Generic

Mirtazapine

Indications

Mirez® is indicated for the treatment of major depression disorder, depression with anxiety, depression with insomnia.

Pharmacology

Pharmacodynamics: The mechanism of action of mirtazapine and other drugs that are effective in treating major depression is unclear. Evidence from preclinical studies shows that mirtazapine can enhance central noradrenergic and serotonergic activity. These studies indicate that mirtazapine may act as an antagonist of central presynaptic alpha 2 adrenergic inhibitory autoreceptors and heterologous receptors, and this effect is believed to lead to increased central noradrenergic and serotonergic activity. Mirtazapine is a potent 5HT2 and 5HT3 receptor antagonist. Mirtazapine does not have a significant affinity for the 5HT1A and 5HT1B receptors. Mirtazapine is a potent histamine (H1) receptor antagonist, which can explain its outstanding sedative effect. Mirtazapine is a moderately peripheral α1 adrenergic antagonist, and this property may explain the occasional orthostatic hypotension associated with its use. Mirtazapine is a moderate muscarinic receptor antagonist, which can explain the relatively low incidence of anticholinergic side effects associated with its use.

Pharmacokinetics: After oral administration of mirtazapine tablets, the active ingredient mirtazapine is absorbed rapidly and well, reaching the peak plasma level after about 2 hours. The binding rate of mirtazapine to plasma proteins is about 85%. The elimination half-life is 2040 hours; (26 hours for men and 37 hours for women). The elimination half-life is sufficient to justify administration once a day. Mirtazapine has linear pharmacokinetics within the recommended dose range. Mirtazapine is extensively metabolized and is excreted in urine and feces for four days. The main biotransformation pathways are demethylation and oxidation, followed by conjugation.

Dosage & Administration

Adult dose: The recommended starting dose for Mirtazapine tablets is 15 mg/day, administered in a single dose, preferably in the evening or prior to sleep. The effective dose range was generally 15 to 45 mg/day and the patients not responding to the initial 15 mg dose may benefit from dose increases up to a 30 mg to maximum of 45 mg/day. Mirtazapine has an elimination half-life of approximately 20 to 40 hours; therefore, dose changes should be made at intervals of less than 1 to 2 weeks in order to allow sufficient time for the therapeutic response to a given dose.

Use in children: Use in children are not recommended to Mirtazapine.

Missed Dose: If anyone misses a dose of mirtazapine, take it as soon as remember unless it is close to when the next dose is due. If anyone missed a dose of medication and it is close to the time of next dose, skip the missed dose and should take next dose at the regularly scheduled time. One should not take double or more than prescribed dose.

Interactions

Mirtazapine and monoamine oxidase inhibitors (MAOIs) and other serotonergic drugs (such as tryptophan, triptans, linezolid, serotonin reuptake inhibitors, venlafaxine, lithium, tramadol, or St. John’s Grass) has clinically significant drug interactions. Mirtazapine can disrupt the metabolism or activity of carbamazepine, phenytoin or cimetidine. Patients should avoid alcohol and diazepam while taking mirtazapine.

Contraindications

Allergy: Patients who are known to be allergic to mirtazapine or any of the excipients should not use mirtazapine.

Monoamine oxidase inhibitor: The simultaneous use of mirtazapine and monoamine oxidase (MAO) inhibitors is prohibited. Mirtazapine should not be used within 14 days of starting or stopping treatment with monoamine oxidase inhibitors (MAOIs).

Side Effects

The most common side effects of mirtazapine are dizziness, drowsiness, dry mouth, increased appetite, and weight gain.

Pregnancy & Lactation

Pregnancy category C. If the patient becomes pregnant or intends to become pregnant during treatment with mirtazapine, the patient should be advised to notify their doctor. If the patient is breastfeeding, the patient should be advised to notify their doctor.

Precautions & Warnings

Epilepsy, hepatic or renal impairment, cardiac disorders,hypotension, history of epilepsy, hepatic or renal impairment, cardiac disorders, hypotension, history of urinary retention, angle-closure glaucoma, diabetes mellitus, psychoses (may aggravate psychotic symptoms), history of bipolar depression, avoid abrupt withdrawal.

Therapeutic Class

Atypical anti-depressant drugs

Storage Conditions

Keep away from light and moisture. Store below 30º C. Keep all medicine out of the reach of children.

Pharmaceutical Name

Healthcare Pharmaceuticals Ltd.