Human exposures to bisphenol A: mismatches between data and assumptions

Human exposure to bisphenol A (BPA), a synthetic estrogen found in numerous consumer products, is widespread. However, scientific knowledge about the sources and routes of exposure remains incomplete. Although human biomonitoring studies report small amounts of bioactive BPA in the blood of most subjects, toxicokinetic models suggest that circulating levels should be undetectable. The conflict between reported data and toxicokinetic models has spurred considerable debate, with some suggesting that data from analyses of human blood should be dismissed in their entirety. This review addresses the assumptions used by previous risk assessment panels regarding the sources and routes of exposure to BPA (specifically, that BPA exposures occur solely via a few dietary sources) and how these assumptions have affected the interpretation of BPA studies. Given new experimental evidence that route of exposure influences BPA pharmacokinetics, we consider the implications of basing regulatory decisions on limited data that have provided incomplete information about the products that contain this chemical and how it enters the body. We also address evidence that challenges the assumption that humans metabolize BPA rapidly enough to result in undetectable levels in blood and therefore determine that there is a possibility of harm from current exposure levels. Our conclusions are consistent with the large number of hazards and adverse effects identified in laboratory animals exposed to low doses of BPA.

Accumulation and pharmacokinetics of estrogenic chemicals in the pre- and post-hatch embryos of the frog Rana rugosa

Amphibian eggs spawned in water are exposed immediately to various chemicals present in their water. The present study aimed to investigate the accumulation and pharmacokinetics of 17α-ethynylestradiol (EE(2)), bisphenol A (BPA), and nonylphenol (NP), as well as 17β-estradiol (E(2)), in the pre-hatch and post-hatch embryos of the frog Rana rugosa. Fertilized eggs were exposed to chemicals at a final concentration of 500 nM in breeding water for two days, then the embryos with jelly coats were reared in fresh-breeding water without supplementation of the xenoestrogens for six more days. All exogenous chemicals were concentrated in the embryo body at two days after fertilization, whereas their concentrations in the jelly coat were the same as those in the breeding water. The bioconcentration factors for E(2), EE(2), BPA, and NP were 217.9, 170.2, 382.3, and 289.1, respectively, suggesting that the estrogenic chemicals were concentrated in the embryo body through the jelly coat.

Pharmacokinetics of empagliflozin, a sodium glucose cotransporter-2 (SGLT-2) inhibitor, coadministered with sitagliptin in healthy volunteers

INTRODUCTION

This randomized, open-label, crossover study investigated potential drug-drug interactions between the sodium glucose cotransporter-2 (SGLT-2) inhibitor empagliflozin and the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin. Empagliflozin is a potent and selective SGLT-2 inhibitor that lowers blood glucose levels by inhibiting renal glucose reabsorption, leading to an increase in urinary glucose excretion. Sitagliptin lowers blood glucose through an insulin-dependent mechanism of action.

METHODS

Sixteen healthy male volunteers received three treatments (A, B, C) in one of two treatment sequences (AB then C, or C then AB). In treatment AB, 50 mg empagliflozin was administered once daily (q.d.) for 5 days (treatment A), immediately followed by coadministration of 50 mg empagliflozin q.d. and 100 mg sitagliptin q.d. over 5 days (treatment B). In treatment C, 100 mg sitagliptin was administered q.d. for 5 days. A washout period of ≥7 days separated treatments AB and C.

RESULTS

Coadministration of sitagliptin with empagliflozin did not have a clinically relevant effect on the area under the concentration-time curve of the analyte in plasma at steady state over a uniform dosing interval τ (AUC(τ,ss)) (geometric mean ratio [GMR] 110.4; 90% confidence interval [CI] 103.9, 117.3) or maximum measured concentration of the analyte in plasma at steady state over a uniform dosing interval τ (C (max,ss)) (GMR 107.6; 90% CI 97.0, 119.4) of empagliflozin. Coadministration of empagliflozin with sitagliptin did not have a clinically meaningful effect on the AUC(τ,ss) (GMR 103.1; 90% CI 98.9, 107.3) or C (max,ss) (GMR 108.5; 90% CI 100.7, 116.9) of sitagliptin. Empagliflozin and sitagliptin were well tolerated when given alone or in combination. Five subjects (31.3%) reported at least one adverse event (AE): three (18.8%) experienced an AE while receiving empagliflozin monotherapy and three (18.8%) while receiving sitagliptin monotherapy. No adverse events were reported during the coadministration period. No AEs were regarded as drug-related by the investigator.

