Association between concentrations of chromium in drinking water and mortality due to suicide in Alabama.

Preclinical studies and clinical data from case series and placebo-controlled trials suggest that chromium might have antidepressant effects. We conducted an observational study in order to assess the association between concentrations of chromium in drinking water and mortality due to suicide in Alabama. Publicly available databases were used to determine both county-level concentrations of chromium in drinking water and county-level rates of mortality due to suicide in the years 2005-2015. Data analyses comparing county-level concentrations of total chromium in drinking water with mortality rate due to suicide were conducted using a two-tailed nonparametric Spearman's rank correlation, with statistical significance set at p ≤ 0.01 and 99% confidence interval. Sub-analyses were conducted examining males, females, whites, and blacks/other minorities. There were no statistically significant findings concerning concentrations of chromium and suicide rate in the general population (p = 0.35, r = -0.12); however, there was a statistically significant inverse relationship between the concentration of chromium and suicide deaths in whites (p = 0.009, r = -0.32). There were no statistically significant findings in the remaining demographic subgroups. Chromium in drinking water might have a protective effect against mortality due to suicide, at least in the Caucasian population.

Age- and Genotype-Specific Effects of the Angiotensin-Converting Enzyme Inhibitor Lisinopril on Mitochondrial and Metabolic Parameters in Drosophila melanogaster.

The angiotensin-converting enzyme (ACE) is a peptidase that is involved in the synthesis of Angiotensin II, the bioactive component of the renin-angiotensin system. A growing body of literature argues for a beneficial impact of ACE inhibitors (ACEi) on age-associated metabolic disorders, mediated by cellular changes in reactive oxygen species (ROS) that improve mitochondrial function. Yet, our understanding of the relationship between ACEi therapy and metabolic parameters is limited. Here, we used three genetically diverse strains of Drosophila melanogaster to show that Lisinopril treatment reduces thoracic ROS levels and mitochondrial respiration in young flies, and increases mitochondrial content in middle-aged flies. Using untargeted metabolomics analysis, we also showed that Lisinopril perturbs the thoracic metabolic network structure by affecting metabolic pathways involved in glycogen degradation, glycolysis, and mevalonate metabolism. The Lisinopril-induced effects on mitochondrial and metabolic parameters, however, are genotype-specific and likely reflect the drug's impact on nutrient-dependent fitness traits. Accordingly, we found that Lisinopril negatively affects survival under nutrient starvation, an effect that can be blunted by genotype and age in a manner that partially mirrors the drug-induced changes in mitochondrial respiration. In conclusion, our results provide novel and important insights into the role of ACEi in cellular metabolism.

Enzymatic Stability of Alteplase Solution for Injection: Effect of Various Methods of Thawing Frozen Solutions.

Objective: To modify and evaluate an established chromogenic assay protocol for measuring plasminogen activator inhibitor type-1 (PAI-1) activity to measure tissue plasminogen activator (tPA) activity and compare the enzymatic activity of alteplase as a function of the conditions under which it is thawed. Methods: A 50 mg vial of alteplase was reconstituted with sterile water to make a 1 mg/mL stock solution (nominal concentration). Plastic syringes were loaded with 0.5 mL of alteplase stock solution and stored at -20°C. After 8 days, samples were thawed by 3 methods - via body temperature (37°C), room temperature (20°C), or in a refrigerator (2°C). Thaw times were recorded. The thawed solutions, along with a freshly prepared alteplase solution, were assayed using the modified protocol of the Spectrolyse PAI-1 kit to determine residual tPA enzyme activity. Results: Validation of the modified protocol for the Spectrolyse PAI-1 kit used to measure tPA activity produced a linear response with coefficients of determination (R2) of greater than 0.9977 when assayed on 2 separate days, which corresponded to an enzymatic activity accuracy between 98.3% and 108.3%. The average percent residual tPA enzyme activity of samples from each group compared to the freshly prepared solution was 106%, 98.7%, and 91.5% for samples thawed at body temperature, room temperature, and refrigerated, respectively. Conclusion: Modifications to the standard procedure for the Spectrolyse PAI-1 kit allows for accurate determination of tPA activity in aqueous based reconstituted solutions of alteplase. Under thawed conditions, alteplase retained greater than 91% enzyme activity as compared to a freshly prepared control.

A Novel Pan-RAS Inhibitor with a Unique Mechanism of Action Blocks Tumor Growth in Mouse Models of GI Cancer.

