Pediatric providers' attitudes toward retail clinics.

OBJECTIVE: To describe pediatric primary care providers' attitudes toward retail clinics and their experiences of retail clinics use by their patients. STUDY DESIGN: A 51-item, self-administered survey from 4 pediatric practice-based research networks from the midwestern US, which gauged providers' attitudes toward and perceptions of their patients' interactions with retail clinics, and changes to office practice to better compete. RESULTS: A total of 226 providers participated (50% response). Providers believed that retail clinics were a business threat (80%) and disrupted continuity of chronic disease management (54%). Few (20%) agreed that retail clinics provided care within recommended clinical guidelines. Most (91%) reported that they provided additional care after a retail clinic visit (median 1-2 times per week), and 37% felt this resulted from suboptimal care at retail clinics "most or all of the time." Few (15%) reported being notified by the retail clinic within 24 hours of a patient visit. Those reporting prompt communication were less likely to report suboptimal retail clinic care (OR 0.20, 95% CI 0.10-0.42) or disruption in continuity of care (OR 0.32, 95% CI 0.15-0.71). Thirty-six percent reported changes to office practice to compete with retail clinics (most commonly adjusting or extending office hours), and change was more likely if retail clinics were perceived as a threat (OR 3.70, 95% CI 1.56-8.76); 30% planned to make changes in the near future. CONCLUSIONS: Based on the perceived business threat, pediatric providers are making changes to their practice to compete with retail clinics. Improved communication between the clinic and providers may improve collaboration.

Novel metabolic bioactivation mechanism for a series of anti-inflammatory agents (2,5-diaminothiophene derivatives) mediated by cytochrome p450 enzymes.

The thiophene moiety is considered a structural alert in molecular design in drug discovery, largely because several thiophene-containing drugs, including tienilic acid and suprofen, have been withdrawn from the market because of toxicities. Reactive thiophene intermediates, activated via sulfur oxidation or ring epoxidation, are possible culprits for these adverse side effects. In this work, the metabolic activation of an anti-inflammatory agent, 1-(3-carbamoyl-5-(2,3,5-trichlorobenzamido)thiophen-2-yl)urea), containing a 2,5-diaminothiophene structure, was studied in liver microsomes in the presence of glutathione or N-acetylcysteine as trapping agents. In addition, the glutathione conjugate was detected in bile from a bile duct-cannulated rat study. The structure of the glutathione conjugate was identified by mass spectrometry and (1)H NMR. The glutathione molecule was attached to the thiophene ring, replacing the existing proton. Metabolic phenotyping experiments, using chemical inhibitors or recombinant cytochromes P450 (P450), demonstrated that CYP3A4 was the major P450 enzyme responsible for the metabolic activation, followed by CYP1A2, 2Cs, and 2D6. A novel metabolic activation mechanism is proposed whereby the 2,5-diaminothiophene moiety undergoes oxidation to a 2,5-diimine thiophene reactive intermediate. This mechanism was used to support efforts to eliminate reactive metabolite generation via structural modification of ring substituents using structure-activity relationships. The disruption of formation of the 2,5-diimine reactive intermediate resulted in the elimination of glutathione conjugate formation both in vitro and in vivo and provided a rational approach to mitigating potential safety risks associated with this class of thiophenes in drug research and development.

Improved extrapolation of hepatobiliary clearance from in vitro sandwich cultured rat hepatocytes through absolute quantification of hepatobiliary transporters.

Previously we have reported that hepatobiliary transporter expressions in sandwich cultured hepatocytes (SCH) are altered 2- to 5-fold. This change could limit the model's predictive power for in vivo biliary clearance. The present study was designed to better establish in vitro to in vivo correlation (IVIVC) of biliary clearance. Eleven compounds representing the substrates of Mrp2/Abcc2, Bcrp/Abcg2 and Bsep/Abcb11 were tested in the sandwich cultured rat hepatocyte (SCRH) model. Simultaneously, the absolute difference of hepatobiliary transporters between rat livers and SCRH at day 5 post culture was determined by LC-MS/MS. This difference was integrated into the well-stirred hepatic prediction model. A correction factor named "g_factor" was mathematically defined to reflect the difference in hepatobiliary transporter expressions between the SCRH model and in vivo models, as well as the contribution of multiple transporters. When the g_factor correction was applied, the in vivo biliary clearance prediction was significantly improved. In addition, for those compounds which are poorly permeable and/or undergo transporter-dependent active uptake, the known intracellular concentrations of substrates were used to estimate intrinsic bile clearance. This led to further improvement in the prediction of in vivo bile secretion. While the rate-limiting processes of uptake transporters in the SCRH model remain to be further determined, we showed that integration of the absolute difference of hepatobiliary transporter proteins and transport contributions could improve the predictability of SCRH model. This integration is fundamental for increased confidence in the IVIVC of human biliary clearance.

