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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Other
Cyclophosphamide is a potent nitrogen mustard alkylating agent and immunosuppressant used to treat various malignancies and severe autoimmune conditions by interfering with DNA replication.
Name
Cyclophosphamide
Raw Name
CYCLOPHOSPHAMIDE
Category
Other
Drug Count
4
Variant Count
78
Last Verified
February 17, 2026
RxCUI
2703027, 2703032, 1734917, 1734919, 1734921, 2386859, 2679073, 1437968, 1437969, 2644738, 2644751, 2644824, 197549, 197550, 2568661, 2568663
UNII
8N3DW7272P
About Cyclophosphamide
Cyclophosphamide is a potent nitrogen mustard alkylating agent and immunosuppressant used to treat various malignancies and severe autoimmune conditions by interfering with DNA replication.
Detailed information about Cyclophosphamide
References used for this content
This page is for informational purposes only and does not replace medical advice. Consult a qualified healthcare professional before using any medication containing Cyclophosphamide.
Healthcare providers typically prescribe cyclophosphamide for a wide range of conditions, spanning from aggressive cancers like lymphoma and leukemia to life-threatening autoimmune disorders such as lupus nephritis and systemic vasculitis. Because it targets rapidly dividing cells, it is highly effective at stopping the growth of cancer cells and suppressing an overactive immune system. However, this same mechanism also affects healthy cells that divide quickly, such as those in the hair follicles, bone marrow, and the lining of the digestive tract, leading to its well-known side effect profile.
The mechanism of action for cyclophosphamide is complex and occurs at the molecular level within the cell nucleus. Once the drug is metabolized by hepatic (liver) enzymes, it transforms into active metabolites, primarily phosphoramide mustard and acrolein. The phosphoramide mustard is the component responsible for the drug's anti-cancer and immunosuppressive actions. It works by forming cross-links between the two strands of the DNA double helix. Specifically, it attaches to the N-7 position of guanine (one of the four building blocks of DNA).
By creating these covalent bonds (strong chemical links), the drug prevents the DNA strands from unzipping, which is a necessary step for DNA replication and cell division. When a cell attempts to divide but cannot replicate its DNA, it triggers a process called apoptosis (programmed cell death). In the context of the immune system, cyclophosphamide is particularly effective at suppressing B-cells and T-cells (white blood cells), which are the primary drivers of autoimmune attacks. The metabolite acrolein, however, does not have therapeutic benefits and is instead responsible for the drug's toxic effects on the bladder, a condition known as hemorrhagic cystitis.
Understanding how the body processes cyclophosphamide is crucial for optimizing its efficacy and minimizing toxicity.
Cyclophosphamide is FDA-approved for a diverse array of indications. In the realm of oncology, it is used as part of combination therapy for:
In non-oncology settings, it is primarily used for:
Cyclophosphamide is available in several formulations to allow for flexible dosing strategies:
> Important: Only your healthcare provider can determine if Cyclophosphamide is right for your specific condition. The choice between oral and intravenous administration depends on the severity of the disease and the specific treatment protocol being followed.
Dosage for cyclophosphamide is highly individualized and depends on the condition being treated, the patient's body surface area (BSA), and their overall health status.
Cyclophosphamide is used in children for specific conditions like neuroblastoma and nephrotic syndrome.
Since cyclophosphamide and its metabolites are primarily cleared by the kidneys, patients with reduced kidney function require careful monitoring. For patients with a creatinine clearance (CrCl) of less than 10 mL/min, healthcare providers typically reduce the dose by 25% to 50%. Patients on hemodialysis should receive their dose after the dialysis session, as the drug is dialyzable.
Because the liver is responsible for activating this prodrug, severe liver disease can lead to unpredictable levels of active metabolites. While there are no standardized formulas for adjustment, doctors may start with a lower dose and monitor blood counts closely.
Older adults are more likely to have decreased renal and cardiac function. Dosing should be conservative, often starting at the lower end of the range, with frequent monitoring of white blood cell counts and kidney function.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your regular schedule. Never double the dose to catch up. If you miss multiple doses, contact your oncology or rheumatology team immediately.
Signs of cyclophosphamide overdose include severe bone marrow suppression (leading to infections or bleeding), intense nausea, and signs of bladder toxicity (blood in the urine). There is no specific antidote for cyclophosphamide. Treatment involves supportive care, aggressive hydration, and potentially the administration of Mesna (a bladder-protecting agent). In severe cases, hemodialysis may be used to remove the drug from the bloodstream.
> Important: Follow your healthcare provider's dosing instructions precisely. Do not adjust your dose or stop taking the medication without medical guidance, as this could lead to a relapse of your condition.
Cyclophosphamide is a systemic treatment that affects many parts of the body. The following side effects occur frequently:
> Warning: Stop taking Cyclophosphamide and call your doctor immediately if you experience any of these serious symptoms:
Cyclophosphamide carries several significant warnings from the FDA:
Report any unusual symptoms to your healthcare provider immediately. Early intervention is key to managing the toxicities associated with this medication.
Cyclophosphamide is a high-alert medication. It must only be administered under the supervision of a physician experienced in the use of cytotoxic or immunosuppressive therapy. Patients must understand that while this drug is effective, it carries a high risk of significant toxicity. Adherence to monitoring schedules and hydration protocols is non-negotiable for safety.
According to the FDA-approved labeling, Cyclophosphamide is associated with the following boxed warnings:
The metabolite acrolein is a potent bladder irritant. To mitigate this risk, patients are often given Mesna (sodium 2-mercaptoethane sulfonate) during high-dose IV therapy. Mesna binds to acrolein in the bladder, neutralizing its toxicity. For oral therapy, aggressive hydration (drinking 8-10 glasses of water daily) is the primary defense.
High doses (usually >120 mg/kg over a short period) have been associated with hemorrhagic myocarditis (inflammation of the heart muscle). Patients with pre-existing heart disease require baseline EKG and echocardiogram monitoring.
Interstitial pneumonitis and pulmonary fibrosis can occur, sometimes years after treatment. Any new or worsening shortness of breath must be investigated immediately.
As a cytotoxic agent, cyclophosphamide can impair the body's ability to heal wounds. If you have an upcoming surgery, your doctor may recommend pausing the medication.
Patients on cyclophosphamide require rigorous laboratory monitoring:
Cyclophosphamide can cause dizziness, blurred vision, and fatigue. Patients should determine how the drug affects them before driving or operating heavy machinery. If nausea is severe, the resulting dehydration can also impair cognitive and motor functions.
Alcohol should be avoided or strictly limited. Both alcohol and cyclophosphamide are processed by the liver, and concurrent use can increase the risk of hepatotoxicity (liver damage). Furthermore, alcohol can contribute to dehydration, which increases the risk of bladder toxicity.
Do not stop taking cyclophosphamide abruptly without consulting your doctor. In autoimmune conditions, sudden discontinuation can lead to a 'flare' or rapid worsening of the disease. In cancer treatment, stopping the drug can allow the malignancy to progress quickly.
> Important: Discuss all your medical conditions, especially any history of bladder problems, kidney disease, or heart issues, with your healthcare provider before starting Cyclophosphamide.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A complete medication review is essential before each cycle of therapy.
Cyclophosphamide must NEVER be used in the following circumstances:
In these cases, the healthcare provider will perform a careful risk-benefit analysis:
Patients who have had allergic reactions to other alkylating agents, such as Ifosfamide, Busulfan, or Chlorambucil, may be at an increased risk for a hypersensitivity reaction to cyclophosphamide. This is due to the similarity in the chemical structure of these 'nitrogen mustard' derivatives.
