Paxil (paroxetine hydrochloride)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Approval Status:

Approved May 1996

Specific Treatments:

panic disorder, obsessive-compulsive disorders

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General Information

Paxil has been approved for the treatment of panic disorder, a disabling condition that will affect three to six million Americans at some time in their lives. Paxil belongs to a class of antidepressants known as selective serotonin reuptake inhibitors (SSRIs).

For many years, the only drug indicated for panic disorder was the benzodiazepine tranquilizer alprazolam. However, alprazolam is associated with dependence and is not indicated for long-term treatment of this chronic condition. Paxil has not been associated with the development of dependence in clinical trials and is indicated for long-term treatment of panic disorder.

In addition, alprazolam is not indicated for major depression, and as many as 65% of patients with panic disorder may also suffer from depression. Paxil is indicated for the treatment of depression as well as panic disorder.

For the treatment of panic disorder, the recommended target dose of Paxil is 40 mg per day. The starting dose is 10 mg per day, and dosage should not exceed 60 mg per day. Paxil is available in 10, 20, 30, and 40 mg tablets.

Paxil has also been approved as treatment for obsessive-compulsive disorder. Obsessions are recurrent and persistent thoughts that are intrusive and inappropriate, as well as distressing or anxiety-provoking. Compulsions are repetitive behaviors such as hand-washing or mental acts such as repeating words silently, and are aimed at reducing the distress or preventing some dreaded event.

The recommended dosage of Paxil in the treatment of obsessive-compulsive disorder is 40 mg daily. The starting dose is 20 mg per day, and dosage should not exceed 60 mg per day.

Clinical Results

In one 10-week double-blind clinical study, 76% of subjects treated with 40 mg per day of Paxil were completely free of full panic attacks at the end point, compared with 44% of subjects who received placebo. Patients who responded to Paxil during the initial 10-week phase and a three-month double-blind extension phase were randomly assigned to continue on Paxil or be switched to placebo for an additional three months. Of the subjects switched to placebo, 30% experienced a relapse, as compared with only 5% of those who were treated with Paxil.

Paxil is the only SSRI that has demonstrated long-term maintenance of efficacy in a six-month relapse-prevention clinical trial. This is important because OCD is a chronic condition and often requires long-term treatment.

Side Effects

Paxil was well tolerated in clinical trials for panic disorder and OCD. Side effects with an incidence of 10% or greater and at least twice that of placebo were sleepiness, nausea, abnormal ejaculation, dry mouth, constipation, dizziness, and tremor.

Additional Information

Panic disorder is characterized by recurrent panic attacks. A panic attack is a sudden, unprovoked episode in which sufferers experience physical symptoms such as racing, pounding heartbeat, chest pain, breathlessness, and choking and may fear they are losing control or are in imminent danger of dying. Panic disorder is diagnosed when a person has:

  • persistent anxiety about having another attack
  • concern over the implications of the attacks or their consequences, including fear of life-threatening illness or "losing control"
  • behavioral changes due to the attacks, including avoidance of everyday activities

Women are twice as likely as men to suffer from panic disorder, and the most common age of onset is the late teens and early twenties. Yet, panic attacks and panic disorder are found in people of all ages. Despite its prevalence, panic disorder is under diagnosed, according to the National Institute of Mental Health, which estimates that only one out of three panic disorder sufferers has been correctly diagnosed and treated.