Healthy volunteers in first-in-human oncology drug development for small molecules.

This review provides tools to consider the inclusion of healthy volunteers (HVs) in first-in-human (FIH) oncology clinical trials with small molecules, including targeted and immunomodulatory agents, a strategy that was not envisioned with classic chemotherapy. To enable an FIH oncology trial in HVs compared to cancer patients (CPs), a robust nonclinical package must be generated, which includes toxicokinetic and pharmacokinetic studies, as well as more extensive safety pharmacology, toxicology and genotoxicity studies. This strategy could provide an early clinical characterization of the pharmacokinetic parameters and clinical safety profile in the absence of comorbidities and concomitant medication. It also avoids the ethical issue of administrating subtherapeutic doses to CPs, and could potentially help to accelerate the timelines of clinical drug development for patient care. That being said, stakeholders involved in these studies need to proceed with caution, fully understand the regulatory guidance and thoroughly evaluate the benefits and risks. This paper serves to address the regulatory guidance and other considerations needed when using healthy volunteers in early oncology trials.

Omecamtiv mecarbil does not prolong QTc intervals at therapeutic concentrations.

AIMS: Omecamtiv mecarbil (OM) is a novel selective cardiac myosin activator under investigation for the treatment of heart failure. This study aimed to evaluate the effect of therapeutic concentrations of OM on electrocardiogram (ECG) parameters and exclude a clinically concerning effect on the rate-corrected QT (QTc) interval. METHODS: In part A, 70 healthy subjects received a 25 mg oral dose of OM, and pharmacokinetics were assessed. Only subjects with maximum observed plasma concentration ≤ 350 ng/mL (n = 60) were randomized into part B, where they received a single oral dose of placebo, 50 mg OM and 400 mg moxifloxacin in a 3-period, 3-treatment, 6-sequence crossover study with continuous ECG collection. RESULTS: After a 50-mg dose of OM, mean placebo-corrected change from baseline QTcF (∆∆QTcF; Fridericia correction) ranged from -6.7 ms at 1 hour postdose to -0.8 ms at 4 hours postdose. The highest upper bound of the 1-sided 95% confidence interval (CI) was 0.7 ms (4 h postdose). Moxifloxacin resulted in a clear increase in mean ∆∆QTcF, with a peak value of 13.1 ms (90% CI: 11.71-14.57) at 3 hours; lower bound of the 1-sided 95% CI was > 5 ms at all of the 3 prespecified time points. Based on a concentration-QTc analysis, an effect on ∆∆QTcF exceeding 10 ms can be excluded up to OM plasma concentrations of ~800 ng/mL. There were no serious or treatment-emergent adverse events leading to discontinuation from the study. CONCLUSION: OM does not have a clinically relevant effect on the studied ECG parameters.

Switchability and minimal effect of food on pharmacokinetics of modified release tablet strengths of omecamtiv mecarbil, a cardiac myosin activator.

Omecamtiv mecarbil (OM) is a cardiac myosin activator in clinical development for the treatment of heart failure. The effect of food on the pharmacokinetics (PK) of 25, 37.5, and 50 mg strength modified release (MR) tablets and the bioequivalence of two 25 mg tablets versus one 50 mg MR tablet were evaluated in two open-label, randomized, cross-over studies in healthy subjects. Subjects received two 25 mg tablets or one 50 mg OM MR tablet under fed or fasted states in Study 1 (n = 39), and single oral doses of 25 and 37.5 mg OM MR tablets and to assess its relative bioavailability to the 25 mg MR tablet, a 25 mg oral solution under fed or fasted states in Study 2 (n = 34). The area under the concentration-time curve (AUC) and the maximum observed concentration (Cmax ) of 25, 37.5, or 50 mg OM MR tablets were approximately 13%-22% higher and 31%-40% higher, respectively, when taken with food. The two 25 mg and one 50 mg OM MR tablets were bioequivalent (90% confidence intervals) of the geometric mean ratios for Cmax and AUC of OM were within 0.8-1.25 under the fasted or fed state. OM was well tolerated and all treatment-emergent events were mild in severity and resolved by the end of the study. In conclusion, these studies demonstrated that the effect of food on the PK of OM was minimal at all three studied strengths of the MR tablets, and two 25 mg MR tablets may be switched for one 50 mg MR tablet (EudraCT Number: 2019-003683-44).

