Mirtazapine

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Mirtazapine
Systematic (IUPAC) name
2-methyl-1,2,3,4,10,14b- hexahydrobenzo[c]pyrazino[1,2-a] pyrido[3,2-f]azepine
Identifiers
CAS number 61337-67-5
ATC code N06AX11
PubChem 4205
Chemical data
Formula C17H19N3 
Mol. mass 265.36
Pharmacokinetic data
Bioavailability 50%
Metabolism Liver
Half life 37 hours (females), 26 hours (males)
Excretion 75% urine 15% feces
Therapeutic considerations
Pregnancy cat.

C
Legal status

Prescription only
Routes Oral tablet, Soluble tablet

Mirtazapine is an antidepressant introduced by Organon International in 1994 used for the treatment of moderate to severe depression. Mirtazapine has a tetracyclic chemical structure and is classified as a noradrenergic and specific serotonergic antidepressant (NaSSA). Mirtazapine and Ludiomil are the only tetracyclic antidepressants that have been approved by the U.S. Food and Drug Administration to treat depression. Because of its unique pharmacologic profile, mirtazapine is virtually devoid of anticholinergic effects, serotonin-related side effects,[1] and adrenergic side effects (orthostatic hypotension and sexual dysfunction). Antihistaminic side effects of drowsiness and weight gain are prominent. It is most useful as an add-on medication to enhance the effectiveness of agents such as duloxetine and venlafaxine in severe and treatment-resistant depression. Mirtazapine is relatively safe if an overdose is taken.[2]

Contents

[edit] Trade names

Mirtazapine is marketed under the tradenames:

[edit] Indications

[edit] Approved use

Mirtazapine is primarily used to treat the symptoms of moderate to severe depression.[3]

[edit] Unapproved and off-label use

There is evidence that mirtazapine can be used to treat panic disorder (PD),[4] generalized anxiety disorder (GAD),[5] obsessive-compulsive disorder (OCD),[6] post traumatic stress disorder (PTSD)[7] sleep apnea,[8] and pruritus.[9] Mirtazapine has been reported to be effective in the prophylactic treatment of chronic tension headache.[10] This drug has also been shown to improve symptoms in Gastroparesis patients.

[edit] Veterinary use

Anecdotal evidence also suggests that mirtazapine may be effective in treating certain vomiting or anorexia-related conditions in dogs and cats. Any such use is still off-label, however.[11]

[edit] Mechanism of action

It is thought to work by blocking presynaptic alpha-2 adrenergic receptors that normally inhibit the release of the neurotransmitters norepinephrine (noradrenaline) and serotonin, thereby increasing active levels in the synapse. Mirtazapine is a potent antagonist of 5-HT2 and 5-HT3 receptors. Mirtazapine has no significant affinity for the 5-HT1A and 5-HT1B receptors.

[edit] Side effects

Interestingly, its side-effect profile can be used for benefit in certain clinical situations. The drowsiness, increased appetite, and weight gain that it causes are useful in patients with depressive disorders with prominent sleep and appetite disturbances. In addition, it is quite useful in patient situations in which patients suffer from nausea, since it also antagonizes the 5-HT3 receptor, the target of the popular anti-emetic ondansetron (Zofran).

At lower doses, mirtazapine is primarily antihistaminergic, causing sedation, which can be beneficial in depressed patients who have difficulty falling asleep. Higher doses are generally less sedating as its antihistaminergic properties are thought to be offset by increased noradrenaline release.[12]

[edit] Side effects occurring commonly:

[edit] Side effects occurring rarely:

[edit] Dangerous side effects

Any of these side effects requires urgent medical attention. Medical advice is also required for taper-off instructions: sudden withdrawal from antidepressants can cause serious symptoms. However, sudden withdrawal can be used, under appropriate medical supervision, when the risks of continuing the antidepressant during a 'taper-off' phase are too great.

  • An allergic reaction; signs of swelling of the lips, face and tongue, difficulty in breathing, rash or itching (especially affecting the whole body) or feeling faint
  • Signs of infection such as fever, sore throat, mouth ulcers or stomach upset
  • Jaundice (yellowing of the skin and/or eyes)
  • Agranulocytosis

[edit] Dosage

The usual starting dose for mirtazapine is 15 mg once daily, usually at bedtime (because of its sedative nature and the possibility of disturbed visual perception). Doses may be increased, following medical advice, every 1-2 weeks up to a dose of 45 mg. It may be taken with or without food. Dispersible tablets (SolTab orally disintegrating tablets) can even be taken without water.

