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Drug Interactions between Rythmol and Spastrin

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

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Interactions between your drugs

Moderate

ergotamine PHENobarbital

Applies to: Spastrin (belladonna / ergotamine / phenobarbital) and Spastrin (belladonna / ergotamine / phenobarbital)

PHENobarbital may reduce the blood levels and effects of ergotamine. Contact your doctor if your symptoms worsen or your condition changes during treatment with these medications. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring 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.

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Minor

PHENobarbital propafenone

Applies to: Spastrin (belladonna / ergotamine / phenobarbital) and Rythmol (propafenone)

Information for this minor interaction is available on the professional version.

Drug and food interactions

Major

PHENobarbital food

Applies to: Spastrin (belladonna / ergotamine / phenobarbital)

Ask your doctor before using PHENobarbital together with ethanol, 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.

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Moderate

ergotamine food

Applies to: Spastrin (belladonna / ergotamine / phenobarbital)

Grapefruit juice may increase the blood levels of certain medications such as ergotamine. You may want to limit your consumption of grapefruit and grapefruit juice during treatment with ergotamine. However, if you have been regularly consuming grapefruit or grapefruit juice with the medication, then it is advisable for you to talk with your doctor before changing the amounts of these products in your diet, as this may alter the effects of your medication. Contact your doctor if your condition changes or you experience increased side effects. Orange juice is not expected to interact.

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Moderate

propafenone food

Applies to: Rythmol (propafenone)

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of propafenone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. In over 90% of patients, propafenone is rapidly and extensively converted to 2 active metabolites: 5-hydroxypropafenone via CYP450 2D6 and N-depropylpropafenone (norpropafenone) via CYP450 3A4 and 1A2. In less than 10% of patients (approximately 6% of Caucasians in the U.S. population), however, metabolism of propafenone is slower because the 5-hydroxy metabolite is not formed, or minimally formed, due to a genetic deficiency in CYP450 2D6. In these poor metabolizers of CYP450 2D6, clearance of propafenone via the CYP450 3A4 and 1A2 metabolic pathways becomes more important, and inhibition of these pathways may substantially increase systemic exposure to propafenone. Likewise, patients taking concomitant inhibitors of CYP450 2D6 and 3A4 may experience similar pharmacokinetic effects. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Increased systemic exposure to propafenone may result in proarrhythmic events and exaggerated beta-adrenergic blocking activity.

MANAGEMENT: It may be advisable for patients to avoid the consumption of grapefruit, grapefruit juice, or supplements that contain grapefruit during treatment with propafenone.

References

  1. Botsch S, Gautier JC, Beaune P, Eichelbaum M, Kroemer HK "Identification and characterization of the cytochrome P450 enzymes involved in N-dealkylation of propafenone: molecular base for interaction potential and variable disposition of active metabolites." Mol Pharmacol 43 (1993): 120-6
  2. "Product Information. Rythmol SR (propafenone)." GlaxoSmithKline (2011):
  3. "Product Information. Apo-Propafenone (propafenone)." Apotex Incorporated (2023):
  4. "Product Information. Propafenone (propafenone)." Accord-UK Ltd (2022):
View all 4 references
Moderate

belladonna food

Applies to: Spastrin (belladonna / ergotamine / phenobarbital)

Ask your doctor before using belladonna together with ethanol. Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking belladonna. You should be warned not to exceed recommended dosages and to avoid activities requiring mental alertness. If your doctor prescribes these medications together, you may need a dose adjustment to safely take this combination. 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

ergotamine food

Applies to: Spastrin (belladonna / ergotamine / phenobarbital)

Nicotine may increase the effects of ergotamine in narrowing the blood vessels and decreasing blood flow. A severe decrease in blood flow to the brain and other parts of the body can lead to dangerous side effects. Contact your doctor immediately if you experience coldness, paleness, discoloration, numbness, tingling, or pain in your hands or feet; muscle pain or weakness; severe or worsening headache; blurred vision; severe abdominal pain; chest pain; or shortness of breath while using these 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.

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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.