What is paroxetine, and how does it work (mechanism of action)?
Paroxetine is an oral drug that is used for treating depression. It is in a
class of drugs called selective serotonin reuptake inhibitors (SSRIs), a class
that also contains fluoxetine (Prozac),
citalopram (Celexa), and sertraline
(Zoloft). Paroxetine affects neurotransmitters, the chemicals that nerves within
the brain use to communicate
with each other. Neurotransmitters are manufactured and released by nerves and
then travel and attach to nearby nerves. Thus, neurotransmitters can be thought
of as the communication system of the brain. Serotonin is one neurotransmitter that is released by nerves in the brain. The serotonin either travels across the
space that lies between nerves and attaches to receptors on the surface of
nearby nerves or it attaches to receptors on the surface of the nerve that
produced it, to be taken up by the nerve and released again (a process referred
to as re-uptake).
Many experts believe that an imbalance among
neurotransmitters is the cause of depression. Paroxetine works by preventing the
reuptake of one neurotransmitter, serotonin, by nerve cells after it has been
released. Since reuptake is an important mechanism for removing released
neurotransmitters and terminating their actions on adjacent nerves, the reduced
uptake caused by paroxetine increases free serotonin that stimulates nerve cells
in the brain. The FDA approved paroxetine in December 1992.
What brand names are available for paroxetine?
Paxil, Paxil CR, Pexeva
Is paroxetine available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for paroxetine?
Yes
What are the side effects of paroxetine?
Common side effects of paroxetine are:
- nausea,
- headaches,
- anxiety,
- insomnia,
- drowsiness,
- constipation,
- weakness,
- dry mouth,
- sweating,
- diarrhea and
- loss of appetite.
Other important side effects include:
- increased blood pressure
- seizures
- sexual dysfunction
Some patients may experience withdrawal reactions upon stopping paroxetine. Symptoms of withdrawal include:
The dose of paroxetine should be gradually
reduced when therapy is discontinued.
Antidepressants increased the risk of suicidal thinking
and behavior (suicidality) in short-term studies in children and adolescents
with depression and other psychiatric disorders. Anyone considering the use of paroxetine or any
other antidepressant in a child or adolescent must balance this risk with the
clinical need. Patients who are started on therapy should be closely observed
for clinical worsening, suicidality, or unusual changes in behavior.
What is the dosage for paroxetine?
The recommended dose
is 20-60 mg daily of immediate release tablets or 12.5-75 mg daily using
controlled release tablets. Paroxetine is given as a single daily dose, usually
in the morning. As with all anti-depressants, the full effect may not occur
until after a few weeks of therapy.
Doses for obsessive-compulsive disorders and panic disorders are often
higher than those for depression. Doses often are adjusted to find the optimal
dose.
Elderly patients, debilitated persons, and patients with certain kidney or
liver diseases may need lower doses because they metabolize and eliminate
paroxetine more slowly and, therefore, are prone to develop high blood levels
and toxicity.
Which drugs or supplements interact with paroxetine?
All SSRIs, including paroxetine, should not be taken with any of the monoamine oxidase inhibitor (MAOI) class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), selegiline (Eldepryl, Carbex), and procarbazine (Matulane) or other drugs that inhibit monoamine oxidase such as linezolid
(Zyvox) and intravenous methylene blue.
Such combinations may lead to confusion, high blood pressure, tremor, hyperactivity, coma, and death. (A period of 14 days without treatment should lapse when switching between paroxetine and MAOIs.) Similar reactions occur when paroxetine is combined with other drugs for example, tryptophan, St. John’s wort, meperidine
(Demerol), tramadol
(Ultram) that increase serotonin in the brain.
Paroxetine may increase the effect of the blood thinner,
warfarin (Coumadin), leading to excessive bleeding. Therefore, warfarin therapy should be
monitored more frequently in patients who are also taking paroxetine. Combining
SSRIs such as paroxetine with aspirin, nonsteroidal anti-inflammatory drugs or
other drugs that affect bleeding may increase the likelihood of upper
gastrointestinal
bleeding. Phenytoin (Dilantin) and phenobarbital may decrease the amount of
paroxetine in the body and possibly reduce its effectiveness.
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Is paroxetine safe to take if I’m pregnant or breastfeeding?
Use of paroxetine
during pregnancy may result in congenital heart defects. Paroxetine should not
be administered to pregnant women unless
the need justifies the risk.
Paroxetine
is secreted in breast milk. Mothers who are taking paroxetine should consider
not breastfeeding.
What else should I know about paroxetine?
What preparations of paroxetine are available?
Tablets: 10, 20, 30, and 40 mg; Paxil CR Tablets: 12.5,
25, and 37.5 mg; Suspension: 10 mg/5ml
How should I keep paroxetine stored?
Tablets should be kept at room temperature, 59 F – 86 F (15 C – 30 C). The suspension and controlled release tablets should be stored at or
below 77 F (25 C).