Pharmacokinetics, safety, and tolerability of GS-9851, a nucleotide analog polymerase inhibitor for hepatitis C virus, following single ascending doses in healthy subjects.

To investigate the pharmacokinetics, safety, and tolerability of GS-9851 (formerly PSI-7851), a new nucleotide analog inhibitor of hepatitis C virus (HCV), we conducted a double-blind, parallel, placebo-controlled, randomized, single-ascending-dose study. Healthy subjects received oral doses of 25 to 800 mg GS-9851. Peak concentrations of GS-9851 in plasma were achieved more rapidly than those of the metabolites GS-566500 (formerly PSI-352707) and GS-331007 (formerly PSI-6206), with time to maximum concentration of drug in plasma (t(max)) values of 1.0 to 1.8 h, 1.5 to 3.0 h, and 3.0 to 6.0 h, respectively. The majority of systemic drug exposure was from the nucleoside GS-331007, with maximum concentration of drug in plasma (C(max)) and area under the concentration-time curve to the last measurable concentration (AUC(0-t)) values at least 7- and 41-fold higher, respectively, than those obtained for GS-9851 after adjusting for differences in molecular weight. The terminal elimination half-life (t(1/2)) of GS-331007 increased with the dose, achieving a t(1/2) of 25.7 h at 800 mg GS-9851. Dose proportionality was not observed for GS-331007. The majority of drug recovered in urine was in the form of GS-331007, with the percentage of this metabolite in urine samples ranging from 57% to 27% with increasing dose. GS-9851 was generally well tolerated, with no maximum tolerated dose identified. In conclusion, GS-9851 and its metabolites demonstrated a favorable pharmacokinetic profile consistent with once-daily dosing, and therefore, further clinical studies evaluating GS-9851 in HCV-infected patients are warranted.

Mass balance and metabolism of aclidinium bromide following intravenous administration of [¹4C]-aclidinium bromide in healthy subjects.

Aclidinium bromide is a novel, inhaled long-acting muscarinic antagonist with low systemic activity developed for the treatment of COPD. It is an ester compound rapidly hydrolysed in plasma into inactive alcohol and acid metabolites. In this Phase I, open-label study, the rates and routes of elimination of radioactivity following intravenous administration of [¹4C]-aclidinium bromide were determined. The metabolites of aclidinium were also characterized and identified in plasma and excreta. Twelve healthy males were randomized (1:1) to receive a single intravenous 400 µg dose of [phenyl-U-¹4C]- or [glycolyl-U-¹4C]-aclidinium bromide (via 5 min infusion) to label alcohol or acid metabolites of aclidinium, respectively. Safety and tolerability were assessed over a 9-day period. Following intravenous administration, the parent compound was rapidly hydrolysed into its acid and alcohol metabolites. Primary excretion routes for [phenyl-U-¹4C]- and [glycolyl-U-¹4C]-aclidinium were renal (urine: 65% and 54%, respectively; feces: 33% and 20%, respectively), with 1% excreted as unchanged aclidinium. A total of three treatment-emergent adverse events in two subjects were reported and were related to infusion site pain. Overall, aclidinium is rapidly hydrolysed into two main metabolites, which are predominantly excreted in urine. Aclidinium bromide 400 µg administered intravenously was safe and well tolerated in healthy subjects.

Pharmacokinetic Drug-Drug Interaction Study of Omecamtiv Mecarbil With Omeprazole, a Proton Pump Inhibitor, in Healthy Subjects.

