POM: Prescription only medicine
This information is intended for use by health professionals
AdultsThe effective daily dose is usually between 15 and 45 mg; the starting dose is 15 or 30 mg. Mirtazapine begins to exert its effect in general after 1-2 weeks of treatment. Treatment with an adequate dose should result in a positive response within 2-4 weeks. With an insufficient response, the dose can be increased up to the maximum dose. If there is no response within a further 2-4 weeks, then treatment should be stopped.
ElderlyThe recommended dose is the same as that for adults. In elderly patients an increase in dosing should be done under close supervision to elicit a satisfactory and safe response.
Children and adolescents under the age of 18 yearsMirtazapine should not be used in children and adolescents under the age of 18 years as efficacy was not demonstrated in two short-term clinical trials (see section 5.1) and because of safety concerns (see section 4.4, 4.8 and 5.1).
Renal impairmentThe clearance of mirtazapine may be decreased in patients with moderate to severe renal impairment (creatinine clearance < 40 ml/min). This should be taken into account when prescribing Mirtazapine to this category of patients (se section 4.4).
Hepatic impairmentThe clearance of mirtazapine may be decreased in patients with hepatic impairment. This should be taken into account when prescribing mirtazapine to this category of patients, particularly with severe hepatic impairment, as patients with severe hepatic impairment have not been investigated (see section 4.4).Mirtazapine has an elimination half-life of 20-40 hours and therefore Mirtazapine is suitable for once-daily administration. It should be taken preferably as a single night-time dose before going to bed. Mirtazapine may also be given in two divided doses (once in the morning and once at night-time, the higher dose should be taken at night).The tablets should be taken orally. The tablet will rapidly disintegrate and can be swallowed without water. Patients with depression should be treated for a sufficient period of at least 6 months to ensure that they are free from symptoms.It is recommended to discontinue treatment with mirtazapine gradually to avoid withdrawal symptoms (see section 4.4).
Use in children and adolescents under 18 years of ageMirtazapine Orodispersible Tablets should not be used in the treatment of children and adolescents under the age of 18 years. Suicide-related behaviours (suicide attempt and suicidal thoughts), and hostility (predominantly aggression, oppositional behaviour and anger) were more frequently observed in clinical trials among children and adolescents treated with antidepressants compared to those treated with placebo. If, based on clinical need, a decision to treat is nevertheless taken, the patient should be carefully monitored for the appearance of suicidal symptoms. In addition, long-term safety data in children and adolescents concerning growth, maturation and cognitive and behavioural development are lacking.
Suicide/suicidal thoughts or clinical worseningDepression is associated with an increased risk of suicidal thoughts, self harm and suicide (suicide-related events). This risk persists until significant remission occurs. As improvement may not occur during the first few weeks or more of treatment, patients should be closely monitored until such improvement occurs. It is general clinical experience that the risk of suicide may increase in the early stages of recovery.Patients with a history of suicide-related events, those exhibiting a significant degree of suicidal ideation prior to commencement of treatment, and young adults, are at a greater risk of suicidal thoughts or suicide attempts, and should receive careful monitoring during treatment. A meta-analysis of placebo-controlled clinical trials of antidepressants in adult patients with psychiatric disorders showed an increased risk of suicidal behaviour with antidepressants compared to placebo in patients less than 25 years old.Close supervision of patients and in particular those at high risk should accompany therapy with antidepressants especially in early treatment and following dose changes. Patients, (and caregivers of patients) should be alerted about the need to monitor for any clinical worsening, suicidal behaviour or thoughts and unusual changes in behaviour and to seek medical advice immediately if these symptoms present.With regard to the chance of suicide, in particular at the beginning of treatment, only a limited number of Mirtazapine orodispersible tablets should be given to the patient consistent with good patient management, in order to reduce the risk of overdose.
Bone marrow depressionBone marrow depression, usually presenting as granulocytopenia or agranulocytosis, has been reported during treatment with Mirtazapine orodispersible tablets. Reversible agranulocytosis has been reported as a rare occurrence in clinical studies with Mirtazapine orodispersible tablets. In the postmarketing period with Mirtazapine orodispersible tablets very rare cases of agranulocytosis have been reported, mostly reversible, but in some cases fatal. Fatal cases mostly concerned patients with an age above 65. The physician should be alert for symptoms like fever, sore throat, stomatitis or other signs of infection; when such symptoms occur, treatment should be stopped and blood counts taken.
JaundiceTreatment should be discontinued if jaundice occurs.
