Dipyridamole is headache, which occurs because the medication dilates blood vessels in the head. Other frequent side effects include dizziness, stomach upset, nausea, and diarrhea, particularly when first starting the medication. Some people may also experience a warm or tingling feeling known as flushing. Most of these symptoms are mild and often improve as your body gets used to the drug over the first week or two. If these side effects are severe or do not go away, you should contact your healthcare provider for advice on managing them.
It is generally recommended to avoid or significantly limit alcohol consumption while taking Dipyridamole. Alcohol also has the effect of widening blood vessels (vasodilation), which can combine with the effects of Dipyridamole to cause a dangerous drop in blood pressure. This can lead to severe dizziness, lightheadedness, and an increased risk of fainting or falling. Furthermore, chronic alcohol use can affect liver function, which is how the body processes this medication. Always discuss your alcohol intake with your doctor to ensure it is safe for your specific health situation.
Dipyridamole is classified as a Pregnancy Category B medication, meaning it is generally considered low-risk, but it should only be used if clearly needed. There are no large-scale studies in pregnant women to confirm its absolute safety, so it is typically reserved for cases where the benefit to the mother outweighs any potential risk to the fetus. If you are pregnant or planning to become pregnant, your doctor will carefully evaluate your condition before prescribing this drug. It is also important to note that Dipyridamole can pass into breast milk in small amounts. You should consult with both your obstetrician and your pediatrician if you need to take this medication while pregnant or breastfeeding.
When taken orally, Dipyridamole begins to inhibit platelet aggregation within about 1 to 2 hours after the first dose. However, its full protective effects for stroke prevention or heart valve management are built up over time with consistent daily use. For diagnostic purposes, the intravenous form works almost immediately to dilate the coronary arteries during a stress test. It is crucial to take the medication exactly as prescribed every day, even if you do not feel any different, because the 'work' it does to prevent clots is not something you can physically feel. Do not stop taking it without talking to your doctor, as the risk of clots returns quickly once the drug is out of your system.
No, you should never stop taking Dipyridamole suddenly without first consulting your healthcare provider. This medication is usually prescribed for serious conditions like preventing a stroke or protecting a new heart valve, and stopping it abruptly can significantly increase your risk of developing a dangerous blood clot. If you need to stop the medication due to side effects or an upcoming surgery, your doctor will provide a specific plan to do so safely. In some cases, they may need to switch you to a different medication to ensure you remain protected. Always keep enough of your prescription on hand so you do not miss any doses.
If you miss a dose of Dipyridamole, you should take it as soon as you remember. However, if it is almost time for your next scheduled dose, you should skip the missed dose and simply take the next one at the regular time. Do not take two doses at once to make up for the one you missed, as this can lead to a severe headache or a dangerous drop in blood pressure. To help you remember your doses, it may be useful to use a pillbox or set a daily alarm on your phone. If you miss multiple doses in a row, contact your doctor for further instructions.
Weight gain is not a recognized or common side effect of Dipyridamole. Clinical trials and post-marketing surveillance have not shown a direct link between this medication and changes in body weight. If you experience rapid weight gain or swelling in your ankles and feet while taking this medication, it could be a sign of a different underlying heart or kidney issue, and you should report it to your doctor immediately. Always maintain a healthy diet and exercise routine as recommended by your healthcare provider for your overall cardiovascular health. If you are concerned about weight changes, discuss them with your medical team.
Dipyridamole can interact with several other types of medications, so it is vital to provide your doctor with a full list of everything you take. It can increase the effects of blood thinners like warfarin or other antiplatelet drugs like aspirin, which increases your risk of bleeding. It also has a very significant interaction with adenosine, a drug used for certain heart rhythm problems, and can interfere with medications for Alzheimer's disease or myasthenia gravis. Additionally, common substances like caffeine can block the effects of Dipyridamole. Your pharmacist can help check for interactions between Dipyridamole and any new prescriptions or over-the-counter supplements you may consider taking.
Yes, Dipyridamole is available as a generic medication in both tablet and injectable forms. The generic versions are required by the FDA to have the same active ingredients, strength, and effectiveness as the brand-name versions, such as Persantine. Choosing the generic version can often be a more cost-effective way to manage your treatment. The combination product that includes both Dipyridamole and aspirin (formerly known by the brand name Aggrenox) is also available as a generic. You should talk to your pharmacist or insurance provider to see which version is covered under your plan and if a generic is right for you.