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

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

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

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]])
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