Omecamtiv mecarbil (OM) is a novel cardiac myosin activator in development for the treatment of heart failure (HF) with reduced ejection fraction. OM is administered as a 25-, 37.5-, or 50-mg modified-release formulation in patients with HF. Proton pump inhibitors are one of the most commonly prescribed drugs in this patient population. Given the potential for coadministration of both drugs in patients with HF, we evaluated the potential for omeprazole to affect the pharmacokinetics of OM in an open-label study in 14 healthy subjects. Subjects received a single 50-mg dose of OM on day 1, followed by 40-mg once-daily doses of omeprazole on days 4 to 8. On day 9, a single 40-mg dose of omeprazole was administered first and immediately followed by 50-mg of OM. Blood samples were collected up to 144 hours after dosing following administration of OM on days 1 and 9 to characterize plasma concentrations of OM. The ratios of the geometric least-square means (90% confidence intervals) of OM coadministered with omeprazole compared to OM alone were 94.5% (81.7%-109.3%), 94.3% (81.5%-109.1%), and 101.2% (95.4%-107.3%) for area under the plasma concentration-time curve from time 0 to infinity, area under the plasma concentration-time curve from time 0 to the last measurable concentration, and maximum observed plasma concentration, respectively. Coadministration of OM with omeprazole was not associated with any clinically significant pharmacokinetic drug interactions. Single doses of OM were safe and well tolerated when coadministered with omeprazole.

Pharmacokinetic Drug-Drug Interaction Study of Omecamtiv Mecarbil With Amiodarone and Digoxin in Healthy Subjects.

Omecamtiv mecarbil (OM), a novel cardiac myosin activator, is being evaluated for the treatment of heart failure with reduced ejection fraction. In vitro studies demonstrate OM as a substrate and inhibitor of P-glycoprotein (P-gp), which can result in drug-drug interactions. Two phase 1, open-label studies assessed the effect of coadministration of OM (50-mg single dose) on the pharmacokinetics of digoxin (0.5-mg single dose; N = 15), a P-gp substrate, and the effect of coadministration of amiodarone (600-mg single dose), a P-gp inhibitor, on the pharmacokinetics of OM (50-mg single dose; N = 14) in healthy subjects. The ratios of the geometric least squares mean (90% confidence interval [CI]) of digoxin coadministered with OM vs digoxin alone for area under the plasma concentration-time curve (AUC) from time 0 to infinity, AUC from time 0 to the time of the last quantifiable concentration, and maximum observed plasma concentration were 1.06 (90%CI, 0.99-1.14), 1.06 (90%CI, 0.98-1.14), and 1.08 (90%CI, 0.92-1.26), respectively. The ratios of the geometric least squares mean of OM coadministered with amiodarone vs OM alone for AUC from time 0 to infinity, AUC from time 0 to the time of the last quantifiable concentration, and maximum observed plasma concentration were 1.21 (90%CI, 1.08-1.36), 1.21 (90%CI, 1.07-1.36), and 1.08 (90%CI, 0.96-1.22), respectively. In conclusion, OM coadministered with digoxin or amiodarone did not result in any clinically relevant pharmacokinetic drug-drug interactions.

Pharmacokinetic Evaluation of the CYP3A4 and CYP2D6 Drug-Drug Interaction and CYP3A4 Induction Potential of Omecamtiv Mecarbil: Two Open-Label Studies in Healthy Subjects.

Omecamtiv mecarbil (OM) is a cardiac myosin activator under development for the treatment of heart failure. The effect of CYP3A4 and CYP2D6 inhibition on OM pharmacokinetics and the potential for OM to induce CYP3A4 was assessed in 2 studies. Study 1, part A, assessed the effect of ketoconazole 200 mg on the pharmacokinetics of OM 10 mg in CYP2D6 extensive metabolizers (EMs; n = 8) or poor metabolizers (PMs; n = 8). Study 1, part B, assessed the effect of diltiazem 240 mg on the pharmacokinetics of OM 10 mg (EM; n = 8). Study 2 assessed the effect of OM 25 mg on the pharmacokinetics of midazolam 5 mg (n = 14). Coadministration with ketoconazole led to 51% and 31% increases in OM AUCinf in EM and PM subjects, respectively, whereas OM Cmax remained similar (3% higher and 14% lower for EM and PM subjects, respectively). No changes in OM pharmacokinetics were observed in EM subjects following coadministration with diltiazem. Midazolam AUCinf and Cmax decreased by 18% and 10%, respectively, when coadministered with OM. In conclusion, CYP3A4 and CYP2D6 inhibitors are unlikely to have a clinically significant effect on the pharmacokinetics of OM. In addition, OM is unlikely to have a clinically relevant effect on the pharmacokinetics of CYP3A4 substrates.

