Lithium/venlafaxine interaction
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Lithium intoxication and other toxicities: case report A 77-year-old woman developed acute confusional state, psychomotor restlessness, dysarthria, increased somnolence, hypernatraemia, attention disorder, severe cognitive-amnestic deficits, atopic gait, worsening of parkinsonian tremor and delirium following concomitant administration of lithium and venlafaxine for bipolar affective disorder leading to lithium intoxication [routes and duration of treatments to reaction onsets not stated]. The woman, who had bipolar affective disorder, had been receiving lithium [Quilonum retard] 675mg daily. Her co-morbidities included essential hypertonia, cerebral insult, epilepsy with complex focal seizures, hypothyroidism, primary Parkinson’s disease and essential tremor. She had been receiving venlafaxine 300 mg/day prolonged-release along with several other co-medications. She experienced rapid clinical deterioration over a period of few weeks, which manifested by significant cognitive decline, increased parkinsonian tremor, atopic gait and slight speech impediment (dysarthria). She presented in an acute confusional state. An electroencephalogram revealed moderate-modulated alpha activity of 8–9Hz along with a significantly increased theta activity of 4–7Hz. Skull imaging ruled out vascular events. Lithium level was found at 1.62 mmol/L. Lithium intoxication was suspected. The woman’s lithium dose was reduced from 675mg to 500 mg/day. Further clinical deterioration was observed in the form of increased somnolence, which resulted in an emergency admission requiring intensive medical care. Laboratory investigations revealed severe hypernatraemia, increased infection parameters and increased renal retention parameters. Lithium levels were significantly increased at 1.44 mmol/L. An ECG revealed sinus rhythm, normal Qtc with no ST-segment alterations. A diagnosis of chronic lithium intoxication with underlying renal insufficiency, dehydration and bronchopulmonary infections was made. Her lithium therapy was discontinued, and she was treated with unspecified antibiotics, unspecified diuretics and fluid substitution. Gradually, the hypernatraemia and lithium levels decreased. However, she remained delirious and was admitted. She also experienced severe attention and cognitive function disorder and psychomotor restlessness. She was fidgety, verbally nonaccessible and almost unmanageable. She received levetiracetam, zonisamide, diazepam, risperidone and levothyroxine sodium [levothyroxine] at admission. Diazepam dose was increased. Over a period of time, a complete recovery of cognitive-amnestic functions was noted. Her mood was balanced and sleep was satisfactory. She was able to walk using walker. The parkinsonian symptoms and postural tremor completely recovered. About 3 months after the admission, she was discharged in a good and stable condition. Her delirium had also resolved, and she received lamotrigine as a prophylaxis for mood disorder. It was concluded that the interaction of venlafaxine and lithium caused severe chr
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