Razapine

Razapine

Generic composition: Mirtazapine

 General Description

Mirtazapine is a tetracyclic piperazino-azepine antidepressant agent

Therapeutic category

  • Atypical Anti-depressant

 Dosage forms available

  • RAZAPINE 7.5mg Tablets
  • RAZAPINE 15mg Tablets
  • RAZAPINE 30mg Tablets

Mechanism of action

Mirtazapine enhances central noradrenergic and serotonergic activity. Mirtazapine acts as an antagonist at

central presynaptic α 2 adrenergic autoreceptors and heteroreceptors, an action that is postulated to increase in

central noradrenergic and serotonergic activity.

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.  Mirtazapine is a potent antagonist of histamine (H1) receptors, a property that may explain its prominent sedative effects.

Mirtazapine is a moderate peripheral α1 adrenergic antagonist, a property that may explain the occasional orthostatic hypotension reported in association with its use. Mirtazapine is a moderate antagonist at muscarinic receptors, a property that may explain the relatively low incidence of anticholinergic side effects associated with its use.

 Pharmacokinetics

Absorption: absorption is rapid and complete, bioavailability is 50% due to first pass metabolism, peak concentration reaches after 2 hours of administration, and food has little effect on drug absorption, about 85% protein bound.

Distribution: volume of distribution after an oral steady-state dose was measured to be 107 ± 42L

Metabolism: extensively metabolized in liver by demthylation and hydroxylation, glucuronide conjugation.

Elimination: excreted by kidney; 75% eliminated in the urine and 15% eliminated in the feces.

Half-life: 20-40 hours

Uses

  • Major depressive disorder
  • Mood disorder
  • Anxiety disorder

Dose

  • 15 mg/day, administered in a single dose, preferably in the evening prior to sleep.
  • Initial 15-mg dose may benefit from dose increases up to a maximum of 45 mg/day.
  • The effective dose range was generally 15 to 45 mg/day.

Side effect

Increase in appetite and weight, nausea, drowsiness and sedation are common. Orthostatic hypotension, dry

mouth, constipation, nightmares, confusion, myalgia, anthralgia, tremor, edema.

Contraindications

  • Use with MAO Inhibitors
  • Hypersensivity to Mitrazapine

 Precaution

  • Gradual withdrawal
  • Hyponatremia

Drug interaction

  • MAO Inhibitors, serotonergic drugs
  • Cimetidine
  • Clonidine
  • Alcohol

Pregnancy Category: C

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  • Phone: +977-01 5904868

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  • Phone: +977-01 6612742 / 6612716

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