Conditions which need supervisionCareful dosing as well as regular and close monitoring is necessary in patients with: - epilepsy and organic brain syndrome: Although clinical experience indicates that epileptic seizures are rare during mirtazapine treatment, as with other antidepressants, mirtazapine should be introduced cautiously in patients who have a history of seizures. Treatment should be discontinued in any patient who develops seizures, or where there is an increase in seizure frequency. - hepatic impairment: Following a single 15 mg oral dose of mirtazapine, the clearance of mirtazapine was approximately 35 % decreased in mild to moderate hepatically impaired patients, compared to subjects with normal hepatic function. The average plasma concentration of mirtazapine was about 55 % increased.- renal impairment: Following a single 15 mg oral dose of mirtazapine, in patients with moderate (creatinine clearance < 40 ml/min) and severe (creatinine clearance ≤ 10 ml/min) renal impairment the clearance of mirtazapine was about 30 % and 50 % decreased respectively, compared to normal subjects. The average plasma concentration of mirtazapine was about 55 % and 115 %increased respectively. No significant differences were found in patients with mild renal impairment (creatinine clearance < 80 ml/min) as compared to the control group.- cardiac diseases like conduction disturbances, angina pectoris and recent myocardial infarct, where normal precautions should be taken and concomitant medicines carefully administered.- low blood pressure.- diabetes mellitus. In patients with diabetes, antidepressants may alter glycaemic control. Insulin and/or oral hypoglycaemic dosage may need to be adjusted and close monitoring is recommended. Like with other antidepressants, the following should be taken into account: - Worsening of psychotic symptoms can occur when antidepressants are administered to patients with schizophrenia or other psychotic disturbances; paranoid thoughts can be intensified. - When the depressive phase of bipolar disorder is being treated, it can transform into the manic phase. Patients with a history of mania/hypomania should be closely monitored. Mirtazapine should be discontinued in any patient entering a manic phase.- Although mirtazapine is not addictive, post-marketing experience shows that abrupt termination of treatment after long term administration may sometimes result in withdrawal symptoms. The majority of withdrawal reactions are mild and self-limiting. Among the various reported withdrawal symptoms, dizziness, agitation, anxiety, headache and nausea are the most frequently reported. Even though they have been reported as withdrawal symptoms, it should be realized that these symptoms may be related to the underlying disease. As advised in section 4.2, it is recommended to discontinue treatment with mirtazapine gradually.- Care should be taken in patients with micturition disturbances like prostate hypertrophy and in patients with acute narrow-angle glaucoma and increased intra-ocular pressure (although there is little chance of problems with Mirtazapine Orodispersible Tablets because of its very weak anticholinergic activity).- Akathisia/psychomotor restlessness: The use of antidepressants have been associated with the development of akathisia, characterised by a subjectively unpleasant or distressing restlessness and need to move often accompanied by an inability to sit or stand still. This is most likely to occur within the first few weeks of treatment. In patients who develop these symptoms, increasing the dose may be detrimental.- Cases of QT prolongation, Torsades de Pointes, ventricular tachycardia, and sudden death, have been reported during the post-marketing use of mirtazapine. The majority of reports occurred in association with overdose or in patients with other risk factors for QT prolongation, including concomitant use of QTc prolonging medicines (see section 4.5 and section 4.9). Caution should be exercised when mirtazapine is prescribed in patients with known cardiovascular disease or family history of QT prolongation , and in concomitant use with other medicinal products thought to prolong the QTc interval.
HyponatraemiaHyponatraemia, probably due to inappropriate antidiuretic hormone secretion (SIADH), has been reported very rarely with the use of mirtazapine. Caution should be exercised in patients at risk, such as elderly patients or patients concomitantly treated with medications known to cause hyponatraemia.
Serotonin syndromeInteraction with serotonergic active substances: serotonin syndrome may occur when selective serotonin reuptake inhibitors (SSRIs) are used concomitantly with other serotonergic active substances (see section 4.5). Symptoms of serotonin syndrome may be hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, mental status changes that include confusion, irritability and extreme agitation progressing to delirium and coma. Caution should be advised and closer clinical monitoring is required when these active substances are combined with mirtazapine. Treatment with mirtazapine should be discontinued if such events occur and supportive symptomatic treatment initiated. From post marketing experience it appears that serotonin syndrome occurs very rarely in patients treated with Mirtazapine Orodispersible Tablets alone (see section 4.8).
Elderly patientsElderly patients are often more sensitive, especially with regard to the undesirable effects of antidepressants. During clinical research with Mirtazapine Orodispersible Tablets, undesirable effects have not been reported more often in elderly patients than in other age groups.
AspartameMirtazapine Orodispersible Tablets contains aspartame, a source of phenylalanine. Each tablet with 15 mg, 30 mg and 45 mg mirtazapine corresponds to 2.6 mg, 5.2 mg and 7.8 mg phenylalanine, respectively. It may be harmful for patients with phenylketonuria.
