Paxil (Paroxetine) Antidepressant Drug Information

Paxil
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Paxil (paroxetine) is an antidepressant that belongs to the same family of drugs as Prozac (fluoxetine), Zoloft (sertraline), Luvox (fluvoxamine), and Celexa (citalopram). All of these are classified as selective serotonin reuptake inhibitors (SSRIs) and can be used to treat depression and a number of disorders related to anxiety, menstruation, or menopause.

Paxil was first approved by the U.S. Food an Drug Administration (FDA) in 1992. Since the patent expiry in 2002, the drug is now available as a low-cost generic. Common side effects include sleepiness and dizziness. Serious, potentially life-threatening interactions can sometimes occur if used certain contraindicated medications.

Despite its many benefits, Paxil poses an increased risk of suicidal thoughts and actions in children, teens, and young adults. As such, Paxil must be used with extreme caution in anyone 24 years or younger and only if no other treatment options are available.

How Paxil Works

Paxil is the most potent SSRI antidepressant. It treats depression by increasing levels of serotonin in the brain. Serotonin is a neurotransmitter associated with mood, cognition, appetite, and sexual desire (libido). SSRIs block the reabsorption (reuptake) of serotonin, making more available to the brain.

Indications

Paxil is approved for the treatment of the following conditions:

Before Paxil is prescribed, your doctor should screen you for bipolar disorder (BD), a common cause of depression. Treating BD with an antidepressant alone increases the risk of a manic or hypomanic episode.

Formulations

Paxil is available as an oral tablet in 10-mg, 20-mg, 30-mg, and 40-mg formulations. Paroxetine is also marketed under the brand name Parexa. A controlled-release formulation (Paxil-CR) comes in 12.5-mg, 25-mg, 37.5-mg doses.

A low-dose 7.5-mg formulation, used solely for the treatment of hot flashes, is marketed under the brand name Brisdelle.

Paxil can be taken with or without food. Alcohol should be avoided as this can intensify the drowsiness and dizziness common with Paxil use.

Recommended Dosage

The dosage of Paxil can vary by the condition being treated. Treatment typically begins with an initial dose to build up the concentration of paroxetine in the blood until the desired effect is achieved. Thereafter, the dose is maintained to ensure that the benefits are sustained over the long term.

The recommended dosages for adults are as follows:

  • MDD: Start with an initial dose of 20 mg per day, increasing in 10-mg increments until the desired effect is achieved. No more than 50 mg should be taken daily.
  • GAD: The recommended dose is 20 mg per day. Although the dose can be increased to up to 50 mg per day, there is no research to suggest that higher doses are more effective than 20 mg per day.
  • OCD: Start with an initial dose of 40 mg per day, increasing in 10-mg increments until the desired effect is achieved. No more than 60 mg should be taken daily.
  • PD: Start with an initial dose of 40 mg per day, increasing in 10-mg increments until the desired effect is achieved. No more than 60 mg should be taken daily.
  • PTSD: The recommended dose is 20 mg per day. Although the dose can be increased to up to 50 mg per day, there is no research to suggest that higher doses are more effective than 20 mg per day.
  • SAD: Start with an initial dose of 20 mg per day, increasing in 10-mg increments until the desired effect is achieved. No more than 60 mg should be taken daily.
  • PMDD: The recommended dose is 12.5 mg to 25 mg per day.
  • Menopausal hot flashes: The recommended dose is 7.5 mg per day.

Because Paxil is metabolized at a slower rate in elderly people, the lowest possible dose should be used to avoid potentially serious side effects.

Side Effects

Paxil shares many of the same side effects as other SSRI drugs. The most common (affecting more than 5 percent of users) include:

  • Nausea
  • Diarrhea
  • Constipation
  • Dry mouth
  • Sexual dysfunction
  • Sleepiness
  • Insomnia
  • Headaches
  • Dizziness
  • Weakness
  • Nervousness
  • Loss of appetite

When compared to other SSRIs, Paxil has a lower incidence of many of these side effects and is less likely to trigger the significant weight gain associated with other antidepressants.

Less commonly, tremors, blurred vision, profuse sweating, and tingling skin sensations (paresthesia) have been known to occur. Paxil can also sometimes "unmask" bipolar disorder by triggering a manic episode in people previously undiagnosed for the disorder.

Most Paxil side effects are mild and will resolve within a week or two. If a side effect is severe, worsens, or persists for more than two weeks, call your doctor.

