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Interactions between Quinidex Extentabs and Treosulfan

1 drug interaction and 15 additional warnings found for the following 2 drugs:

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Drug interactions

Moderate drug interactions

Moderate:

quiNIDine treosulfan

Applies to: Quinidex Extentabs (quinidine) and treosulfan
Monitor

Coadministration with treosulfan may increase the plasma concentrations of drugs that are substrates of CYP450 3A4, 2C19, and/or the efflux transporter P-glycoprotein (P-gp). The proposed mechanism is decreased clearance due to inhibition of these routes of elimination due to treosulfan. According to physiologically-based pharmacokinetic modeling, treosulfan is predicted to be a weak to moderate CYP450 3A4 inhibitor and weak inhibitor of CYP450 2C19, with negligible inhibitory effects on P-gp. However, according to the manufacturer, in vitro studies were unable to exclude potential drug-drug interactions with high plasma concentrations of treosulfan and CYP450 3A4, 2C19, and/or P-gp substrates.

Management

Caution is recommended if treosulfan is coadministered with substrates of CYP450 3A4, 2C19, and/or P-gp, particularly those with a narrow therapeutic range. Some authorities advise that if concomitant use is required, the dosage of these substrates should be administered either 2 hours before or 8 hours after administration of the treosulfan infusion. The prescribing information of the substrates may be consulted for potential dose reductions.

References (4)
  1. (2021) "Product Information. Trecondyv (treosulfan)." Medexus Pharmaceuticals Inc.
  2. (2022) "Product Information. Trecondi (treosulfan)." Link Medical Products Pty Ltd T/A Link Pharmaceuticals, 1
  3. (2021) "Product Information. Trecondi (treosulfan)." medac UK
  4. (2025) "Product Information. Grafapex (treosulfan)." Medexus pharma Inc

Food/lifestyle interactions

Moderate food/lifestyle interactions

Moderate:

quiNIDine Food/Lifestyle

Applies to: Quinidex Extentabs (quinidine)
Generally avoid

In a small, randomized, crossover study, the administration of quinidine with grapefruit juice (compared to water) to healthy volunteers significantly prolonged the time to reach peak plasma quinidine concentrations and decreased the plasma concentrations of its major metabolite, 3-hydroxyquinidine. These changes were associated pharmacodynamically with both a delay and a reduction in the maximal effect on QTc interval. The proposed mechanism is delay of gastric emptying as well as inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits.

Management

Given the drug's narrow therapeutic index, patients receiving quinidine therapy should avoid the consumption of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels.

References (4)
  1. Ace LN, Jaffe JM, Kunka RL (1983) "Effect of food and an antacid on quinidine bioavailability." Biopharm Drug Dispos, 4, p. 183-90
  2. Min DI, Ku YM, Geraets DR, Lee HC (1996) "Effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of quinidine in healthy volunteers." J Clin Pharmacol, 36, p. 469-76
  3. Ha HR, Chen J, Leuenberger PM, Freiburghaus AU, Follah F (1995) "In vitro inhibition of midazolam and quinidine metabolism by flavonoids." Eur J Clin Pharmacol, 48, p. 367-71
  4. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR (2000) "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther, 68, p. 468-77

Disease interactions

14 potential interactions Applies to: 12 conditions, including Heart Failure, Seizures, Hypokalemia, Hypotension, and Myasthenia Gravis.

Glaucoma/Intraocular Hypertension

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Glaucoma/Intraocular Hypertension.

The use of quinidine is contraindicated in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as myasthenia gravis, glaucoma, and urinary retention or obstruction.

Heart Block

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Heart Block.

The use of quinidine is contraindicated for use in patients without a functioning artificial pacemaker whose cardiac rhythm is dependent upon a junctional or idioventricular pacemaker, including patients with complete AV block. Therapy with quinidine should be administered with caution in patients with severe sinus-node dysfunction such as sick sinus syndrome, bradycardia-tachycardia syndrome, or second- or third-degree heart block.

Heart Failure

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Heart Failure.

Antiarrhythmic agents can induce severe hypotension (particularly with IV administration) or induce or worsen congestive heart failure (CHF). Patients with primary cardiomyopathy or inadequately compensated CHF are at increased risk. Antiarrhythmic agents should be administered cautiously and dosage and/or frequency of administration modified in patients with hypotension or adequately compensated CHF. Alternative therapy should be considered unless these conditions are secondary to cardiac arrhythmia.