Randomized, Double-Blind, Controlled Study to Evaluate Safety and Pharmacokinetics of Single Ascending Doses of ASP5354, an Investigational Imaging Product, in Healthy Adult Volunteers.

Intraoperative ureter identification helps reduce the risk of ureteral injury. Currently, no suitable agents for real-time ureter visualization are approved. ASP5354 (TK-1) is a novel indocyanine green derivative. In this first-in-human phase 1, double-blind, sequential ascending-dose study, urethral catheters were placed in 6 healthy volunteers who were randomized to single-dose, intravenous ASP5354 0.1 mg (n = 4) or placebo (n = 2). Sequential dose escalations to 0.5-, 2-, 8-, and 24-mg ASP5354 in new cohorts were contingent upon Dose-Escalation Committee approval after review of pharmacokinetic (PK) and safety data. Blood and urine samples were collected over 24 hours following dose administration. Objectives were to assess the safety/tolerability and PK of ASP5354. Treatment-emergent adverse events (TEAEs) were reported in 3 (15%) and 2 (20%) participants in the ASP5354 and placebo groups, respectively. In the former, there were 6 TEAEs (5/6 grade 1-2). One ASP5354 participant experienced grade 3 pyelonephritis, attributed to the catheter. No TEAEs were related to ASP5354. Mean plasma terminal elimination half-life ranged from 2.1 to 3.6 hours, with near complete urinary excretion of unchanged ASP5354 within 24 hours after administration. Linear and dose-proportional PK were observed. These results support further evaluation of ASP5354 at doses up to 24 mg for intraoperative near-infrared fluorescence ureter visualization.

Effect of Varying Degrees of Renal Impairment on the Pharmacokinetics of Omecamtiv Mecarbil.

BACKGROUND AND OBJECTIVE: Omecamtiv mecarbil is a novel selective cardiac myosin activator (myotrope) under investigation for the treatment of heart failure with reduced ejection fraction. The objective of this clinical study was to estimate the effect of varying degrees of renal impairment on the pharmacokinetics of omecamtiv mecarbil single dose (50 mg) under fasted conditions. METHODS: This phase I, open-label, non-randomized, parallel-group study evaluated the pharmacokinetics, safety, and tolerability of a single oral dose of omecamtiv mecarbil 50 mg in individuals with normal renal function or mild, moderate, and severe renal impairment, including end-stage renal disease requiring dialysis. Geometric least-squares mean ratios of maximum observed concentration (Cmax) and area under the plasma concentration-time curve (AUC) and 90% confidence intervals were derived for comparisons of renal impairment vs normal renal function. Participants were monitored for adverse events. RESULTS: Thirty-one participants received treatment and completed the study. Geometric mean exposures were similar for participants with renal impairment (AUC∞ range, 2550-3220 h*ng/mL; Cmax range, 78.9-107 ng/mL) and participants with normal renal function (AUC∞, 2790 h*ng/mL; Cmax, 92.6 ng/mL), with geometric least-squares mean ratios of 85.2-125.9. Exposure was similar on dialysis vs non-dialysis days in participants with end-stage renal disease (AUC0-24, 1650 vs 1700 h*ng/mL; Cmax, 100.0 vs 107.0 ng/mL). Four participants (12.9%) reported four treatment-emergent adverse events. No deaths, treatment-emergent adverse events leading to discontinuation, or serious adverse events occurred. CONCLUSIONS: Omecamtiv mecarbil pharmacokinetics were not meaningfully affected by renal function or hemodialysis, suggesting the same dosing strategy can be used in individuals with normal renal function or renal impairment. Oral administration of omecamtiv mecarbil was not associated with major tolerability findings. This study supports omecamtiv mecarbil for the treatment of heart failure in individuals with or without renal impairment.