CONCLUSION

These results indicate that empagliflozin and sitagliptin can be coadministered without dose adjustments.

[Pharmacokinetics--pharmacodynamics of modafinil in mice]

To guide the reasonable clinical application of modafinil (MOD), pharmacokinetics and pharmacodynamics of MOD in mice and the correlation between them were investigated. Male mice (Kunming strain) were given a single oral dose of MOD (120 mg x kg(-1)). The plasma concentration of MOD was measured by HPLC and the pharmacokinetic parameters were calculated with DAS 3.0 software. For another batch of male Kunming strain mice, their locomotor activities were recorded by an infrared ray passive sensor after a same oral dose of MOD, and the synchronization and correlation between the changes of MOD plasma concentration and the locomotor activity induced by MOD were compared and analyzed. The results showed that the plasma concentration-time curve of MOD was fitted to two-compartment open model with a first order absorption. The main pharmacokinetic parameters t1/2alpha, t1/2beta, t(max), C(max) and AUC(0-inifinity) were 0.42 h, 3.10 h, 1.00 h, 41.34 mg x L(-1) and 142.22 mg x L(-1) x h, respectively. MOD significantly increased locomotor activity and the effect lasted for about 4 h. The changes of MOD plasma concentration and the locomotor activity induced by MOD were synchronous. In conclusion, there is a significant correlation between the effect of MOD and its plasma concentration after administration of 120 mg x kg(-1) in mice.

Studies on the preparation, characterization and pharmacological evaluation of tolterodine PLGA microspheres

In this study, poly(d,l-lactide-co-glycolide) (PLGA) microspheres of tolterodine depot formulation were prepared using oil in water (o/w) method to investigate their potential pharmacokinetic and pharmacodynamic advantages over tolterodine l-tartrate tablets. Morphological studies of the microspheres showed a spherical shape and smooth surface with mean size of 50.69-83.01 microm, and the encapsulation efficiency was improved from 62.55 to 79.10% when the polymer concentration increased from 180 to 230 mg/ml. The addition of stearic or palmitic acids could significantly raise the drug entrapment efficiency but only slightly affected the in vitro release. A low initial burst followed by a proximately constant release of tolterodine was noticed in the in vitro release profiles. The in vivo study was carried out by intramuscular (i.m.) administration of tolterodine-loaded microspheres on beagle dogs, and a sustained release of drug from the PLGA microspheres was achieved until the 18th day with a low initial burst. Since the absence of hepatic first pass metabolism, only a single active compound-tolterodine was detected in the plasma. This avoided the coexistence of two active compounds in plasma in the case of oral administration of tolterodine, which may lead to a difficulty in dose control due to the different metabolic capacity of patients. In the pharmacodynamic study, the influence of tolterodine PLGA microspheres on the inhibition of carbachol-induced rat urinary bladder contraction was more significant than that of tolterodine l-tartrate tablets. There were invisible changes in rat bladder slices between tolterodine-loaded PLGA microspheres group and tolterodine l-tartrate tablets group. These results indicate that the continuous inhibition of muscarinic receptor may offer an alternative therapy of urge incontinence.

Anti-tussive activity of benproperine enantiomers on citric-acid-induced cough in conscious guinea-pigs

The anti-tussive effect of the R-(+)- and S-(-)-enantiomers of benproperine was evaluated and compared with that of the racemate on cough induced by 7.5% citric acid in conscious guineapigs. All the three compounds, intraperitoneally administered 1.5 h before the test, significantly inhibited citric-acid-induced cough. The ID50 values (effective doses for 50% inhibition) (with 95% confidence intervals) were 16.1 (9.1–28.4), 23.3 (11.2–48.6), 25.4 (11.7–55.1) mg kg−1 for the number of coughs in the 3 min of challenge, and 11.9 (5.3–26.6), 13.5 (5.6–32.4), 19.2 (12.8–28.9) mg kg−1 for the number of coughs in the 5 min immediately after the challenge, for (+)-benproperine, R-(+)-benproperine and S-(-)-benproperine, respectively. These findings suggest that the use of either enantiomer does not show any advantage over the racemate with regard to their anti-tussive effect.

