Characterization of transplacental transfer of paroxetine in perfused human placenta: development of a pharmacokinetic model to evaluate tapered dosing.

The aim of this study was to determine whether a tapered dosage regimen of paroxetine in pregnant women might be useful to avoid withdrawal syndromes in neonates after delivery. We characterized the transplacental transfer of paroxetine in perfused human placenta, fitting a pharmacokinetic model to the results and applying the model and parameters to evaluate a tapered dosage regimen. Paroxetine was perfused from the maternal or fetal side of an isolated human placental preparation with various perfusion protocols, and paroxetine concentrations in the effluent and placental tissue were determined. The transplacental pharmacokinetic parameters of paroxetine were estimated by simultaneous fitting of a five-compartment transplacental pharmacokinetic model to the set of paroxetine concentration profiles. The developed model and parameters were used to simulate the maternal and fetal concentrations of paroxetine, and the results were compared with reported data. Paroxetine showed a larger distribution volume in placental tissue and a smaller transplacental transfer as compared with antipyrine, a passive diffusion marker. A five-compartment model could well describe the transplacental transfer of paroxetine and could well simulate the maternal and umbilical venous concentrations of paroxetine at delivery. Transplacental transfer kinetic parameters of paroxetine were estimated by fitting a pharmacokinetic model to perfusion study data. The model and parameters appeared to be suitable for simulation of paroxetine kinetics in fetus. The model was also applicable to design a dosage regimen to avoid an abrupt decrease of paroxetine concentration in fetal plasma.

TAFRO Syndrome in a Kidney Transplant Recipient That Was Diagnosed on Autopsy: A Case Report.

A 57-year-old man who received a kidney transplant 4 years previously owing to unknown underlying disease presented with thrombocytopenia and fever. Hepatosplenomegaly and lymphadenopathy were observed, and development of prominent anasarca and worsening of renal function yielded the diagnosis of TAFRO syndrome. He was treated with high-dose steroids and plasmapheresis, and a thrombopoietin receptor agonist was administered for refractory thrombocytopenia. However, his general condition worsened, and he died on day 92. Histopathological analysis of a kidney autopsy specimen showed thrombotic microangiopathy characterized by glomerular endothelial swelling, mesangiolysis, and double contours of the glomerular capillary walls. His bone marrow showed megakaryocytic hyperplasia with mild reticulin fibrosis. Interestingly, these clinical and pathological features were remarkably similar to those the patient demonstrated before the kidney transplant, suggesting the recurrence of TAFRO syndrome. TAFRO syndrome is a rare systemic disorder whose concept has recently been established, but information on its long-term outcome is scarce. To our knowledge, this is the first case of TAFRO syndrome developing in a kidney transplant recipient, which suggests that disease recurrence occurs many years after the kidney transplant.

Inhibitory effects of herbal extracts on the activity of human sulfotransferase isoform sulfotransferase 1A3 (SULT1A3).

Sulfotransferase 1A3 (SULT1A3) is a phase II detoxifying enzyme of xenobiotics predominantly expressed in the intestinal epithelium. Recent increase in the use of herbal extracts as dietary supplements may lead to an increase in the possibility of dietary supplement-drug interactions. The purpose of the present study was to investigate the effects of 18 herbal extracts on SULT1A3 activity and the possibility of interaction between medicinal drugs and herbal extracts. We examined the inhibitory potencies of 18 herbal extracts on the sulfation of dopamine, a typical substrate of SULT1A3, and ritodrine, a beta(2) stimulant, by human recombinant SULT1A3. The sulfation of dopamine was inhibited by extracts of banaba, green tea, Rafuma, grape seed, peanut seed coat, gingko biloba leaf, St. John's wort, gymnema and milkthistle. The IC(50) values of these herbal extracts were lower than the putative gastrointestinal concentration when the recommended dose was ingested. On the other hand, chlorella extract and rutin showed no inhibitory effects and wheat, mulberry and siberian ginseng had IC(50) values exceedingly higher than the putative gastrointestinal concentration. The inhibitory profiles of herbal extracts for the sulfation of ritodrine were comparable to those for the sulfation of dopamine. In conclusion, the extracts of herbs such as banaba and green tea potently inhibited SULT1A3 activity. These extracts may increase the bioavailability of drugs whose bioavailabilities were limited by the function of SULT1A3 on the intestinal epithelium.