Overview
11 DESCRIPTION Irinotecan hydrochloride injection, USP is an antineoplastic agent of the topoisomerase I inhibitor class. Irinotecan hydrochloride injection, USP is supplied as a sterile, pale yellow, clear, aqueous solution. Each milliliter of solution contains 20 mg of irinotecan hydrochloride (on the basis of the trihydrate salt), 45 mg of sorbitol, NF, and 0.9 mg of lactic acid, USP.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Irinotecan is a derivative of camptothecin. Camptothecins interact specifically with the enzyme topoisomerase I, which relieves torsional strain in DNA by inducing reversible single-strand breaks. Irinotecan and its active metabolite SN-38 bind to the topoisomerase I-DNA complex and prevent religation of these single-strand breaks. Current research suggests that the cytotoxicity of irinotecan is due to double-strand DNA damage produced during DNA synthesis when replication enzymes interact with the ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38. Mammalian cells cannot efficiently repair these double-strand breaks. 12.
Indications
- 1 INDICATIONS AND USAGE Irinotecan hydrochloride injection is a topoisomerase inhibitor indicated for: • Patients with metastatic carcinoma of the colon or rectum whose disease has recurred or progressed following initial fluorouracil-based therapy. ( 1 ) • Irinotecan hydrochloride injection is indicated for patients with metastatic carcinoma of the colon or rectum whose disease has recurred or progressed following initial fluorouracil-based therapy.
Common Doses
- 125 mg
- 350 mg
- 2 mg
- 150 mg
Dosage
2 DOSAGE AND ADMINISTRATION Colorectal cancer single agent regimen 1: Irinotecan hydrochloride injection 125 mg/m 2 intravenous infusion over 90 minutes on days 1, 8, 15, 22 then 2-week rest. ( 2.2 ) Colorectal cancer single agent regimen 2: Irinotecan hydrochloride injection 350 mg/m 2 intravenous infusion over 90 minutes on day 1 every 3 weeks. ( 2.2 ) 2.2 Colorectal Single Agent Regimens 1 and 2 Administer irinotecan hydrochloride injection as a 90-minute intravenous infusion. The currently recommended regimens are shown in Table 3.
Black Box Warning
WARNING FULL PRESCRIBING INFORMATION WARNING: DIARRHEA and MYELOSUPPRESSION Early and late forms of diarrhea can occur. Early diarrhea may be accompanied by cholinergic symptoms which may be prevented or ameliorated by atropine. Late diarrhea can be life threatening and should be treated promptly with loperamide. Monitor patients with diarrhea and give fluid and electrolytes as needed. Institute antibiotic therapy if patients develop ileus, fever, or severe neutropenia. Interrupt Irinotecan hydrochloride injection and reduce subsequent doses if severe diarrhea occurs.
Contraindications
- 4 CONTRAINDICATIONS Hypersensitivity to Irinotecan hydrochloride injection or its excipients ( 4 ) Irinotecan hydrochloride injection is contraindicated in patients with a known hypersensitivity to the drug or its excipients.
Side Effects
- 6 ADVERSE REACTIONS Common adverse reactions ( > 30%) observed in single agent therapy clinical studies are: nausea, vomiting, abdominal pain, diarrhea, constipation, anorexia, neutropenia, leukopenia (including lymphocytopenia), anemia, asthenia, fever, body weight decreasing, alopecia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact 1-888-557-1212 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Studies Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly...
Interactions
- 7 DRUG INTERACTIONS Strong CYP3A4 Inducers: Do not administer strong CYP3A4 inducers with Irinotecan hydrochloride. ( 7.2 ) Strong CYP3A4 Inhibitors: Do not administer strong CYP3A4 inhibitors with Irinotecan hydrochloride. ( 7.3 ) 7.2 Strong CYP3A4 Inducers Exposure to irinotecan or its active metabolite SN-38 is substantially reduced in adult and pediatric patients concomitantly receiving the CYP3A4 enzyme-inducing anticonvulsants phenytoin, phenobarbital, carbamazepine, or St. John's wort.