Modafinil: new indication. For a minority of patients with sleep apnoea

(1) The first-line treatment for patients with troublesome obstructive sleep apnoea syndrome is night-time nasal continuous positive airway pressure, which reduces daytime drowsiness and improves cognitive performance. (2) Modafinil, a non amphetamine psychostimulant already marketed for idiopathic narcolepsy and hypersomnia, is the first drug to be approved in France for the treatment of patients with residual daytime drowsiness despite nasal continuous positive airway pressure treatment. (3) Clinical evaluation of modafinil for this indication consists of two short-term double-blind placebo-controlled trials, lasting 4 and 12 weeks, and including a total of about 500 patients. At a dose of 400 mg/day, 68% of patients experienced an improvement in their daytime drowsiness (usually partial), compared to 37% of patients on placebo. It is not known how many patients no longer had any daytime drowsiness. A major improvement occurred in about 14% of patients (7% on placebo). (4) The main adverse effects of modafinil are neuropsychological (headache, nervousness, insomnia, anxiety, nausea). (5) In short, modafinil is an option to consider when continuous positive airway pressure is not sufficiently effective and when drowsiness continues to significantly interfere with daily activities. However, it only appears to provide a major benefit to about 10% of patients. The only important improvement is in daytime drowsiness, and this is often offset by adverse effects such as headache. Effects of long-term treatment are not known.

Comparative evaluation of central muscarinic receptor binding activity by oxybutynin, tolterodine and darifenacin used to treat overactive bladder

PURPOSE

We characterized muscarinic receptor binding in the mouse cerebral cortex after oral administration of anticholinergic agents used to treat overactive bladder.

MATERIALS AND METHODS

Muscarinic receptors in the mouse cerebral cortex and bladder after oral administration of anticholinergic agents were measured using [(3)H]N-methylscopolamine.

RESULTS

In vitro binding affinities of tolterodine and its metabolite 5-hydroxymethyl metabolite in the mouse cerebral cortex and bladder were considerably greater than those of oxybutynin and darifenacin. Also, muscarinic receptor binding affinity of oxybutynin and its metabolite N-desethyl-oxybutynin in the cerebral cortex compared with that in the bladder was 2 to 3 times higher, whereas that of tolterodine and 5-hydroxymethyl metabolite was approximately 2 times lower. Oral administration of oxybutynin (76.1 micromol/kg), tolterodine (6.31 micromol/kg) and darifenacin (59.1 micromol/kg) showed binding activity that was approximately equal to that of bladder muscarinic receptors. Oral administration of oxybutynin (76.1 micromol/kg) showed significant binding of cerebral cortical muscarinic receptors in mice, as indicated by about a 2-fold increase in K(d) values for specific [(3)H]N-methylscopolamine binding 0.5 and 2 hours later. On the other hand, tolterodine and darifenacin given at oral doses that would exert a similar extent of bladder receptor binding activity as oxybutynin showed only a low level of binding activity of central muscarinic receptors in mice.

CONCLUSIONS

Significant binding of brain muscarinic receptors in mice was observed by the oral administration of oxybutynin but not tolterodine and darifenacin.

Characterization of metabolites of a NK1 receptor antagonist, CJ-11,972, in human liver microsomes and recombinant human CYP isoforms by liquid chromatography/tandem mass spectrometry

The in vitro metabolism of CJ-11,972, (2-benzhydryl-1-aza-bicyclo[2.2.2]oct-3-yl)-(5-tert-butyl-2-methoxybenzyl)amine, an NK1 receptor antagonist, was studied in human liver microsomes and recombinant human CYP isoforms. Liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry (LC/MS/MS) coupled to radioactive detection were used to detect and identify the metabolites. CJ-11,972 was extensively metabolized in human liver microsomes and recombinant human CYP 3A4/3A5 isoforms. A total of fourteen metabolites were identified by a combination of various MS techniques. The major metabolic pathways were due to oxidation of the tert-butyl moiety to form an alcohol (M6) and/or O-demethylation of the anisole moiety. The alcohol metabolite M6 was further oxidized to the corresponding aldehyde (M7) and carboxylic acid (M4). Two unusual metabolites (M13, M17), formed by C-demethylation of the tert-butyl group, were identified as 2-{3-[(2-benzhydryl-1-aza-bicyclo[2.2.2]oct-3-ylamino)methyl]-4-methoxyphenyl}propan-2-ol and (2-benzhydryl-1-aza-bicyclo[2.2.2]oct-3-yl)-(5-isopropenyl-2-methoxybenzyl)amine. A plausible mechanism for C-demethylation may involve oxidation of M6 to form an aldehyde metabolite (M7), followed by cytochrome P450-mediated deformylation leaving an unstable carbon-centered radical, which would quickly form either the alcohol metabolite M13 and the olefin metabolite M17.