Effect of Omecamtiv Mecarbil on the Pharmacokinetics of Metformin, a Probe Substrate for MATE1/MATE2-K, in Healthy Subjects.

BACKGROUND AND OBJECTIVE: Omecamtiv mecarbil (OM) is a novel cardiac myosin activator in development for the treatment of heart failure with reduced ejection fraction. The objective of this study was to evaluate the potential for OM to affect the pharmacokinetics of metformin. METHODS: This was an open-label, fixed-sequence study in 14 healthy subjects. On Day 1, subjects received an 850 mg oral dose of metformin. From Days 4 to 9, subjects received twice-daily 25 mg oral doses of OM tablets. On Day 10, subjects received an 850 mg oral dose of metformin and a single 25 mg tablet of OM. Blood and urine samples were collected up to 36 h post-dose following administration of metformin on Days 1 and 10 to characterize concentrations of metformin in plasma and urine. RESULTS: The ratios of the geometric least square means of metformin coadministered with OM compared to metformin alone were 98.7%, 99.3%, and 110.2% for AUCinf, AUClast, and Cmax, respectively. The mean renal clearance of metformin was similar following metformin administered alone (34.2 L/h) compared to metformin coadministered with OM (32.9 L/h). All adverse events were mild in severity and resolved prior to the end of the study. No serious adverse events or treatment-emergent adverse events led to discontinuation from the study. CONCLUSIONS: There was no clinically relevant effect of OM on the pharmacokinetics of metformin in healthy subjects.

Effect of Varying Degrees of Hepatic Impairment on the Pharmacokinetics of Omecamtiv Mecarbil.

Omecamtiv mecarbil (OM) is a novel selective cardiac myosin activator under investigation for the treatment of heart failure with reduced ejection fraction. OM is primarily eliminated via metabolism mediated by multiple cytochrome P450 enzymes. This phase 1 single-dose, multicenter, open-label, nonrandomized study evaluated the pharmacokinetics (PK) of OM and major metabolites M3 and M4, safety, and tolerability following oral administration of a single dose of 25-mg MR tablet in subjects with mild (n = 6) or moderate (n = 6) hepatic impairment (according to Child-Pugh classification) versus subjects with normal hepatic function (n = 6). Relative to subjects with normal hepatic function, for subjects with mild or moderate hepatic impairment, OM AUCinf was 103.2% (90%CI, 58.0%-183.6%) and 94.8% (90%CI, 54.7%-164.1%), respectively, and OM Cmax was 126.8% (90%CI, 85.7%-187.7%) and 117.3% (90%CI, 80.7%-170.5%), respectively. Exposures to M3 were similar across groups, whereas slightly lower exposures were observed for M4 with worsening hepatic function. The OM, M3, and M4 tmax and t1/2 values were similar between groups. There were no serious adverse events (AEs) or treatment-related treatment-emergent AEs. Overall, OM, M3, and M4 PK were not meaningfully affected by mild or moderate hepatic impairment, suggesting the same dosing strategy can be used in subjects with mild or moderate hepatic impairment.

Relative Bioavailability of Omecamtiv Mecarbil Pediatric Minitablet Formulations in Healthy Adult Subjects.

