Paxil CR - General Information
A serotonin uptake inhibitor that is effective in the treatment of depression. [PubChem]
Pharmacology of Paxil CR
Paxil CR, an antidepressant drug of the selective serotonin reuptake inhibitor (SSRI) type, has no active metabolites and has the highest specificity for serotonin receptors of all the SSRIs. It is used to treat depression resistant to other antidepressants, depression complicated by anxiety, panic disorder, social and general anxiety disorder, obsessive-compulsive disorder (OCD), premenstrual dysphoric disorder, premature ejaculation, and hot flashes of menopause in women with breast cancer.
Paxil CR for patients
Prescribers or other health professionals should inform patients, their families, and their caregivers about the benefits and risks associated with treatment with PAXIL and should counsel them in its appropriate use. A patient Medication Guide About Using Antidepressants in Children and Teenagers is available for PAXIL. The prescriber or health professional should instruct patients, their families, and their caregivers to read the Medication Guide and should assist them in understanding its contents. Patients should be given the opportunity to discuss the contents of the Medication Guide and to obtain answers to any questions they may have. The complete text of the Medication Guide is reprinted at the end of this document.
Patients should be advised of the following issues and asked to alert their prescriber if these occur while taking PAXIL.
Clinical Worsening and Suicide Risk: Patients, their families, and their caregivers should be encouraged to be alert to the emergence of anxiety, agitation, panic attacks, insomnia, irritability, hostility, aggressiveness, impulsivity, akathisia (psychomotor restlessness), hypomania, mania, other unusual changes in behavior, worsening of depression, and suicidal ideation, especially early during antidepressant treatment and when the dose is adjusted up or down. Families and caregivers of patients should be advised to observe for the emergence of such symptoms on a day-to-day basis, since changes may be abrupt. Such symptoms should be reported to the patientís prescriber or health professional, especially if they are severe, abrupt in onset, or were not part of the patientís presenting symptoms. Symptoms such as these may be associated with an increased risk for suicidal thinking and behavior and indicate a need for very close monitoring and possibly changes in the medication.
Drugs That Interfere With Hemostasis (NSAIDs, Aspirin, Warfarin, etc.)
Patients should be cautioned about the concomitant use of paroxetine and NSAIDs, aspirin, or other drugs that affect coagulation since the combined use of psychotropic drugs that interfere with serotonin reuptake and these agents has been associated with an increased risk of bleeding.
Interference With Cognitive and Motor Performance
Any psychoactive drug may impair judgment, thinking, or motor skills. Although in controlled studies PAXIL has not been shown to impair psychomotor performance, patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that therapy with PAXIL does not affect their ability to engage in such activities.
Completing Course of Therapy
While patients may notice improvement with treatment with PAXIL in 1 to 4 weeks, they should be advised to continue therapy as directed.
Patients should be advised to inform their physician if they are taking, or plan to take, any prescription or over-the-counter drugs, since there is a potential for interactions.
Although PAXIL has not been shown to increase the impairment of mental and motor skills caused by alcohol, patients should be advised to avoid alcohol while taking PAXIL.
Patients should be advised to notify their physician if they become pregnant or intend to become pregnant during therapy.
Patients should be advised to notify their physician if they are breast-feeding an infant.
PAXIL® (PAX-il) (paroxetine hydrochloride) Tablets and Oral Solution
About Using Antidepressants in Children and Teenagers
What is the most important information I should know if my child is being prescribed an antidepressant?
Parents or guardians need to think about 4 important things when their child is prescribed an antidepressant:
- There is a risk of suicidal thoughts or actions
- How to try to prevent suicidal thoughts or actions in your child
- You should watch for certain signs if your child is taking an antidepressant
- There are benefits and risks when using antidepressants
1. There is a Risk of Suicidal Thoughts or Actions
Children and teenagers sometimes think about suicide, and many report trying to kill themselves.
Antidepressants increase suicidal thoughts and actions in some children and teenagers. But suicidal thoughts and actions can also be caused by depression, a serious medical condition that is commonly treated with antidepressants. Thinking about killing yourself or trying to kill yourself is called suicidality or being suicidal.