Disposition and metabolic profiling of bisphenol F in pregnant and nonpregnant rats

The distribution of bisphenol F (4,4'-dihydroxydiphenyl-methane, BPF) was studied in female Sprague-Dawley rats. Pregnant and nonpregnant animals were gavaged with a single dose of 7 or 100 mg/kg [3H]BPF and were kept for 96 h in metabolic cages. The excretion of BPF residues occurred mainly in urine (43-54% of the administered dose), which was found to contain at least six different metabolites, and to a lesser extent in feces (15-20% of the administered dose). Sulfatase treatment and subsequent high-performance liquid chromatography analyses suggest that the major urinary metabolite (more than 50% of the radioactivity present in urine) is a sulfate conjugate of BPF. At 96 h, BPF residues were detectable in all tissues examined with the largest amounts in the liver (0.5% of the dose). In pregnant rats dosed at day 17 of gestation, BPF residues were detected in the uterus, placenta, amniotic fluid, and fetuses (0.9-1.3% of the administered dose). Large amounts of radioactivity (8-10% of the dose) were still located in the digestive tract lumen at the end of the study. After administration of a single oral dose of [3H]BPF, 46% of the distributed radioactivity was excreted in bile over a 6 h period. In rats, BPF and/or its metabolites very likely undergo enterohepatic cycling, which could be responsible for the relatively high amounts of residues still excreted 4 days after BPF administration. This bisphenol is efficiently absorbed and distributed to the reproductive tract in female rats, and its residues pass the placental barrier at a late stage of gestation in rats.

Armodafinil, the R-enantiomer of modafinil: wake-promoting effects and pharmacokinetic profile in the rat

Modafinil reduces the excessive sleepiness associated with narcolepsy, obstructive sleep apnea/hypopnea syndrome, and shift work sleep disorder. In rats, modafinil promotes dose-dependent increases in wake duration. The wake-promoting activity of the R-enantiomer of modafinil (armodafinil) was evaluated in WKY rats and compared to the classical stimulant, D-methamphetamine. Electroencephalographic and electromyographic signals were assessed via a tethered cranial implant. Body temperature and locomotor activity were assessed by telemetry via intraperitoneal implant. Rats (n=60, 12 per group) were subjected to one of five parallel treatments: armodafinil at 30, 100 and 300 mg/kg i.p.; D-methamphetamine, 1 mg/kg i.p. and vehicle. Armodafinil and D-methamphetamine increased time spent awake relative to vehicle. Armodafinil-evoked increases in wake duration were dose-dependent and proportional to plasma compound exposure. Induction of wakefulness by D-methamphetamine was associated with an approximately two-fold increase in locomotor activity during the 2-h period immediately following administration relative to vehicle. D-methamphetamine also increased body temperature over the same time interval. The dose of armodafinil (100 mg/kg, i.p.) that was closest to D-methamphetamine in its wake-promoting efficacy did not produce changes in either body temperature or the intensity of locomotor activity relative to vehicle. Acute rebound hypersomnolence, characterized by increases in non-rapid eye movement sleep (NREMS) as a percentage of time and NREMS bout duration and by a decreased frequency of brief awakenings following sleep deprivation, occurred following D-methamphetamine-but not armodafinil-induced wake in this rat model which has been shown to be predictive of human drug responses.