Pharmacokinetic Interactions- Carbamazepine and phenytoin, CYP3A4 inducers, increased mirtazapine clearance about twofold, resulting in a decrease in average plasma mirtazapine concentration of 60 % and 45 %, respectively. When carbamazepine or any other inducer of hepatic metabolism (such as rifampicin) is added to mirtazapine therapy, the mirtazapine dose may have to be increased. If treatment with such medicinal product is discontinued, it may be necessary to reduce the mirtazapine dose.- Co-administration of the potent CYP3A4 inhibitor ketoconazole increased the peak plasma levels and the AUC of mirtazapine by approximately 40 % and 50 % respectively. - When cimetidine (weak inhibitor of CYP1A2, CYP2D6 and CYP3A4) is administered with mirtazapine, the mean plasma concentration of mirtazapine may increase more than 50 %. Caution should be exercised and the dose may have to be decreased when co-administering mirtazapine with potent CYP3A4 inhibitors, HIV protease inhibitors, azole antifungals, erythromycin, cimetidine or nefazodone.- Interaction studies did not indicate any relevant pharmacokinetic effects on concurrent treatment of mirtazapine with paroxetine, amitriptyline, risperidone or lithium.
Pharmacodynamic Interactions- Mirtazapine should not be administered concomitantly with MAO inhibitors or within two weeks after discontinuation of MAO inhibitor therapy. In the opposite way about two weeks should pass before patients treated with mirtazapine should be treated with MAO inhibitors (see section 4.3).- In addition as with SSRIs, co-administration with other serotonergic active substances (L-trytophan, triptans, tramadol, linezolid, methylene blue, SSRIs, venlafaxine, lithium and St, John's Wort-Hypericum perforatum-prearations) may lead to an incidence of serotonin associated effects (serotonin syndrome: see section 4.4). Caution should be advised and a closer clinical monitoring is required when these active substances are combined with mirtazapine.- Mirtazapine may increase the sedating properties of benzodiazepines and other sedatives (notably most antipsychotics, antihistamine H1 antagonists, opioids). Caution should be exercised when these medicinal products are prescribed together with mirtazapine.- Mirtazapine may increase the CNS depressant effect of alcohol. Patients should therefore be advised to avoid alcoholic beverages while taking mirtazapine.- Mirtazapine dosed at 30 mg once daily caused a small but statistically significant increase in the international normalised ratio (INR) in subjects treated with warfarin. As at a higher dose of mirtazapine a more pronounced effect can not be excluded, it is advisable to monitor the INR in case of concomitant treatment of warfarin with mirtazapine.- The risk of QT prolongation and/or ventricular arrhythmias (e.g. Torsade de Pointes) may be increased with concomitant use of medicines which prolong the QTc interval (e.g. some antipsychotics and antibiotics).
Paediatric populationInteraction studies have only been performed in adults.
PregnancyLimited data of the use of mirtazapine in pregnant women do not indicate an increased risk for congenital malformations. Studies in animals have not shown any teratogenic effects of clinical relevance, however developmental toxicity has been observed (see section 5.3). Caution should be exercised when prescribing to pregnant women. If mirtazapine is used until, or shortly before birth, postnatal monitoring of the newborn is recommended to account for possible discontinuation effects. Epidemiological data have suggested that the use of SSRIs in pregnancy, particularly in late pregnancy, may increase the risk of persistent pulmonary hypertension in the newborn (PPHN). Although no studies have investigated the association of PPHN to mirtazapine treatment, this potential risk cannot be ruled out taking into account the related mechanism of action (increase in serotonin concentrations).
Breast-feedingAnimal studies and limited human data have shown excretion of mirtazapine in breast milk only in very small amounts. A decision on whether to continue/discontinue breast-feeding or to continue/discontinue therapy with mirtazapine should be made taking into account the benefit of breastfeeding to the child and the benefit of mirtazapine therapy to the woman.
FertilityNon-clinical reproductive toxicity studies in animals did not show any effect on fertility.
|System organ class||Very common (☐ 1/10)||Common (☐ 1/100 to <1/10)||Uncommon (☐ 1/1,000 to <1/100)||Rare (☐ 1/10,000 to <1/1,000)||Frequency not known|
|Blood and the lymphatic system disorders||•Bone marrow depression (granulocytopenia, agranulocytosis, aplastic anemia thrombocytopenia) •Eosinophilia|
|Nervous system disorders||•Somnolence1,4 •Sedation1,4, •Headache2||•Lethargy1 •Dizziness •Tremor||•Paraesthesia2 •Restless legs •Syncope||•Myoclonus||•Convulsions (insults) •Serotonin syndrome •Oral paraesthesia •Dysarthria|
|Gastrointestinal disorders||•Dry mouth||•Nausea3 •Diarrhoea2 •Vomiting2||•Oral hypoaesthesia||•Pancreatitis||•Mouth oedema • Increased salivation|
|Skin and subcutaneous tissue disorders||•Exanthema2||•Stevens-Johnson Syndrome •Dermatitis bullous •Erythema mutliforme •Toxic epidermal necrolysis|
|Musculoskeletal and connective tissue disorders||•Arthralgia •Myalgia •Back pain1|
|Metabolism and nutrition disorders||•Weight increased1 •Increase in appetite1||•Hyponatraemia|
|Vascular disorders||•Orthostatic hypotension||•Hypotension2|
|General disorders and administration site conditions||•Oedema peripheral1 •Fatigue||• Somnambulism • Generalised oedema •Localised oedema|
|Hepatobiliary disorders||•Elevations in serum transaminase activities|
|Psychiatric disorders||•Abnormal dreams •Confusion •Anxiety2,5 Insomnia3,5||•Nightmares2 •Mania •Agitation2 •Hallucinations •Psychomotor restlessness (incl. akathisia, hyperkinesia)||•Aggression||•Suicidal ideation6 Suicidal behavious6|
|Endocrine disorders||Inappropriate antidiuretic hormone secretion|
Paediatric population:The following adverse events were observed commonly in clinical trials in children: weight gain, urticaria and hypertriglyceridaemia (see also section 5.1).
Reporting of suspected adverse reactionsReporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard.
Paediatric populationThe appropriate actions as described for adults should be taken in case of an overdose in paediatrics.
Mechanism of action/pharmacodynamic effectsMirtazapine is a centrally active presynaptic α2-antagonist, which increases central noradrenergic and serotonergic neurotransmission. The enhancement of serotonergic neurotransmission is specifically mediated via 5-HT1 receptors, because 5-HT2 and 5-HT3 receptors are blocked by mirtazapine. Both enantiomers of mirtazapine are presumed to contribute to the antidepressant activity, the S(+) enantiomer by blocking α2 and 5-HT2 receptors and the R(-) enantiomer by blocking 5-HT3 receptors.
Clinical efficacy and safetyThe histamine H1-antagonistic activity of mirtazapine is responsible for its sedative properties. Mirtazapine is generally well tolerated. It has practically no anticholinergic activity and, at therapeutic doses, has practically no effect on the cardiovascular system.
Paediatric population:Two randomised, double-blind, placebo-controlled trials in children aged between 7 and 18 years with major depressive disorder (n=259) using a flexible dose for the first 4 weeks (15-45mg mirtazapine) followed by a fixed dose (15, 30 or 45 mg mirtazapine) for another 4 weeks failed to demonstrate significant differences between mirtazapine and placebo on the primary and all secondary endpoints. Significant weight gain (≥7%) was observed in 48.8% of the mirtazapine treated subjects compared to 5.7% in the placebo arm. Urticaria (11.8% vs 6.8%) and hypertriglyceridaemia (2.9% vs 0%) were also commonly observed.
AbsorptionAfter oral administration of Mirtazapine orodispersible tablets, the active constituent mirtazapine is rapidly and well absorbed (bioavailability 50%), reaching peak plasma levels after about 2 hours.
DistributionBinding of mirtazapine to plasma proteins is approx. 85%. Food intake has no influence on the pharmacokinetics of mirtazapine.
BiotransformationMajor pathways of biotransformation are demethylation and oxidation, followed by conjugation. In vitro data from human liver microsomes indicate that cytochrome P450 enzymes CYP2D6 and CYP1A2 are involved in the formation of the 8-hydroxy metabolite of mirtazapine, whereas CYP3A4 is considered to be responsible for the formation of the N-demethyl and N-oxide metabolites. The demethyl metabolite is pharmacologically active and appears to have the same pharmacokinetic profile as the parent compound.
EliminationMirtazapine is extensively metabolised and eliminated via the urine and faeces within a few days. The mean half-life of elimination is 20-40 hours; longer half-lives, up to 65 hours, have occasionally been recorded and shorter half-lives have been seen in young men. The half-life of elimination is sufficient to justify once-a-day dosing. Steady state is reached after 3-4 days, after which there is no further accumulation.
Linearity/non-linearityMirtazapine displays linear pharmacokinetics within the recommended dose range.
Special populationsThe clearance of mirtazapine may be decreased as a result of renal or hepatic insufficiency.
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