PEXEVA
Clinical safety rating: caution
Comprehensive 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 |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PEXEVA (PEXEVA).
| Breastfeeding | Paroxetine is excreted into breast milk with a milk-to-plasma (M/P) ratio of approximately 0.5-0.7. Though relative infant doses are low (typically <2% of maternal weight-adjusted dose), adverse effects such as irritability, poor feeding, and drowsiness have been reported. Caution is advised, particularly with high maternal doses; non-pharmacologic strategies or alternative antidepressants with more favorable lactation profiles may be preferred. |
| 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. |
■ 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 |
["Concurrent use with monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing MAOI","Concurrent use with tryptophan","Concurrent use with pimozide","Known hypersensitivity to paroxetine or any excipient"]
| 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"] |
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| 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. |