Here, we describe a novel pan-RAS inhibitor, ADT-007, that potently inhibited the growth of RAS mutant cancer cells irrespective of the RAS mutation or isozyme. RAS WT cancer cells with activated RAS from upstream mutations were equally sensitive. Conversely, cells from normal tissues or RAS WT cancer cells harboring downstream BRAF mutations were insensitive. Insensitivity to ADT-007 was attributed to low activated RAS levels and metabolic deactivation by UDP-glucuronosyltransferases expressed in normal cells but repressed in RAS mutant cancer cells. Cellular, biochemical, and biophysical experiments show ADT-007 binds nucleotide-free RAS to block GTP activation of RAS and MAPK/AKT signaling. Local administration of ADT-007 strongly inhibited tumor growth in syngeneic immune-competent and xenogeneic immune-deficient mouse models of colorectal and pancreatic cancer while activating innate and adaptive immunity in the tumor immune microenvironment. Oral administration of ADT-007 prodrug inhibited tumor growth, supporting further development of this novel class of pan-RAS inhibitors for treating RAS-driven cancers. SIGNIFICANCE: ADT-007 is a 1 st -in-class pan-RAS inhibitor with ultra-high potency and unique selectivity for cancer cells with mutant or activated RAS capable of circumventing resistance and activating antitumor immunity. Further development of ADT-007 analogs or prodrugs with oral bioavailability as a generalizable monotherapy or combined with immunotherapy is warranted.

The brain-penetrant cell-cycle inhibitor p28 sensitizes brain metastases to DNA-damaging agents.

Background: Brain metastases (BMs), the most common tumors of the central nervous system, are life-threatening with a dismal prognosis. The major challenges to developing effective treatments for BMs are the limited abilities of drugs to target tumors and to cross the blood-brain barrier (BBB). We aimed to investigate the efficacy of our therapeutic approach against BMs in mouse models that recapitulate the clinical manifestations of BMs. Methods: BMs mouse models were constructed by injecting human breast, lung cancer, and melanoma intracardially, which allowed the BBB to remain intact. We investigated the ability of the cell-penetrating peptide p28 to cross the BBB in an in vitro 3D model and in the BMs animal models. The therapeutic effects of p28 in combination with DNA-damaging agents (radiation and temozolomide) on BMs were also evaluated. Results: p28 crossed the intact BBB more efficiently than the standard chemotherapeutic agent, temozolomide. Upon crossing the BBB, p28 localized preferentially to tumor lesions and enhanced the efficacy of DNA-damaging agents by activating the p53-p21 axis. In the BMs animal models, radiation in combination with p28 significantly reduced the tumor burden of BMs. Conclusions: The cell-cycle inhibitor p28 can cross the BBB localize to tumor lesions in the brain and enhance the inhibitory effects of DNA-damaging agents on BMs, suggesting the potential therapeutic benefits of this molecule in BMs.

Interaction between buprenorphine and norbuprenorphine in neonatal opioid withdrawal syndrome.

Buprenorphine (BUP) is the preferred treatment for opioid use disorder during pregnancy but can cause neonatal opioid withdrawal syndrome (NOWS). Norbuprenorphine (NorBUP), an active metabolite of BUP, is implicated in BUP-associated NOWS. We hypothesized that BUP, a low-efficacy agonist of mu opioid receptors, will not antagonize NorBUP, a high-efficacy agonist of mu opioid receptors, in producing NOWS. To test this hypothesis, we treated pregnant Long-Evans rats with BUP (0, 0.01, 0.1 or 1mg/kg/day) ± NorBUP (1mg/kg/day) from gestation day 9 until pup delivery, and tested pups for opioid dependence using our established NOWS model. We used LC-MS-MS to quantify brain concentrations of BUP, NorBUP, and their glucuronide conjugates. BUP had little effect on NorBUP-induced NOWS, with the exception of 1mg/kg/day BUP significantly increasing NorBUP-induced NOWS by 58% in females. BUP and NorBUP brain concentrations predicted NOWS in multiple linear regression models. Interestingly, NorBUP contributed more to NOWS in females (ßNorBUP = 51.34, p = 0.0001) than in males (ßNorBUP = 19.21, P = 0.093), while BUP was similar for females (ßBUP = 10.62, P = 0.0017) and males (ßBUP = 11.38, P = 0.009). We are the first to report that NorBUP induces NOWS in the presence of BUP and it is more influential in females than males in the contribution of NorBUP to BUP-associated NOWS. These findings suggest that females are more susceptible to NorBUP-induced NOWS, and that treatment strategies that reduce prenatal NorBUP exposure may be more effective for females than males.

