Irinotecan

Selected form

Irinotecan Hydrochloride Trihydrate

Method of action: Antitumour, Cytostatic

Treatment option: Carcinoma, Colorectal Cancer, Cancer, Chemotherapy

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 Irinotecan

Property	Description
Active ingredient	Irinotecan Hydrochloride Trihydrate
Form	Sterile Solution for Intravenous Infusion
Pharmacological class	DNA Topoisomerase I Inhibitor
General purpose	Systemic Antitumor Effect
Origin	Semisynthetic Derivative (from Camptothecin)

Understanding Irinotecan and its Pharmacological Classification

Irinotecan is a highly specific antineoplastic agent—a formal term for medicine used to treat cancer—chemically known as Irinotecan Hydrochloride Trihydrate. It belongs to the precise pharmacological category of a DNA Topoisomerase I Inhibitor. This classification is clinically recognized for defining a group of drugs that specifically disrupt the cellular mechanisms of replication. This means the substance is designed to interfere with a fundamental enzyme crucial for cell replication, distinguishing it from broader classes of chemotherapy. Irinotecan is prepared as a sterile solution suitable for intravenous administration, a delivery method essential for achieving systemic effect in adult patients.

Composition and Semisynthetic Origin

The active ingredient is a semisynthetic derivative of the natural plant alkaloid Camptothecin, a structure originally found in the Chinese tree Camptotheca acuminata. This origin distinguishes Irinotecan from fully synthetic chemotherapies. The compound itself functions as a prodrug, meaning it requires metabolic conversion within the body to become the highly potent active agent, SN-38, which ultimately performs the therapeutic function. The drug is considered a single-ingredient product, dissolved in an aqueous base appropriate for infusion.

The General Purpose of this Cytotoxic Agent

The general purpose of Irinotecan is to exert a systemic antitumor effect by selectively disrupting the life cycle of rapidly multiplying cells. By interfering with DNA Topoisomerase I, the active metabolite, SN-38, prevents the rejoining of DNA strands after they are broken during replication. This targeted damage forces malignant cells to undergo apoptosis, or programmed self-destruction, which is instrumental in reducing tumor proliferation and achieving the overall therapeutic goal of controlling the progression of cancer.

What side effects are possible with Irinotecan?

Possible Side Effects and Safety Information

Irinotecan's safety profile is documented by government health authorities through classifications that categorize potential adverse reactions based on their frequency and the body systems affected. The official safety information structures the risk by identifying high-frequency and low-frequency events, along with specific safety limitations.

Official Adverse Reaction Classification

The most commonly listed adverse reactions are classified as Very Common, which are expected to be observed in a large proportion of patients based on clinical data. These often involve the Gastrointestinal System (including diarrhea, nausea, and vomiting) and the Blood and Lymphatic System (such as neutropenia, a decrease in a type of white blood cell, and anemia). Other very common effects include stomatitis, fatigue (asthenia), and hair loss (alopecia).

Reactions classified as Uncommon or Rare include more severe events such as Interstitial Lung Disease (ILD), colitis, intestinal perforation, and severe hypersensitivity reactions including anaphylaxis.

Serious Adverse Reactions and Safety Patterns

The regulatory profile explicitly highlights risks of Severe Myelosuppression and Severe Late-Onset Diarrhea (occurring more than 24 hours after infusion). Both are recognized as clinically significant serious adverse reactions. The onset of gastrointestinal and neurological symptoms, such as the cholinergic syndrome, is often categorized as Early-Onset, typically occurring during or shortly after administration.

Population-Specific Safety Considerations

Safety statements include specific considerations for certain patient groups. Individuals who have specific genotypes, such as reduced UGT1A1 activity, are officially documented as having an increased risk for severe neutropenia. Older adults are advised to be closely monitored due to a heightened risk of severe diarrhea. Furthermore, the drug is known to carry a risk of Embryo-Fetal Toxicity, and its use during pregnancy is advised against.

Overdose and Emergency Response

Irinotecan overdosage is formally documented in regulatory labeling as resulting primarily in severe neutropenia and severe diarrhea, which are the most significant adverse reactions reported in such cases. The official prescribing information notes that overdosage, even at approximately twice the recommended therapeutic dose, may be fatal.