A large study combined the results of 24 different studies of children and teenagers with depression or other illnesses. In these studies, patients took either a placebo (sugar pill) or an antidepressant for 1 to 4 months. No one committed suicide in these studies, but some patients became suicidal. On sugar pills, 2 out of every 100 became suicidal. On the antidepressants, 4 out of every 100 patients became suicidal.
For some children and teenagers, the risks of suicidal actions may be especially high. These include patients with
- Bipolar illness (sometimes called manic-depressive illness)
- A family history of bipolar illness
- A personal or family history of attempting suicide
If any of these are present, make sure you tell your healthcare provider before your child takes an antidepressant.
2. How to Try to Prevent Suicidal Thoughts and Actions
To try to prevent suicidal thoughts and actions in your child, pay close attention to changes in her or his moods or actions, especially if the changes occur suddenly. Other important people in your child's life can help by paying attention as well (e.g., your child, brothers and sisters, teachers, and other important people). The changes to look out for are listed in Section 3, on what to watch for.
Whenever an antidepressant is started or its dose is changed, pay close attention to your child.
After starting an antidepressant, your child should generally see his or her healthcare provider:
- Once a week for the first 4 weeks
- Every 2 weeks for the next 4 weeks
- After taking the antidepressant for 12 weeks
- After 12 weeks, follow your healthcare provider's advice about how often to come back
- More often if problems or questions arise
You should call your child's healthcare provider between visits if needed.
3. You Should Watch for Certain Signs If Your Child is Taking an Antidepressant
Contact your child's healthcare provider right away if your child exhibits any of the following signs for the first time, or if they seem worse, or worry you, your child, or your child's teacher:
- Thoughts about suicide or dying
- Attempts to commit suicide
- New or worse depression
- New or worse anxiety
- Feeling very agitated or restless
- Panic attacks
- Difficulty sleeping (insomnia)
- New or worse irritability
- Acting aggressive, being angry, or violent
- Acting on dangerous impulses
- An extreme increase in activity and talking
- Other unusual changes in behavior or mood
Never let your child stop taking an antidepressant without first talking to his or her healthcare provider. Stopping an antidepressant suddenly can cause other symptoms.
4. There are Benefits and Risks When Using Antidepressants
Antidepressants are used to treat depression and other illnesses. Depression and other illnesses can lead to suicide. In some children and teenagers, treatment with an antidepressant increases suicidal thinking or actions. It is important to discuss all the risks of treating depression and also the risks of not treating it. You and your child should discuss all treatment choices with your healthcare provider, not just the use of antidepressants.
Other side effects can occur with antidepressants.
Of all the antidepressants, only fluoxetine (Prozac®) has been FDA approved to treat pediatric depression.
For obsessive compulsive disorder in children and teenagers, FDA has approved only fluoxetine (Prozac®)*, sertraline (Zoloft®)*, fluvoxamine, and clomipramine (Anafranil®)*.
Your healthcare provider may suggest other antidepressants based on the past experience of your child or other family members.
Is this all I need to know if my child is being prescribed an antidepressant?
No. This is a warning about the risk for suicidality. Other side effects can occur with antidepressants. Be sure to ask your healthcare provider to explain all the side effects of the particular drug he or she is prescribing. Also ask about drugs to avoid when taking an antidepressant. Ask your healthcare provider or pharmacist where to find more information.
*The following are registered trademarks of their respective manufacturers: Prozac®/Eli Lilly and Company; Zoloft®/Pfizer Pharmaceuticals; Anafranil®/Mallinckrodt Inc.
This Medication Guide has been approved by the U.S. Food and Drug Administration for all antidepressants.
Research Triangle Park, NC 27709
©2005, GlaxoSmithKline. All rights reserved.
Paxil CR Interactions
As with other serotonin reuptake inhibitors, an interaction between paroxetine and tryptophan may occur when
they are coadministered. Adverse experiences, consisting primarily of headache, nausea, sweating, and dizziness,
have been reported when tryptophan was administered to patients taking PAXIL. Consequently, concomitant use of
PAXIL with tryptophan is not recommended.