Deuterated buprenorphine retains pharmacodynamic properties of buprenorphine and resists metabolism to the active metabolite norbuprenorphine in rats.

Introduction: An active metabolite of buprenorphine (BUP), called norbuprenorphine (NorBUP), is implicated in neonatal opioid withdrawal syndrome when BUP is taken during pregnancy. Therefore, reducing or eliminating metabolism of BUP to NorBUP is a novel strategy that will likely lower total fetal exposure to opioids and thus improve offspring outcomes. Precision deuteration alters pharmacokinetics of drugs without altering pharmacodynamics. Here, we report the synthesis and testing of deuterated buprenorphine (BUP-D2). Methods: We determined opioid receptor affinities of BUP-D2 relative to BUP with radioligand competition receptor binding assays, and the potency and efficacy of BUP-D2 relative to BUP to activate G-proteins via opioid receptors with [35S]GTPγS binding assays in homogenates containing the human mu, delta, or kappa opioid receptors. The antinociceptive effects of BUP-D2 and BUP were compared using the warm-water tail withdrawal assay in rats. Blood concentration versus time profiles of BUP, BUP-D2, and NorBUP were measured in rats following intravenous BUP-D2 or BUP injection. Results: The synthesis provided a 48% yield and the product was ≥99% deuterated. Like BUP, BUP-D2 had sub-nanomolar affinity for opioid receptors. BUP-D2 also activated opioid receptors and induced antinociception with equal potency and efficacy as BUP. The maximum concentration and the area under the curve of NorBUP in the blood of rats that received BUP-D2 were over 19- and 10-fold lower, respectively, than in rats that received BUP. Discussion: These results indicate that BUP-D2 retains key pharmacodynamic properties of BUP and resists metabolism to NorBUP and therefore holds promise as an alternative to BUP.

Nontoxic Tumor-Targeting Optical Agents for Intraoperative Breast Tumor Imaging.

Precise identification of the tumor margins during breast-conserving surgery (BCS) remains a challenge given the lack of visual discrepancy between malignant and surrounding normal tissues. Therefore, we developed a fluorescent imaging agent, ICG-p28, for intraoperative imaging guidance to better aid surgeons in achieving negative margins in BCS. Here, we determined the pharmacokinetics (PK), biodistribution, and preclinical toxicity of ICG-p28. The PK and biodistribution of ICG-p28 indicated rapid tissue uptake and localization at tumor lesions. There were no dose-related effect and no significant toxicity in any of the breast cancer and normal cell lines tested. Furthermore, ICG-p28 was evaluated in clinically relevant settings with transgenic mice that spontaneously developed invasive mammary tumors. Intraoperative imaging with ICG-p28 showed a significant reduction in the tumor recurrence rate. This simple, nontoxic, and cost-effective method can offer a new approach that enables surgeons to intraoperatively identify tumor margins and potentially improves overall outcomes by reducing recurrence rates.

Pharmacokinetic and Histopathologic Study of an Extended-Release, Injectable Formulation of Buprenorphine in Sprague-Dawley Rats.

A novel buprenorphine (BUP) extended-release formulation (BUP-XR) produced as a lipid-encapsulated, low viscosity BUP suspension for SC injection to control pain was evaluated for pharmacokinetics and safety in Sprague-Dawley rats given either 0.65 mg/kg (low dose) or 1.30 mg/kg (high dose). The 2 dosage groups each contained 6 male and 6 female rats to determine whether BUP-XR behaved differently in male or female animals. Blood samples were obtained from each animal before BUP-XR administration and at 6, 24, 48, 72, 96, and 168 h after administration. For necropsy and injection-site histopathology evaluation, 3 animals of each sex from each test group were euthanized on day 8, with the remaining animals euthanized on day 15. Mean plasma BUP concentration peaked from 6 to 24 h in all test groups, then declined in a linear fashion. Quantifiable plasma BUP was measured in all male rats at all time points except for one low dose group sample taken at 168 h. Female rats had quantifiable plasma BUP at all time points except for 1 low dose group sample at 72 and 96 h, and 2 low dose group samples at 168 h. The low dose groups, whether male or female, had lower mean plasma BUP levels at all time points as compared with their high dose counterparts, and female rats had lower mean plasma BUP levels than male rats at all time points. Results indicate that a single BUP-XR dose at either dose concentration can reliably provide plasma levels of BUP reported in the literature to be therapeutically relevant for up to 72 h, although lower plasma BUP levels can be anticipated in female rats compared with male counterparts. Mild to moderate injection-site granulomatous inflammation was observed in 6 of 12 rats in the low dose group and 7 of 12 in the high dose group. This reaction is characteristic of lipid material designed to persist in situ.

