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Drug Interactions between tamoxifen and Vanflyta

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Major

tamoxifen quizartinib

Applies to: tamoxifen and Vanflyta (quizartinib)

GENERALLY AVOID: Quizartinib can cause dose- and concentration-dependent prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may increase the risk of ventricular arrhythmias including torsade de pointes and sudden death. In a clinical study where 265 patients with newly diagnosed FLT3-ITD-positive acute myeloid leukemia (AML) were treated with quizartinib (38% for >=6 months; 30% for >1 year) in combination with chemotherapy, 2.3% had a Fridericia-corrected QT interval (QTcF) greater than 500 ms and 10% had a QTcF increase from baseline greater than 60 ms. Overall, QT prolongation of any grade occurred in 14% of the quizartinib patients (compared to 4.1% of patients treated with placebo and chemotherapy), and 4% required dose reductions of quizartinib due to QT prolongation. The study excluded patients with a QTcF >=450 ms or other risk factors for QT prolongation or arrhythmic events. Based on an analysis of the exposure-response relationship, quizartinib is predicted to produce a median increase of 18 and 24 ms in the QTcF at steady-state peak plasma concentration during maintenance therapy at the 26.5 mg and 53 mg dose levels, respectively. Across premarketing clinical trials, torsade de pointes arrhythmia was reported in approximately 0.2%, cardiac arrest in 0.6% (including 0.4% with a fatal outcome), and ventricular fibrillation in 0.1% of the total 1,081 patients with AML treated with quizartinib. These severe cardiac events occurred predominantly during the induction phase. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemias). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Coadministration of quizartinib with other drugs that can prolong the QT interval should generally be avoided. If concomitant use is required, more frequent monitoring with electrocardiograms (ECGs) is recommended to guide continued treatment. All patients treated with quizartinib should have ECGs performed as well as potassium and magnesium serum levels measured prior to initiation of treatment, at regular intervals during treatment, and when clinically indicated such as following dose escalation or during episodes of diarrhea or vomiting. Do not initiate quizartinib or escalate the dose if QTcF interval is greater than 450 ms. In addition, hypokalemia and hypomagnesemia should be corrected before and during treatment. If QTcF increases to greater than 480 ms during treatment, reduce the dose, interrupt therapy, or permanently discontinue quizartinib as clinically appropriate in accordance with the prescribing information. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. Quizartinib should be permanently discontinued in patients who experience torsade de pointes, polymorphic ventricular tachycardia, or QT prolongation with signs or symptoms of life-threatening arrhythmia.

References

  1. (2023) "Product Information. Vanflyta (quizartinib)." Daiichi Sankyo, Inc.

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Drug and food interactions

Moderate

tamoxifen food

Applies to: tamoxifen

GENERALLY AVOID: Due to their estrogenic effect, isoflavones present in soy such as genistein and daidzein may stimulate breast tumor growth and antagonize the antiproliferative action of tamoxifen. Supportive data are derived primarily from in vitro and animal studies. In vitro, low concentrations of these phytoestrogens have been found to promote DNA synthesis and reverse the inhibitory effect of tamoxifen on estrogen-dependent breast cancer cell proliferation. In contrast, high concentrations of genistein greater than 10 microM/L have been found to enhance tamoxifen effects by inhibiting breast cancer cell growth. It is not known if these high concentrations are normally achieved in humans. Plasma concentrations below 4 microM/L have been observed in healthy volunteers given a soy diet for one month or large single doses of genistein. These concentrations are comparable to the low plasma concentrations associated with tumor stimulation reported in animals. In a study of 155 female breast cancer survivors with substantially bothersome hot flashes, a product containing 50 mg of soy isoflavones (40% to 45% genistein; 40% to 45% daidzein; 10% to 20% glycitein) taken three times a day was found to be no more effective than placebo in reducing hot flashes. No toxicity or recurrence of breast cancer was reported during the 9-week study period.

Green tea does not appear to have significant effects on the pharmacokinetics of tamoxifen or its primary active metabolite, endoxifen. In a study consisting of 14 patients who have been receiving tamoxifen treatment at a stable dose of 20 mg (n=13) or 40 mg (n=1) once daily for at least 3 months, coadministration with green tea supplements twice daily for 14 days resulted in no significant differences in the pharmacokinetics of either tamoxifen or endoxifen with respect to peak plasma concentration (Cmax), systemic exposure (AUC), and trough plasma concentration (Cmin) compared to administration of tamoxifen alone. The combination was well tolerated, with all reported adverse events categorized as mild (grade 1) and none categorized as serious or severe (grade 3 or higher) during the entire study. Although some adverse events such as headache, polyuria, gastrointestinal side effects (e.g., constipation, dyspepsia), and minor liver biochemical disturbances were reported more often during concomitant treatment with green tea, most can be attributed to the high dose of green tea used or to the caffeine in green tea. The green tea supplements used were 1000 mg in strength and contained 150 mg of epigallocatechin-3-gallate (EGCG), the most abundant and biologically active catechin in green tea. According to the investigators, the total daily dose of EGCG taken by study participants is equivalent to the amount contained in approximately 5 to 6 cups of regular green tea. However, it is not known to what extent the data from this study may be applicable to other preparations of green tea such as infusions, since the bioavailability of EGCG and other catechins may vary between preparations.

MANAGEMENT: Until more information is available, patients treated with tamoxifen may consider avoiding or limiting the consumption of soy-containing products. Consumption of green tea and green tea extracts during tamoxifen therapy appears to be safe.

References

  1. Therapeutic Research Faculty (2008) Natural Medicines Comprehensive Database. http://www.naturaldatabase.com
  2. Braal CL, Hussaarts KGAM, Seuren L, et al. (2020) "Influence of green tea consumption on endoxifen steady-state concentration in breast cancer patients treated with tamoxifen." Breast Cancer Res Treat, 184, p. 107-13

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.


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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.