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Drug Interactions between Rythmol SR and Signifor LAR

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

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Interactions between your drugs

Major

propafenone pasireotide

Applies to: Rythmol SR (propafenone) and Signifor LAR (pasireotide)

MONITOR CLOSELY: Pasireotide can cause bradycardia and QT prolongation. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In healthy study subjects given therapeutic (0.6 mg twice daily) and supratherapeutic (1.95 mg twice daily) dosages of pasireotide, the maximum mean placebo-subtracted QTcI change from baseline was 12.7 msec and 16.6 msec, respectively. Both dosages decreased heart rate, with a maximum mean placebo-subtracted change from baseline of -10.9 beats per minute (bpm) observed at 1.5 hours for the therapeutic dosage and -15.2 bpm at 0.5 hours for the supratherapeutic dosage. The mean steady-state peak plasma concentration (Cmax) produced by the supratherapeutic dosage was 3.3-fold that observed with the therapeutic dosage. In clinical studies of patients with Cushing's disease, two of 201 patients experienced single occurrences of QTcF exceeding 500 msec. Torsade des pointes arrhythmias were not observed in these or other studies. 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: Caution is recommended if pasireotide is used in combination with other drugs that can prolong the QT interval. ECG and serum electrolytes, including potassium, magnesium and calcium, should be monitored before starting pasireotide therapy and periodically during treatment in accordance with the product labeling. Hypokalemia and hypomagnesemia must be corrected prior to pasireotide administration. 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.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  3. Cerner Multum, Inc. "Australian Product Information."
  4. (2013) "Product Information. Signifor (pasireotide)." Novartis Pharmaceuticals
View all 4 references

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Drug and food interactions

Moderate

propafenone food

Applies to: Rythmol SR (propafenone)

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 (1993) "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, p. 120-6
  2. (2011) "Product Information. Rythmol SR (propafenone)." GlaxoSmithKline
  3. (2023) "Product Information. Apo-Propafenone (propafenone)." Apotex Incorporated
  4. (2022) "Product Information. Propafenone (propafenone)." Accord-UK Ltd
View all 4 references

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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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