Effect of the proton pump inhibitor omeprazole on the pharmacokinetics of extended-release formulations of oxybutynin and tolterodine

This study assessed the effect of the proton pump inhibitor omeprazole on the bioavailability of the extended-release formulations of oxybutynin and tolterodine. Forty-four healthy volunteers received each of 4 treatments in a 4-period crossover design. The treatments consisted of osmotically controlled extended-release oxybutynin chloride tablets at 10 mg/d or extended-release tolterodine tartrate capsules at 4 mg/d, with and without preceding treatment with 20 mg omeprazole daily for 4 days. Blood samples collected predose and at scheduled time points for 36 hours postdose were analyzed for oxybutynin and its active metabolite, N-desethyloxybutynin, or tolterodine and its active 5-hydroxymethyl metabolite, as appropriate. The AUCinfinity ratios for oxybutynin and its metabolite with and without prior omeprazole fell within the 80% to 125% range (accepted as the criterion for bioequivalence), as did those for tolterodine and its active moiety. The peak concentration ratios for oxybutynin and metabolite also conformed to this range; those for tolterodine did not. Increasing gastric pH with omeprazole does not substantially alter the pharmacokinetic properties of extended-release oxybutynin but may alter those of extended-release tolterodine.

A review of the use of modafinil for attention-deficit hyperactivity disorder

Modafinil (Provigil) is a novel wakefulness-promoting agent that has been shown to have greater efficacy than placebo in the treatment of attention-deficit hyperactivity disorder (ADHD) in children and adults. In particular, three large, drug-company sponsored trials of a film-coated formulation of modafinil (modafinil-ADHD; Sparlon) in children and adolescents with ADHD demonstrated consistent improvements in ADHD symptoms compared with placebo. Mean reductions in symptom ratings (measured using the ADHD-Rating Scale-IV school version questionnaire) ranged from 15.0 to 19.7 (7.3 to 10.1 for placebo). The most common adverse events were insomnia, headache and decreased appetite. Modafinil was generally well tolerated with most side effects considered mild to moderate in severity. Modafinil may have advantages over current therapies for ADHD in that it can be administered once daily and has fewer reinforcing properties than traditional stimulants. Modafinil could potentially be a valuable new treatment option for patients with ADHD. However, rigorous comparative studies with current first-line treatments for ADHD and longer-term independent studies are necessary before modafinil's role in the treatment of ADHD can be fully established.

Modafinil: is it ready for prime time?

Psychostimulants have been used to treat many symptoms associated with advanced cancer. The primary role of psychostimulants in such cases is the treatment of symptoms such as cancer-related fatigue, opioid-induced sedation, depression, and cognitive dysfunction associated with malignancies. These uses for psychostimulants came after approval for treatment of disorders such as attention deficit disorder. Modafinil, a new psychostimulant, is following a similar path after its approval for use in attention deficit disorder in 1998. Modafinil has been used to treat fatigue associated with neurodegenerative disorders such as multiple sclerosis and amyotrophic lateral sclerosis. It is now being increasingly used for cancer-related symptoms targeted by psychostimulants. Preliminary evidence from literature review suggests that modafinil is efficacious in improving opioid-induced sedation, cancer-related fatigue, and depression. There is no evidence to support its use in the treatment of cognitive dysfunction related to cancer or to support its having analgesic properties. Well-designed, randomized, controlled clinical trials are still needed to further elucidate the precise role of this drug in the care of patients with cancer. Specifically, large placebo-controlled trials with modafinil must be conducted in patients with cancer, with specific attention paid to pain control, depression, cognitive function, and adverse effects.

Modafinil: new indications for wake promotion

In January 2004, the wake-promoting agent, modafinil, was approved in the US for the treatment of excessive sleepiness (ES) associated with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) and shift-work sleep disorder (SWSD), representing an expansion of its labelling from the initial indication for ES associated with narcolepsy. A total of five randomised, placebo-controlled studies in these three disorders showed statistically significant benefits on various objective measures and subjective estimates of ES, including the Multiple Sleep Latency Test, Maintenance of Wakefulness Test, Epworth Sleepiness Scale and Karolinska Sleepiness Scale. Significant improvement was also seen in overall clinical condition (on the Clinical Global Impression of Change) and measures of sustained attention and reaction time (on the Psychomotor Vigilance Task). The clinical efficacy of modafinil, combined with improved safety over CNS stimulants, has made it the most prescribed medication for the treatment of ES associated with narcolepsy. Modafinil is the only medication approved for ES associated with OSAHS and SWSD (for OSAHS, it is indicated as an adjunct to standard treatments for the under-lying obstruction). Unlike many other medications used for ES, modafinil is not known to be abused. The most common adverse event reported in clinical studies was headaches; most were transient and mild-to-moderate in severity. Modafinil also has the potential for interactions with other drugs metabolised via cytochrome P450 enzyme pathways. Potential obstacles to the use of modafinil include an under-recognition of ES and its consequences. Increased education, both of the public and the medical community, should improve the recognition and therapy of ES.