BACKGROUND AND OBJECTIVE: Omecamtiv mecarbil (OM) is a cardiac myosin activator under clinical development for the treatment of heart failure. Two modified-release (MR) novel OM minitablet formulations were developed to support the planned investigation of chronic heart failure in pediatric patients. The primary objective of this study was to determine the bioavailability of the minitablets relative to the adult matrix MR formulation tablets. METHODS: In a randomized, 5-period, crossover study, 20 healthy subjects received each of the following treatments orally: one 25-mg adult matrix MR tablet, 25 1-mg slow-release minitablets, 25 1-mg fast-release minitablets, six 1-mg slow-release minitablets, or six 1-mg fast-release minitablets after an overnight fast of at least 10 h with a minimum washout of 7 days between treatments. Blood samples were collected for up to 168 h. OM pharmacokinetic parameters were estimated using non-compartmental methods. RESULTS: When OM was administered as 25 1-mg OM slow-release minitablets, AUClast, AUCinf, and Cmax were 0.998-, 1.00-, and 1.29-fold of a single 25-mg OM matrix MR tablet, respectively. When OM was administered as 25 1-mg OM fast-release minitablets, AUClast, AUCinf, and Cmax were 1.26-, 1.25-, and 2.21-fold of a single 25-mg OM matrix MR tablet, respectively. The slow- and fast-release minitablets display approximately dose-proportional pharmacokinetics. There were no serious adverse events or treatment-emergent adverse events leading to discontinuation from the study. CONCLUSIONS: Relative bioavailability of slow-release minitablets was demonstrated to be similar to the adult matrix MR formulation.

Evaluation of drug-drug interaction potential between omecamtiv mecarbil and rosuvastatin, a BCRP substrate, with a clinical study in healthy subjects and using a physiologically-based pharmacokinetic model.

Omecamtiv mecarbil (OM) is a novel cardiac myosin activator in development for the treatment of heart failure. In vitro, OM is an inhibitor of BCRP. Rosuvastatin, a BCRP substrate, is one of the most commonly prescribed medications in patients with heart failure. The potential for a pharmacokinetic (PK) drug-drug interaction (DDI) was investigated, specifically to determine whether a single 50 mg dose of OM would impact the PKs of a single 10 mg dose of rosuvastatin in an open-label study in 14 healthy subjects. The ratios of the geometric least-square means (90% confidence intervals [CIs]) of rosuvastatin co-administered with OM compared to rosuvastatin alone were 127.1% (90% CI 113.8-141.9), 132.8% (90% CI 120.7-146.1), and 154.2% (90% CI 132.8-179.1) for area under the plasma-concentration time curve from time zero to infinity (AUCinf ), area under the plasma-concentration time curve from time zero to time of last quantifiable concentration (AUClast ), and maximum observed plasma concentration (Cmax ), respectively. Whereas the DDI study with rosuvastatin was conducted with the co-administration of a single dose of OM, in the clinical setting, patients receive OM at doses of 25, 37.5, or 50 mg twice daily (b.i.d.). Hence, to extrapolate the results of the DDI study to a clinically relevant scenario of continuous b.i.d. dosing with OM, physiologically-based pharmacokinetic (PBPK) modeling was performed to explore the potential of BCRP inhibition following continuous b.i.d. dosing of OM at the highest 50 mg dose. Modeling results indicated that following 50 mg b.i.d. dosing of OM, the predicted ratios of the geometric means (90% CIs) for rosuvastatin AUCinf and Cmax were 1.18 (90% CI 1.16-1.20) and 2.04 (90% CI 1.99-2.10), respectively. Therefore, these results suggest that OM, following multiple dose administration, is a weak inhibitor of BCRP substrates and is in accordance with that observed in the single dose OM DDI clinical study.

Metabolism and excretion of [14C]taranabant, a cannabinoid-1 inverse agonist, in humans.

Taranabant (N-[(1S,2S)-3-(4-chlorophenyl)-2-(3-cyanophenyl)-1-methylpropyl]-2-methyl-2-{[5-(trifluoromethyl)pyridin-2-yl]oxy}propanamide or MK-0364) is an orally active inverse agonist of the cannabinoid 1 (CB-1) receptor that was under development for the management of obesity. The metabolism and excretion of taranabant were investigated following a single oral dose of 5 mg/201 µCi [14C]taranabant to six healthy male subjects. The overall excretion recovery of the administered radioactivity was nearly quantitative (∼92%), with the majority of the dose (∼87%) excreted into faeces and a much smaller fraction (∼5%) into urine. Taranabant was absorbed rapidly, with C(max) of radioactivity attained at 1-2-h postdose. The parent compound and its monohydroxylated metabolite, M1, were the major radioactive components circulating in plasma and comprised ∼12-24% and 33-42%, respectively, of the plasma radioactivity for up to 48 h. A second monohydroxylated metabolite, designated as M1a, represented ∼10-12% of the radioactivity in the 2- and 8-h postdose plasma profiles. Metabolite profiles of the faeces samples consisted mainly of the (unabsorbed) parent compound and multiple diastereomeric carboxylic acid derivatives derived from oxidation of the geminal methyl group of the parent compound and of the hydroxylated metabolite/s. These data suggest that, similar to rats and monkeys, taranabant is primarily eliminated in humans via oxidative metabolism and excretion of metabolites via the biliary/faecal route.

