TRISENOX: Uses, Dosage & Side Effects

What Is TRISENOX and What Is It Used For?

TRISENOX contains the active substance arsenic trioxide (chemical formula As₂O₃), a compound with a remarkable history in medicine. Although arsenic has been recognized as a toxin for centuries — appearing throughout the history of poisoning and forensic science — its therapeutic potential in leukemia was first explored in traditional Chinese medicine during the 1970s at Harbin Medical University. Researchers there observed that patients with certain types of leukemia responded dramatically to arsenic-containing preparations. These observations, later validated through rigorous Western clinical trials in the 1990s, revolutionized the treatment of acute promyelocytic leukemia. Today, arsenic trioxide — originally marketed under the brand name TRISENOX — is considered one of the most important advances in hematology, having transformed APL from one of the most lethal forms of acute leukemia into one of the most curable.

Acute promyelocytic leukemia (APL) is a unique and distinct subtype of acute myeloid leukemia (AML) that accounts for approximately 5–8% of all AML cases. APL is characterized by the accumulation of immature white blood cells called promyelocytes in the bone marrow and peripheral blood. In virtually all cases (>98%), APL is driven by a specific chromosomal abnormality — the reciprocal translocation t(15;17)(q24;q21) — which creates the pathognomonic PML-RARα fusion gene. This abnormal gene encodes a fusion protein that aberrantly recruits transcriptional co-repressors and blocks the normal differentiation of promyelocytes, trapping them in an immature state and causing them to proliferate uncontrollably. Clinically, APL often presents with life-threatening coagulopathy (a tendency toward both bleeding and clotting simultaneously), making early recognition and prompt initiation of treatment absolutely critical.

Arsenic trioxide exerts its anti-leukemic effects through multiple complementary molecular mechanisms. Its primary action is the direct targeting and degradation of the PML-RARα oncoprotein. By binding to cysteine residues within the PML moiety of the fusion protein, arsenic trioxide promotes its SUMOylation (a type of post-translational protein modification), ubiquitination, and subsequent degradation by the proteasome. This removal of the oncogenic driver allows the previously blocked promyelocytes to resume their normal differentiation pathway, maturing into functional granulocytes that eventually die through apoptosis. Additionally, arsenic trioxide induces direct apoptosis (programmed cell death) in APL cells through several parallel pathways, including increased generation of reactive oxygen species (ROS), activation of caspase cascades, disruption of mitochondrial membrane potential, and modulation of the balance between pro-apoptotic (Bax, Bad) and anti-apoptotic (Bcl-2) proteins. TRISENOX also appears to inhibit angiogenesis and modulate the bone marrow microenvironment supporting leukemic cell survival.

TRISENOX is approved for use in the following clinical scenarios, consistent across EMA and FDA labelling:

• Newly diagnosed low-to-intermediate risk APL: TRISENOX is used in combination with all-trans retinoic acid (ATRA) as first-line induction and consolidation therapy. This ATRA+ATO (arsenic trioxide) regimen represents a groundbreaking chemotherapy-free approach to APL treatment. The landmark APL0406 trial by Lo-Coco et al., published in the New England Journal of Medicine in 2013, demonstrated that ATRA+ATO was non-inferior — and in fact superior — to traditional ATRA plus anthracycline-based chemotherapy (the AIDA protocol) in low-to-intermediate risk patients, with significantly better event-free survival, fewer relapses, and lower treatment-related mortality. Long-term follow-up data published in 2020 confirmed sustained cure rates exceeding 90% with the ATRA+ATO combination. Risk stratification in APL is based primarily on the initial white blood cell (WBC) count at diagnosis: low-to-intermediate risk is defined as WBC ≤10 × 10⁹/L; high risk is defined as WBC >10 × 10⁹/L.
• Relapsed or refractory APL: For patients whose APL has not responded to or has returned after prior treatments (including ATRA and/or chemotherapy), TRISENOX is used as salvage therapy. In the pivotal clinical trials conducted by Soignet and colleagues that led to initial FDA approval in 2000, arsenic trioxide achieved complete remission rates of 85–87% in relapsed APL, including molecular remission (negative PML-RARα by RT-PCR) in the majority of responding patients. This established TRISENOX as the single most effective agent available for relapsed APL and as a rescue option enabling some patients to proceed to hematopoietic stem cell transplantation in second remission.