A comparison of the pharmacokinetics of perfluorobutanesulfonate (PFBS) in rats, monkeys, and humans.

Materials derived from perfluorobutanesulfonyl fluoride (PBSF, C(4)F(9)SO(2)F) have been introduced as replacements for eight-carbon homolog products that were manufactured from perfluorooctanesulfonyl fluoride (POSF, C(8)F(17)SO(2)F). Perfluorobutanesulfonate (PFBS, C(4)F(9)SO(3)(-)) is a surfactant and potential degradation product of PBSF-derived materials. The purpose of this series of studies was to evaluate the pharmacokinetics of PFBS in rats, monkeys, and humans, thereby providing critical information for human health risk assessment. Studies included: (1) intravenous (i.v.) elimination studies in rats and monkeys; (2) oral uptake and elimination studies in rats; and (3) human serum PFBS elimination in a group of workers with occupational exposure to potassium PFBS (K(+)PFBS). PFBS concentrations were determined in serum (all species), liver (rats), urine (all species), and feces (rats). In rats, the mean terminal serum PFBS elimination half-lives, after i.v. administration of 30mg/kg PFBS, were: males 4.51+/-2.22h (standard error) and females 3.96+/-0.21h. In monkeys, the mean terminal serum PFBS elimination half-lives, after i.v. administration of 10mg/kg PFBS, were: males 95.2+/-27.1h and females 83.2+/-41.9h. Although terminal serum half-lives in male and female rats were similar, without statistical significance, clearance (CL) was significantly greater in female rats (469+/-40mL/h) than male rats (119+/-34mL/h) with the area under the curve (AUC) significantly larger in male rats (294+/-77microg.h/mL) than female rats (65+/-5microg.h/mL). These differences were not observed in male and female monkeys. Volume of distribution estimates suggested distribution was primarily extracellular in both rats and monkeys, regardless of sex, and urine appeared to be a major route of elimination. Among 6 human subjects (5 male, 1 female) followed up to 180 days, the geometric mean serum elimination half-life for PFBS was 25.8 days (95% confidence interval 16.6-40.2). Urine was observed to be a pathway of elimination in the human. Although species-specific differences exist, these findings demonstrate that PFBS is eliminated at a greater rate from human serum than the higher chain homologs of perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonate (PFHxS). Thus, compared to PFOS and PFHxS, PFBS has a much lower potential for accumulation in human serum after repeated occupational, non-occupational (e.g., consumer), or environmental exposures.

Comparison of pharmacokinetic and metabolic profiling among gossypol, apogossypol and apogossypol hexaacetate.

