our patient , a 60-year - old italian man , was admitted to the psychiatric unit because of spatial and temporal disorientation , mental confusion , restlessness and agitation . one year before admission to the psychiatric unit he had been diagnosed with a small cell lung cancer with a metastatic lesion in the right parietal cerebral lobe and had been treated with chemotherapy and radiotherapy . he worked in a petrochemical industry and smoked about 1 pack of cigarettes per day . on admission , his medications were desametason 1 mg b.i.d . , pantoprazole 20 mg b.i.d . , and fentanil 100 g / h transdermal patch . on a psychic evaluation the patient was confused , irritable , and disoriented . clinical phenomena had a fluctuating course and the patient showed a sundown syndrome , characterized by reduced daytime alertness , insomnia and confusion . the mini mental state examination ( mmse ) he was afebrile , his blood pressure was 130/80 mm hg with a heart rate of 90 bpm , a respiratory rate of 24 breaths per minute , and an oxygen saturation of 93% . laboratory tests presented decreased haemoglobin ( 11.3 g / dl ) and hct ( 35.0% ) . wbc , glucose , creatinine , platelets , bun , electrolytes , ast , and alt were within normal range . he was treated , after written informed consent , with quetiapine ( sr ) 300 mg / day and continued therapy with desametason 1 mg b.i.d . , pantoprazole 20 mg / day and fentanil 100 g / h transdermal patch . after four days of treatment with quetiapine sr the consciousness , the patient normalized his sleep - wake cycle , and was not aggressive or irritable . the use of quetiapine was effective and safe in the treatment of delirium , improving delirious symptoms as cognitive dysfunction , delusional and behavioural phenomena , and regularizing the sleep - wake rhythm . receptorial profile of quetiapine includes dopaminergic ( d1 , d2 ) and serotoninergic ( 5ht1a , 5ht2 ) antagonism . this double receptorial affinity could be useful to regularize the alterations of serotoninergic and dopaminergic neurotransmission in delirium . serotonin plays a role in the pathogenesis of delirium   and the receptorial profile of quetiapine could be more specific in treating delirious patients . in fact , quetiapine , at doses of 300 mg / day , shows a high ratio of 5-ht2a / d2 receptor occupancy . quetiapine has a very low incidence of extrapyramidal side effects , lacks anticholinergic and antimuscarinic effects   and does not cause a further reduction of cholinergic neurotransmission , which is compromised in delirium . in sum , quetiapine sr presents a rapid effect , improving cognitive impairments , thought disorders and behavioural disorders , without relevant side effects .
while haloperidol represents the first - line treatment of delirium , some studies have shown that atypical antipsychotics could be used as an efficacious treatment in delirium management . 
 this article reports a case of a delirious patient , treated effectively and quickly with quetiapine sustained release with negligible side effects .