Analysis of biomarkers in rats and dogs exposed to polymeric methylenediphenyl diisocyanate (pMDI) and its glutathione adduct

Hemoglobin adducts (Hb-MDX) of monomeric methylenediphenyl diisocyanate (MDI) are often interpreted as indirect evidence of hydrolysis of the diisocyanate moiety to the respective amine (diphenylmethane-4,4'-diamine, 4,4'-MDA) which constitutes the rationale of using this biomarker as an internal dosimeter of exposure to putatively formed MDA. In contrast, more recently published data suggest that following inhalation the high concentration of glutathione (GSH) present in lungs favor an adduct formation with GSH and/or peptides/proteins rather than hydrolysis. The focus of this study was to test this alternate hypothesis, viz. whether Hb-MDX can also be formed by the GSH bis-adduct of monomeric MDI. The synthesized mMDI-GSH bis-adduct was administered to rats by single intratracheal instillation. Additional groups were dosed by gavage and intraperitoneal injection. Biomarkers of exposure were determined in blood (plasma protein and hemoglobin adducts) and urine after harsh alkaline and acid hydrolysis, respectively. Data from previous single inhalation exposure studies with aerosols of MDI and 4,4'-MDA in rats served as reference. As to whether N-acetylation plays any modifying role to yield these mMDI-specific biomarkers was addressed in similarly head-only exposed dogs, a species with no appreciable N-acetylation capacity whereas rats are strong N-acetylators. The results obtained suggest that biomarkers in blood from controlled exposures above current workplace standards of mMDI appear not to be suitable for reliable assessments of past exposures. The biomarkers typically used to assess past exposures to MDI were also identified following exposure to the MDI-GSH bis-adduct. Their yield was low but quite similar for MDI aerosol and the MDI-GSH bis-adduct, whilst that of MDA was distinctively higher. The findings of this study are supportive of a conceptual pathway that the MDI-derived biomarkers of exposure are formed through MDI-GSH adducts rather than MDA. Data from dogs support the findings from rats and show that N-acetylation does not appear to be an essential modifying factor. It is concluded that the yield of MDI-related markers of exposure is relatively low and dependent on the exposure dose (and route). MDA originating from hydrolyzed serum protein or hemoglobin appear to be confounded by false-positive background levels which are surmised to be associated with the method of hydrolysis. The determination of urinary biomarkers might be a useful tool to identify recent exposures (by any route). Due methodological uncertainties associated with the harsh hydrolysis of biological specimens may be reduced substantially when using incremental pre- to post-shift changes rather than relying solely on absolute data.

Identification and quantitative determination of benproperine metabolites in human plasma and urine by liquid chromatography–tandem mass spectrometry

Two novel metabolites of benproperine (BPP), 1-[1-methyl-2-[2-(phenylmethyl)phenoxy]ethyl]-3-piperidinol (3-OH-BPP) and 1-[1-methyl-2-[2-(phenylmethyl)phenoxy]ethyl]-4-piperidinol (4-OH-BPP), were confirmed by comparison of retention times and mass spectra with those of synthetic standards using liquid chromatography-tandem mass spectrometry. Selective and sensitive procedures were developed for the simultaneous determination of BPP, 3-OH-BPP and 4-OH-BPP in human plasma and urine. The analytes were extracted from plasma sample and enzymatically hydrolyzed urine samples by liquid-liquid extraction, separated through a Diamonsil C(18) column (150 mm x 4.6 mm i.d.) and determined by tandem mass spectrometry with an electrospray ionization interface in selected reaction monitoring mode. Dextromethorphan was used as internal standard. The mobile phase consisted of acetonitrile-water-formic acid (34:66:1, v/v/v), and flow-rate was 0.5 ml min(-1). This method has a lower limit of quantification (LLOQ) of 60, 4.0 and 4.0 nmol l(-1)for BPP, 3-OH-BPP and 4-OH-BPP in plasma, 4.9, 4.7 and 2.4 nmol l(-1) in urine, respectively. The intra- and inter-run precision were measured to be below 9.2%, and the accuracy was within +/-4.3% for the analytes. The method was successfully used to determine BPP, 3-OH-BPP and 4-OH-BPP in plasma and urine for pharmacokinetic investigation. The results indicated residue of 3-OH-BPP in the body at least 192 h after an oral dose of BPP.