APL is a medical emergency at the time of diagnosis because of the severe coagulopathy that accompanies it. Disseminated intravascular coagulation (DIC), hyperfibrinolysis, and the release of proteolytic enzymes (annexin A2, tissue factor) from leukemic promyelocytes can cause fatal hemorrhage, particularly intracranial bleeding. Early mortality (death within the first 30 days of diagnosis) remains the greatest contemporary challenge in APL management and is most commonly caused by hemorrhagic complications that occur before or shortly after treatment initiation. Current international guidelines from the European LeukemiaNet (ELN), the National Comprehensive Cancer Network (NCCN), and the European Society for Medical Oncology (ESMO) uniformly emphasize that treatment with ATRA should begin immediately upon clinical suspicion of APL — often even before genetic confirmation — and that TRISENOX should be started as soon as the diagnosis is confirmed by cytogenetic or molecular testing.

What Should You Know Before Taking TRISENOX?

Contraindications

There are specific situations in which TRISENOX must not be used. Understanding these absolute contraindications is essential before treatment begins, and your healthcare team will verify these before administering the first dose.

• Hypersensitivity: Do not receive TRISENOX if you are allergic to arsenic trioxide or to any of the other ingredients in the product (sodium hydroxide, hydrochloric acid for pH adjustment, and water for injections). Allergic reactions can range from mild skin reactions to severe anaphylaxis and require immediate discontinuation and supportive management.

Warnings and Precautions

Before and during treatment with TRISENOX, your doctor will implement the following precautions, and you should inform them if any of these conditions apply to you:

• Cardiac monitoring: A 12-lead electrocardiogram (ECG) must be performed before the first dose to assess your baseline heart rhythm, with particular attention to the QT interval corrected for heart rate (QTc). TRISENOX can prolong the QT interval, which increases the risk of potentially fatal cardiac arrhythmias, including torsade de pointes. ECGs are then performed at least twice weekly throughout the treatment course. If the QTc interval exceeds 500 milliseconds, treatment is typically interrupted until the QTc returns to a safer value (<460 ms) and any electrolyte abnormalities have been corrected. Patients with pre-existing QT prolongation, congestive heart failure, a history of torsade de pointes, or those taking concomitant QT-prolonging medications are at particularly high risk.
• Electrolyte monitoring: Blood tests for potassium, magnesium, calcium, and creatinine are required before the first dose and are repeated at least twice weekly during treatment — and more frequently during induction. Electrolyte imbalances, particularly hypokalemia (low potassium) and hypomagnesemia (low magnesium), significantly increase the risk of QT prolongation and cardiac arrhythmias. Your doctor will correct any electrolyte abnormalities before starting treatment and will aim to maintain potassium levels above 4.0 mEq/L and magnesium levels above 1.8 mg/dL (0.74 mmol/L) throughout treatment.
• Kidney function: If you have impaired renal function, inform your doctor. Since arsenic and its methylated metabolites are primarily excreted by the kidneys, reduced renal function may lead to accumulation of arsenic species in the body and increased toxicity. Creatinine and, where feasible, estimated glomerular filtration rate (eGFR) are monitored before and during treatment. Dose modifications may be considered in patients with severe renal impairment.
• Liver function: If you have any pre-existing liver disease, tell your doctor. TRISENOX can cause hepatotoxicity, manifesting as elevated serum transaminases (ALT, AST), alkaline phosphatase, and bilirubin. Liver function tests are performed at baseline and at least twice weekly during treatment. Grade 3 or higher hepatic toxicity (ALT/AST >5× upper limit of normal or bilirubin >3× upper limit of normal) typically requires treatment interruption until values improve.
• Vitamin B1 (thiamine) deficiency: Patients at risk of thiamine deficiency — including those with poor nutrition, chronic alcohol use, malabsorption, or prolonged parenteral nutrition — should be monitored closely for cognitive dysfunction and gait abnormalities. TRISENOX may worsen or precipitate Wernicke encephalopathy, a serious neurological syndrome caused by thiamine deficiency, presenting classically with the triad of confusion, ataxia, and ophthalmoplegia. Prophylactic thiamine supplementation is advisable in at-risk patients.
• Secondary malignancies: Your doctor may monitor your health during and after treatment because long-term exposure to arsenic compounds has been associated historically with an increased risk of developing certain other cancers, particularly cutaneous, urothelial, hepatic, and pulmonary malignancies. Report any new or unusual symptoms at every visit. Life-long dermatological and oncological surveillance may be appropriate after completion of TRISENOX therapy.
• Leukocytosis and tumor lysis: During induction, the white blood cell count may rise significantly (hyperleukocytosis) as leukemia cells undergo synchronized differentiation. This can contribute to differentiation syndrome and may require management with hydroxyurea or, in severe cases, temporary interruption of TRISENOX. Tumor lysis syndrome — with elevated uric acid, potassium, phosphate, and low calcium — is rare but requires aggressive hydration and allopurinol or rasburicase.
• Infection risk: Cytopenias during induction and consolidation phases increase susceptibility to bacterial, fungal, and viral infections. Prophylactic antimicrobials and growth factors may be used according to institutional protocols. Report fever (≥38°C / 100.4°F) immediately.

