Adverse Reactions to Psychotropic Medications

Introduction to Serotonin Syndrome and Neuroleptic Malignant Syndrome

• Serotonin Syndrome is caused by excessive serotonergic activity and is associated with serotonergic medications, including SSRIs, other antidepressants, antibiotics, opiate analgesics, antiemetics, anticonvulsants, antimigraine drugs, anti-Parkinsonism drugs, muscle relaxants, weight-reduction medications, over-the-counter medications, herbal supplements, and drugs of abuse, according to the American Academy of Pediatrics 1
• Neuroleptic Malignant Syndrome is caused by dopamine blockade or withdrawal of dopaminergic agents and is associated with antipsychotic medications and withdrawal of anti-Parkinsonism drugs, according to the American Academy of Pediatrics 1

Clinical Presentation

• The clinical triad of Serotonin Syndrome includes mental status changes, autonomic hyperactivity, and neuromuscular abnormalities, according to the American Academy of Pediatrics 1
• The key features of Neuroleptic Malignant Syndrome include hyperthermia, "lead-pipe" muscle rigidity, mental status alteration, and autonomic instability, according to the American Academy of Pediatrics 1
• Toxic appearance is characterized by a constellation of signs and symptoms that collectively indicate severe systemic illness, including fever or hypothermia, tachycardia, tachypnea, hypotension, altered mental status, and poor peripheral perfusion, which can be associated with conditions such as sepsis, severe pneumonia, and necrotizing soft tissue infections 2
• Toxidromes can present with distinct clinical features, such as:

Diagnostic Criteria

• The Delphi Panel Criteria for Neuroleptic Malignant Syndrome include exposure to dopamine antagonist or withdrawal of dopamine agonist, hyperthermia, rigidity, mental status alteration, creatine kinase elevation, sympathetic nervous system lability, hypermetabolism, and negative workup for other causes, according to the American Academy of Pediatrics 1
• The Hunter criteria are considered the diagnostic standard for SS, requiring a patient to have taken a serotonergic drug within the past 5 weeks and exhibiting specific symptoms, including:

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• The American Academy of Pediatrics recommends that key diagnostic features for NMS include:

Treatment and Management

• Discontinuation of the offending antipsychotic agent or serotonergic medication is the most critical first step in management of Neuroleptic Malignant Syndrome (NMS) and Serotonin Syndrome (SS) 1
• Supportive care, including IV fluid administration for dehydration, external cooling for hyperthermia, cardiac monitoring, and respiratory support if needed, should be provided after discontinuing the offending agent 1
• Dantrolene is recommended for severe rigidity and hyperthermia in NMS, and cyproheptadine is recommended for moderate to severe SS 1, 4
• Benzodiazepines are recommended for agitation control in both NMS and SS 1, 4
• Early administration of broad-spectrum antibiotics is crucial in suspected severe infections, and fluid resuscitation should be initiated for hypotension, with specific antidotes administered if a toxidrome is identified 2
• The American Heart Association recommends immediate assessment and stabilization of patients with toxic appearance, including applying the ABCDE approach, obtaining vital signs, and securing airway if compromised 3

Special Considerations

• Elderly patients may present atypically with blunted fever response or absence of tachycardia due to medications or comorbidities, and immunocompromised patients may have severe infections with minimal signs 2
• Patients with chronic illness may have altered baseline vital signs, and it is essential to consider these factors when assessing and managing toxic appearance 3
• The combination of multiple psychotropic agents, including antipsychotic medications like risperidone, increases the risk of NMS 1
• The use of serotonergic medications, such as MAOIs, increases the risk of SS, and combining MAOIs with other serotonergic medications should be avoided 1, 5

Prognosis and Outcomes

• Mortality from NMS has decreased significantly due to early recognition and prompt discontinuation of the offending agent, with current mortality rates of <10-15% 1
• The American Academy of Pediatrics and the National Institute of Mental Health report an approximately 11% mortality rate for untreated SS, with potential complications including rhabdomyolysis, renal failure, disseminated intravascular coagulation, seizures, and death 1, 5, 4, 6
• Dismissing subtle signs of toxicity in vulnerable populations, focusing only on one organ system, delaying antibiotics in suspected severe infections, missing necrotizing infections, and overlooking toxidromes can lead to poor outcomes and increased mortality 2