Predictors of urinary tract infection based on artificial neural networks and genetic algorithms.

BACKGROUND: Among women who present with urinary complaints, only 50% are found to have urinary tract infection. Individual urinary symptoms and urinalysis are not sufficiently accurate to discriminate those with and without the diagnosis. METHODS: We used artificial neural networks (ANN) coupled with genetic algorithms to evolve combinations of clinical variables optimized for predicting urinary tract infection. The ANN were applied to 212 women ages 19-84 who presented to an ambulatory clinic with urinary complaints. Urinary tract infection was defined in separate models as uropathogen counts of > or =10(5) colony-forming units (CFU) per milliliter, and counts of > or =10(2) CFU per milliliter. RESULTS: Five-variable sets were evolved that classified cases of urinary tract infection and non-infection with receiver-operating characteristic (ROC) curve areas that ranged from 0.853 (for uropathogen counts of > or =10(5) CFU per milliliter) to 0.792 (for uropathogen counts of > or =10(2) CFU per milliliter). Predictor variables (which included urinary frequency, dysuria, foul urine odor, symptom duration, history of diabetes, leukocyte esterase on urine dipstick, and red blood cells, epithelial cells, and bacteria on urinalysis) differed depending on the pathogen count that defined urinary tract infection. Network influence analyses showed that some variables predicted urine infection in unexpected ways, and interacted with other variables in making predictions. CONCLUSIONS: ANN and genetic algorithms can reveal parsimonious variable sets accurate for predicting urinary tract infection, and novel relationships between symptoms, urinalysis findings, and infection.

Four-year cost-utility analyses of sealed and nonsealed first permanent molars in Iowa Medicaid-enrolled children.

OBJECTIVES: Dental sealants, by their ability to prevent caries and maintain teeth in better health, have some inherent utility to individuals, programs, or society. This study assessed the 4-year incremental cost utility of sealing first permanent molars of 6-year-old Iowa Medicaid enrollees from a societal perspective and identified the group of teeth or children in whom sealants are most cost effective. METHODS: Dental services for first permanent molars were assessed using claims and encounter data for a group of continuously enrolled Medicaid enrollees who turned 6 between 1996 and 1999. Previously published utilities were used to weight the different health states. The weighted sum of outcomes [Quality-Adjusted Tooth-Years (QATYs)] was the measure of effectiveness. Costs and QATYs were discounted to the time of the child's sixth birthday. RESULTS: For all first molars, the cost of treatment associated with sealed teeth was higher but the utility was also slightly higher over the 4-year period. The relative incremental cost per 0.19 QATY ratio [changing the health state from a restored tooth (utility= 0.81) to a nonrestored tooth (utility = 1)] by sealing the molar ranged from $36.7 to $83.5 per 0.19 QATY. The incremental cost/QATY ratio was lower for sealing lower utilizers and for mandibular versus maxillary molars. CONCLUSIONS: Sealants improved overall utility of first permanent molars after 4 years. The 4-year cost/QATY ratio of sealing the first permanent molar varied by arch and type of utilizers. Sealing first permanent molars in lower dental utilizers is the most cost-effective approach for prioritizing limited resources.

A cost analysis of the Iowa Medicaid primary care case management program.