Children and Adolescents

TRISENOX is not recommended for use in children and adolescents under 18 years of age. The safety and efficacy of arsenic trioxide in pediatric patients have not been established in adequate, well-controlled trials. Pediatric APL is managed according to specific pediatric protocols, typically involving ATRA in combination with anthracycline-based chemotherapy, under the direct supervision of pediatric hematology-oncology specialists. Several pediatric oncology cooperative groups (including the Children’s Oncology Group, AIEOP-GIMEMA, and the International Consortium for Childhood APL) have conducted studies using arsenic trioxide in children with newly diagnosed and relapsed APL, with encouraging results, but data remain limited and TRISENOX does not currently hold a formal pediatric indication in most jurisdictions.

Pregnancy and Breastfeeding

Breastfeeding: Arsenic passes into breast milk and may cause serious harm to a nursing infant. Women must not breastfeed during treatment with TRISENOX and for at least two weeks after the final dose. Discuss alternative feeding options with your healthcare team before starting treatment. If breastfeeding is initiated at any point during or after APL therapy, confirmation of complete elimination of arsenic from breast milk may be appropriate.

Driving and Using Machines

TRISENOX is expected to have no or negligible direct effect on the ability to drive and use machines under normal circumstances. However, if you experience side effects such as dizziness, confusion, blurred vision, or fatigue after receiving an infusion, do not drive or operate machinery until these symptoms resolve completely. Because TRISENOX is administered in a hospital setting, most patients will not be driving immediately after treatment. Patients should arrange transportation to and from their infusion appointments, particularly during induction therapy.

How Does TRISENOX Interact with Other Drugs?

TRISENOX has clinically significant interactions primarily related to its ability to prolong the QT interval on the electrocardiogram. When combined with other QT-prolonging medications, the risk of potentially fatal cardiac arrhythmias, including torsade de pointes, is substantially amplified. Additionally, drugs that deplete electrolytes (particularly potassium and magnesium) can indirectly worsen QT prolongation and should be used with extreme caution, or with aggressive electrolyte repletion, during TRISENOX therapy. Unlike many oncology drugs, TRISENOX is not extensively metabolized by hepatic cytochrome P450 enzymes, so it does not have major CYP-mediated pharmacokinetic interactions with most other medications.

The following table summarizes the most important drug interactions. However, this list is not exhaustive. Always inform your doctor, pharmacist, or nurse about all medications you are taking, have recently taken, or might start, including over-the-counter products, dietary supplements, and herbal remedies.

