Neuronal Communication and Antidepressants

Neuronal Communication and Antidepressants

• Neurones communicate at synapses, where neurotransmitters like dopamine, serotonin, noradrenaline, and GABA are released.
• Neurotransmitters stimulate receptors on the post-synaptic membrane, creating a response.
• Reuptake returns neurotransmitters to the pre-synaptic axon terminal.

Antidepressant Mechanisms

• Selective serotonin reuptake inhibitors (SSRIs) block serotonin reuptake, increasing serotonin levels in synapses.
• Serotonin and norepinephrine reuptake inhibitors (SNRIs) block reuptake of both serotonin and noradrenaline.
• Tricyclic antidepressants (TCAs) block serotonin and noradrenaline reuptake, and also block other receptors like acetylcholine and histamine causing side effects.

Types of Antidepressants and Side Effects

• SSRIs: Sertraline, citalopram, escitalopram, fluoxetine, paroxetine
  • Sertraline: Helpful for anxiety, safer in heart disease, higher risk of diarrhea.
  • Citalopram: Can prolong QT interval, dose-dependent risk, less safe in heart patients.
  • Escitalopram: Similar to citalopram, less safe in heart patients.
  • Fluoxetine: Long half-life (4-7 days), first-line in children/adolescents.
  • Paroxetine: Potential weight gain, higher risk of discontinuation symptoms.
• SNRIs: Duloxetine, venlafaxine
  • Similar side effects to SSRIs.
  • Increased blood pressure, contraindicated in uncontrolled hypertension.
  • Venlafaxine: Potentially higher risk of death from overdose..
  • Duloxetine: Used for neuropathic pain, especially diabetic neuropathy.
• TCAs: Amitriptyline, nortriptyline
  • Commonly used in low doses for neuropathic pain.
  • High risk of death from overdose, Arrhythmias (tachycardia, prolonged QT interval).
  • Severe anticholinergic side effects (e.g., dry mouth, constipation, urinary retention).
• Mirtazapine:
  • Key side effects are sedation, increased appetite, weight gain.
  • Best taken at night; helpful for loss of appetite and poor sleep, used in older patients.
• Vortioxetine:
  • Third-line treatment,
  • Serotonin reuptake inhibitor and serotonin receptor modulator.
  • Helpful anti-anxiety effects, low risk of sexual dysfunction or discontinuation symptoms.
  • Nausea possible initially.

Starting and Managing Antidepressants

• Initial worsening of symptoms (agitation, anxiety, suicidal thoughts) is possible, especially in younger patients.
• Monitor patients closely within two weeks (one week for ages 18-25).
• Note response typically happens in 2-4 weeks.
• Dose adjustment or switching may be needed for inadequate response.
• Switching strategies dependent on the meds. Some medications can be directly switched, others require cross-tapering.
• Discontinuation should require slow reductions over at least four weeks.
• Long-term treatment (at least 6 months, 2 years for recurrent depression) is important.

Serotonin Syndrome

• Excessive serotonin activity, often from high doses or multiple antidepressants.
• Symptoms range from mild to severe and potentially life-threatening.
• Severe symptoms: Confusion, seizures, severe hyperthermia, respiratory failure.
• Management: Supportive care, medication withdrawal is critical.

Treatment Tips

• Consult with healthcare professionals for diagnosis and treatment.
• Check the guidelines for proper antidepressant swaps.
• Use the provided website for further knowledge.

This quiz explores the mechanisms of neuronal communication at synapses, focusing on neurotransmitters such as serotonin and their role in mental health. Additionally, it covers various types of antidepressants, including SSRIs, SNRIs, and TCAs, detailing their functions and potential side effects.