Classification and occurrence of clinically significant drug interactions with irinotecan and oxaliplatin in patients with metastatic colorectal cancer.
BACKGROUND
Pharmacokinetic and pharmacodynamic drug interactions with cytotoxic drugs may significantly influence the efficacy and toxicity of chemotherapy.


OBJECTIVE
The purpose of this study was to identify drug interactions with irinotecan and oxaliplatin reported in the literature, to assess their clinical significance, and to examine the occurrence of these interactions in patients with metastatic colorectal cancer treated with either irinotecan or oxaliplatin or both.


METHODS
To obtain data on drug-drug interactions with irinotecan and oxaliplatin, a literature search of PubMed and EMBASE was conducted using the search terms irinotecan, oxaliplatin, and interactions (English-language studies only published between 1980 and August 2004). The interactions found were subsequently classified for documentation evidence and severity of clinical effect, according to a 5-level classification system of a standard reference text, by a study panel of medical oncologists and clinical pharmacists. Comedication of patients who were treated with irinotecan or oxaliplatin, or both, was then examined to determine the occurrence of clinically significant interactions.


RESULTS
Ninety-eight patients (50 women, 48 men;mean age, 60 years) were included in the study. Seventeen interactions with irinotecan were found in the literature, and 11 were classified as clinically significant. Only 1 nonspecific, clinically significant interaction was identified for oxaliplatin. Irinotecan-treated patients received a mean of 8 different comedications and oxaliplatin-treated patients received a mean of 6. Apart from antiemetic and antidiarrheal drugs that were prescribed for treatment-related toxicities, only 1 patient appeared to be exposed to a possible clinically significant interaction (between irinotecan and phenytoin).


CONCLUSIONS
Eleven of the 17 interactions with irinotecan that were found in the literature were classified as clinically significant versus 1 clinically significant interaction with oxaliplatin. The occurrence of these interactions in the study patients with metastatic colorectal cancer was low. For medication surveillance purposes, however, the significant interactions should be considered in clinical practice.
Jansman
Frank G A
FG
Department of Clinical Pharmacy, Isala Klinieken, Zwolle, the Netherlands. f.g.a.jansman@isala.nl
Idzinga
Froukje S F
FS
Smit
Willem M
WM
de Graaf
Jacques C
JC
Coenen
Jules L L M
JL
Sleijfer
Dirk Th
DT
Brouwers
Jacobus R B J
JR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology / Q000627:therapeutic use; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D004347:Drug Interactions; D005260:Female; D006801:Humans; D000077146:Irinotecan; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009944:Organoplatinum Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D000077150:Oxaliplatin
D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D000077146:Irinotecan; D002166:Camptothecin