> Important: Your healthcare provider will evaluate your complete medical history, including your current immune status and bladder health, before prescribing Cyclophosphamide.
Cyclophosphamide is classified as FDA Pregnancy Category D (and in some contexts, effectively Category X for non-life-threatening uses). There is clear evidence of human fetal risk based on adverse reaction data.
Cyclophosphamide is excreted into human breast milk. Because of the potential for serious adverse reactions in the nursing infant (including bone marrow suppression and growth inhibition), breastfeeding is strictly contraindicated during therapy. Most guidelines recommend waiting at least 1 to 2 weeks after the final dose before resuming breastfeeding.
Cyclophosphamide is approved for use in children for specific indications like neuroblastoma and minimal change nephrotic syndrome.
Clinical studies have not identified significant differences in response between elderly and younger patients. However, older adults are more likely to have:
Healthcare providers typically start with lower doses in this population.
For patients with a GFR (Glomerular Filtration Rate) between 10-50 mL/min, a 25% dose reduction is common. For GFR < 10 mL/min, a 50% reduction is often required. Since the drug is cleared by dialysis, it should be administered after the procedure on dialysis days.
There are no specific GFR-like formulas for liver disease. However, since the liver activates the drug, patients with cirrhosis or hepatitis may have lower levels of the active drug but higher levels of the parent compound. Monitoring of the white blood cell count is the most reliable way to gauge if the dose is appropriate in these patients.
> Important: Special populations require individualized medical assessment and more frequent monitoring of blood work and organ function.
Cyclophosphamide is a cell-cycle non-specific alkylating agent. Its primary molecular target is the DNA of rapidly dividing cells. The process begins with the hepatic activation of the parent drug into 4-hydroxycyclophosphamide. This molecule then spontaneously tautomerizes into aldophosphamide, which enters the peripheral tissues and cells. Within the cell, it cleaves into phosphoramide mustard and acrolein.
The phosphoramide mustard acts by forming highly reactive carbonium ions. these ions react with the nucleophilic groups on DNA, particularly the N7 position of the nitrogenous base guanine. This results in the formation of intra-strand and inter-strand DNA cross-links. These cross-links are physically impossible for the cell's repair machinery to fix during the S-phase of the cell cycle, leading to DNA strand breakage and the induction of apoptosis via the p53 pathway.
The onset of the immunosuppressive effect usually takes several days to weeks, while the cytotoxic effect on cancer cells begins shortly after administration. The duration of the effect on the bone marrow is approximately 7 to 21 days. Tolerance does not typically develop to the drug's primary mechanism, but cancer cells can develop resistance by increasing their production of aldehyde dehydrogenase (ALDH), an enzyme that detoxifies the drug's intermediates.
| Parameter | Value |
|---|---|
| Bioavailability | 75% - 90% (Oral) |
| Protein Binding | < 20% (Parent drug); > 60% (Metabolites) |
| Half-life | 3 to 12 hours (Parent drug) |
| Tmax | 1 hour (Oral) |
| Metabolism | Hepatic (CYP2B6, CYP3A4, CYP2C9) |
| Excretion | Renal (70-80% as metabolites), Fecal (<5%) |
Cyclophosphamide is classified as an Alkylating Agent within the sub-class of Nitrogen Mustards. It is related to other drugs like Ifosfamide (its structural isomer) and Chlorambucil. In the context of the WHO Model List of Essential Medicines, it is categorized as both an antineoplastic (cancer) agent and an immunosuppressant.
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Common questions about Cyclophosphamide
Cyclophosphamide is a versatile medication used primarily to treat various types of cancer and severe autoimmune diseases. In oncology, it is commonly prescribed for lymphomas, leukemias, multiple myeloma, and breast cancer. In rheumatology, it is used for life-threatening conditions like lupus nephritis and systemic vasculitis when other treatments have failed. It is also FDA-approved for treating nephrotic syndrome in children. Because it is a potent drug, it is reserved for serious conditions where its benefits outweigh the risks of significant side effects.
