What Factors Affect a Sufficient Mirtazapine Dose?

Mirtazapine is a white crystalline solid with molecular formula C17H19N3, molecular weight 265.35300, density 1.22 g / cm3, melting point 114-116ºC, boiling point 432.448ºC at 760 mmHg, and flash point 215.337ºC.

Chinese name: Mirtazapine
Foreign name: mirtazapine

CAS number: 61337-67-5
Molecular formula: C17H19N3

Mirtazapine compounds

Mirtazapine Basic Information

Chinese name: azapine

English name: mirtazapine

English alias: Mirtazapine

CAS number: 61337-67-5

Molecular formula: C ₁₇ H ₁₉ N ₃

Molecular weight: 265.35300

Structural formula:

Exact mass: 265.15800

PSA: 19.37000

LogP: 2.48180 ^[1]

Physical and chemical properties of mirtazapine

Appearance and properties: white crystalline solid

Density: 1.22 g / cm3

Melting point: 114-116ºC

Boiling point: 432.448ºC at 760 mmHg

Flash point: 215.337ºC ^[1]

Storage conditions: Store at RT

Mirtazapine Computational Chemical Data

1. Hydrophobic parameter calculation reference value (XlogP): None

2.Number of hydrogen bond donors: 0

3.Number of hydrogen bond acceptors: 3

4.Number of rotatable chemical bonds: 0

5.Number of tautomers: none

6. Topological molecular polar surface area 19.4

7.Number of heavy atoms: 20

8.Surface charge: 0

9.Complexity: 345

10.Number of isotope atoms: 0

11. Determine the number of atomic stereocenters: 0

12. Uncertain number of atomic stereocenters: 1

13. Determine the number of chemical bond stereocenters: 0

14. Uncertain number of chemical bond stereocenters: 0

15. Number of covalent bond units: 1 ^[2]

Mirtazapine pharmacological action

Mirtazapine is a central presynaptic 2 receptor antagonist that enhances adrenergic nerve conduction. It interacts with central serotonin (5-HT2, 5-HT3) receptors to regulate the function of 5-HT. Both mirtazapine optical enantiomers have antidepressant activity, L-body blocks 2 and 5-HT2 receptors, and D-body blocks 5-HT3 receptors. Mirtazapine has a sedative effect, is well tolerated, has almost no anticholinergic effect, and its therapeutic dose has no effect on the cardiovascular system. ^[3]

Mirtazapine Pharmacokinetics

It is absorbed quickly after oral administration, and the bioavailability is about 50%. After about 2 hours, the plasma concentration reaches a peak, and the plasma protein binding rate is about 85%. The average half-life is 20 to 40 hours, occasionally as long as 65 hours, and shorter half-life is also occasionally seen in young people. The blood drug concentration reached a steady state 3 to 4 days after taking the drug, and no body aggregation phenomenon occurred after that. Its main metabolic mode is demethylation and oxidation reaction. Metabolites after demethylation still have pharmacological activity as the original compound. Mirtazapine is excreted through urine and feces within a few days after taking the drug. Poor liver and kidney function can cause reduced mirtazapine clearance. ^[3]

Mirtazapine indication

Used to treat various depressions. It is effective for symptoms such as lack of pleasure, psychomotor depression, poor sleep (early awakening), and weight loss. It can also be used for other symptoms such as loss of interest in things, suicidal ideation, and mood swings (good morning, poor evening). This medicine takes effect after 1-2 weeks of administration. ^[3]

Mirtazapine dosage forms and specifications

15mg / tablet; 30mg / tablet; 45mg / tablet.

Mirtazapine is a two-sided raised oval tablet with the word "Organon" on one side and a code on the other. 15 mg and 30 mg tablets are scored. This medicine is packed in a child-resistant, squeezed slat. Each board is formed by pressing opaque white polyethylene film and aluminum foil, and the side of the aluminum foil on the side of the tablet is insulated. If stored in a dry and dark place (2-30oC), the shelf life is 3 years. ^[3]

Mirtazapine contraindications

1. Disable allergy to mirtazapine.

2. Patients with schizophrenia and other psychiatric disorders will worsen their symptoms after taking it, and paranoia may be exacerbated and disabled.

3. Manic depression patients who are in depression may change to manic phase after use, and should be disabled.

4. A very small amount of drugs can be secreted from breast milk, which is contraindicated in lactating women.

5. Lack of clinical trial data, disabled women and children during pregnancy. ^[3]

Mirtazapine precautions

1. Patients with liver and kidney dysfunction need to pay attention to reducing the dose, and should stop taking the drug when jaundice occurs.

2. If the patient is found to have fever, sore throat or other infections after 4 to 6 weeks of continuous medication, the medication should be stopped immediately and a peripheral blood test should be performed.

3. Mirtazapine is not addictive, but sudden withdrawal after long-term use may cause nausea, headache and discomfort.

4. The dosage for elderly patients is the same as that for adults, but it should be gradually increased under the close observation of a doctor to achieve a satisfactory effect.

5. Mirtazapine may affect attention. Use mirtazapine should avoid engaging in activities that require better attention and mobility.

6. Patients continue to take the drug until the symptoms completely disappear 4 to 6 months before gradually stopping the drug; if the effect is not significant, the dose can be increased to the maximum dose. However, if the dose does not increase after 2 to 4 weeks, the drug should be stopped.

7. Suicide-prone patients should control the number of mirtazapine tablets in the early stage of treatment.

8. Use with caution in patients with hypotension and diabetes.

9. Patients with heart disease such as conduction block, angina pectoris and recent myocardial infarction should be used with caution.

10. Mirtazapine has a very weak anticholinergic effect, and should be used with caution in patients with enlarged prostate, acute narrow-angle glaucoma, and patients with increased intraocular pressure. ^[3]

Mirtazapine adverse reactions

1. Common side effects include increased appetite, weight gain, drowsiness, and sedation, which usually occur in the first few weeks after taking the drug (reducing the dose at this time does not reduce the side effects, but will affect its antidepressant effect).

2. Rare side effects include orthostatic hypotension, mania, seizures, tremors, muscle spasms, acute myelosuppression (erythrocytosis, agranulocytosis, aplastic anemia, and thrombocytopenia), increased serum transaminase levels, Drug rash and so on.

3. Drug overdose does not cause obvious cardiotoxicity and has the side effects of excessive sedation. ^[3]

Mirtazapine dosage

Oral administration, should not be chewed when swallowed, 15mg each time, once a day, and gradually increase the dose to obtain the best effect. The effective dose is usually 15 to 45 mg / d. It is recommended to take it before going to bed, but it can also be taken in divided doses (for example, once each morning and evening). Patients should take the drug continuously, preferably after 4-6 months of complete disappearance of the drug. When the dosage is appropriate, the drug should have a significant effect within 2-4. If the effect is not significant, the dose can be increased to the maximum dose. However, if the effect is not increased after 2-4 weeks, the drug should be stopped. ^[3]