Metoclopramide in the context of "Serotonin syndrome"

Tardive dyskinesia (TD) is an iatrogenic disorder that results in involuntary repetitive body movements, which may include grimacing, sticking out the tongue or smacking the lips, which occurs following treatment with medication. Additional motor symptoms include chorea or athetosis. In about 20% of people with TD, the disorder interferes with daily functioning. If TD is present in the setting of a long-term drug therapy, reversibility can be determined primarily by severity of symptoms and how long symptoms have been present before the long-term drug has been stopped.

Tardive dyskinesia occurs as a result of long-term use of dopamine-receptor-blocking medications such as antipsychotics and metoclopramide. These medications are usually used for mental illness but may also be given for gastrointestinal or neurological problems. The condition typically develops only after months to years of use. The diagnosis is based on the symptoms after ruling out other potential causes.

Akathisia (/æ.kə.ˈθɪ.si.ə/ a-kə-THI-see-ə) is a movement disorder characterized by a subjective feeling of inner restlessness accompanied by mental distress and/or an inability to sit still. Usually, the legs are most prominently affected. Those affected may fidget, rock back and forth, or pace, while some may just have an uneasy feeling in their bodies. The most severe cases may result in poor adherence to medications, exacerbation of psychiatric symptoms, and, because of this, aggression, violence, and/or suicidal thoughts. Akathisia is also associated with threatening behaviour and physical aggression in mentally disordered patients. However, the attempts to find potential links between akathisia and emerging suicidal or homicidal behaviour were not systematic and were mostly based on a limited number of case reports and small case series. Apart from these few low-quality studies, there is another more recent and better quality study (a systematic review from 2021) that concludes akathisia cannot be reliably linked to the presence of suicidal behavior in patients treated with antipsychotic medication.

Antipsychotic medication, particularly the first generation antipsychotics, are a leading cause. Other agents commonly responsible for this side-effect may also include selective serotonin reuptake inhibitors, metoclopramide, and reserpine, though any medication listing agitation as a side effect may trigger it. It may also occur upon stopping antipsychotics. The underlying mechanism is believed to involve dopamine. When antidepressants are the cause, there is no agreement on the distinction between activation syndrome and akathisia. Akathisia is often included as a component of activation syndrome. However, the two phenomena are not the same since the former, namely antipsychotic-induced akathisia, suggests a known neuroreceptor mechanism (e.g., dopamine-receptor blockade). Diagnosis is based on the symptoms. It differs from restless leg syndrome in that akathisia is not associated with sleeping. However, despite a lack of historical association between restless leg syndrome and akathisia, this does not guarantee that the two conditions do not share symptoms in individual cases.