Given the increase in prescribing of antipsychotic medication, it is more important than ever for providers to be screening for Tardive Dyskinesia (TD) and other extrapyramidal symptoms (EPS) related to antipsychotic use. Partially, the increase in prescribing of antipsychotic medications is related to their use in non-psychotic disorders, like monotherapy for bipolar disorder and adjunctive treatment for major depression. Additionally some antipsychotic medications are FDA approved for Irritability in Autism. Children and women are more susceptible to TD and other EPS from antipsychotic medications than adult males. The newer antipsychotic medications are shown to be less likely than the older antipsychotic medications to cause EPS, but it is still a concerning side effect that needs to be monitored, especially for these populations. EPS can occur even at lower doses although it is more common at higher doses. Other forms of EPS (like dystonia and akathisia) are early indicators that TD might develop later in the course of treatment. The risk for TD increases the longer a patient is on an antipsychotic medication. Approximately 15% of patients on long-term antipsychotic medication will develop TD.
The Abnormal Involuntary Movement Scale (AIMS) is a screening tool that was developed in the 1970s as a quick screening for TD. It can be used as a baseline assessment for TD as well as to monitor the progress and severity of a patient’s TD over time. It can be completed by any trained staff in a provider’s office and takes 5-10 minutes to complete. It should be completed and documented in the chart at regular intervals when an antipsychotic is being prescribed. Here is a link with instructions on how to conduct the assessment:
Until recently, while there have been treatments for other forms of EPS, medication treatment for TD did not exist. Sometimes reducing the dose of the antipsychotic medication or stopping the medication is helpful, but often the TD becomes chronic and lifelong. If the offending medication is discontinued, the TD resolves in 1/3 of patients and there is no real change in the remainder of patients. The conservative option is to discontinue the medication and change to a lower potency (in terms of dopamine blockade) antipsychotic medication or non-antipsychotic medication if appropriate. That is sometimes clinically not an option.
Recently, two medications have been approved by the FDA to treat TD – valbenazine and deutrabenazine. Both drugs are selective vesicular monoamine transporter 2 (VMAT2) inhibitors, which is a relatively new mechanism of action being utilized in psychiatry. Valbenazine (Ingrezza) is a highly selective vesicular monoamine transporter 2 inhibitor. It is dosed as 80mg once per day. Side effects include sleepiness and QT prolongation. It is therefore important to monitor an EKG on patients taking valbenazine. Deutrabenazine (Austedo) is another vesicular monoamine transporter 2 inhibitor. It is also used as a treatment for Huntington’s chorea. It is initially dosed at 6 mg bid and can be titrated at increments of 6mg/day up to 48 mg/day. Side effects include somnolence, dry mouth, and abdominal discomfort. There is a risk for QT prolongation as well. The idea behind these new medications is to allow patients to potentially continue on an antipsychotic medication at a dose that is helpful for their psychotic symptoms without having to change medication or reduce the dose to treat their side effects.
Take Home Messages:
- Avoid antipsychotic medications unless necessary.
- If you have to prescribe an antipsychotic, pick one with less risk for EPS if possible.
- If you have to prescribe an antipsychotic, use the lowest dose for the shortest length of time that is clinically possible.
- Regularly use the AIMS to monitor for TD when prescribing antipsychotic medications.
- Consider medication treatment for problematic and impairing TD if medication reduction is not an option.