The regulatory guidance defines specific conditions under which immediate medical help must be sought. Urgent attention is required for severe diarrhea that is uncontrolled, particularly if accompanied by fever or vomiting, or when diarrhea necessitates intravenous hydration. Hospitalization is mandated for any suspected overdosage due to the documented risk of severe outcomes.

Management procedures are defined as symptomatic and supportive treatment. This includes the prompt administration of Atropine sulfate for acute cholinergic syndrome and the immediate use of Loperamide for delayed diarrhea. Due to severe hematological risk, urgent antibiotic support is required for febrile neutropenia. No specific antidote is known for Irinotecan overdose. Furthermore, regulatory documents state that individuals who are *homozygous for the UGT1A128 allele** have a documented increased risk for the core overdose manifestation of severe neutropenia.

Therapeutic Uses of Irinotecan

What Irinotecan Treats: Main Uses and Benefits

Irinotecan is commonly used as part of the management strategy for specific advanced cancers, primarily metastatic colon or rectal cancer. This medication is applied in addressing the overall disease progression, which includes conditions presenting with systemic or localized discomfort.

Irinotecan helps address symptoms related to physical discomfort and symptoms that interfere with daily functioning, such as fatigue and weakness. “It may assist with maintaining functional stability and managing routine activities.”

In complex clinical settings, Irinotecan is relevant in contexts marked by increased discomfort or tension. By providing this therapeutic assistance, the medication supports patients during episodes of heightened discomfort and helps them cope more steadily with their condition.

Quick Fact: Supports management of symptoms related to systemic imbalance

Regulatory References

NIH MedlinePlus Drug Information

Eligibility and Restrictions for Use

Eligibility Map: Who can and cannot use Irinotecan — official regulatory information

The following rules reflect the documented population eligibility and non-eligibility information as defined in governmental regulatory sources.

Eligibility scope

The medicine is primarily designated for adults with metastatic carcinoma of the colon or rectum. Use is contraindicated in patients with a history of severe hypersensitivity, severe bone marrow failure, chronic inflammatory bowel disease, or bowel obstruction. Contraindication is also specified for patients with serum bilirubin levels greater than three times the upper limit of normal or a poor general condition (WHO performance status > 2).

Pregnancy and breastfeeding are absolute contraindications, and effective contraception is mandated for patients of reproductive potential. Safety and effectiveness have not been established in the pediatric population.

Eligibility is conditional for several groups: Geriatric patients (age ge 65 years) require close monitoring. Patients with reduced UGT1A1 activity (e.g., 28/28 homozygotes) or a history of prior pelvic/abdominal radiotherapy are restricted and may require a reduced starting dose. Use is not recommended for patients with impaired renal function or those on dialysis.

Resulting eligibility structure

Official eligibility statements:

Use is contraindicated in patients with severe bone marrow failure, bowel obstruction, and serum bilirubin levels above regulatory thresholds.
Pregnancy and breastfeeding are absolute contraindications; pediatric safety is not established.
Patients with reduced UGT1A1 activity or of geriatric age require special surveillance or dose adjustment.

Connection to the overall eligibility profile: Regulatory documents define eligibility by establishing absolute exclusions based on severe health issues and physiological states, particularly those affecting elimination, such as hepatic function. Eligibility is further restricted for specific patient groups, including those with certain genetic metabolic profiles or those in the geriatric population, where conditional use or specific monitoring is mandated.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Irinotecan's interaction profile is primarily defined by its clearance pathways, which involve the metabolic enzymes Cytochrome P450 3A4 (CYP3A4) and UDP-glucuronosyl transferase 1A1 (UGT1A1). Regulatory labeling defines restrictions based on agents that modify the activity of these enzymes.

Pharmacokinetic Interaction Constraints

Interacting Substance Category	Official Restriction/Outcome
Strong CYP3A4 Inducers (e.g., Rifampin, Phenytoin)	Do not administer due to documented risk of significantly reducing the exposure of the active metabolite, SN-38.
Strong CYP3A4 Inhibitors (e.g., Atazanavir, Ketoconazole)	Do not administer due to documented risk of significantly increasing the systemic exposure of SN-38.

