Effect of gefitinib on warfarin antithrombotic activity.

BACKGROUND: Despite the literature indicating adverse interactions between warfarin and cytotoxic agents, whether such an interaction occurs when warfarin and gefitinib are used concomitantly is unknown. We analyzed the prevalence of the concomitant use of warfarin and gefitinib, and the incidence of prothrombin time-international normalized ratio (PT-INR) alterations or adverse interactions in concomitant users of warfarin and gefitinib. METHODS: We conducted a retrospective study of patients with non-small cell lung cancer treated at the Kitasato University Hospital who received concomitant warfarin and gefitinib between September 2002 and January 2007. Medical information, including the indication for warfarin use, warfarin dosing and dosing changes, and exposure to gefitinib were collected from computerized databases and medical records. RESULTS: Twelve (4.1%) of 296 patients treated with gefitinib received warfarin. PT-INR elevation occurred in 6 patients (50.0%). Two (16.7%) of the 12 patients had liver metastases. Liver dysfunction was associated with PT-INR elevation (P = 0.0100). CONCLUSION: As there is a possibility of PT-INR abnormalities occurring during the concomitant use of gefitinib and warfarin, clinicians should be aware of this interaction. Because of the potentially severe consequences of this interaction, close monitoring of PT-INR and warfarin dose adjustment are recommended for patients receiving warfarin and gefitinib, especially during the first 2 weeks in the beginning of warfarin therapy.

Metabolism of irinotecan and its active metabolite SN-38 by intestinal microflora in rats.

One of the dose-limiting toxicities of irinotecan (CPT-11) is delayed-onset diarrhea, which is the greatest barrier to treatment with CPT-11-containing regimens. CPT-11 is converted to its active metabolite, SN-38, which is conjugated by hepatic uridine diphosphate glucuronosyl transferase to SN-38 glucuronide (SN-38G). SN-38G, once excreted in the intestinal lumen via bile, is extensively deconjugated by bacterial beta-glucuronidase with the regeneration of SN-38 in the intestinal lumen, which may cause diarrhea. However, the metabolism of CPT-11 and its metabolites by intestinal microflora are yet to be reported. This study was carried out to investigate the microbial transformation of CPT-11 and SN-38 using an anaerobic mixed culture of rat cecal microorganisms. No reaction in the mixed cultures was observed when CPT-11 or SN-38 lactone was added to the culture medium. When CPT-11 was added to the culture broth, a significant amount of water-soluble CPT-11 was detected in the spent culture medium. In contrast, only a slight amount of SN-38 was found in the supernatant when SN-38 lactone was added to the broth. A significant quantity of SN-38 was found in the sediment. In conclusion, these results strongly suggest that SN-38 produced from SN-38G by the action of bacterial beta-glucuronidase is rapidly adsorbed by the intestinal bacterial cell walls in the sediment because of the hydrophobic and lipophilic nature of SN-38, and a small amount of SN-38 remains in the intestinal luminal fluid. Thus, we need to reconsider the role of SN-38 in the intestinal lumen in CPT-11-induced late-onset diarrhea.

Phase I and pharmacologic study of irinotecan and amrubicin in advanced non-small cell lung cancer.

PURPOSE: We conducted a Phase I trial of irinotecan (CPT-11), a topoisomerase I inhibitor, combined with amrubicin, a topoisomerase II inhibitor. The aim was to determine the maximum tolerated dose (MTD) of amrubicin combined with a fixed dose of CPT-11 as well as the dose-limiting toxicities (DLT) of this combination in patients with advanced non-small cell lung cancer. PATIENTS AND METHODS: Eleven patients with stage IIIB or IV disease were treated at 3-week intervals with amrubicin (5-min intravenous injection on days 1-3) plus 60 mg/m2 of CPT-11 (90-min intravenous infusion on days 1 and 8). The starting dose of amrubicin was 25 mg/m2, and it was escalated in 5 mg/m2 increments until the maximum tolerated dose was reached. RESULTS: The 30 mg/m2 of amrubicin dose was one dose level above the MTD, since three of the five patients experienced DLT during the first cycle of treatment at this dose level. Diarrhea and leukopenia were the DLT, while thrombocytopenia was only a moderate problem. Amrubicin did not affect the pharmacokinetics of CPT-11, SN-38 or SN-38 glucuronide. Except for one patient, the biliary index on day-1 correlated well with the percentage decrease of neutrophils in a sigmoid Emax model. There were five partial responses among 11 patients for an overall response rate of 45%. CONCLUSION: The combination of amrubicin and CPT-11 seems to be active against non-small cell lung cancer with acceptable toxicity. The recommended dose for Phase II studies is 60 mg/m2 of CPT-11 (days 1 and 8) and 25 mg/m2 of amrubicin (days 1-3) administered every 21 days.

