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Venlafaxine is among the new generation of antidepressants whose
tolerable side effects have allowed many people to be treated for
depression. In addition to
depression, venlafazine also treats anxiety and
has been approved for use in generalized anxiety disorder and social
anxiety disorder.
Venlafaxine is unique in that it works differently depending on
the dose. In the lower doses, it
acts similar to a serotonin
reuptake inhibitor (SSRI). At higher doses, it effects norepinephrine as well, making it similar to the older
antidepressants – tricyclics – but
without as many side effects as those.
There is some evidence that venlafaxine
may work well for people who did not respond to other antidepressants, and
its unique effects on serotonin and norepinephrine
may be why.
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?
Venlafaxine
enhances serotonin transmission in the brain and, at higher doses (above
150mg/day), it enhances norepinephrine
transmission as well. Both of these neurotransmitters are involved in
depression and anxiety.
What types are available and how is it taken?
Venlafaxine
is available in regular release capsules taken three times a day and an
extended-release (XR) form which can be taken once or twice a day. It can
be taken morning or night, with or without food. Available doses are 37.5,
75 and 150mg; there is no generic. The XR capsule is coated so that the
medicine will absorb slowly from your stomach. This capsule should not be
crushed or chewed, as that can break the extended-release coating.
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 venlafaxine: 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.
What happens
if I stop it?
Venlafaxine
needs to be
stopped gradually to prevent withdrawal symptoms. These are flu-like symptoms that are
unpleasant but not dangerous; examples
include:
•
Dizziness, nausea, lethargy, sensory changes (numbness, tingling,
shock-like feelings), blurred vision, headache, vivid dreams, anxiety.
You
cannot become addicted to venlafaxine. In other words, if you stop the medicine,
you will not crave it or be more likely to have depression or anxiety than
before. In fact, treatment, either
with psychotherapy or medication, allows the brain to reorganize itself in
ways that help prevent future symptoms.
Can it cause
harm? Should children take it?
Venlafaxine 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.
There is currently controversy about whether children
and teenagers should take venlafaxine due to
concern about suicide on it. Click here to learn more about these concerns.
What side
effects can I expect?
The following
side effects are usually mild and often improve over time:
Nausea, vomiting, constipation, diarrhea, stomach distress, dry mouth,
dizziness, headache, palpitations, tingling or numbness, sweating,
drowsiness, vivid dreams, anxiety, yawning.
The following side
effects may persist and can be treated or will go away if the medicine is
stopped:
Decreased sex drive, delayed orgasm, tiredness or low motivation.
Skin sensitivity to sunlight, difficulty urinating,
blurred vision, excessive sweating
At higher doses (e.g. 300mg/day),
venlafaxine can raise blood pressure in a small
number of people (2-5%).
The following
side effects indicate that the medicine may need to be stopped; call me if
they occur:
Agitation, intense mood swings, racing thoughts, insomnia, restless
feelings like you can’t stop moving.
Serotonin
Syndrome: this condition is very
rare with venlafaxine but can be more common if
it is taken with other antidepressants or with lithium, tryptophan,
buspar, or St. John’s Wort. It is caused by too much serotonin in the
brain. 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
Venlafaxine
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:
Venlafaxine 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: Venlafaxine appears to pose no special risks to older
adults.
Medical conditions which require caution
with venlafaxine:
- Liver
or kidney disease
- Urinary
retention, glaucoma, high blood pressure
Drug Interactions
Venlafaxine may
increase levels of:
Haloperidol (Haldol)
Medicines
that should be avoided with venlafaxine:
MAOIs (phenelzine, Nardil, tranylcypromine, Parnate, isocarboxazid, Marplan, procarbazine, Matulane, selegiline, Eldepryl)
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.
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