PURPOSE: To characterize the stability, pharmacokinetics and metabolism of analogs of gossypol, apogossypol and apogossypol hexaacetate to provide a basis for comparison. METHODS: Gossypol, apogossypol and apogossypol hexaacetate were incubated in plasma or liver microsomes from various species, or administered to mice, respectively, from which the stability, metabolism and pharmacokinetic profiles of these analogs were quantitatively determined using a liquid chromatography-mass spectrometry (LC/MS/MS) method. RESULTS: In various species of plasma, apogossypol and gossypol exhibited similar stability, while 20-40% of apogossypol hexaacetate was converted into apogossypol with concurrent formation of the corresponding di-, tri-, tetra-, and penta-acetates of apogossypol. (+/-)-Gossypol and (-)-gossypol showed comparable pharmacokinetic profile and oral bioavailability (12.2-17.6%) with some variations of clearance and V (ss) following oral and intravenous administration to mice. At the same molar dose, apogossypol showed delayed T (max)(1 h), a slower clearance rate and less distribution after administration to mice. Mono- and di-glucuronide conjugates of apogossypol were readily observed in mouse plasma following administration. Apogossypol formulated in sesame oil appeared to possess larger AUC and thus higher oral bioavailability than that formulated in cremophor EL:ethanol:saline. In contrast, intravenous apogossypol hexaacetate exhibited highest clearance rate partially due to its conversion into apogossypol. Concomitant with disappearance of apogossypol hexaacetate (iv), apogossypol converted from apogossypol hexaacetate was quantitatively detected, and accounted for approximately 30% of total plasma apogossypol hexaacetate. Oral apogossypol hexaacetate showed no bioavailability with little apogossypol occurring in the plasma. In human and mouse liver microsomes, glucuronide conjugates of apogossypol and its acetates were readily identified with the exception of gossypol glucuronidation. Apogossypol appeared more stable in human and mouse liver microsomal preparations than gossypol and apogossypol hexaacetate. CONCLUSIONS: Apogossypol and gossypol show similar oral and intravenous pharmacokinetic profiles and in vitro stability although apogossypol appears to have a slower clearance rate, larger AUC, and better microsomal stability. Apogossypol hexaacetate converts to apogossypol in both in vitro and in vivo settings and lacks any quantifiable oral bioavailability.

Pharmacokinetics and pharmacodynamics of Phor21-betaCG(ala), a lytic peptide conjugate.

Phor21-betaCG(ala), a 36-amino acid peptide comprised of a lytic peptide (Phor21) conjugated to a modified 15-amino acid segment of the beta-chain of chorionic gonadotropin (betaCG(ala)), selectively kills cancer cells that over-express luteinizing hormone/chorionic gonadotropin (LH/CG) receptors by disrupting cellular membrane structure. These studies were designed to further characterize its in-vitro inhibition and in-vivo destruction of prostate cancer cells, biostability and pharmacokinetics to determine its pharmacokinetic and pharmacodynamic profile. Inhibitory effects of Phor21-betaCG(ala) were tested in PC-3 and Caco-2 cells as well as in nude mice bearing PC-3 cells transfected with the luciferase gene (PC-3.luc). Plasma stability, protease hydrolysis and pharmacokinetics of Phor21-betaCG(ala) were measured by using liquid chromatography mass spectrometry (LC/MS/MS). Phor21-betaCG(ala) selectively inhibited proliferation in-vitro and in-vivo metastases of PC-3 cells. Phor21-betaCG(ala) was relatively stable in mouse, rat, dog and human plasma. Its degradation was partially due to protease hydrolysis and thermodynamic catalysis. Intravenous administration of Phor21-betaCG(ala) showed its blood C(max) and AUC(0-->infinity) around the in-vitro effective levels. In the tested rodents, Phor21-betaCG(ala) displayed a moderate volume of distribution at steady state (Vd(ss)) and slow clearance (Cl) in the rodents. In conclusion, Phor21-betaCG(ala) displayed promising in-vitro and in-vivo anti-cancer activity with favourable pharmacokinetics, and may offer a novel approach to metastatic cancer chemotherapy.

13C enrichment of carbons 2 and 8 of purine by folate-dependent reactions after [13C]formate and [2-13C]glycine dosing in adult humans.

The 10-formyl moiety of 10-formyltetrahydrofolate is the source of carbons at the positions 8 (C(8)) and 2 (C(2)) of the purine ring, originating from formate and a few amino acids. Uric acid is the final catabolic product of purines. In adult humans, we independently measured the (13)C enrichment of the C(2) and C(8) positions of urinary uric acid after an oral dose of [(13)C]sodium formate and that of the C(2) and C(8) plus C(5) positions after [2-(13)C]glycine. A liquid chromatography-mass spectrometric method was used to measure the (13)C enrichment of uric acid in urine, which was collected for 3 to 4 days. Purine catabolism to uric acid does not alter the positions of carbons in the ring. After the formate dose, the (13)C enrichment at C(2) was greater than at C(8), and a circadian rhythm was observed in the enrichment at C(2). After the glycine dose, the C(8) plus C(5) positions were enriched, whereas no significant enrichment at C(2) was found. These (13)C enrichment patterns are not consistent with previous accepted metabolism. To our knowledge, this is the first study to investigate (13)C enrichment from formate and glycine independently into the C(2) and C(8) positions of purine in the same subjects. Possible mechanisms explaining our findings are discussed. Oral [(13)C]formate or [2-(13)C]glycine dosing and urine collection can be used to study purine biosynthesis in humans.