Official prescribing information advises specific timing separation requirements for these strong inhibitors and inducers, generally recommending discontinuation periods of up to two weeks before Irinotecan initiation. The herbal product St. John's wort is specifically listed in regulatory documents as a strong CYP3A4 inducer that reduces active metabolite exposure, posing a risk to therapeutic effect.

Mechanism of Action

Targeting DNA Topoisomerase I for Genome Disruption

The primary action involves the drug's active metabolite, SN-38, which functions as a Topoisomerase Poison by trapping the enzyme DNA Topoisomerase I ( Top I) on a single-strand break in the DNA. This complex structural block is converted into an irreparable double-strand break ( DSB) when the DNA replication fork collides with it . This severe damage forces the cell to activate the apoptotic cascade, leading to the physiological consequence of programmed cell death (apoptosis) in cells undergoing high rates of proliferation.

⏳ Distinct Modulation of Autonomic Signaling

A separate mechanistic action is exerted by the parent drug, Irinotecan, which weakly and transiently inhibits the enzyme acetylcholinesterase. This enzyme is essential for breaking down the neurotransmitter acetylcholine in the parasympathetic nervous system. The temporary inhibition leads to an acute increase in acetylcholine activity, causing physiological consequences such as heightened smooth muscle tone and increased glandular secretions.

Dosage and Administration Information

How to Use Irinotecan: Official Administration Guidelines

The administration of Irinotecan Hydrochloride Injection is governed by official protocols detailing the route, dosing structure, and required procedural steps.

Administration Scope

Property	Official Guideline
Route of Administration	Administration is strictly via intravenous (IV) infusion.
Dosing Schedule	Standard starting doses are calculated based on body surface area (measured in mg/m²), typically 125 mg/m² for the weekly schedule or 350 mg/m² for the every-three-week schedule, with predefined reduction levels officially documented.
Age-Group Rules	A lower starting dose is officially recommended for patients 70 years of age or older when the every-three-week schedule is used. Additionally, starting dose reduction is considered for patients with certain UGT1A1 genotypes due to metabolic factors.
Preparation	The concentrated solution must be diluted prior to administration, typically using 5% Dextrose Injection, USP, according to the official label instructions.
Special Conditions	The required infusion duration is 90 minutes. If the criteria for starting a new cycle are not met, the dose must be delayed until recovery is established.

Instruction Classifications (High-Level)

Property	Pattern
Administration Method	Intravenous (IV) Infusion.
Frequency Pattern	Cyclic use on a weekly (Days 1, 8, 15, 22) or every-three-week (Day 1) basis.
Use-Context Constraints	Administration is constrained by requirements for pre-infusion dilution, a mandatory 90-minute infusion time, and sequential timing relative to certain co-administered therapies.

Connection to the Overall Use Protocol

Official documents establish a precise protocol for Irinotecan, specifying the mandatory intravenous route and the precise cyclic delivery pattern. This protocol structures the standardized delivery of the medicine by requiring dose calculation by body surface area and adherence to set administration intervals, with provisions for dose modification based on age or metabolic status.

Recent Clinical Evidence

Research evidence / Overview of studies for Irinotecan

1. Evidence for Metastatic Colorectal Cancer (mCRC)

The research for Irinotecan for colorectal cancer was evaluated in large, randomized controlled trials (RCTs). These studies were designed to evaluate treatment regimens that include Irinotecan, often in combination with drugs like fluorouracil and leucovorin, against control groups receiving alternative standards or supportive care. Researchers explored core questions such as Overall Survival (OS)—the length of time patients lived following treatment—and Progression-Free Survival (PFS), which is the time until disease progression was observed. They also monitored the Objective Response Rate (ORR), which measures measurable changes in tumor size.

Studies reported measurements of survival time and provided data showing patterns related to tumor response in the observed patient groups. Research examined adult patients with confirmed metastatic disease, distinguishing between first-line and second-line settings. Evidence is frequently drawn from Irinotecan’s use as part of combination regimens. Data isolating outcomes of Irinotecan as a single agent in the initial treatment setting are less commonly the basis for current regulatory evaluations.

