What is mirtazapine and when it should be used?
Mirtazapine is one of the drugs called tetracyclic antidepressants group. Generally, antidepressants are used in cases when it is required to relieve the signs and symptoms of depression (these usually include depressed mood, sleep disorders, feeling low, loss of appetite, and loss of interest in activities that you would normally enjoy in your usual life). When you start to suffer depression, certain chemical substances in the brain, which provide certain signals transduction and connection between different brain areas, are out of their normal balance.
Medicinal products called antidepressants, such as mirtazapine, work usually by helping to bring these chemicals back into their natural balance (these medicinal products increases the levels of serotonin and other neurotransmitters in the brain). In order to achieve beneficial effects of antidepressants it is usually required at least a few weeks after the start of treatment. Therefore it is important for you to have patience and to be compliant to the prescribed treatment, and take the prescribed medication exactly as your treating physician told you. Mirtazapine is a prescription only drug: you cannot buy it without medicinal prescription.
Also mirtazapine is commonly used in dogs and cats (although it is not officially approved for veterinary use in many countries). Anorexia and behavioral disorders in pets are a quite frequent cause for visits to veterinary. And it should be noted that the most common use of mirtazapine in pets is for stimulation of appetite. Behavioral problems in pets that are manifested by unacceptable or dangerous behavior commonly require such a unwanted measure as euthanasia.
How Mirtazapine Is Supplied?
Mirtazapine as a medicinal product is available in tablets of 15 mg, 30 mg, and 45 mg.
Dosing Information for Mirtazapine in Human
The recommended mirtazapine starting dose for adults is 15 mg. It is to be taken once daily in the evening (before you are going to bed). After 1 or 2 weeks after the start of treatment the physician may increase your dose up to 30 mg, depending on circumstances and achieved results of a therapy. The maximum mirtazapine recommended dose of is 45 mg per day – it is considered as a high dose therapy with mirtazapine. Many things can affect the dose of medication that a person needs, these factors include the following: body weight, other medical conditions and diseases, and other concurrent medications.
If your doctor has recommended a dose that is different from those listed here, do not make any change in the way that you are taking the medication without prior consulting with your doctor. In many cases it is normal to not see or feel any difference during a period of first 2 to 4 weeks of taking this medication. And if you notice any side effects resulting from this medication, you should talk to your doctor or a pharmacist before stopping taking this medication.
Dosing Information for Mirtazapine in Dogs and Cats
You should note that Mirtazapine is never to be administered without veterinarian prescription.
The dose of Mirtazapine for dogs is in the range from 3.75 to 30 mg per dog, depending on weight of the animal, and the dose should be given once daily.
- For dogs weighing less than 20 pounds the dose is 3.75 mg once daily
- For dogs weighing approximately 21 to 50 pounds the dose is 7.5 mg once daily
- For dogs weighing approximately 50 to 75 pounds the dose is 15 mg once daily
- For dogs weighing more than 75 pounds the dose is 30 mg once daily
In cats the medicinal product is given once every 72 hours. The dose from a range of 1.875 mg to 3.75 mg is the most frequently used (which is 1/8 to 1/4 of a 15 mg tablet) every 72 hours. For cats weighing under 15 pounds – 1/8 of a 15 mg tablet (1.875 mg) is used most commonly. Larger cats may be given 1/4 of a 15 mg tablet, which is 3.75 mg.
In order to prevent side effects and toxicity the lowest possible dose should be used – especially in cats.
The duration of medicinal product administration depends on the condition being treated, response to the medication and the development of any adverse effects.
Precautions and Side Effects in Human
Commonly reported side effects of mirtazapine include the following:
- Severe sedation (when you are very slow in reaction and feel sleepy),
- Constipation (when you have very rare stool),
- Increased serum cholesterol (increase of some lipids in your blood),
- Weight gain,
- Increased appetite,
- Xerostomia (when you feel dry in your mouth), and decreased appetite.
Other side effects include: dizziness, vertigo, increased serum triglycerides (increase of some lipids in your blood), abnormal dreams, tremor, dyspepsia (disturbance of normal digestion), hot flash (feeling hot and heavy of your face), palpitations (if you feel strong heartbeat), bitter taste, decreased libido, and diaphoresis. For a comprehensive list of adverse effects see special documentation for this medicinal product.
You should consult your doctor or pharmacist as soon as possible if you feel unwell while you are taking Mirtazapine. Mirtazapine may have unwanted side effects in a few people. All medicines can have side effects. Sometimes they are serious, but most of the time they are not. You may need medical attention if you get some of the side effects. Other side effects not listed above may also occur in some patients. Tell your doctor if you notice anything else that is making you feel unwell.
Precautions and Side Effects in animals
While this medicinal product is generally safe and effective when prescribed by a veterinarian, in some animals mirtazapine may cause side effects. This medicinal product should not be used in animals with established hypersensitivity or allergy to this drug. Also Mirtazapine may come into drug interactions with other medications. Veterinarian should always be consulted to determine if other medicinal products your pet is receiving could interact with mirtazapine. Such drugs include for example cimetidine, drugs classified as serotonin reuptake inhibitors or drugs classified as monoamine oxidase inhibitors. Mirtazapine has many side effects caused by actions on other body systems. It also acts as an antihistamine, blocks the parasympathetic nervous system and blocks other nervous system effects. Consequences of these effects in your pet include increased water consumption, dry mouth, sedation, rapid heart rate, and urine retention.
Mirtazapine in case of accidental ingestion in a large dose, can exert very serious effects on the heart. Pets that have accidentally consumed large amounts of this medicinal product (for example ingested several tablets) should promptly be taken to a veterinarian. Failure to provide quick medical attention in the instance of an overdose may have fatal consequences for the pet.