Issues for surgery
Risk of withdrawal symptoms if omitted (see Further information).
Risk of serotonin syndrome if continued (see Interactions with common anaesthetic agents and Interactions with other common medicines used in the perioperative period).
Risk of QT-interval prolongation if continued (see Interactions with other common medicines used in the perioperative period).
Advice in the perioperative period
Elective and emergency surgery
Continue.
Post-operative advice
If a long nil by mouth (NBM) period is anticipated, or if there are concerns with enteral absorption, advice on alternative preparations/routes should be sought from a psychiatrist.
Interactions with common anaesthetic agents
Central Nervous System (CNS) excitation (serotonin syndrome)
Some opioids act as weak serotonin reuptake inhibitors (SRIs) and can precipitate serotonin syndrome in conjunction with other serotonergic medication. Symptoms of serotonin syndrome may occur if trazodone is given concomitantly with:
- fentanyl
- methadone
- pentazocine
- pethidine
- tapentadol
- tramadol
Patients should be monitored closely and the possibility of serotonin toxicity considered if patients experience altered mental state, autonomic dysfunction or neuromuscular adverse effects with concomitant treatment.
CNS depression
See also Interactions with other common medicines used in the perioperative period.
Trazodone has CNS depressant effects which may be additive with other medicines that also have CNS depressant effects such as:
- benzodiazepines
- inhalational anaesthetics and intravenous anaesthetics
- local anaesthetics
- opioids
(Consult British National Formulary for available drugs in each class.)
QT-Interval prolongation
See also Interactions with other common medicines used in the perioperative period.
Cases of QT-interval prolongation have been reported during post-marketing use of trazodone. Co-administration with other medicines known to prolong the QT-interval must be based on careful assessment of the potential risks and benefits for each patient.
Anaesthetic agents that may be used in the perioperative period that are known to, or predicted to, prolong the QT-interval include:
- desflurane, isoflurane, sevoflurane*
- thiopental (theoretical)**
*monitor ECG if concurrent use unavoidable; if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia) use greater caution
**monitor ECG with concurrent use if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia).
Interactions with other common medicines used in the perioperative period
CNS excitation (serotonin syndrome)
Opioids
For a discussion of opioids see Interactions with common anaesthetic agents above. In addition, trazodone lowers the seizure threshold; concurrent use with tramadol, which also lowers the seizure threshold, may have an additive effect on the risk of seizures.
Methylthioninium chloride (methylene blue)
There has been a case report of serotonin syndrome in a patient taking trazodone who were also given methylthioninium chloride. The MHRA advise that methylthioninium chloride should be avoided in patients taking drugs that enhance serotonergic transmission. If concurrent use is necessary the lowest possible dose of methylthioninium chloride should be given and the patients should be closely monitored for signs of CNS toxicity for 4 hours after administration. However, this advice is contested in one report which suggests even doses as low as 1mg/kg may be sufficient to inhibit monoamine oxidase-A, thus causing a reaction.
Other medications
There is also an increased risk of developing serotonin syndrome when trazadone is used concurrently with the following:
- granisetron (also see QT-Interval prolongation below)
- ondansetron (also see QT-Interval prolongation below)
- linezolid
Monitor patients for symptoms of serotonin syndrome such as fever, tremors, diarrhoea, and agitation. Concurrent treatment should be stopped if serotonin syndrome occurs.
CNS depression
See Interactions with common anaesthetic agents above for information on opioids.
Trazodone has CNS depressant effects which may be additive with antiemetics that also have CNS depressant effects such as cyclizine, droperidol and prochlorperazine.
QT-Interval prolongation
Cases of QT-interval prolongation have been reported during post-marketing use of trazodone. Co-administration with other medicines known to prolong the QT-interval must be based on a careful assessment of the potential risks and benefits for each patient since the risk of torsade de pointes may increase.
Medicines that may be used in the perioperative period that are known to prolong the QT-interval include:
- ciprofloxacin*
- clarithromycin* (also see Macrolide antibiotics below)
- domperidone – avoid
- droperidol*
- erythromycin (especially intravenous)* (also see Macrolide antibiotics below)
- granisetron*
- haloperidol – if concurrent use not avoidable*
- loperamide (increased risk with high doses)*
- ondansetron*
- prochlorperazine*
*monitor ECG with concurrent use if risk factors for QT-interval prolongation also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia)
Macrolide antibiotics
Clarithromycin and erythromycin are predicted to moderately increase the exposure to trazodone through inhibition of CYP3A4. Whilst single surgical prophylactic doses should not pose a problem, monitor for side effects and consider reducing trazodone dose if concurrent use cannot be avoided and a prolonged course is required.
Further information
Withdrawal
Ideally trazodone should not be withdrawn abruptly as withdrawal effects may occur within 5 days of stopping treatment1; they are usually mild and self-limiting, e.g. headache, nausea, malaise3, but in some cases may be severe. The risk of withdrawal is increased if trazodone is stopped suddenly after regular administration for more than 8 weeks.
References
Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 10th August 2019]
Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 10th August 2019]
Summary of Product Characteristics – Molipaxin® (trazodone) 100mg. Zentiva. Accessed via www.medicines.org.uk 10/08/2019 [date of revision of the text August 2018]