Mirtazapine is mainly used as a second or third line antidepressant. However, it has many other beneficial uses, ranging from the treatment of anxiety and insomnia to improving symptoms of OCD and PTSD. Mirtazapine is a drug with a complex mechanism of action, but it shows promising results in a number of off-label uses.
Disclaimer: By writing this post, we are not recommending this drug. Some of our readers who were already taking the drug requested that we commission a post on it, and we are simply providing information that is available in the clinical and scientific literature. Please discuss your medications with your doctor.
What is Mirtazapine?
Mirtazapine has a number of interactions with other medications that you should be aware of [R]:
- H2 Antagonists (cimetidine, ranitidine, etc.) decrease the breakdown of mirtazapine resulting in increased levels of the drug in the body.
- Phenytoin and carbamazepine increase the breakdown of mirtazapine resulting in decreased levels of the drug in the body.
- Antibiotics (macrolides: erythromycin, clarithromycin, etc.) and antifungals (metronidazole) can also cause increased levels of mirtazapine in the body when taken together.
- Beta-blockers (metoprolol, propranolol, etc.), vasodilators (hydralazine, prazosin, doxazosin, etc.), centrally-acting antihypertensives (clonidine), ACEIs (lisinopril, captopril, etc.), calcium channel antagonists (nifedipine and verapamil), and thiazide diuretics (hydrochlorothiazide) taken with mirtazapine can increase the risk of postural hypotension (low blood pressure associated with a change in body position).
- Anticoagulants (warfarin) can have an increased effect when taken with mirtazapine.
- Antihistamines (chlorphenamine, hydroxyzine, promethazine, cetirizine, loratadine, etc.), phenothiazines (prochlorperazine), nabilone, and hyoscine can cause increased sedation when taken with mirtazapine.
- Hypnotics (temazepam and promethazine), benzodiazepines (diazepam, alprazolam, lorazepam, etc.), antipsychotics (chlorpromazine, haloperidol, clozapine, and olanzapine), opioids (oxycodone, hydrocodone, codeine, morphine, etc.), and buprenorphine can also cause increased sedation when taken with mirtazapine.
- Monoamine oxidase inhibitors (MAOIs: phenelzine and tranylcypromine), triptans (sumatriptan), lithium, fentanyl, tramadol, and St. John’s wort can increase your risk for serotonin syndrome if taken together with mirtazapine.
Forms and Dosage of Mirtazapine
Mirtazapine is available as tablets and orally disintegrating tablets (ODTs). It seems to be more sedating at lower doses and more activating at higher doses. In patients simply trying to treat insomnia, it is not unheard of to use 7.5 mg. The normal starting dosage is 15 to 30 mg and can be titrated up to a maximum dosage of 45 mg [R, R, R].