Drug Interactions between Quadrinal and Tamoxifen Hexal
This report displays the potential drug interactions for the following 2 drugs:
- Quadrinal (ephedrine/phenobarbital/potassium iodide/theophylline)
- Tamoxifen Hexal (tamoxifen)
Interactions between your drugs
PHENobarbital tamoxifen
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline) and Tamoxifen Hexal (tamoxifen)
Consumer information for this interaction is not currently available.
GENERALLY AVOID: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of tamoxifen and its major metabolite, N-desmethyltamoxifen. According to the product labeling, tamoxifen is primarily metabolized by CYP450 3A4 to N-desmethyltamoxifen, an antiestrogenic metabolite with similar biological activity to tamoxifen but an elimination half-life that is estimated to be approximately 10 to 14 days versus 5 to 7 days for tamoxifen. N-desmethyltamoxifen itself is further metabolized by CYP450 2D6 to endoxifen, a major metabolite that is thought to be primarily responsible for tamoxifen's therapeutic effect. When a single 80 mg oral dose of tamoxifen was administered to 10 healthy volunteers following pretreatment with the potent CYP450 3A4 inducer rifampin at a dosage of 600 mg once daily for 5 days, tamoxifen peak plasma concentration (Cmax), systemic exposure (AUC) and elimination half-life decreased by 55%, 86% and 44%, respectively, compared to pretreatment with placebo. In addition, rifampin decreased the AUC and half-life of N-desmethyltamoxifen by 62% and 36%, respectively, and increased the Cmax by approximately 50% compared to placebo. These changes indicate that rifampin enhanced the metabolism of tamoxifen during both the presystemic and elimination phases. In another study, patients with glioma who received high-dose tamoxifen with phenytoin (n=15) demonstrated a 60% lower mean plasma tamoxifen concentration than patients not on concomitant phenytoin (n=10), although the difference did not reach statistical significance due to high interpatient variability and low patient numbers. The interaction has also been described in case reports of two tamoxifen-treated patients who had significantly reduced and subtherapeutic endoxifen levels during or after coadministration with a potent CYP450 inducer. One of them was receiving phenytoin and the other, rifampin. Induction of endoxifen clearance via P-glycoprotein-mediated efflux and/or uridine diphosphate glucuronosyltransferase (UGT)-mediated metabolism may be involved. The extent to which other potent CYP450 3A4 inducers may affect tamoxifen and its active metabolites is unknown.
MANAGEMENT: Until more information is available, concomitant use of tamoxifen with potent CYP450 3A4 inducers should be avoided when possible, particularly if they are to be administered for a prolonged period. Otherwise, therapeutic drug monitoring of tamoxifen and endoxifen is recommended to optimize therapy.
theophylline PHENobarbital
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline) and Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Using PHENobarbital together with theophylline may decrease the effects of theophylline. Contact your doctor if your condition changes or if you experience breathing difficulties. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. 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.
theophylline ePHEDrine
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline) and Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Information for this minor interaction is available on the professional version.
Drug and food interactions
PHENobarbital food
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Ask your doctor before using PHENobarbital together with ethanol (alcohol), this can add to dizziness, drowsiness and other side effects of PHENobarbital. Be careful if you drive or do activities that require you to be awake and alert. Talk with your doctor before using any medications together, or drinking alcohol with PHENobarbital. 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.
theophylline food
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Both smoking and excessive caffeine consumption can alter the blood levels of theophylline, which may affect the dosing. Tobacco and marijuana smoke (including secondhand exposure) generally reduces, while caffeine increases, blood levels. In addition, caffeine is a stimulant and may add to the side effects of theophylline such as headache, insomnia, and increases in blood pressure and heart rate. It is best to avoid smoking and to limit caffeine consumption during theophylline therapy. Talk to a healthcare professional if you have any questions or concerns. If you start smoking or undergo smoking cessation, your doctor may need to monitor your blood levels more closely to determine if you need a dose adjustment of theophylline. You should stop taking theophylline and seek medical attention if you experience potential signs and symptoms of excessive drug levels such as nausea, vomiting, persistent headache, insomnia, and rapid heartbeat. 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.
When theophylline is given with enteral (tube) feedings, blood levels may be decreased due to interference with its absorption. This may reduce the effectiveness of the medication. To minimize potential for interaction, you may interrupt the feeding for one hour before and one hour after the theophylline dose. You may need more frequent blood tests to monitor theophylline levels.
tamoxifen food
Applies to: Tamoxifen Hexal (tamoxifen)
Talk to your doctor before using tamoxifen with soy products. There is some evidence that substances present in soy may stimulate breast tumor growth and interfere with the action of tamoxifen, 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.
theophylline food
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Ask your doctor before using theophylline together with caffeine. Using these medications together may increase some of the side effects of theophylline. This can cause nausea, vomiting, insomnia, tremors, restlessness, uneven heartbeats, and seizure (convulsions). Avoid drinks or foods that contain caffeine, such as coffee, tea, cola, and chocolate. You may need a dose adjustment or special test if you use both medications. 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.
ePHEDrine food
Applies to: Quadrinal (ephedrine / phenobarbital / potassium iodide / theophylline)
Both ePHEDrine and caffeine can increase blood pressure and heart rate, and combining them may enhance these effects. Talk to your doctor before using these medications, especially if you have a history of high blood pressure or heart disease. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if your condition changes or you experience increased side effects. 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.
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.
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| 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. | |
| 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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