Major Interactions

Additional Considerations

If you are taking or have recently taken any medication that may affect your liver, inform your doctor before starting TRISENOX. Although arsenic trioxide is not extensively metabolized by hepatic cytochrome P450 enzymes and therefore has limited classical pharmacokinetic drug–drug interactions, concomitant hepatotoxic medications (e.g., acetaminophen at high cumulative doses, isoniazid, nitrofurantoin) may increase the risk of additive liver damage during treatment.

There are no known strict food or beverage restrictions during treatment with TRISENOX. However, maintaining adequate nutrition and hydration is essential to support electrolyte balance, renal clearance of arsenic metabolites, and overall tolerance of cancer therapy. Seafood intake (which can contain organic arsenic) does not appear to interfere with TRISENOX pharmacodynamics but may transiently elevate urinary arsenic measurements if these are being tracked for research purposes.

Herbal supplements, traditional medicines, and “natural” products should be reviewed with your healthcare team, as some may have QT-prolonging properties or affect electrolyte balance. Products containing St. John’s wort (Hypericum perforatum), licorice root (Glycyrrhiza glabra, which can deplete potassium), grapefruit juice (less relevant for TRISENOX but relevant for concomitant drugs), and certain Ayurvedic or Traditional Chinese Medicine preparations — some of which may themselves contain arsenic or heavy metals — must be disclosed and typically discontinued during treatment.

What Is the Correct Dosage of TRISENOX?

TRISENOX is administered exclusively by intravenous infusion in a supervised healthcare setting. The product comes as a concentrate (1 mg/ml, 10 mg per 10 ml vial) that must be diluted in 100–250 ml of 5% glucose (dextrose) solution or 0.9% sodium chloride solution immediately before infusion. PVC-free infusion bags and tubing are recommended, although modern PVC products without DEHP plasticizer are also acceptable. The prepared solution is administered over 1–2 hours; however, the infusion time may be extended to up to 4 hours if vasomotor reactions (such as flushing, dizziness, or lightheadedness) occur. A central venous catheter is not required but may be used if peripheral venous access is difficult or if concomitant supportive care mandates central access. TRISENOX must not be mixed with or administered through the same intravenous line as other medications.

Adults — Newly Diagnosed Low-to-Intermediate Risk APL

Adults — Relapsed or Refractory APL

Children and Adolescents

TRISENOX is not recommended for use in patients under 18 years of age due to insufficient data on safety and efficacy in this population. Pediatric APL should be managed by a specialized pediatric hematology-oncology team following appropriate pediatric protocols (for example, the AIDA-2000 or COG AAML1331 regimens). When arsenic trioxide is used off-label in children with relapsed APL, dosing is often weight-based with careful attention to cardiac monitoring.

Elderly Patients

No specific dose adjustment is recommended for elderly patients based on age alone, and older adults have been successfully treated in clinical trials. However, older patients may be more susceptible to electrolyte imbalances, cardiac toxicity (including QT prolongation), renal dysfunction, and other adverse effects. Careful baseline and ongoing assessment of cardiac function, electrolytes, and renal function is particularly important in this population. Dose modifications or treatment interruptions may be necessary based on individual tolerance and comorbidities.

Renal and Hepatic Impairment

There are limited data on the use of TRISENOX in patients with severe renal or hepatic impairment. In patients with renal impairment, arsenic elimination may be delayed, and dose reductions or extended dosing intervals may be considered in consultation with a clinical pharmacologist. In patients with hepatic impairment, additional hepatotoxicity monitoring is warranted. No formal dose-adjustment algorithm exists in the product label; individualized management by a specialist is required.

Missed Dose

Since TRISENOX is administered in a hospital or clinic setting by healthcare professionals, missed doses are managed by your medical team. If a scheduled infusion is missed (for example, due to weekend scheduling, a public holiday, or an intercurrent medical problem), your doctor will adjust the treatment schedule accordingly. Do not attempt to compensate by receiving a double dose or by extending daily dosing, as this increases the risk of cardiac toxicity.