2. Evidence for Metastatic Pancreatic Adenocarcinoma

Research for Irinotecan in advanced pancreatic cancer has focused on a specific version of the medicine called liposomal Irinotecan. The evidence base comes from Randomized Phase III Trials that evaluated the liposomal formulation when used in specific combination regimens against other existing treatment standards. These studies monitored Overall Survival (OS) and Progression-Free Survival (PFS). Findings indicate patterns related to the use of the liposomal formulation when administered as part of a multi-drug combination.

3. Long-Term Studies and Follow-up Duration

The major clinical trials for Irinotecan involved intermediate to long-term follow-up, with observation periods often spanning several years to capture survival endpoints. However, there is limited information for long-term outcomes or the durability of observed effects many years after treatment is completed. Research primarily describes patterns observed during the actual study period, and evidence is limited when it comes to effects that persist far into the future.

4. Evidence in Special Populations

Research examined Irinotecan in various groups beyond the general adult population, including older adult patients and some pediatric populations. The evidence often originates from smaller studies focused on establishing appropriate parameters. Consequently, data for certain groups remain insufficient to draw broad conclusions, and the results apply only to the populations studied under the specific conditions of those trials.

5. Research Gaps and What is Still Uncertain

While high-quality research exists for Irinotecan's primary uses, certainty remains low in several areas still being explored. One consistent gap is the lack of long-term outcomes data. Additionally, the evidence is associated with combination regimens, so comparative evidence is lacking for Irinotecan's use as a single agent in many settings. Research findings have also been mixed or heterogeneous in some of the less-common solid tumors studied. Overall, the research provides context but not individual predictions, and new studies are continually being developed to address these outstanding questions.

Frequently Asked Questions (FAQ)

Common questions about Irinotecan (FAQ)

Q: Is Irinotecan the same as Camptosar?

A: Irinotecan is the name of the active chemical ingredient in the medicine. Camptosar is one of the trade names under which the drug has been manufactured and sold.

Q: Does Irinotecan cause permanent side effects?

A: Irinotecan has documented adverse reactions categorized by frequency and severity during the study period. However, according to studies and official documents, there is limited information available regarding the durability or permanence of effects that may persist many years after treatment is completed.

Q: Do food or supplements affect how Irinotecan works?

A: Official documents warn against taking Irinotecan with certain supplements or herbal products that are strong CYP3A4 inducers, such as St. John's wort. This is because these substances may interfere with the metabolic processes needed for the medicine to work effectively. However, the official product information does not document any special restrictions regarding the timing of food consumption relative to the intravenous infusion.

Q: Is Irinotecan considered a chemotherapy drug?

A: Irinotecan is officially classified as an antineoplastic and cytotoxic agent, which are the formal scientific terms for medicines used to treat cancer. It specifically belongs to a class of drugs called a DNA Topoisomerase I Inhibitor.

Q: Why is the infusion time for Irinotecan so long?

A: According to official product guidelines, the medicine must be administered intravenously over a 90-minute period. This fixed duration is a mandatory clinical procedure. This requirement is a mandatory part of the administration protocol designed to promote the safe delivery of the medicine.

Q: What happens if a scheduled Irinotecan dose is missed?

A: Administration of Irinotecan is governed by strict clinical protocols and timing. If a dose is not administered on its scheduled date, official guidance states that this circumstance should be communicated to the prescribing doctor right away. This allows the clinical team to determine the necessary next steps for the treatment plan.

Q: Does Irinotecan have a black box warning, and what does it mean?

A: Yes, regulatory documents, including the U.S. FDA label, include a Boxed Warning that highlights specific serious risks. The warning highlights the potential for severe diarrhea and severe myelosuppression, which is a condition involving significantly low white blood cell counts. These potential serious risks are reasons why patients are closely monitored throughout treatment.

Q: What are the known interactions between Irinotecan and herbal supplements?