Monoamine Oxidase Inhibitors
Preliminary data suggest that there may be a pharmacodynamic interaction (that causes an increased bleeding diathesis
in the face of unaltered prothrombin time) between paroxetine and warfarin. Since there is little clinical experience,
the concomitant administration of PAXIL and warfarin should be undertaken with caution
There have been rare postmarketing reports describing patients with weakness, hyperreflexia, and incoordination following
the use of a selective serotonin reuptake inhibitor (SSRI) and sumatriptan. If concomitant treatment with sumatriptan and
an SSRI (e.g., fluoxetine, fluvoxamine, paroxetine, sertraline) is clinically warranted, appropriate observation of the
patient is advised.
Drugs Affecting Hepatic Metabolism
The metabolism and pharmacokinetics of paroxetine may be affected by the induction or inhibition of drug-metabolizing enzymes.
Cimetidine inhibits many cytochrome P450 (oxidative) enzymes. In a study where PAXIL (30 mg once daily) was dosed orally for
4 weeks, steady-state plasma concentrations of paroxetine were increased by approximately 50% during coadministration with
oral cimetidine (300 mg three times daily) for the final week. Therefore, when these drugs are administered concurrently,
dosage adjustment of PAXIL after the 20-mg starting dose should be guided by clinical effect. The effect of paroxetine on
cimetidine�s pharmacokinetics was not studied.
Phenobarbital induces many cytochrome P450 (oxidative) enzymes. When a single oral 30-mg dose of PAXIL was administered at
phenobarbital steady state (100 mg once daily for 14 days), paroxetine AUC and T� were reduced (by an average of 25% and 38%,
respectively) compared to paroxetine administered alone. The effect of paroxetine on phenobarbital pharmacokinetics was not
studied. Since PAXIL exhibits nonlinear pharmacokinetics, the results of this study may not address the case where the 2 drugs
are both being chronically dosed. No initial dosage adjustment of PAXIL is considered necessary when coadministered with
phenobarbital; any subsequent adjustment should be guided by clinical effect.
When a single oral 30-mg dose of PAXIL was administered at phenytoin steady state (300 mg once daily for 14 days), paroxetine
AUC and T� were reduced (by an average of 50% and 35%, respectively) compared to PAXIL administered alone. In a separate study,
when a single oral 300-mg dose of phenytoin was administered at paroxetine steady state (30 mg once daily for 14 days), phenytoin
AUC was slightly reduced (12% on average) compared to phenytoin administered alone. Since both drugs exhibit nonlinear
pharmacokinetics, the above studies may not address the case where the 2 drugs are both being chronically dosed. No initial
dosage adjustments are considered necessary when these drugs are coadministered; any subsequent adjustments should be guided by
Drugs Metabolized by Cytochrome P450IID6
Many drugs, including most drugs effective in the treatment of major depressive disorder (paroxetine, other SSRIs and many
tricyclics), are metabolized by the cytochrome P450 isozyme P450IID6. Like other agents that are metabolized by P450IID6,
paroxetine may significantly inhibit the activity of this isozyme. In most patients (>90%), this P450IID6 isozyme is saturated
early during dosing with PAXIL. In 1 study, daily dosing of PAXIL (20 mg once daily) under steady-state conditions increased
single dose desipramine (100 mg) Cmax, AUC, and T� by an average of approximately 2-, 5-, and 3-fold, respectively. Concomitant
use of PAXIL with other drugs metabolized by cytochrome P450IID6 has not been formally studied but may require lower doses than
usually prescribed for either PAXIL or the other drug.
Therefore, coadministration of PAXIL with other drugs that are metabolized by this isozyme, including certain drugs effective in
the treatment of major depressive disorder (e.g., nortriptyline, amitriptyline, imipramine, desipramine, and fluoxetine),
phenothiazines, risperidone, and Type 1C antiarrhythmics (e.g., propafenone, flecainide, and encainide), or that inhibit this
enzyme (e.g., quinidine), should be approached with caution.
However, due to the risk of serious ventricular arrhythmias and sudden death potentially associated with elevated plasma levels
of thioridazine, paroxetine and thioridazine should not be coadministered (see CONTRAINDICATIONS and WARNINGS).
At steady state, when the P450IID6 pathway is essentially saturated, paroxetine clearance is governed by alternative P450 isozymes
that, unlike P450IID6, show no evidence of saturation (see PRECAUTIONS�Tricyclic Antidepressants).