The most frequent side effects include hair loss (alopecia), nausea, vomiting, and a significant drop in white blood cell counts, which increases the risk of infection. Many patients also experience a loss of appetite and general fatigue. Hair loss is usually reversible after the medication is stopped, but it can be complete across the entire body. Nausea is often managed with modern anti-nausea medications (antiemetics). Monitoring for fever is critical, as a low white blood cell count can make even minor infections dangerous.
It is generally advised to avoid alcohol while taking cyclophosphamide. Both substances are processed by the liver, and combining them can increase the risk of liver toxicity and irritation. Furthermore, alcohol is a diuretic that can lead to dehydration. Since staying well-hydrated is the most important way to prevent the drug's toxic effects on the bladder (hemorrhagic cystitis), alcohol consumption can be counterproductive and dangerous. Always consult your healthcare provider before consuming any alcohol during chemotherapy.
No, cyclophosphamide is not considered safe during pregnancy and is classified as a known human teratogen. Exposure, especially during the first trimester, can cause severe birth defects, including malformations of the limbs, skull, and internal organs. Women of childbearing age must use effective birth control during treatment and for several months afterward. Men should also use contraception, as the drug can damage sperm cells. If pregnancy occurs while taking this medication, it must be reported to a doctor immediately.
The timeframe for cyclophosphamide to show results varies depending on the condition being treated. In cancer therapy, the drug begins working at the cellular level almost immediately, though visible shrinkage of tumors or changes in blood markers may take several weeks or multiple cycles of treatment. For autoimmune diseases like lupus or vasculitis, it may take 3 to 12 weeks of consistent therapy before a significant reduction in inflammation or symptoms is observed. Your doctor will use blood tests and imaging to track your progress.
You should never stop taking cyclophosphamide suddenly without your doctor's explicit instructions. If you are taking it for an autoimmune disease, stopping abruptly can cause a 'rebound' effect where your symptoms return more severely than before. In cancer treatment, stopping the drug prematurely can allow the cancer cells to grow and potentially develop resistance to the medication. If you are experiencing side effects that make you want to stop, contact your medical team to discuss dose adjustments or supportive care.
If you miss a dose of the oral tablet, take it as soon as you remember on the same day. If you don't remember until the next day, skip the missed dose and continue with your regular schedule; do not double the dose. It is important to notify your doctor if you miss more than one dose, as this could affect the efficacy of your treatment. If you miss an appointment for an intravenous (IV) infusion, call your oncology or rheumatology clinic immediately to reschedule, as timing is often critical in 'pulse' therapy.
Cyclophosphamide itself is more likely to cause weight loss due to side effects like nausea, vomiting, and loss of appetite. However, many patients taking cyclophosphamide for autoimmune diseases are also prescribed corticosteroids (like prednisone). Corticosteroids are well-known for causing weight gain, fluid retention, and increased appetite. If you notice rapid weight gain or swelling in your ankles, it is more likely related to the steroids or potential changes in kidney or heart function, and you should inform your doctor.
Cyclophosphamide has several significant drug interactions, so it must be used cautiously with other medications. It can interact with allopurinol, warfarin, and certain anti-seizure medications, potentially increasing toxicity or changing the effectiveness of the other drugs. It also interacts with 'live' vaccines, which can be dangerous while your immune system is suppressed. Always provide your healthcare provider with a complete list of all prescription drugs, over-the-counter medicines, and herbal supplements you are taking to ensure safety.
Yes, cyclophosphamide is available as a generic medication in both tablet and injectable forms. Generic versions are typically much more affordable than the original brand-name versions (such as Cytoxan, which is no longer marketed in the U.S.). The FDA ensures that generic versions have the same active ingredient, strength, and effectiveness as the brand-name drug. Availability may vary by region, but most major pharmacies and hospital systems carry the generic form of this essential medication.