Pharmacology: Extrapyramidal Effects and Serotonin Syndrome

Extrapyramidal Effects

• Drug-induced movement disorders that include a range of symptoms
• Caused by blockade of dopamine receptors in the brain, particularly in areas involved in motor control
• Associated with antipsychotic medications, especially first-generation antipsychotics (e.g., haloperidol) and some second-generation antipsychotics (e.g., risperidone)
• Symptoms include:
  • Dystonia: Involuntary muscle contractions that cause repetitive or twisting movements
  • Akathisia: A state of restlessness and an urgent need to move
  • Parkinsonism: Symptoms similar to Parkinson's disease, such as tremors, bradykinesia, and rigidity
  • Tardive Dyskinesia: Involuntary, repetitive body movements, often involving the face and tongue

Serotonin Syndrome

• Potentially life-threatening condition caused by excessive serotonin activity in the central nervous system
• Caused by medications that increase serotonin levels, taken in combination or in high doses
• Common culprits include:
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Serotonin-norepinephrine reuptake inhibitors (SNRIs)
  • Monoamine oxidase inhibitors (MAOIs)
  • Certain pain medications, such as tramadol
  • Recreational drugs like MDMA (ecstasy)
• Symptoms range from mild to severe and include:
  • Cognitive effects: Agitation, confusion, hallucinations
  • Autonomic effects: Hyperthermia, hypertension, tachycardia, sweating
  • Neuromuscular effects: Tremor, clonus, hyperreflexia, muscle rigidity
• Severe cases can lead to seizures, high fever, irregular heartbeat, and unconsciousness

Key Differences

• Cause: Dopamine receptor blockade for extrapyramidal effects vs. excessive serotonin activity for serotonin syndrome
• Symptoms: Movement disorders for extrapyramidal effects vs. cognitive, autonomic, and neuromuscular symptoms for serotonin syndrome
• Medications: Antipsychotics for extrapyramidal effects vs. serotonergic agents for serotonin syndrome