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Mirtazapine is an antidepressant introduced by Organon International in 1996 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). It is the only tetracyclic antidepressant, other than Ludiomil, that has been approved by the Food and Drug Administration to treat depression. Because of its unique pharmacologic profile, mirtazapine is virtually devoid of anticholinergic effects, serotonin-related side effects, 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.
Additional recommended knowledge
Mirtazapine is marketed under the tradenames:
Mirtazapine is primarily used to treat the symptoms of mild to severe depression.
There is also evidence that mirtazapine can be used to treat panic disorder (PD), and pruritus. Mirtazapine has not been reported to be effective in the prophylactic treatment of chronic tension headache. This drug has also been shown to improve symptoms in Gastroparesis patients.generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), post traumatic stress disorder (PTSD) sleep apnea,
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. Mirtazapine is NOT recommended for elderly dogs with renal weakness.
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.
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 dosages, such as 7.5 mg, mirtazapine is primarily antihistaminergic, causing sedation, which can be beneficial in depressed patients who have difficulty falling asleep. At doses higher than 15 mg, its effect is primarily in inducing the release of norepinephrine, and is thus less sedating.
Side effects occurring commonly:
Side effects occurring rarely:
Dangerous side effects
If you experience any of these, tell your doctor immediately. You will need to consult your doctor for taper-off instructions. Sudden withdrawal from antidepressants can cause serious symptoms. However, sudden withdrawal can be used (under supervision of the appropriate medical services) when the risks of continuing the antidepressant during a 'taper-off' phase are too great.
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.
Pregnancy and Lactation
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.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Mirtazapine". A list of authors is available in Wikipedia.|