Overdose

Overdose with arsenic trioxide can cause seizures, profound muscle weakness, confusion, and severe cardiac arrhythmias. Symptoms of acute arsenic toxicity include severe gastrointestinal distress (abdominal pain, bloody diarrhea, vomiting), hypovolemic shock, encephalopathy, and ventricular arrhythmias. If an overdose is suspected, treatment must be stopped immediately and supportive care initiated in an intensive care environment. The specific chelating antidote for acute arsenic poisoning is dimercaprol (British Anti-Lewisite, BAL) — typically 3–5 mg/kg IM every 4–6 hours for the first 24 hours — which chelates arsenic and facilitates its urinary excretion. Penicillamine or DMSA (succimer) may be used for ongoing oral chelation. Your medical team will provide appropriate management, which includes continuous cardiac monitoring, aggressive electrolyte correction, and supportive intensive care.

What Are the Side Effects of TRISENOX?

Like all medicines, TRISENOX can cause side effects, although not everybody gets them. Some side effects can be serious and require immediate medical attention. Your healthcare team will monitor you closely throughout treatment to detect and manage adverse reactions as early as possible. The frequency categories below follow the standard convention used in EMA Summary of Product Characteristics documents and in most international drug safety databases.

Side effects are categorized below by frequency according to standard medical conventions. The frequency of specific adverse reactions reflects data from pivotal clinical trials and post-marketing surveillance.

Management of Key Adverse Reactions

Differentiation syndrome is managed with immediate initiation of high-dose dexamethasone (typically 10 mg IV twice daily for at least 3 days or until symptoms resolve) and temporary interruption of TRISENOX and/or ATRA if symptoms are severe or do not improve within 24–48 hours. Prophylactic corticosteroids are now commonly used in patients at higher risk (WBC >5 × 10⁹/L at diagnosis).

QT prolongation is managed by interrupting TRISENOX if the QTc exceeds 500 ms, correcting electrolyte abnormalities (potassium, magnesium), reviewing concomitant QT-prolonging medications, and resuming treatment at a reduced frequency or dose once the QTc returns to a safe range and electrolytes are normalized.

Hepatotoxicity typically responds to temporary treatment interruption and generally resolves without sequelae. TRISENOX is usually restarted at a reduced dose once liver function tests return to grade 1 or lower.

Reporting Side Effects

It is important to report suspected side effects after a medicine has been approved. This allows ongoing monitoring of the medicine’s benefit-risk balance. Healthcare professionals and patients can report suspected adverse reactions to their national pharmacovigilance authority — such as the FDA MedWatch program in the United States, the Yellow Card Scheme in the United Kingdom, the EMA EudraVigilance system in the European Union, the Therapeutic Goods Administration (TGA) in Australia, or Health Canada’s Canada Vigilance Program. Your healthcare team can provide details on how to submit a report in your country.

How Should You Store TRISENOX?

As TRISENOX is administered exclusively in a hospital or specialized clinic setting, storage is managed by pharmacy and nursing staff. However, understanding the storage requirements provides important context about the medication’s stability, handling, and preparation.

• Keep out of sight and reach of children. Although this medication is handled exclusively in healthcare settings, standard safe-handling precautions for cytotoxic drugs apply.
• Shelf life: Do not use after the expiry date stated on the vial label and outer carton. The expiry date refers to the last day of the stated month.
• Unopened vials: No special storage conditions are required for the unopened product. Do not freeze.
• After opening: The medication must be used immediately after the vial is opened. TRISENOX does not contain preservatives, so opened vials cannot be stored for later use.
• After dilution: Chemical and physical in-use stability has been demonstrated for up to 24 hours at 15–25°C and up to 48 hours refrigerated at 2–8°C. From a microbiological perspective, the product should be used immediately after dilution. If not used immediately, in-use storage should normally not exceed 24 hours at 2–8°C unless dilution has taken place under controlled and validated aseptic conditions.
• Visual inspection: Healthcare professionals inspect the solution before administration. Do not use the solution if it contains visible particles, if the solution is discolored, or if the vial is damaged. The concentrate and the diluted solution should be clear and colorless.
• Disposal: Unused medicine and contaminated waste must be disposed of in accordance with local regulations for cytotoxic drugs and hazardous pharmaceutical waste. As with all cytotoxic medications, TRISENOX must not be disposed of via household waste or wastewater. Healthcare facilities typically use licensed cytotoxic waste contractors.
• Occupational safety: Staff preparing TRISENOX infusions should work within a biological safety cabinet (class II minimum) using personal protective equipment including gowns, gloves, goggles, and masks, in compliance with USP <800> (United States) or equivalent international standards for handling hazardous drugs.