OBJECTIVE: To determine the cost savings attributable to the implementation and expansion of a primary care case management (PCCM) program on Medicaid costs per member in Iowa from 1989 to 1997. DATA SOURCES: Medicaid administrative data from Iowa aggregated at the county level. STUDY DESIGN: Longitudinal analysis of costs per member per month, analyzed by category of medical expense using weighted least squares. We compared the actual costs with the expected costs (in the absence of the PCCM program) to estimate cost savings attributable to the PCCM program. PRINCIPAL FINDINGS: We estimated that the PCCM program was associated with a savings of US dollars 66 million to the state of Iowa over the study period. Medicaid expenses were 3.8 percent less than what they would have been in the absence of the PCCM program. Effects of the PCCM program appeared to grow stronger over time. Use of the PCCM program was associated with increases in outpatient care and pharmaceutical expenses, but a decrease in hospital and physician expenses. CONCLUSIONS: Use of a Medicaid PCCM program was associated with substantial aggregate cost savings over an 8-year period, and this effect became stronger over time. Cost reductions appear to have been mediated by substituting outpatient care for inpatient care.

The cost-effectiveness of large amalgam and crown restorations over a 10-year period.

OBJECTIVE: To assist clinical decision making for an individual patient or on a community level, this study was done to determine the differences in costs and effectiveness of large amalgams and crowns over 5 and 10 years when catastrophic subsequent treatment (root canal therapy or extraction) was the outcome. METHODS: Administrative data for patients seen at the University of Iowa, College of Dentistry for 1735 large amalgam and crown restorations in 1987 or 1988 were used. Annual costs and effectiveness values were calculated. Costs of initial treatment (large amalgam or crown), and future treatments were determined, averaged and discounted. The effectiveness measure was defined as the number of years a tooth remained in a state free of catastrophic subsequent treatment. Years free of catastrophic treatment were averaged, and discounted. The years free of catastrophic treatment accounted for individuals who dropped out or withdrew from the study. RESULTS: Teeth with crowns had higher effectiveness values at a much higher cost than teeth restored with large amalgams. The cost of an addition year free of catastrophic treatment for crowns was 1088.41 dollars at 5 years and 500.10 dollars at 10 years. Teeth in women had more favorable cost-effectiveness ratios than those in men, and teeth in the maxillary arch had more favorable cost-effectiveness ratios than teeth in the mandibular arch. CONCLUSIONS: Neither the large amalgam or crown restoration had both the lowest cost and the highest effectiveness. The higher incremental cost-effectiveness ratio for crowns should be considered when making treatment decisions between large amalgam and crown restorations.

Pharmacokinetics, absorption, and excretion of radiolabeled revexepride: a Phase I clinical trial using a microtracer and accelerator mass spectrometry-based approach.

PURPOSE: Gastroesophageal reflux disease involves the reflux of gastric and/or duodenal content into the esophagus. Prokinetic therapies, such as the selective 5-hydroxytryptamine receptor 4 agonist revexepride, may aid gastric emptying. This Phase I study evaluated the pharmacokinetics and excretion pathways of [14C]revexepride in healthy individuals using a microtracer approach with accelerator mass spectrometry. PARTICIPANTS AND METHODS: Six healthy men received a single oral dose of 2 mg [14C]revexepride containing ~200 nCi of radioactivity; blood, urine, and fecal samples were collected over a 10-day period. RESULTS: Almost 100% of 14C was recovered: 38.2%±10.3% (mean ± standard deviation) was recovered in urine, and 57.3%±0.4% was recovered in feces. Blood cell uptake was low, based on the blood plasma total radioactivity ratio of 0.8. The mean revexepride renal clearance was 8.6 L/h, which was slightly higher than the typical glomerular filtration rate in healthy individuals. Time to reach maximal concentration was 1.75±1.17 hours (mean ± standard deviation). No safety signals were identified. CONCLUSION: This study demonstrated that revexepride had rapid and moderate-to-good oral absorption. Excretion of radioactivity was completed with significant amounts in feces and urine. Renal clearance slightly exceeded the typical glomerular filtration rate, suggesting the involvement of active transportation in the renal tubules.