Drugs Metabolized by Cytochrome P450IIIA4
An in vivo interaction study involving the coadministration under steady-state conditions of paroxetine and terfenadine, a
substrate for cytochrome P450IIIA4, revealed no effect of paroxetine on terfenadine pharmacokinetics. In addition, in vitro
studies have shown ketoconazole, a potent inhibitor of P450IIIA4 activity, to be at least 100 times more potent than paroxetine as
an inhibitor of the metabolism of several substrates for this enzyme, including terfenadine, astemizole, cisapride, triazolam, and
cyclosporine. Based on the assumption that the relationship between paroxetine�s in vitro Ki and its lack of effect on terfenadine's
in vivo clearance predicts its effect on other IIIA4 substrates, paroxetine�s extent of inhibition of IIIA4 activity is not likely to
be of clinical significance.
Tricyclic Antidepressants (TCAs)
Caution is indicated in the coadministration of tricyclic antidepressants (TCAs) with PAXIL, because paroxetine may inhibit TCA
metabolism. Plasma TCA concentrations may need to be monitored, and the dose of TCA may need to be reduced, if a TCA is coadministered
with PAXIL (see PRECAUTIONS�Drugs Metabolized by Cytochrome P450IID6).
Drugs Highly Bound to Plasma Protein
Because paroxetine is highly bound to plasma protein, administration of PAXIL to a patient taking another drug that is highly protein
bound may cause increased free concentrations of the other drug, potentially resulting in adverse events. Conversely, adverse effects
could result from displacement of paroxetine by other highly bound drugs.
Drugs That Interfere With Hemostasis (NSAIDs, Aspirin, Warfarin, etc.)
Serotonin release by platelets plays an important role in hemostasis. Epidemiological studies of the case-control and cohort design
that have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of
upper gastrointestinal bleeding have also shown that concurrent use of an NSAID or aspirin potentiated the risk of bleeding. Thus,
patients should be cautioned about the use of such drugs concurrently with paroxetine.
Although PAXIL does not increase the impairment of mental and motor skills caused by alcohol, patients should be advised to avoid
alcohol while taking PAXIL.
A multiple-dose study has shown that there is no pharmacokinetic interaction between PAXIL and lithium carbonate. However, since there
is little clinical experience, the concurrent administration of paroxetine and lithium should be undertaken with caution.
The steady-state pharmacokinetics of paroxetine was not altered when administered with digoxin at steady state. Mean digoxin AUC at
steady state decreased by 15% in the presence of paroxetine. Since there is little clinical experience, the concurrent administration
of paroxetine and digoxin should be undertaken with caution.
Under steady-state conditions, diazepam does not appear to affect paroxetine kinetics. The effects of paroxetine on diazepam were not
Daily oral dosing of PAXIL (30 mg once daily) increased steady-state AUC0- 24, Cmax, and Cmin values of procyclidine (5 mg oral once
daily) by 35%, 37%, and 67%, respectively, compared to procyclidine alone at steady state. If anticholinergic effects are seen, the
dose of procyclidine should be reduced.
In a study where propranolol (80 mg twice daily) was dosed orally for 18 days, the established steady-state plasma concentrations of
propranolol were unaltered during coadministration with PAXIL (30 mg once daily) for the final 10 days. The effects of propranolol on
paroxetine have not been evaluated
Reports of elevated theophylline levels associated with treatment with PAXIL have been reported. While this interaction has not been
formally studied, it is recommended that theophylline levels be monitored when these drugs are concurrently administered.
Electroconvulsive Therapy (ECT)
There are no clinical studies of the combined use of ECT and PAXIL.
Paxil CR Contraindications
Concomitant use in patients taking either monoamine oxidase inhibitors (MAOIs) or thioridazine is contraindicated.
PAXIL is contraindicated in patients with a hypersensitivity to paroxetine or any of the inactive ingredients in PAXIL.