What Does TRISENOX Contain?

Understanding the composition of TRISENOX is important for healthcare professionals preparing the infusion, for patients or caregivers with allergies or sensitivities to specific excipients, and for patients on restricted diets (for example, sodium-restricted diets).

Active Substance

The active substance is arsenic trioxide (chemical formula As₂O₃, molecular weight 197.84 g/mol, CAS number 1327-53-3). Each milliliter of concentrate contains 1 mg of arsenic trioxide. Each glass vial contains 10 ml of concentrate, providing a total of 10 mg of arsenic trioxide per vial. In solution at physiological pH, arsenic trioxide predominantly exists as the trivalent arsenite species (As(III)), which is the pharmacologically active form responsible for the clinical effects on APL cells.

Other Ingredients (Excipients)

• Sodium hydroxide — used to adjust the pH of the solution during manufacturing
• Hydrochloric acid (concentrated) — also used for pH adjustment
• Water for injections — the solvent

TRISENOX does not contain any preservatives. This is why the vial must be used immediately after opening, and strict aseptic technique must be maintained throughout preparation and administration. The product also does not contain lactose, gluten, or animal-derived ingredients.

Appearance and Pack Sizes

TRISENOX is a concentrate for solution for infusion supplied in clear glass vials with elastomeric stoppers and aluminum over-seals. The concentrate is a clear, colorless aqueous solution. Depending on the country and marketing authorization, cartons may contain 1, 5, or 10 vials. Not all pack sizes may be marketed in every jurisdiction.

Preparation Instructions (for Healthcare Professionals)

TRISENOX must be diluted before intravenous administration. Strict aseptic technique is mandatory throughout all handling because the product contains no preservative. Healthcare staff preparing cytotoxic drugs must be trained in safe handling and must wear appropriate personal protective equipment (impervious gown, double nitrile or neoprene gloves, eye protection, and respiratory protection as required by local hazardous drug guidelines). The contents of the vial are withdrawn using a syringe and closed-system transfer device (CSTD) where available, and the withdrawn concentrate is immediately diluted with 100–250 ml of glucose 50 mg/ml (5%) solution or sodium chloride 9 mg/ml (0.9%) solution for intravenous infusion. PVC-free plastic infusion bags and administration sets are preferred where feasible. Any unused solution remaining in the vial must be discarded appropriately as cytotoxic waste; TRISENOX vials are for single use only. The drug must not be infused simultaneously with other medications through the same intravenous line.

Marketing Authorisation Holder and Manufacturer

In the European Union, the marketing authorisation for TRISENOX is held by Teva B.V., Haarlem, Netherlands. In the United States, TRISENOX is marketed by Teva Pharmaceuticals USA, Inc., a subsidiary of Teva Pharmaceutical Industries Ltd. TRISENOX was originally developed by Cell Therapeutics and PolaRx Biopharmaceuticals, with subsequent global commercialization rights acquired by Cephalon and later by Teva following its 2011 acquisition of Cephalon. Generic and licensed versions of arsenic trioxide (such as Arsenic Trioxide Accord, Arsenic Trioxide Medac, and others) are now available in many markets since the expiry of data exclusivity, offering therapeutic equivalence at typically lower acquisition cost.