IRINOTECAN HYDROCHLORIDE
| IRINOTECAN HYDROCHLORIDE (eye-ri-no'te-can) Camptosar Classifications: antineoplastic; camptothecin; Therapeutic: antineoplastic Prototype: Topotecan Pregnancy Category: D |
Availability
20 mg/mL injection
Action
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.
Therapeutic Effect
Irinotecan inhibits both DNA and RNA synthesis.
Uses
Metastatic carcinoma of colon or rectum.
Contraindications
Previous hypersensitivity to irinotecan, topotecan, or other camptothecin analogs; acute infection, diarrhea, pregnancy (category D), lactation. Safety and effectiveness in children are not established.
Cautious Use
Gastrointestinal disorders, myelosuppression, renal or hepatic function impairment, history of bleeding disorders, previous cytotoxic or radiation therapy.
Route & Dosage
| Metastatic Carcinoma 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 effects) |
Administration
Intravenous
PREPARE: IV Infusion: Dilute the ordered dose in enough D5W (preferred) or NS to yield a concentration of 0.12–2.8 mg/mL. Typical amount of diluent used is 250–500 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 and pain, flatulence, stomatitis, dyspepsia, increased alkaline phosphatase and AST. Hematologic: Leukopenia, neutropenia, anemia. Respiratory: Dyspnea, cough, rhinitis. Skin: Alopecia, sweating, rash.Interactions
Drug: anticoagulants, antiplatelet agents, nsaids may increase risk of bleeding; carbamazepine, phenytoin, phenobarbital may decrease irinotecan levels. Herbal: St. John's wort may decrease irinotecan levels.Pharmacokinetics
Peak: 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 SN-38. Elimination: 10 h for SN-38; 20% excreted in urine. Half-Life: 10–20 h.Nursing Implications
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.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug