Mirtazapine 45mg Tablets
Overview
What is this medicine?
How to Use This Medicine
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. If this medication makes you sleepy, take it at bedtime. You can take it with or without food.
It's essential to continue taking this medication as directed by your doctor or healthcare provider, even if you start feeling well. Don't stop taking it without consulting your doctor first.
Storing and Disposing of Your Medication
To keep your medication effective and safe:
Store it at room temperature, away from light and moisture.
Keep it in a dry place, such as a closet or drawer.
Avoid storing it in a bathroom, where it may be exposed to heat and humidity.
Keep all medications in a safe and secure location, out of the reach of children and pets.
When you're finished with your medication or it expires, dispose of it properly. Don't flush it down the toilet or pour it down the drain unless you're instructed to do so. Instead, ask your pharmacist about the best way to dispose of it. You may also want to check if there are any drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's almost time for your next dose, skip the missed dose and go back to your regular schedule. Don't take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take Mirtazapine exactly as prescribed, usually once daily at bedtime due to its sedating effects.
- Avoid alcohol and other CNS depressants (e.g., sleeping pills, anxiety medications) as they can increase drowsiness and dizziness.
- Be cautious when driving or operating machinery until you know how this medication affects you, especially at the start of treatment.
- Do not stop taking Mirtazapine suddenly without talking to your doctor, as this can cause withdrawal symptoms.
- Monitor your weight and appetite, as this medication can cause weight gain.
- Report any unusual changes in mood or behavior, especially worsening depression or suicidal thoughts, to your doctor immediately.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Condition-Specific Dosing:
Pediatric Dosing
Dose Adjustments
Renal Impairment:
Hepatic Impairment:
Pharmacology
Mechanism of Action
Pharmacokinetics
Absorption:
Distribution:
Elimination:
Pharmacodynamics
Safety & Warnings
BLACK BOX WARNING
Side Effects
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Trouble focusing
+ Memory problems
+ Feeling confused
+ Weakness
+ Seizures
+ Changes in balance
Redness or irritation of the palms of hands or soles of feet
Flu-like symptoms
Mouth irritation or mouth sores
Restlessness
Fast or abnormal heartbeat
Severe dizziness or fainting
Joint pain
Serotonin Syndrome: A Potentially Life-Threatening Condition
There is a risk of developing serotonin syndrome, a severe and potentially deadly condition, especially when taking certain other medications. Seek medical help immediately if you experience:
Agitation
Changes in balance
Confusion
Hallucinations
Fever
Fast or abnormal heartbeat
Flushing
Muscle twitching or stiffness
Seizures
Shivering or shaking
Excessive sweating
Severe diarrhea, nausea, or vomiting
Severe headache
Severe Skin Reactions: Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)
This medication may cause severe skin reactions, which can be life-threatening. Seek medical help immediately if you notice:
Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in your mouth, throat, nose, eyes, genitals, or any areas of skin
Fever
Chills
Body aches
Shortness of breath
Swollen glands
Other Side Effects
Most people do not experience severe side effects, and some may only have minor side effects. However, if you notice any of the following side effects, contact your doctor or seek medical attention if they bother you or do not go away:
Feeling dizzy, sleepy, tired, or weak
Constipation
Dry mouth
Increased appetite
Weight gain
Strange or odd dreams
Reporting Side Effects
If you have questions about side effects or want to report any side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Worsening depression or suicidal thoughts
- New or worsening anxiety, panic attacks, agitation, restlessness, irritability, aggression, impulsivity, or insomnia
- Mania or hypomania (e.g., greatly increased energy, severe trouble sleeping, racing thoughts, reckless behavior, extreme happiness or irritability)
- Signs of serotonin syndrome: agitation, hallucinations, confusion, fast heartbeat, fever, sweating, shivering, muscle stiffness or twitching, loss of coordination, nausea, vomiting, diarrhea
- Signs of infection: fever, sore throat, mouth sores, flu-like symptoms (rare, but serious)
- Severe dizziness or fainting (orthostatic hypotension)
- Unexplained swelling in hands or feet (peripheral edema)
Before Using This Medicine
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction and its symptoms.
If you are currently taking or have recently taken certain medications, including:
+ Anxiety or sleep aids like alprazolam or diazepam
+ Depression or Parkinson's disease medications, such as isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, within the last 14 days, as this may increase the risk of very high blood pressure
+ Linezolid or methylene blue
* Note that this is not an exhaustive list of all potential interactions. Therefore, it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist to ensure safe use.
Remember, before starting, stopping, or changing the dose of any medication, including this one, you must consult with your doctor to verify that it is safe to do so in conjunction with your other medications and health conditions.
Precautions & Cautions
Do not abruptly stop taking this medication without consulting your doctor, as this may increase your risk of side effects. If you need to discontinue this drug, your doctor will likely instruct you to gradually taper off the dosage to minimize potential risks.
Until you are familiar with how this medication affects you, avoid operating a vehicle or engaging in activities that require alertness.
Certain individuals may be at a higher risk of developing eye problems while taking this drug. Your doctor may recommend an eye examination to assess your risk. Immediately contact your doctor if you experience eye pain, changes in vision, or swelling and redness in or around the eye.
This medication has been associated with rare cases of low white blood cell counts, which can increase the risk of infection. If you have a history of low white blood cell counts, inform your doctor. Be vigilant for signs of infection, such as fever, chills, or sore throat, and promptly contact your doctor if you experience any of these symptoms.
There have been reports of abnormal heart rhythms (long QT on ECG) and rare instances of sudden death in individuals taking this medication. Discuss these risks with your doctor.
Additionally, this drug may cause elevated cholesterol and triglyceride levels. Consult with your doctor about monitoring your blood work as directed.
Avoid consuming alcohol while taking this medication. Before using marijuana, cannabis products, or prescription or over-the-counter medications that may impair your reactions, consult with your doctor.
If you are 65 years or older, exercise caution when taking this medication, as you may be more susceptible to side effects. If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential benefits and risks to you and your baby with your doctor.
Overdose Information
Overdose Symptoms:
- Disorientation
- Drowsiness
- Impaired memory
- Tachycardia
- Sedation
- Agitation
- Hypotension
- Rarely, cardiac arrhythmias, severe hypotension, respiratory depression, or coma
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is generally supportive and symptomatic. There is no specific antidote.
Drug Interactions
Contraindicated Interactions
- Monoamine Oxidase Inhibitors (MAOIs) (concurrent use or within 14 days of discontinuing MAOI or mirtazapine)
- Linezolid (reversible MAOI)
- Methylene Blue (IV) (reversible MAOI)
Major Interactions
- Serotonergic drugs (e.g., SSRIs, SNRIs, triptans, fentanyl, lithium, tramadol, St. John's Wort) - increased risk of serotonin syndrome
- CNS depressants (e.g., alcohol, benzodiazepines, opioids, sedatives, hypnotics) - increased CNS depression
- Drugs that prolong QT interval (e.g., Class IA and III antiarrhythmics, some antipsychotics, macrolide antibiotics) - theoretical risk of QT prolongation
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, ritonavir) - increased mirtazapine levels
- Strong CYP3A4 inducers (e.g., carbamazepine, phenytoin, rifampin) - decreased mirtazapine levels
Moderate Interactions
- Warfarin (potential for increased INR, monitor closely)
- Cimetidine (may increase mirtazapine levels)
- Other drugs metabolized by CYP2D6 (mirtazapine is a weak inhibitor)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Rationale: Assess baseline severity of depression and risk of suicidality.
Timing: Prior to initiation and at each visit during early treatment.
Rationale: Mirtazapine can cause significant weight gain.
Timing: Prior to initiation.
Rationale: Mirtazapine can cause dyslipidemia.
Timing: Prior to initiation.
Rationale: Assess for orthostatic hypotension, though less common than with some other antidepressants.
Timing: Prior to initiation.
Rationale: Rare risk of agranulocytosis. Baseline is important for comparison if symptoms arise.
Timing: Prior to initiation (consider, especially if patient has history of blood dyscrasias).
Routine Monitoring
Frequency: Weekly for first 4 weeks, then every 2-4 weeks for first 3 months, then periodically as clinically indicated.
Target: Improvement in depressive symptoms, absence of suicidal thoughts/behaviors.
Action Threshold: Worsening depression, emergence of suicidal ideation/behavior, or unusual changes in behavior require immediate assessment and intervention.
Frequency: Monthly for first 3-6 months, then every 3-6 months.
Target: Maintain healthy weight.
Action Threshold: Significant or rapid weight gain (e.g., >5% body weight) may warrant intervention (diet, exercise, or medication change).
Frequency: At 3 months, then annually or as clinically indicated.
Target: Within normal limits.
Action Threshold: Significant elevations may require lifestyle modification or lipid-lowering agents.
Frequency: Periodically, especially if patient reports dizziness or orthostasis.
Target: Within normal limits.
Action Threshold: Symptomatic orthostatic hypotension.
Frequency: Only if patient develops signs/symptoms of infection (e.g., fever, sore throat, stomatitis) or other signs of bone marrow suppression.
Target: Normal WBC count.
Action Threshold: Significant decrease in WBC count, especially neutropenia (<1000/mm3), requires immediate discontinuation and further evaluation.
Symptom Monitoring
- Worsening depression
- Suicidal thoughts or behavior
- Unusual changes in behavior (e.g., agitation, irritability, anxiety, panic attacks, insomnia, impulsivity, aggression, mania/hypomania)
- Signs of serotonin syndrome (e.g., agitation, hallucinations, delirium, tachycardia, labile blood pressure, hyperthermia, hyperreflexia, incoordination, nausea, vomiting, diarrhea)
- Signs of agranulocytosis (e.g., fever, sore throat, stomatitis, other signs of infection)
- Dizziness or lightheadedness (orthostatic hypotension)
- Excessive sedation or somnolence
- Increased appetite or weight gain
- Dry mouth
- Constipation
- Peripheral edema
Special Patient Groups
Pregnancy
Category C. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. There are no adequate and well-controlled studies in pregnant women. Neonates exposed to antidepressants in late third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding.
Trimester-Specific Risks:
Lactation
L3 (Moderately Safe). Mirtazapine is excreted into breast milk in small amounts. Monitor breastfed infants for sedation, poor feeding, and poor weight gain. Weigh the benefits of breastfeeding against the potential risks to the infant.
Pediatric Use
Safety and efficacy not established for MDD in pediatric patients. Black Box Warning regarding increased risk of suicidal thoughts and behavior in children, adolescents, and young adults. Generally not recommended for routine use in this population for depression.
Geriatric Use
Lower starting doses (e.g., 7.5 mg/day) and slower titration are recommended due to increased sensitivity to adverse effects and potential for reduced clearance. Monitor closely for sedation, orthostatic hypotension, and hyponatremia. The risk of suicidality in adults aged 65 and older was reduced in short-term studies.
Clinical Information
Clinical Pearls
- Mirtazapine is often chosen for patients with depression who also experience significant insomnia, poor appetite, or weight loss due to its sedating and appetite-stimulating effects.
- The sedating effect is more pronounced at lower doses (e.g., 7.5 mg, 15 mg) due to saturation of H1 receptors. At higher doses (e.g., 30 mg, 45 mg), the noradrenergic effects become more prominent, which can counteract some of the sedation.
- It has a relatively low risk of sexual dysfunction compared to SSRIs/SNRIs.
- Withdrawal symptoms can occur if discontinued abruptly, including dizziness, abnormal dreams, agitation, and headache. Taper slowly over several weeks.
- Monitor for rare but serious adverse effects like agranulocytosis (fever, sore throat) and serotonin syndrome.
Alternative Therapies
- Selective Serotonin Reuptake Inhibitors (SSRIs) e.g., fluoxetine, sertraline, escitalopram
- Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) e.g., venlafaxine, duloxetine
- Tricyclic Antidepressants (TCAs) e.g., amitriptyline, nortriptyline
- Atypical Antidepressants e.g., bupropion, vortioxetine, vilazodone
- Monoamine Oxidase Inhibitors (MAOIs) e.g., phenelzine, tranylcypromine (reserved for refractory cases)
- Electroconvulsive Therapy (ECT)
- Transcranial Magnetic Stimulation (TMS)
- Psychotherapy (e.g., Cognitive Behavioral Therapy - CBT)