Classifications: antineoplastic; camptothecin; Therapeutic: antineoplastic
Pregnancy Category: D
20 mg/mL injection
Irinotecan is a camptothecin analog that displays antitumor activity by inhibiting the intranuclear enzyme topoisomerase
I. Thus, it is a strong inhibitor of DNA and RNA synthesis. Topoisomerase I is an essential intranuclear enzyme that relaxes
the supercoiled DNA, thus enabling replication and transcription to take place. By inhibiting topoisomerase I, irinotecan
and its active metabolite SN-38 cause double-stranded DNA damage during the synthesis (S) phase of DNA synthesis.
Irinotecan inhibits both DNA and RNA synthesis.
Metastatic carcinoma of colon or rectum.
Previous hypersensitivity to irinotecan, topotecan, or other camptothecin analogs; acute infection, diarrhea, pregnancy
(category D), lactation. Safety and effectiveness in children are not established.
Gastrointestinal disorders, myelosuppression, renal or hepatic function impairment, history of bleeding disorders, previous
cytotoxic or radiation therapy.
Route & Dosage
Adult: IV 125 mg/m2 once weekly for 4 wk, then a 2-wk rest period (future courses may be adjusted to range from 50 to 150 mg/m2 depending on tolerance; see complete prescribing information for specific dosage adjustment recommendations based on toxic
- Administer only after premedication (at least 30 min prior) with an antiemetic.
- Wash immediately with soap and water if skin contacts drug during preparation.
PREPARE: IV Infusion: Dilute the ordered dose in enough D5W (preferred) or NS to yield a concentration of 0.122.8 mg/mL. Typical amount
of diluent used is 250500 mL.
ADMINISTER: IV Infusion: Infuse over 90 min. Closely monitor IV site; if extravasation occurs, immediately flush with sterile water and apply ice.
INCOMPATIBILITIES Y-site: Gemcitabine.
- Store undiluted at 15°30° C (59°86° F) and protect from light. Use reconstituted solutions
within 24 h.
Adverse Effects (≥1%)Body as a Whole: Asthenia, fever, pain,
chills, edema, abdominal enlargement, back pain. CNS:
Headache, insomnia, dizziness. CV:
Vasodilation/flushing. GI: Diarrhea (early and late onset), dehydration, nausea, vomiting, anorexia, weight loss, constipation, abdominal cramping
, dyspepsia, increased alkaline phosphatase
and AST. Hematologic: Leukopenia, neutropenia, anemia. Respiratory: Dyspnea,
cough, rhinitis. Skin: Alopecia,
, antiplatelet agents
may increase risk of bleeding; carbamazepine, phenytoin, phenobarbital
may decrease irinotecan levels. Herbal: St. John's wort
may decrease irinotecan levels.
1 h. Distribution:
Irinotecan is 30% protein bound; active metabolite
SN-38 is 95% protein bound. Metabolism:
In liver by carboxylesterase enzyme
to active metabolite
10 h for SN-38; 20% excreted in urine. Half-Life:
Assessment & Drug Effects
- Lab tests: Monitor WBC with differential, Hgb, and platelet count before each dose; monitor closely coagulation parameters
especially with concurrent use of other drugs which affect these parameters.
- Lab tests: Monitor fluid and electrolyte balance closely during and after periods of diarrhea. Monitor liver and renal function
tests and blood glucose periodically.
- Monitor for acute GI distress, especially early diarrhea (within 24 h of infusion), which may be preceded by diaphoresis
and cramping, and late diarrhea (>24 h after infusion).
Patient & Family Education
- Learn about common adverse effects and measures to control or minimize when possible.
- Notify physician immediately when you experience diarrhea, vomiting, and S&S of infection. Diarrhea requires prompt treatment
to prevent serious fluid and electrolyte imbalances.