[edit] Pregnancy and lactation

  • Pregnancy : Sufficient data in humans is lacking. The use should be justified by the severity of the condition to be treated.
  • Lactation : Sufficient data in humans is also lacking. Additionally, Mirtazapine may be found in the maternal milk in significant concentrations. The use in breastfeeding women should be carefully weighed against possible risks.

[edit] Interactions with other drugs

Because of the sedative effects of Mirtazapine, excessive sedation may result when it is used with other sedating substances, such as alcohol or benzodiazepines.

According to official prescribing information from Organon, Mirtazapine should not be used within 14 days of the use of an MAOI because of the risk of serious effects such as hypertensive emergency and hyperthermia.

[edit] References

  1. ^  Gillman, PK (2006). "A systematic review of the serotonergic effects of mirtazapine: implications for its dual action status". Human Psychopharmacology Clinical and Experimental 21 (2): 117-25. PMID 16342227. 
  2. ^  Burrows GD, Kremer CM. (1997). "Mirtazapine: clinical advantages in the treatment of depression.". Journal of Clinical Psychopharmacology 17 (2S): 34S-39S. PMID 9090576. 
  3. ^  Velazquez C, Carlson A, Stokes KA, Leikin JB. (2001). "Relative safety of mirtazapine overdose.". Veterinary and Human Toxicology 43 (6): 342-344. PMID 11757992. 
  4. ^  Gorman JM (1999). "Mirtazapine: clinical overview.". Journal of Clinical Psychiatry 60 (17): 9-13. PMID 10446735. 
  5. ^  Baldwin DS, Anderson IM, Nutt DJ, Bandelow B, Bond A, Davidson JR, den Boer JA, Fineberg NA, Knapp M, Scott J, Wittchen HU (2005). "Evidence-based guidelines for the pharmacological treatment of anxiety disorders: recommendations from the British Association for Psychopharmacology.". Journal of Psychopharmacology 19 (6): 567-596. PMID 16272179. 
  6. ^  Goodnick PJ, Puig A, DeVane CL, Freund BV (1999). "Mirtazapine in major depression with comorbid generalized anxiety disorder". Journal of Clinical Psychiatry 60 (7): 446-448. PMID 10453798. 
  7. ^  Koran LM, Gamel NN, Choung HW, Smith EH, Aboujaoude EN (2005). "Mirtazapine for obsessive-compulsive disorder: an open trial followed by double-blind discontinuation". Journal of Clinical Psychiatry 66 (4): 515-520. PMID 15816795. 
  8. ^ First Effective Drug For Sleep Disorder Identified. Science Daily (2003-06-05). Retrieved on 2008-05-01.
  9. ^  Baldwin DS, Anderson IM, Nutt DJ, Bandelow B, Bond A, Davidson JR, den Boer JA, Fineberg NA, Knapp M, Scott J, Wittchen HU (2005). "Evidence-based guidelines for the pharmacological treatment of anxiety disorders: recommendations from the British Association for Psychopharmacology.". Journal of Psychopharmacology 19 (6): 567-596. PMID 16272179. 
  10. ^  Davis MP, Frandsen JL, Walsh D, Andresen S, Taylor S. (2003). "Mirtazapine for pruritus.". Journal of pain and symptom management 25 (3): 288-291. PMID 12614964. 
  11. ^  Bendtsen L, Jensen R (2004). "Mirtazapine is effective in the prophylactic treatment of chronic tension-type headache.". Neurology 62 (10): 1706-1711. PMID 15159466. 
  12. ^  Brooks DVM, DipABVP, Wendy C. (2007-04-30). Mirtazapine (Remeron). The Pet Pharmacy. Retrieved on 2008-03-06.
  13. ^  Nash J, Nutt D (2004). "Antidepressants.". Psychiatry 6 (7): 289-294. 

[edit] External links

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Psychoanaleptics: antidepressants (N06A)
MAOIs
RIs
SSREs
AAs
Tetras (Mianserin, Mirtazapine)