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Drug Interactions between Fareston and posaconazole

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

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Interactions between your drugs

Major

toremifene posaconazole

Applies to: Fareston (toremifene) and posaconazole

Consumer information for this interaction is not currently available.

CONTRAINDICATED: Coadministration with posaconazole may increase the plasma concentrations of CYP450 3A4 substrates that can prolong the QT interval, possibly resulting in QT prolongation and cases of torsade de pointes (TdP). The underlying mechanism is decreased clearance due to inhibition of CYP450 3A4 activity by posaconazole. 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, hypomagnesemia). 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 posaconazole with CYP450 3A4 substrates that can prolong the QT interval is considered contraindicated.

References

  1. "Product Information. Noxafil (posaconazole)." Schering-Plough Corporation (2006):
  2. Agencia Española de Medicamentos y Productos Sanitarios Healthcare "Centro de información online de medicamentos de la AEMPS - CIMA. https://cima.aemps.es/cima/publico/home.html" (2008):
  3. "Product Information. Posaconazole (AKM) (posaconazole)." Pharmacor Pty Ltd (2022):
  4. "Product Information. Posaconazole (posaconazole)." Morningside Healthcare Ltd (2024):
  5. "Product Information. Posaconazole (posaconazole)." Eugia US LLC (2023):
  6. "Product Information. Gln-Posaconazole (posaconazole)." Glenmark Pharmaceuticals Canada Inc (2023):
View all 6 references

Drug and food interactions

Moderate

toremifene food

Applies to: Fareston (toremifene)

You should avoid drinking grapefruit juice during treatment with toremifene. Grapefruit juice may increase the blood levels of toremifene. This can make you more likely to develop side effects such as vaginal bleeding, blood clots, or an irregular heart rhythm that may be serious or life-threatening. Contact your doctor if you experience potential signs and symptoms of blood clots such as chest pain, shortness of breath, sudden loss of vision, and pain, redness or swelling your arms or legs. You should also seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, or fast or pounding heartbeats during treatment with toremifene.

Talk to your doctor before using toremifene with soy products. There is some evidence that substances present in soy may stimulate breast tumor growth and interfere with the action of toremifene, although this has not been proven. Whether soy products are effective for hot flashes is also uncertain. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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Moderate

posaconazole food

Applies to: posaconazole

Food significantly increases the absorption of posaconazole from the tablet or suspension formulations. The manufacturer recommends that you take the tablet with food and the oral suspension during or immediately (within 20 minutes) after a full meal. If you cannot eat a full meal, you should take the oral suspension with a liquid nutritional supplement like Ensure or an acidic carbonated beverage like ginger ale. Do not take these medications on an empty stomach, as it may lead to inadequate blood levels and reduced effectiveness. Ask your doctor before using alcohol together with posaconazole from delayed release suspension formulations as this may cause an increase in side effects. Talk to your doctor or pharmacist if you have any questions on how to use the medication properly.

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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.

See also

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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.

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