Pre-existing Parkinsons disease or dementia with Lewy bodies

Interactions
Amiodarone: Q-Tc interval prolongation (potentially dangerous change in heart rhythm). Amphetamine and methylphenidate: counteracts increased action of norepinephrine and dopamine in patients with narcolepsy or ADD/ADHD
Epinephrine:  action antagonized, paradoxical decrease in blood pressure may result
Guanethidine:  antihypertensive action antagonized
Levodopa:  decreased action of levodopa
Lithium:  rare cases of the following symptoms have been noted: encephalopathy, early and late extrapyramidal side effects, other neurologic symptoms, and coma. Methyldopa:  increased risk of extrapyramidal side effects and other unwanted central effects
Other central depressants (alcohol, tranquilizers, narcotics):  actions and side effects of these drugs (sedation, respiratory depression) are increased. In particular, the doses of concomitantly used opioids for chronic pain can be reduced by 50%. Other drugs metabolized by the CYP3A4 enzyme system: inducers such as carbamazepine, phenobarbital, and rifampicin decrease plasma levels and inhibitors such as quinidine, buspirone, and fluoxetine increase plasma levels
Tricyclic antidepressants:  metabolism and elimination of tricyclics significantly decreased, increased toxicity noted (anticholinergic and cardiovascular side effects, lowering of seizure threshold)

Discontinuation
The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time.There is tentative evidence that discontinuation of antipsychotics can result in psychosis.
Daridorexant did not produce signs of withdrawal or dependence upon discontinuation in animal studies and clinical trials, and orexin receptor antagonists are not associated with rebound insomnia. Loss of sleep-promoting effectiveness occurs rapidly upon discontinuation of daridorexant. Preclinical research has suggested that orexin antagonists may reduce appetite, but daridorexant and other orexin antagonists have not been associated with weight loss in rigorous clinical trials.Orexin receptor antagonists can affect the reward system and produce drug-liking responses in humans. Daridorexant at a dose of 50 mg (the maximum recommended dose) showed significantly greater drug liking than placebo but significantly less drug liking than zolpidem (30 mg) and suvorexant (150 mg) in recreational sedative drug users. At higher doses of 100 and 150 mg (greater than the recommended maximum dose), drug liking with daridorexant was similar to that with zolpidem (30 mg) and suvorexant (150 mg). In other studies, suvorexant showed similar drug liking compared to zolpidem but lower misuse potential on other measures (e.g., overall rate of misuse potential adverse events of 58% for zolpidem and 31% for suvorexant in recreational drug users). No reports indicative of misuse liability were observed in large clinical trials with daridorexant, although these studies excluded participants with history of drug or alcohol misuse. Overdose
There is limited clinical experience with overdose of daridorexant. Overdose of the medication at a dose of up to four times the maximum recommended dose may result in adverse effects including somnolence, muscle weakness, catalepsy-like symptoms, sleep paralysis, attention disturbances, fatigue, headache, and constipation.