Pharmacodynamic effects on alertness of single doses of armodafinil in healthy subjects during a nocturnal period of acute sleep loss

OBJECTIVE

To assess the pharmacodynamics of armodafinil compared with modafinil and placebo on measures of alertness in healthy volunteers undergoing sleep loss.

RESEARCH DESIGN AND METHODS

In a double-blind, active- and placebo-controlled, parallel-group study, 107 healthy male volunteers (aged 18-40 years) were randomized to receive a single oral dose of armodafinil (100, 150, 200, or 300 mg), modafinil (200 mg), or placebo administered at 19:25 h.

MAIN OUTCOME MEASURES

The primary outcome was the Maintenance of Wakefulness Test (MWT), administered every 2 hours from 22:00-08:00 h. Secondary outcomes included the Psychomotor Vigilance Task (PVT) and the Karolinska Sleepiness Scale. Blood samples for pharmacokinetic analysis were collected hourly. Adverse events were evaluated throughout the 2-day laboratory stay and by telephone on day 9.

RESULTS

All four doses of armodafinil, and the dose of 200 mg modafinil, improved wakefulness as measured by increased MWT latencies (treatment effect, p < 0.0001) and reduced PVT lapses of attention (treatment effect, p < 0.0001). The magnitude and duration of these effects at the later time points appeared to be dose and concentration dependent. Armodafinil at 200 mg resulted in comparable C(max), a later t(max), and higher plasma concentrations 6-14 hours post-drug administration than with 200 mg modafinil. Following armodafinil, longer MWT latencies and fewer PVT lapses 6 to approximately 14 hours post-drug administration were observed compared with modafinil. Armodafinil doses were well tolerated, with the most common adverse events including abdominal pain, nausea, and headache. There were reports of tachycardia/palpitations. Decreased mean sleep efficiency and increased mean blood pressure were also observed.

CONCLUSION

Armodafinil improved alertness at all doses studied. Relative to modafinil 200 mg, armodafinil 200 mg showed a comparable peak plasma concentration with higher concentrations 6-14 hours post-drug, and improved wakefulness and sustained attention for a longer time post-dose. Both drugs were well tolerated; however, further research on the efficacy, safety, and tolerability of armodafinil in patients with disorders of excessive sleepiness (ES) is required.

High performance liquid chromatography-electrospray ionization mass spectrometric determination of tolterodine tartrate in human plasma

A selective and sensitive high performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the determination of tolterodine tartrate in human plasma. With oxybutynin as internal standard, tolterodine tartrate was extracted from plasma with n-hexane: isopropanol (95:5, v/v). The organic layer was evaporated and the residue was redissolved in mobile phase comprised of acetonitrile-water (10 mM CH3COONH4, pH 3.0)=50:50 (v/v). An aliquot of 10 microl was chromatographically analyzed on a prepacked Shimadzu Shim-pack VP-ODS C18 column (150 mmx2.0 mm I.D.) by means of selected-ion monitoring (SIM) mode mass spectrometry. Standard curves were linear (r=0.9993) over the concentration range of 0.1-30.0 ng/ml and had good accuracy and precision. The within- and between-batch precisions were within 10% relative standard deviation. The limit of detection (LOD) was 0.05 ng/ml. The validated LC-ESI-MS method has been used successfully to study tolterodine tartrate pharmacokinetic, bioavailability and bioequivalence in 20 healthy male volunteers.

