Mirtazapine (Remeron, Avanza, Axit, Mirtaz, Mirtazon, Zispin)

Indications

  • Anorexia/Weight Loss (see Anorexia, [[Anorexia]]): mirtazapine has appetite-stimulant properties
  • Antipsychotic-Induced Akathisia: investigational use
  • Anxiety/Panic Disorder (see Anxiety, [[Anxiety]]): mirtazapine has anxiolytic properties
  • Depression (see Depression, [[Depression]]): tetracyclic antidepressant
  • Drug Addiction: investigational use
    = Headache/Migraine (see Migraine, [[Migraines]])
  • Insomnia
  • Nausea/Vomiting (see Nausea and Vomiting, [[Nausea and Vomiting]]): mirtazapine has anti-emetic properties
  • Obsessive-Compulsive Disorder (OCD)
  • Obstructive Sleep Apnea (OSA): investigational use
  • Parkinson’s Disease Psychosis: investigational use
  • Post-Traumatic Stress Disorder (PTSD)
  • Pruritus
  • Social Anxiety Disorder

Pharmacology

  • Selective Antagonism at α2-Adrenergic Receptor (see α-Adrenergic Receptor Antagonists, [[α-Adrenergic Receptor Antagonists]])
    • Increases Norepinephrine Release
    • Increased Serotonin Release -> acts as a functional “indirect agonist” at the 5-HT1A receptor
      • Increased 5-HT1A receptor activation is believed to be major mediator of mirtazapine and most antidepressant drugs
      • However, mirtazapine does not have any significant affinity for the serotonin, norepinephrine, or dopamine transporters -> lacks any significant effects as a reuptake inhibitor of these neurotransmitters
      • Also, mirtazapine does not have any significant inhibitory effects on monoamine oxidase (MAO)
  • Antagonism at 5-HT2 Serotonin Subfamily Receptors and Inverse Agonism at 5-HT2C Serotonin Receptor: likely responsible for at least part of mirtazapine’s antidepressant effect
  • Antagonism at 5-HT3 Serotonin Receptor (see Serotonin 5-HT3 Receptor Antagonists, [[Serotonin 5-HT3 Receptor Antagonists]])
    • Responsible for anti-emetic effects (and for its use in nausea/vomiting, diarrhea, and irritable bowel syndrome)
    • Effective in the treatment of drug addiction
  • Very Potent Inverse Agonism at H1 Receptor: results in sedative effects
  • Anti-Nociceptive Properties: similar to other antidepressants

Administration

  • PO: xxx

Adverse Effects

Gastrointestinal Adverse Effects

  • Constipation: present in 13% of cases = very common
  • Dry Mouth: present in 25% of cases = very common
  • Increased Appetite: present in 17% of cases = very common
  • Increased ALT: present in 2% of cases = common
  • Weight Gain (at least 7% weight gain): present in 49% of pediatric cases = very common

Neurologic Adverse Effects

  • Asthenia: present in 8% of cases = common
  • Disturbance in Thinking: present in 3% of cases = common
  • Dizziness: present in 7% of cases = common
  • Headache: uncommon
  • Somnolence: present in 54% of cases = very common

Other Adverse Effects

  • Blood Dyscrasias (agranulocytosis, anaemia, aplastic anaemia, eosinophilia, granulocytopenia, neutropenia, pancytopenia, thrombocytopenia): rare
  • Bullous Dermatitis: rare
  • Hypertroglyceridemia (>500 mg/dL): present in 6% of cases = common
  • Lower Extremity Edema (see Lower Extremity Edema, [[Lower Extremity Edema]]): common
  • Serotonin Syndrome (see Serotonin Syndrome, [[Serotonin Syndrome]])
  • xxx

References

  • xxx