Hyperkalemia

Moderate:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a moderate potential interaction with Hyperkalemia.

Electrolyte imbalance can alter the therapeutic effectiveness of antiarrhythmic agents. Hypokalemia and hypomagnesemia can reduce the effectiveness of antiarrhythmic agents. In some cases, these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsade de pointes. Hyperkalemia can potentiate the toxic effects of antiarrhythmic agents. Electrolyte imbalance should be corrected prior to initiating antiarrhythmic therapy. Clinical monitoring of cardiac function and electrolyte concentrations is recommended.

Hypokalemia

Moderate:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a moderate potential interaction with Hypokalemia.

Electrolyte imbalance can alter the therapeutic effectiveness of antiarrhythmic agents. Hypokalemia and hypomagnesemia can reduce the effectiveness of antiarrhythmic agents. In some cases, these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsade de pointes. Hyperkalemia can potentiate the toxic effects of antiarrhythmic agents. Electrolyte imbalance should be corrected prior to initiating antiarrhythmic therapy. Clinical monitoring of cardiac function and electrolyte concentrations is recommended.

Hypotension

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Hypotension.

Antiarrhythmic agents can induce severe hypotension (particularly with IV administration) or induce or worsen congestive heart failure (CHF). Patients with primary cardiomyopathy or inadequately compensated CHF are at increased risk. Antiarrhythmic agents should be administered cautiously and dosage and/or frequency of administration modified in patients with hypotension or adequately compensated CHF. Alternative therapy should be considered unless these conditions are secondary to cardiac arrhythmia.

Liver Disease

Moderate:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a moderate potential interaction with Liver Disease.

Quinidine is primarily metabolized by the liver to active and inactive forms. Hepatic dysfunction causes a slowed metabolism and elimination of the drug which can lead to quinidine toxicity if dosage is not appropriately reduced. Clinical monitoring of hepatic function is recommended.

Moderate:

treosulfan

Treosulfan has a moderate potential interaction with Liver Disease.

Treosulfan has not been studied in patients with moderate or severe liver and renal dysfunction.

Magnesium Imbalance

Moderate:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a moderate potential interaction with Magnesium Imbalance.

Electrolyte imbalance can alter the therapeutic effectiveness of antiarrhythmic agents. Hypokalemia and hypomagnesemia can reduce the effectiveness of antiarrhythmic agents. In some cases, these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsade de pointes. Hyperkalemia can potentiate the toxic effects of antiarrhythmic agents. Electrolyte imbalance should be corrected prior to initiating antiarrhythmic therapy. Clinical monitoring of cardiac function and electrolyte concentrations is recommended.

Myasthenia Gravis

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Myasthenia Gravis.

The use of quinidine is contraindicated in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as myasthenia gravis, glaucoma, and urinary retention or obstruction.

Renal Dysfunction

Moderate:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a moderate potential interaction with Renal Dysfunction.

Renal dysfunction causes a slowed elimination of quinidine which can lead to quinidine toxicity if dosage is not appropriately reduced. Therapy with quinidine should be administered cautiously and dosages reduced in patients with compromised renal function. Quinidine is not appreciably removed by hemodialysis.

Moderate:

treosulfan

Treosulfan has a moderate potential interaction with Renal Dysfunction.

Treosulfan has not been studied in patients with moderate or severe liver and renal dysfunction.

Seizures

Moderate:

treosulfan

Treosulfan has a moderate potential interaction with Seizures.

There have been reports of seizures in patients following treatment with treosulfan. Patients should be monitored for signs of neurological adverse reactions, and clonazepam prophylaxis may be considered for patients at higher risk for seizures, including infants.

Urinary Retention

Major:

Quinidex Extentabs

The quiNIDine in Quinidex Extentabs has a major potential interaction with Urinary Retention.

The use of quinidine is contraindicated in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as myasthenia gravis, glaucoma, and urinary retention or obstruction.

More resources

Quinidex Extentabs

A total of 669 drugs are known to interact with Quinidex Extentabs.

treosulfan

A total of 546 drugs are known to interact with treosulfan.

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.