To : Martha Re : Paxil From my newest edition out last week. Please note new fields including Pregnancy risk factors, MW =molecular weight, pKa= equilibrium coef., drug interactions, Australian, Canadian tradnames, etc. Also, the pediatric concerns are "Only" those via breastmilk, NOT the direct administration to the infant. Regards Tom Hale, PH.D. ----------------------------------------------------- Paroxetine Fax # 1333 Trade: Paxil Canadian/Australian: Aropax 20 Uses: Antidepressant, serotonin reuptake inhibitor AAP: Not reviewed Paroxetine is a typical serotonin reuptake inhibitor. Although it undergoes hepatic metabolism, the metabolites are not active. Paroxetine is exceedingly lipophilic and distributes throughout the body with only 1% remaining in plasma. In one case report of a mother receiving 20 mg/day paroxetine at steady state, the breastmilk level at peak (4 hours) was 7.6 µg/L. While the maternal paroxetine dose was 333 µg/kg, the maximum daily dose to the infant was estimated at 1.14 µg/kg or 0.34% of the maternal dose. Pregnancy Risk Category: B Adult Concerns: Sedation, headache, dry mouth, dizziness, nausea, insomnia, constipation, seizures. Pediatric Concerns: Although this product has been occasionally used in breastfeeding and pregnant women, no reports of untoward effects have been found. Drug Interactions: Decreased effect with phenobarbital and phenytoin. Increased toxicity with alcohol, cimetidine, MAO inhibitors (serotonergic syndrome). Increased effect with fluoxetine, tricyclic antidepressants, sertraline, phenothiazines, warfarin. AHL = 21 hours M/P = 0.09 PHL = PB = 95% PK = 5-8 hours Oral = Complete MW = 329 pKa = Vd = 3-28 References: 1. Pharmaceutical Manufacturers Package Insert, 1996. 2. Kaye CM, Haddock RE, Langley PF et al. a review of the metabolism and pharmacokinetics of paroxetine in man. Acta Psychiatr Scand 80(Suppl 350):60-75, 1989. 3. Spigset O. Paroxetine level in breast milk. J. Clin Psy. 57(1):39, 1996.