|
Mirtazipine is a newer antidepressant whose sedative effects
make it a good choice for people with depression who have difficulty
sleeping. Mirtazipine
has benefits in anxiety and depression and is one of few antidepressants
which has been beneficial in post-traumatic stress disorder. Although it is
generally as effective as other antidepressants, there is some preliminary
evidence that mirtazipine can help people who
haven’t responded to other drugs.
A unique property of mirtazipine is that lower doses produce more
side effects than higher ones. Its two main side effects, drowsiness
and weight gain, are both greater at 15mg than 30mg.
One risk which has limited its
use is its potential to lower platelets. Platelets help your blood to clot,
and when they fall too low there can be a serious risk of bleeding. Fortunately, the risk of this event with mirtazipine is very low (approximately 1 in 20,000).
It
does not change who you are, although it may allow you freedom to develop
in ways that depression had prevented.
Some people say that they feel more like their usual self, or are
better able to deal with stress, after taking it.
How does it work?
Mirtazipine
enhances serotonin transmission in the brain through an indirect mechanism
which is different from the selective serotonin reuptake inhibitors (SSRIs). It also enhances norepinephrine
function. Both of these neurotransmitters are involved in depression and anxiety.
What types are available and how is it taken?
Mirtazipine
is available in regular tablets and “Sol Tabs” that dissolve in
your mouth. It should be taken once a day, at night, with or without food.
Available doses are 15, 30 and 45mg tabs; there is also a generic form.
If you miss a dose, ask yourself
if you are closer to the dose you missed or to your next dose. If you are closer to your next dose, just
wait and take it then, otherwise it’s ok to take the dose you missed.
How long do I
need to take it?
There are two reasons to take mirtazipine: to treat
current symptoms and to prevent the return of symptoms. These two reasons will be different in
each condition, and in many cases the decision to continue or stop it will
be a personal one.
Can it cause
harm? Should children take it?
Mirtazipine may worsen certain psychiatric
conditions, such as bipolar disorders (“manic-depression”). If
you notice these signs while taking them, call me:
•
Feeling “high”, speeded up, giddy or “too happy”;
decreased need for sleep, paranoid feelings,
hyperactivity, racing thoughts, high anxiety or irritability, talking fast.
Other
problems with antidepressants, including with children, are described here. Other than bipolar reactions, these problems have
not been associated with mirtazipine, but it is
important to be aware of them. Mirtazipine has not been studied in children.
What side
effects can I expect?
The following
side effects are more common:
Drowsiness, increased appetite, weight gain, dry mouth, dizziness,
decreased sex drive or delayed orgasm.
The following side
effects are less common:
Stomach discomfort, back pain, dizziness
or fainting when getting up suddenly from a lying or sitting position (from
low blood pressure), increased need to urinate, increased sensitivity
to touch, increased thirst, low blood pressure, muscle
pain, nausea, feeling like you have to keep
moving, trembling or shaking, weakness.
The following
side effects are rare:
Seizures, agitation, intense mood swings, racing thoughts, insomnia, restless feelings like you can’t stop moving. Any unexpected bleeding should be taken
seriously (call me; we may need to check your platelet count) since this
can herald a serious side effect called thrombocytopenia (lowering of
blood-clotting platelets). This
occurs in approximately 1 in 20,000 people, and more rarely mirtazipine can lower other blood cells (white blood
cells that fight infection or red blood cells that deliver oxygen).
Serotonin
Syndrome: this rare condition
which probably does not occur with mirtazipine
(in fact, mirtazipine has been reported to treat
it) but is associated with other antidepressants that affect serotonin,
especially when they are taken together.
Symptoms include fever, muscle jerks, diarrhea, sweats, racing
heart, stomach pain, confusion and mood swings. If this occurs, stop the medication and
call me or go to your local emergency room.
An allergic
reaction is possible with any medication.
Symptoms include the following; stop the medication and call me if
these occur:
Pounding heartbeat; swelling of the face, throat, tongue, lips, eyes,
hands, feet, ankles, or lower legs; hoarseness; difficulty swallowing or
breathing; hives; rash.
Precautions
Mirtazipine
may make you drowsy. Do not drive a car or operate machinery until you know
how this drug affects you. Remember that alcohol and other medications can
add to the drowsiness caused by this drug.
Pregnancy and Breast-feeding:
It is not known whether mirtazipine passes
into breast milk. It has not been studied in pregnancy. Although no problems have been reported
with it, it is probably best to plan pregnancy and breast-feeding so as to
avoid any exposure to medication.
Older adults: Mirtazipine is removed from the body more slowly in
older adults but appears to pose no special risks here.
Medical conditions which require caution
with mirtazipine:
- Liver
or kidney disease
- Seizures,
heart disease, stroke
- Phenylketonuria (PKU): the SolTabs
may contain aspartame, a food-ingredient which needs to be avoided in
PKU.
Drug Interactions
Medicines that may increase mirtazipine
levels:
Haloperidol (Haldol)
Medicines
that should be avoided with mirtazipine:
MAOIs (phenelzine, Nardil, tranylcypromine, Parnate, isocarboxazid, Marplan, procarbazine, Matulane, selegiline, Eldepryl)
Note: this is not a complete list; speak with your
pharmacist or ask me if you have other questions about interactions.
Storage
- Keep
out of the reach of children.
- Store
away from heat and direct light.
- Do
not store in the bathroom, near the kitchen sink, or in other damp
places. Heat or moisture may cause the medicine to break down.
- Do
not keep outdated medicine or medicine no longer needed. Be sure that
any discarded medicine is out of the reach of children.
Updated 6/1/4
by Chris Aiken, M.D.
|