Detection of modafinil in human urine by gas chromatography–mass spectrometry

The main purpose of this study was to detect and quantify modafinil in human urine by gas chromatography-mass spectrometry (GC-MS). Urinary samples were collected from three healthy male volunteers following oral administration of a clinical dose (100 mg) of modafinil (Provigil). Urine specimens were extracted with t-butylmethyl ether (TBME) prior to GC-MS analysis. The results demonstrate that the chromatographic characteristics and the mass spectrum of the unchanged parent drug extracted from urine samples were identical to that obtained from the authentic standard. The times for the unchanged modafinil to reach peak concentration in the urine of the three volunteers were at 2 h (6.14 microg/mL), 4 h (9.93 microg/mL) and 8 h (3.58 microg/mL), respectively. Total clearance occurred in approximately 48-72 h with 2-5% eliminated through urine as unchanged modafinil. The present study demonstrates that modafinil is detectable in the absence of hydrolysis and derivatization steps.

Reinforcing effects of modafinil: influence of dose and behavioral demands following drug administration

RATIONALE

The reinforcing effects of stimulant drugs are modulated by behavioral demands following drug administration.

OBJECTIVE

The objective of this study was to assess the reinforcing effects of modafinil, a drug with purportedly low abuse potential, under different behavioral demands using a modified progressive-ratio procedure.

METHODS

The reinforcing effects of oral modafinil (0, 100, 200, and 400 mg) were assessed in six healthy adult volunteers under both performance and relaxation conditions. Performance sessions required volunteers to complete simple arithmetic problems for three 50-min blocks. Relaxation sessions required volunteers to sit quietly in a semi-reclined position in a darkened room for three 50-min blocks. Two sampling sessions (one performance and one relaxation session) always preceded two self-administration sessions (one performance and one relaxation session), and the order of performance and relaxation sessions was constant within a dose condition.

RESULTS

Modafinil significantly increased break point and number of capsules earned on the modified progressive-ratio procedure as an increasing function of dose under the performance, but not the relaxation, condition. Modafinil produced comparable stimulant-like subjective ratings under both the performance and relaxation conditions.

CONCLUSION

The findings of the present experiment demonstrate that modafinil can function as a reinforcer and that the reinforcing effects of modafinil are influenced by behavioral demands following drug administration, similar to those of other stimulant drugs.

USE OF TOLTERODINE IN CHILDREN WITH NEUROGENIC DETRUSOR OVERACTIVITY: RELATIONSHIP BETWEEN DOSE AND URODYNAMIC RESPONSE

PURPOSE

Three exploratory studies were conducted to investigate the pharmacokinetics (PK) and safety of tolterodine in children 1 month to 15 years old with neurogenic detrusor overactivity. We urodynamically evaluated the dose and concentration effects of tolterodine to establish safe and effective dosing regimens.

MATERIALS AND METHODS

Three open-label, dose escalating studies were conducted in children with stable neurological disease and detrusor overactivity. In studies 1 (patient aged 1 month to 4 years) and 2 (5 to 10 years) patients received 0.03, 0.06 and 0.12 mg/kg tolterodine solution day twice daily for 4 weeks each. In study 3 (patient age 11 to 15 years) patients received 2, 4 and 6 mg tolterodine extended-release capsules once daily for 4 weeks each. PK was assessed after 8 weeks, urodynamic assessments were conducted after each 4-week dosing period and 3-day micturition diaries were completed.

RESULTS

Patients in studies 1 (19) and 2 (15) showed some dose related increases in volume to first detrusor contraction and cystometric bladder capacity. In study 3 (11 patients) there were no obvious dose-response relationships. PK results from studies 1 and 2 suggest that there was no apparent effect of age (< or =10 y) on these parameters. In study 3 time of maximum observed serum concentration and apparent terminal half-life were delayed, which is consistent with the extended-release formulation. Tolterodine was well tolerated, and there was no apparent relationship between tolterodine dose and adverse events in any study.

CONCLUSIONS

These results support the safety of age and body weight adjusted dosing regimens for further clinical evaluation of tolterodine in children with neurogenic detrusor overactivity.

Tolterodine for the treatment of overactive bladder: a review

Overactive bladder (OAB) is a prevalent condition. Numerous clinical trials have demonstrated the efficacy and safety of immediate release tolterodine in the treatment of OAB in different patient populations. This review details the characteristics, clinical efficacy and safety of extended release (ER) tolterodine. This formulation yields a flatter serum concentration profile and provides clinically meaningful symptom improvement as early as week 1 of treatment. Tolterodine ER is effective in diverse patient populations with varying levels of symptom severity, and efficacy is maintained with long-term treatment. Tolterodine is an effective, safe, and convenient treatment option for long-term relief of OAB symptoms.