PEXEVA
Clinical safety rating
cautionComprehensive clinical and safety monograph for PEXEVA (PEXEVA).
Paroxetine is a selective serotonin reuptake inhibitor (SSRI); it potentiates serotonergic activity in the CNS by inhibiting the reuptake of serotonin at the presynaptic neuronal membrane.
| Metabolism | Extensively metabolized by CYP2D6; minor pathways include CYP3A4; undergoes oxidative and conjugation reactions. |
| Excretion | Primarily renal (70% as metabolites, 2% unchanged); fecal (27%) |
| Half-life | 60-120 hours (chronic dosing); steady-state achieved in 4-5 weeks |
| Protein binding | 98% bound to albumin and α1-acid glycoprotein |
| Volume of Distribution | 20-30 L/kg; large Vd indicates extensive tissue distribution |
| Bioavailability | Oral: 50-80% (first-pass metabolism) |
| Onset of Action | Oral: 2-4 weeks for antidepressant effect; full response 6-8 weeks |
| Duration of Action | After discontinuation, pharmacological effects persist for 2-3 weeks due to long half-life |
| Molecular Weight | 329.38 |
Initial 10 mg orally once daily, increased gradually based on response and tolerability; maximum 50 mg once daily (paroxetine hydrochloride equivalent).
| Dosage form | TABLET |
| Renal impairment | Creatinine clearance (CrCl) 30-59 mL/min: initially 10 mg once daily, maximum 40 mg once daily. CrCl < 30 mL/min or hemodialysis: initially 10 mg once daily, maximum 30 mg once daily. |
| Liver impairment | Child-Pugh Class B or C: initially 10 mg once daily, maximum 30 mg once daily. Child-Pugh Class A: no adjustment recommended. |
| Pediatric use | Not FDA-approved for patients < 18 years; use not recommended due to increased risk of suicidal thoughts and behaviors. |
| Geriatric use | Initial dose 10 mg orally once daily; maximum 40 mg once daily. Elderly patients may have increased plasma concentrations and require slower titration. |
| 1st trimester | Paroxetine (Pexeva) is a pregnancy category D drug. First trimester exposure is associated with increased risk of cardiovascular malformations, particularly ventricular septal defects. Use only if potential benefit justifies risk. |
| 2nd trimester | Second trimester use may be considered but with caution. No specific teratogenicity reported, but there is risk of persistent pulmonary hypertension of the newborn (PPHN). |
| 3rd trimester | Third trimester exposure may cause neonatal complications including serotonin syndrome, respiratory distress, feeding difficulties, and withdrawal symptoms. Avoid or use with close monitoring. |
Clinical note
Comprehensive clinical and safety monograph for PEXEVA (PEXEVA).
| Placental transfer | Paroxetine crosses the placenta; umbilical cord plasma concentrations range from 0.5-1.0 times maternal plasma levels. Active transport mechanisms may concentrate levels in the fetal compartment. Evidence from case-control studies suggests placental transfer is significant. |
| Breastfeeding | Paroxetine (Pexeva) is excreted into breast milk in low to moderate amounts. Higher relative infant doses have been reported compared to other SSRIs. Adverse effects such as irritability, poor feeding, and withdrawal symptoms have been observed in some infants. Alternative SSRIs with lower milk/plasma ratios (e.g., sertraline, paroxetine) are preferred when breastfeeding. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | PEXEVA (paroxetine) is classified as FDA Pregnancy Category D. First trimester exposure is associated with a 1.5- to 2-fold increased risk of congenital cardiac malformations, particularly ventricular septal defects, and an increased risk of omphalocele and craniosynostosis. Third trimester exposure may result in neonatal adaptation syndrome (e.g., respiratory distress, jitteriness, poor feeding, persistent crying) and rare cases of persistent pulmonary hypertension of the newborn (PPHN). The risk is dose-dependent and highest with doses above 25 mg/day. |
| Fetal Monitoring | During pregnancy, monitor for fetal congenital malformations via detailed ultrasound and fetal echocardiography (especially if exposed in first trimester). In third trimester, monitor for signs of neonatal adaptation syndrome and PPHN. For the mother, assess for worsening depression, suicidal ideation, and adherence to treatment. Consider maternal serum drug levels if toxicity or non-adherence suspected. |
| Fertility Effects | Paroxetine may adversely affect male and female fertility. In animal studies, decreased spermatogenesis and increased sperm abnormalities have been observed. In humans, reversible sexual dysfunction (delayed ejaculation, anorgasmia, decreased libido) is common and may impact fertility indirectly. Oligospermia and reduced semen quality have been reported in men taking paroxetine, likely due to hormonal changes (increased prolactin, decreased testosterone). Women may experience menstrual irregularities and anovulation. Effects are generally reversible upon discontinuation. |
■ FDA Black Box Warning
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
| Serious Effects |
Hypersensitivity to paroxetine or any component of the formulationConcomitant use with monoamine oxidase inhibitors (MAOIs) or within 14 days of MAOI discontinuationConcomitant use with linezolid or intravenous methylene blue (due to risk of serotonin syndrome)Use with pimozide or thioridazine (due to QT prolongation risk)
| Precautions | Suicidality in children, adolescents, and young adults, Serotonin syndrome, Discontinuation syndrome (withdrawal), Activation of mania/hypomania, Seizures, Angle-closure glaucoma, Increased intraocular pressure, Hyponatremia, Abnormal bleeding, Sexual dysfunction, Bone fracture risk, Drug interactions with MAOIs and other serotonergic drugs |
| Food/Dietary | Avoid grapefruit and grapefruit juice, as they can increase paroxetine levels and risk of toxicity. Alcohol may exacerbate CNS depression and should be limited. No other significant food interactions. |
| Clinical Pearls | Pexeva (paroxetine mesylate) is an SSRI antidepressant. Due to its short half-life, abrupt discontinuation may cause withdrawal syndrome. It is also indicated for panic disorder, OCD, and social anxiety disorder. Use with caution in patients with narrow-angle glaucoma, as it can precipitate acute angle closure. Monitor for hyponatremia in elderly patients. Avoid concurrent use with MAOIs or other serotonergic agents due to risk of serotonin syndrome. |
| Patient Advice | Take exactly as prescribed; do not stop suddenly. If you miss a dose, take it as soon as you remember unless it is close to the next dose. Do not double doses. · May take up to 4 weeks to feel full benefit. Continue medication even if you feel better. · Avoid alcohol and grapefruit juice. Grapefruit can increase Pexeva levels and side effects. · May cause drowsiness, dizziness, or blurred vision. Do not drive or operate machinery until you know how Pexeva affects you. · Report any suicidal thoughts, agitation, or worsening depression immediately to your doctor. · Common side effects include nausea, dry mouth, constipation, decreased appetite, and sexual dysfunction. These often improve over time. |
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