A: Official documents specifically advise against using the herbal product St. John's wort alongside Irinotecan. This is because it is known to reduce the amount of the active metabolite, SN-38, in the body. It is important that patients disclose the use of all supplements, prescription medicines, and over-the-counter products to their clinical team.

Q: Is the diarrhea caused by Irinotecan different from regular diarrhea?

A: Official safety information describes two distinct types of diarrhea that may be associated with the drug. Early-Onset diarrhea often happens during the infusion and is linked to a transient effect on the nervous system. Severe Late-Onset diarrhea occurs more than 24 hours after treatment and is classified as a serious adverse reaction requiring careful management.

Q: What should be done about mouth sores that might be related to Irinotecan?

A: Stomatitis (or mouth sores) is a very common adverse reaction documented in the official safety profile of Irinotecan. Because this is a medical condition, it is important that the symptoms are reported to the prescribing doctor. This ensures that the patient receives appropriate clinical management and supportive care.

Q: What is the risk of infection when taking Irinotecan?

A: Official safety information indicates that Irinotecan carries a serious risk of severe myelosuppression, which is a sharp decrease in blood cell counts, particularly white blood cells (neutropenia). This condition is documented as making a person more susceptible to developing infections.

Q: Is it necessary to have blood work done frequently while on Irinotecan?

A: According to official protocols, regular blood work is required before receiving each dose of the medicine. Specifically, Complete Blood Counts (CBCs) must be monitored to check levels of blood cells. Certain liver function measures are also monitored to determine if the patient is eligible for the scheduled dose.

Q: Can Irinotecan be used to treat other types of cancer besides the main ones?

A: Official regulatory approval for Irinotecan is limited to the treatment of metastatic carcinoma of the colon or rectum. A specific liposomal formulation of the medicine is also approved for use in advanced pancreatic adenocarcinoma.

Q: Does Irinotecan change your ability to drive?

A: Regulatory documents list certain adverse reactions, such as fatigue (asthenia) and dizziness, that may occur during treatment. These symptoms can potentially impair a person’s ability to operate machinery or drive.

Q: Does taking Irinotecan affect fertility in men or women?

A: Yes, official warnings indicate that the drug carries a risk of Embryo-Fetal Toxicity. Because of this, effective contraception is mandated for both male and female patients of reproductive potential according to official guidelines. The official product information includes documented warnings that the drug may impair fertility in both men and women.

Q: How long does Irinotecan stay in the body after the last treatment?

A: Irinotecan is metabolized by the body into the highly potent active agent, SN-38. Official pharmacokinetic data states that the median elimination half-life for the original drug is roughly 6 to 12 hours. The half-life for the active metabolite SN-38 is documented as approximately 10 to 20 hours.

Q: Are there any special dietary requirements while on Irinotecan?

A: Official regulatory documents do not mandate any universal special dietary requirements for all patients using Irinotecan. However, since the drug is associated with common gastrointestinal adverse reactions like diarrhea, temporary dietary modifications may be necessary as clinically directed during treatment.

Q: Does Irinotecan cause weight gain or loss?

A: Official product information notes that weight loss was documented as a common adverse reaction during clinical trials of the medicine. Weight gain is not listed as a common side effect of the drug.

Q: Does Irinotecan affect sleep patterns?

A: Somnolence (a term for drowsiness or excessive sleepiness) is documented as an adverse reaction associated with Irinotecan treatment in official product information.

How should Irinotecan be stored and disposed of?

Storage and Disposal of Irinotecan

Irinotecan hydrochloride injection must be stored strictly according to regulatory labeling to maintain potency and safety. The unopened vial requires storage at controlled room temperature (15 C to 30 C) and must be protected from light by remaining in its original carton. It is mandatory not to freeze the concentrate.

Stability of the Infusion Solution

Diluent	Usable Shelf-Life (Room Temperature)	Prohibition
5% Dextrose	24 hours	Do not freeze
0.9% Sodium Chloride	6 hours	Do not refrigerate

Irinotecan is classified as a cytotoxic and hazardous drug. Disposal of all unused product and waste materials must be carried out at a special waste collection point in accordance with local and national regulations. Waste must not be allowed to enter sewers or water systems.

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