Additional information about Paxil CR
Paxil CR Indication: For the treatment of depression, depression accompanied by anxiety, obsessive compulsive disorder and panic attacks
Mechanism Of Action: Paxil CR is a potent and highly selective inhibitor of neuronal serotonin reuptake. Paxil CR likely inhibits the reuptake of serotonin at the neuronal membrane, enhances serotonergic neurotransmission by reducing turnover of the neurotransmitter, therefore it prolongs its activity at synaptic receptor sites and potentiates 5-HT in the CNS; paroxetine is more potent than both sertraline and fluoxetine in its ability to inhibit 5-HT reuptake. Compared to the tricyclic antidepressants, SSRIs have dramatically decreased binding to histamine, acetylcholine, and norepinephrine receptors.
Drug Interactions: Almotriptan Increased risk of CNS adverse effects
Eletriptan Increased risk of CNS adverse effects
Frovatriptan Increased risk of CNS adverse effects
Naratriptan Increased risk of CNS adverse effects
Rizatriptan Increased risk of CNS adverse effects
Sumatriptan Increased risk of CNS adverse effects
Zolmitriptan Increased risk of CNS adverse effects
Warfarin The SSRI increases the effect of the anticoagulant
Acenocoumarol The SSRI increases the effect of the anticoagulant
'5'-O-(N-(L-Alanyl)-Sulfamoyl)Adenosine The SSRI increases the effect of the anticoagulant
Anisindione The SSRI increases the effect of the anticoagulant
Risperidone The SSRI increases the effect and toxicity of risperidone
Carvedilol The SSRI increases the effect of the beta-blocker
Propranolol The SSRI increases the effect of the beta-blocker
Metoprolol The SSRI increases the effect of the beta-blocker
Tranylcypromine Possible severe adverse reaction with this combination
Rasagiline Possible severe adverse reaction with this combination
Selegiline Possible severe adverse reaction with this combination
Phenelzine Possible severe adverse reaction with this combination
Moclobemide Possible severe adverse reaction with this combination
Isocarboxazid Possible severe adverse reaction with this combination
Amphetamine Risk of serotoninergic syndrome
Diethylpropion Risk of serotoninergic syndrome
Atomoxetine The CYP2D6 inhibitor could increases the effect and toxicity of atomoxetine
Benzphetamine Risk of serotoninergic syndrome
Dexfenfluramine Risk of serotoninergic syndrome
Dextroamphetamine Risk of serotoninergic syndrome
Dextromethorphan Combination associated with possible serotoninergic syndrome
Fenfluramine Risk of serotoninergic syndrome
Galantamine Paxil CR increases the effect and toxicity of galantamine
Linezolid Combination associated with possible serotoninergic syndrome
Mazindol Risk of serotoninergic syndrome
Methamphetamine Risk of serotoninergic syndrome
Oxycodone Increased risk of serotonin syndrome
Phendimetrazine Risk of serotoninergic syndrome
Phentermine Risk of serotoninergic syndrome
Phenylpropanolamine Risk of serotoninergic syndrome
Propafenone Fluoxetine increases the effect and toxicity of propafenone
Sibutramine Risk of serotoninergic syndrome
Tramadol Risk of serotoninergic syndrome
St. John's Wort St. John's Wort increases the effect and toxicity of the SSRI
Thioridazine Increased risk of cardiotoxicity and arrhythmias
Mesoridazine Increased risk of cardiotoxicity and arrhythmias
Pimozide Increased risk of cardiotoxicity and arrhythmias
Food Interactions: Not Available
Generic Name: Paroxetine
Synonyms: Paroxetina [Inn-Spanish]; Paroxetine Hcl; Paroxetinum [Inn-Latin]
Drug Category: Antidepressants; Selective Serotonin Reuptake Inhibitors (SSRIs)
Drug Type: Small Molecule; Approved; Investigational
Absorption: completely absorbed after oral dosing
Toxicity (Overdose): LD50=500mg/kg (orally in mice); Coma, dizziness, drowsiness, facial flushing, nausea, sweating, tremor, vomiting
Protein Binding: 95%
Half Life: 24 hours
Dosage Forms of Paxil CR: Tablet, extended release Oral
Chemical IUPAC Name: (3S,4R)-3-(1,3-benzodioxol-5-yloxymethyl)-4-(4-fluorophenyl)piperidine
Chemical Formula: C19H20FNO3
Paroxetine on Wikipedia: https://en.wikipedia.org/wiki/Paroxetine
Organisms Affected: Humans and other mammals