Trazodoneinteractions

CNS Depressants: Trazodone may enhance effects of alcohol, barbiturates, or other CNS depressants.

CYP3A4 Inhibitors: Consider trazodone dose reduction based on tolerability.

CYP3A4 Inducers: Increase in trazodone dosage may be necessary.

Digoxin or Phenytoin: Monitor for increased digoxin or phenytoin serum levels.

Warfarin: Monitor for increased or decreased prothrombin time. MAOIs MAOIs should not be used within 14 days of trazodone. Central Nervous System (CNS) Depressants Trazodone may enhance the response to alcohol, barbiturates, and other CNS depressants. Cytochrome P450 3A4 Inhibitors In vitro drug metabolism studies suggest that there is a potential for drug interactions when trazodone is given with cytochrome P450 3A4 (CYP3A4) inhibitors. The effect of short-term administration of ritonavir (200 mg twice daily, 4 doses) on the pharmacokinetics of a single dose of trazodone (50 mg) has been studied in 10 healthy subjects. The C max of trazodone increased by 34%, the AUC increased 2.4 fold, the half-life increased by 2.2 fold, and the clearance decreased by 52%. Adverse effects including nausea, hypotension, and syncope were observed when ritonavir and trazodone were coadministered. It is likely that ketoconazole, indinavir, and other CYP3A4 inhibitors such as itraconazole may lead to substantial increases in trazodone plasma concentrations with the potential for adverse effects. If trazodone is used with a potent CYP3A4 inhibitor, the risk of cardiac arrhythmia may be increased and a lower dose of trazodone should be considered. Cytochrome P450 Inducers (e.g., Carbamazepine) Carbamazepine induces CYP3A4. Following coadministration of carbamazepine 400 mg per day with trazodone 100 mg to 300 mg daily, carbamazepine reduced plasma concentrations of trazodone and m-chlorophenlypiperazine (an active metabolite) by 76% and 60% respectively, compared to pre-carbamazepine values. Patients should be closely monitored to see if there is a need for an increased dose of trazodone when taking both drugs. Digoxin and Phenytoin Increased serum digoxin or phenytoin levels have been reported in patients receiving trazodone concurrently with either of these drugs. Monitor serum levels and adjust dosages as needed. Serotonergic Drugs Based on the mechanism of action of trazodone and the potential for serotonin syndrome, caution is advised when trazodone is coadministered with other drugs that may affect the neurotransmitter systems. NSAIDs, Aspirin, or Other Drugs Affecting Coagulation or Bleeding Due to a possible association between serotonin modulating drugs and gastrointestinal bleeding, patients should be monitored for and cautioned about the potential risk of bleeding associated with the concomitant use of trazodone and NSAIDs, aspirin, or other drugs that affect coagulation or bleeding [s ee Warnings and Precautions ]. Warfarin There have been reports of altered (either increased or decreased) prothrombin times in taking both warfarin and trazodone.

7.1 Drugs Having

Clinically Important Interactions with Trazodone Table 3 Clinically Important Drug Interactions with Trazodone Monoamine Oxidase Inhibitors (MAOIs) Clinical Impact: The concomitant use of MAOIs and serotonergic drugs including trazodone increases the risk of serotonin syndrome.

Intervention: Trazodone is contraindicated in patients taking MAOIs, including MAOIs such as linezolid or intravenous methylene blue.

Examples: isocarboxazid, moclobemide, phenelzine, selegiline, tranylcypromine Other Serotonergic Drugs Clinical Impact: The concomitant use of serotonergic drugs including trazodone and other serotonergic drugs increases the risk of serotonin syndrome.

Intervention: Monitor patients for signs and symptoms of serotonin syndrome, particularly during trazodone initiation. If serotonin syndrome occurs, consider discontinuation of trazodone and/or concomitant serotonergic drugs.

Examples: triptans, antidepressants (tricyclic and serotonin uptake inhibitors), fentanyl, lithium, tramadol, tryptophan, buspirone, and St. John's Wort Antiplatelet Agents and Anticoagulants Clinical Impact: Serotonin release by platelets plays an important role in hemostasis. The concurrent use of an antiplatelet agent or anticoagulant with trazodone may potentiate the risk of bleeding.

Intervention: Inform patients of the increased risk of bleeding with the concomitant use of trazodone and antiplatelet agents and anticoagulants. For patients taking warfarin, carefully monitor the international normalized ratio (INR) when initiating or discontinuing trazodone.

Examples: warfarin, rivaroxaban, dabigatran, clopidogrel Strong CYP3A4 Inhibitors Clinical Impact: The concomitant use of trazodone and strong CYP3A4 inhibitors increased the exposure of trazodone compared to the use of trazodone alone.

Intervention: If trazodone is used with a potent CYP3A4 inhibitor, the risk of adverse reactions, including cardiac arrhythmias, may be increased and a lower dose of trazodone should be considered.

Examples: itraconazole, ketoconazole, clarithromycin, indinavir Strong CYP3A4 Inducers Clinical Impact: The concomitant use of trazodone and strong CYP3A4 inducers decreased the exposure of trazodone compared to the use of trazodone alone.

Intervention: Patients should be closely monitored to see if there is a need for an increased dose of trazodone when taking CYP3A4 inducers.

Examples: rifampin, carbamazepine, phenytoin, St. John's wort Digoxin and Phenytoin Clinical Impact: Digoxin and phenytoin are narrow therapeutic index drugs. Concomitant use of trazodone can increase digoxin or phenytoin concentrations.

Intervention: Measure serum digoxin or phenytoin concentrations before initiating concomitant use of trazodone. Continue monitoring and reduce digoxin or phenytoin dose as necessary.

Examples: digoxin, phenytoin Central Nervous System (CNS) Depressants Clinical Impact: Trazodone may enhance the response CNS depressants.

Intervention: Patients should be counseled that trazodone may enhance the response to alcohol, barbiturates, and other CNS depressants.

Examples: alcohol, barbiturates QT Interval Prolongation Clinical Impact: Concomitant use of drugs that prolong the QT interval may add to the QT effects of trazodone and increase the risk of cardiac arrhythmia.

Intervention: Avoid the use of trazodone in combination with other drugs known to prolong QTc.

Examples: Class 1A antiarrhythmics: quinidine, procainamide, disopyramide;

Class 3 antiarrhythmics: amiodarone, sotalol;

Antipsychotics: ziprasidone, chlorpromazine, thioridazine;

Antibiotics: gatifloxacin