Saturation of multidrug-resistant protein 2 (mrp2/abcc2)-mediated hepatobiliary secretion: nonlinear pharmacokinetics of a heterocyclic compound in rats after intravenous bolus administration.

Multidrug-resistant protein 2 (MRP2/ABCC2), expressed on the canalicular membrane of hepatocytes, mediates the secretion of conjugated or nonconjugated compounds into bile and plays an important role in physiology and drug elimination. A heterocyclic compound, BPCPU [1-(1-(4-bromophenyl)-3-carbamoyl-1H-pyrazol-4-yl) urea], which was metabolically stable in vitro in rat liver microsomes and freshly isolated rat hepatocytes, demonstrated a saturable nonlinear pharmacokinetic profile in the rat. Polarized efflux was observed for this compound in Caco-2 cells, with a low K(m) = 1.06 +/- 0.06 microM. The Caco-2 efflux was dose-dependent and saturable. Coadministration of 25 microM MK571 ([3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid]), an MRP inhibitor, blocked the polarized efflux in Caco-2 cells. In contrast, this compound did not inhibit calcein efflux in MRP2 gene-transfected Madin-Darby canine kidney cells, suggesting that it is a substrate, not an inhibitor, of the MRP2/ABCC2 transporter. To investigate the mechanism for the nonlinear pharmacokinetics, bile duct-cannulated rats were used to obtain time profiles of plasma concentration, biliary, and urinary excretion after intravenous administration at various doses. The plasma clearance increased remarkably with decreased dose, from 1.5 ml/min/kg at 5 mg/kg to 14.9 ml/min/kg at 0.05 mg/kg. A dose-dependent biliary excretion also was observed. The results revealed that saturation of hepatobiliary secretion played a role in the dose-dependent changes in total body clearance and biliary clearance. Saturating concentrations of the Mrp2/Abcc2 substrate, BPCPU, causing decreased hepatobiliary clearance could be the major cause for the nonlinear pharmacokinetics observed in rats.

Parents' experiences with pediatric care at retail clinics.

IMPORTANCE: Little is known about the use of retail clinics (RCs) for pediatric care. OBJECTIVE: To describe the rationale and experiences of families with a pediatrician who also use RCs for pediatric care. DESIGN AND SETTING: Cross-sectional study with 19 pediatric practices in a Midwestern practice-based research network. PARTICIPANTS: Parents attending the pediatrician's office. MAIN OUTCOMES AND MEASURES: Parents' experience with RC care for their children. RESULTS: In total, 1484 parents (91.9% response rate) completed the self-administered paper survey. Parents (23.2%) who used the RC for pediatric care were more likely to report RC care for themselves (odds ratio, 7.79; 95% CI, 5.13-11.84), have more than 1 child (2.16; 1.55-3.02), and be older (1.05; 1.03-1.08). Seventy-four percent first considered going to the pediatrician but reported choosing the RC because the RC had more convenient hours (36.6%), no office appointment was available (25.2%), they did not want to bother the pediatrician after hours (15.4%), or they thought the problem was not serious enough (13.0%). Forty-seven percent of RC visits occurred between 8 am and 4 pm on weekdays or 8 am and noon on the weekend. Most commonly, visits were reportedly for acute upper respiratory tract illnesses (sore throat, 34.3%; ear infection, 26.2%; and colds or flu, 19.2%) and for physicals (13.1%). While 7.3% recalled the RC indicating it would inform the pediatrician of the visit, only 41.8% informed the pediatrician themselves. CONCLUSIONS AND RELEVANCE: Parents with established relationships with a pediatrician most often took their children to RCs for care because access was convenient. Almost half the visits occurred when the pediatricians' offices were likely open.