Serious Side Effects

Paxil and other SSRIs pose a risk of a potentially life-threatening condition known as serotonin syndrome. Serotonin syndrome occurs most commonly when Paxil is used with drugs that either stimulate serotonin production (such as triptans used to treat migraines) or impair the metabolization of serotonin (such as MAOI antidepressants).

Serotonin syndrome can cause a cascade of psychiatric and physical symptoms, including agitation, rapid heart rate (tachycardia), excessive body temperature (hyperthermia), hyperactive reflexes (hyperreflexia), hallucinations, and coma.

Anaphylaxis, a potentially life-threatening, all-body allergy, is less commonly seen with Paxil than other antidepressants.

Black Box Warning

On May 2, 2007, the FDA issued a black box warning advising doctors and consumers about the increased risk of suicide in children, teens, and adults under 24 who take antidepressants, including Paxil.

Call your doctor or seek emergency care if you experience any of the following:

  • Suicidal thoughts or actions
  • Thoughts of dying
  • Aggressive or violent behaviors
  • New or worsening anxiety
  • New or worsening panic attack
  • Worsening depression
  • Manic behavior and inability to sleep
  • Talking faster and more frenetically than normal
  • Acting on dangerous impulses
  • Any unusual change in mood, thoughts, or behavior

The risk of suicidal thoughts or behaviors is further increased if you or anyone in your family has a history of bipolar disorder.

Contraindications

Paxil or any formulation of the drug, including generics, should not be used in persons with a known hypersensitivity to paroxetine.

Paxil should also not be used in combination with monoamine oxidase inhibitors (MAOIs) as doing so may trigger serotonin syndrome. These include such commonly prescribed MAOIs as:

  • Eldepryl (selegiline)
  • Marplan (isocarboxazid)
  • Nardil (phenelzine)
  • Parnate (tranylcypromine)
  • Zyvox (linezolid)

Moreover, if you stop taking Paxil, you should wait for at least 14 days before starting an MAOI to ensure the SSRI is fully cleared from your system. 

Other drugs contraindicated for use with Paxil include thioridazine (used to treat schizophrenia), and the antipsychotic drug Orap (pimozide).

Drug Interactions

There is a significant number of drugs that can interact with Paxil, either by increasing or decreasing the concentration of paroxetine in the blood or by intensifying the drug's psychoactive effects. In some cases, dosages can be adjusted to compensate for the interaction; in others, drug substitution may be needed.

Among the drugs known to interact with Paxil:

  • Alcohol
  • Anticoagulant drugs, such as Coumadin (warfarin)
  • Azedar (iIobenguane), an injectable dye used in radiology
  • Cerdelga (eliglustat), used to treat Gaucher's disease
  • Dapoxetine, used to treat premature ejaculation
  • Demerol (meperidine), used to treat addiction
  • Farydak (panobinostat), used to treat certain cancers
  • Lithium, used to treat bipolar disorder and severe depression
  • Metoclopramide, used to promote stomach emptying in people with diabetes
  • Nuedexta (dextromethorphan/quinidine) used to treat uncontrollable laughter or crying (pseudobulbar affect )
  • Soltamox (tamoxifen), used to treat breast cancer
  • St. John's Wort
  • Terfenadine, an antihistamine
  • Trazadone, a type of antidepressant
  • Ultram (tramadol), used to treat addiction
  • Vortioxeine, a type of antidepressant

Because many other drugs can interact with Paxil, advise your doctor about any medications you are taking, including over-the-counter supplements and herbal remedies.

Other Considerations

Paxil should be used with caution in people with pre-existing kidney or liver impairment. Renal function tests and liver function tests should be used to evaluate kidney and liver function prior to the start of therapy and monitored regularly thereafter.

Paxil is classified as a Category D drug in pregnancy, meaning that it has the potential to cause birth defects, mainly in the first trimester. While not contraindicated for use in pregnancy, Paxil should be used with caution in women of child-bearing age and in conjunction with a reliable form of birth control.

If you are pregnant or intend to get pregnant, speak with your doctor to fully weigh the benefits and risks of treatment relative to your condition. Breastfeeding should be avoided while on Paxil.

Never stop taking Paxil without speaking with your doctor. Doing so can lead to withdrawal symptoms, including anxiety, tremors, and vomiting. To avoid withdrawal, Paxil doses should be gradually tapered rather than stopped abruptly.

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