[Recurrent pulmonary edema associated with obstructive sleep apnea syndrome].

A 70-year-old non-obese man with no history of cardiopulmonary disease presented 4 times to the emergency room because of sudden onset of seizure during sleep. Each time he recovered within a few hours without any medication. Nocturnal polysomnographic recording revealed severe obstructive sleep apnea syndrome (OSAS, AHI 52.4/Hr). Nasal continuous positive airway pressure (n-CPAP) therapy was performed with 10cmH2O of pressure. His symptoms of severe daytime sleepiness and seizure were diminished. CPAP was decreased from 10cmH2O to 6 cmH2O later, because the patient complained with its high pressure. He then felt daytime sleepiness and suffered seizures during sleep again, and was re-admitted to our hospital. Chest roentgenogram taken at this admission showed remarkable pulmonary edema. We found that the pulmonary edema was recognized every time on his chest roentgenogram taken when he complained seizure. In addition, subsequesnt roentgenograms also showed that the pulmonary edema was diminished soon. On the other hand, his AHI was high (24.7/hr) even when he was under 6cmH2O of n-CPAP. We concluded that incompletely treated OSAS might lead not only to pulmonary edema, but also to seizures in this patient.

Phase I trial of irinotecan and amrubicin with granulocyte colony-stimulating factor support in extensive-stage small-cell lung cancer.

PURPOSE: We conducted a phase I trial of irinotecan (CPT-11), a topoisomerase I inhibitor, combined with amrubicin, a topoisomerase II inhibitor, with recombinant human granulocyte colony-stimulating factor (rhG-CSF) support to overcome the neutropenia associated with this particular combination. The aim was to determine the maximum tolerated dose (MTD) of amrubicin combined with a fixed dose of CPT-11 and the dose-limiting toxicities (DLTs) of this combination in extensive-stage small-cell lung cancer (ED-SCLC) patients. METHODS: Fifteen patients with ED-SCLC were treated at 3-week intervals with amrubicin on days 1-3 plus 60 mg/m(2) CPT-11 on days 1 and 8. In addition, prophylactic rhG-CSF (50 µg/m(2)) was given from day 4 to day 21, except on the day of CPT-11 administration. Amrubicin was started at 30 mg/m(2) and then escalated in 5 mg/m(2) increments until MTD was reached. RESULTS: The MTD of amrubicin was 35 mg/m(2), since 2 of 4 patients experienced DLTs during the first cycle of treatment at the 40 mg/m(2) dose level. Neutropenia, neutropenic fever, ileus, and diarrhea were the DLTs. There were 13 partial responses among the 13 assessable patients, yielding an overall response rate of 100 %. Median progression-free survival and overall survival were 7.4 months and 13.4 months, respectively. CONCLUSION: The combination of amrubicin and CPT-11 showed high activity against ED-SCLC with acceptable toxicity. Use of rhG-CSF allowed the dose of amrubicin to be raised 40 % above that in the original regimen (60 mg/m(2) CPT-11 and 25 mg/m(2) amrubicin).

Drug interaction between gefitinib and warfarin.

Gefitinib is a synthetic, oral anilinoquinazoline specifically designed to inhibit the epidermal growth factor receptor tyrosine kinase, and is the first targeted drug to demonstrate reproducible activity in non-small cell lung cancer patients who do not respond to platinum-based chemotherapy. In this report, we present two cases of an interaction between gefitinib and warfarin which has not been reported previously. Because of the potentially serious consequences of this interaction, close monitoring of the International Normalized Ratio and warfarin dosage adjustment are recommended for patients receiving warfarin together with gefitinib.