17 - Interactions of antiseizure medications22

Interactions of antiseizure medications22

Drug treatment of psychiatric symptoms in the context of other conditions CHAPTER 10 Interactions of antiseizure medications22 Pharmacokinetic interactions Important pharmacokinetic interactions occur in both directions between antiseizure medications and psychotropics, primarily mediated through cytochrome enzymes.9,23 Psychotropics with enzyme-­inhibiting effects (e.g. fluoxetine, fluvoxamine, paroxetine and, at higher doses, sertraline) may increase antiseizure plasma levels. This is especially relevant to antiseizure medications with a narrow therapeutic index (e.g. carbamazepine and phenytoin). Plasma levels should be monitored, and dosage adjustment may be required. Citalopram and escitalopram are very weak inhibitors of CYP1A2 and CYP2D6, and so may be preferred in some cases. Some antiseizure medications are potent enzyme inducers (e.g. phenytoin, carbamazepine, phenobarbital, primidone) and others are weak inducers (e.g. oxcarbazepine at doses ≥900mg/day, topiramate at doses ≥400mg/day). These drugs can lower plasma levels of many psychotropics, leading to treatment failure. Antiseizure medication Adverse psychiatric symptoms Psychiatric benefits Ethosuximide Behavioural disturbance, depression, psychosis None reported Felbamate Anxiety, depression None reported Gabapentin, pregabalin Depression and anxiety on cessation Anxiolytic Lacosamide None reported None reported Lamotrigine Anxiogenic in some. Behavioural disturbance in cognitive impairment Antidepressant, mood stabilising Levetiracetam Anxiety, behavioural disturbance, depression, suicidality None confirmed Perampanel Behavioural disturbance, depression, psychosis None reported Phenytoin Behavioural disturbance, depression Anti-­manic Rufinamide Anxiety, insomnia None reported Tiagabine Behavioural disturbance, depression Anxiolytic Topiramate Anxiety, behavioural disturbance, depression, psychosis Unclear. Possible anti-­manic/antipsychotic Valproate Behavioural disturbance (at high doses in children) Mood stabilising, anti-­manic, anti-­panic Vigabatrin Behavioural disturbance/ADHD symptoms, depression, psychosis None reported Zonisamide Behavioural disturbance, depression None confirmed Table 10.4  (Continued)