Interspecies pharmacokinetics and in vitro metabolism of SQ109.

This study aimed at characterizing the interspecies absorption, distribution, metabolism and elimination (ADME) profile of N-geranyl-N'-(2-adamantyl)ethane-1,2-diamine (SQ109), a new diamine-based antitubercular drug. Single doses of SQ109 were administered (intravenously (i.v.) and per os (p.o.)) to rodents and dogs and blood samples were analyzed by liquid chromatography tandem mass spectrometry (LC/MS/MS). Based on i.v. equivalent body surface area dose, the terminal half-life (t1/2) of SQ109 in dogs was longer than that in rodents, reflected by a larger volume of distribution (Vss) and a higher clearance rate of SQ109 in dogs, compared to that in rodents. The oral bioavailability of SQ109 in dogs, rats and mice were 2.4-5, 12 and 3.8%, respectively. After oral administration of [14C]SQ109 to rats, the highest level of radioactivity was in the liver, followed by the lung, spleen and kidney. Tissue-to-blood ratios of [14C]SQ109 were greater than 1. Fecal elimination of [14C]SQ109 accounted for 22.2% of the total dose of [14C]SQ109, while urinary excretion accounted for only 5.6%. The binding of [14C]SQ109 (0.1-2.5 microg ml-1) to plasma proteins varied from 6 to 23% depending on the species (human, mouse, rat and dog). SQ109 was metabolized by rat, mouse, dog and human liver microsomes, resulting in 22.8, 48.4, 50.8 or 58.3%, respectively, of SQ109 remaining after a 10-min incubation at 37 degrees C. The predominant metabolites in the human liver microsomes gave intense ion signals at 195, 347 and 363m/z, suggesting the oxidation, epoxidation and N-dealkylation of SQ109. P450 reaction phenotyping using recombinant cDNA-expressed human CYPs in conjunction with specific CYP inhibitors indicated that CYP2D6 and CYP2C19 were the predominant CYPs involved in SQ109 metabolism.

Simultaneous estimation of pharmacokinetic properties in mice of three anti-tubercular ethambutol analogs obtained from combinatorial lead optimization.

Integrating combinatorial lead optimization of [1,2]-diamine core structure based on ethambutol with high-throughput screening has led us to focus on three promising analogs (SQ37, SQ59 and SQ109) as potential anti-tubercular drug candidates from thousands of synthesized diamine analogs for further characterization of their biopharmaceutical and pharmacokinetic properties by using liquid chromatography/tandem mass spectrometry (LC/MS/MS) and cassette dosing for pharmacokinetic screening. Simultaneous separation of the three analogs was achieved on reversed phase HPLC using a gradient mobile phase composed of MeOH/CH(3)COONH(4) (5mM)/trifluoroacetic acid: 80/20/0.1 (v/v/v). After extraction with acetonitrile from biomatrices, samples were analyzed on the LC/MS/MS system in the positive mode using an electrospray ion source. The retention time for the analogs ranged from 3.70 to 4.48 min. Incubation of SQ37 with plasma at 37 degrees C for 6h resulted in its degradation in human and rat plasma (20-35%), but no significant degradation was observed in mouse and dog plasma. SQ59 was relatively stable in the plasma of the four species. SQ109 was degraded in human and dog plasma (30-40%), but stable in mouse and rat plasma during the 6h incubation. A rapid multiple pharmacokinetic screening was taken by cassette dosing of the three analogs to mice and simultaneous analysis of their plasma concentrations. The analogs showed large Vd(ss) ranging from 11,300 (SQ37), 12,800 (SQ109) to 63,900 ml/kg (SQ59). The clearance ranged from 3240 (SQ109), 3530 (SQ37) and 8043 ml/kg/h (SQ59). The elimination t(1/2) ranged from 4.4 to 21.1h dependent on the routes. The oral bioavailability was 5.1 (SQ59), 20.1 (SQ37) and 7.8% (SQ109), respectively. Both SQ37 and SQ109 possess good pharmacokinetic properties.

Effects of herbal supplements on the bioactivation of chemotherapeutic agents.

OBJECTIVES: The aim of this study was to investigate the impact of commercially available, over-the-counter herbal supplements (St John's wort, black cohosh and ginger root extract) on the metabolic activation of tamoxifen and irinotecan. METHODS: Co-incubation of each drug and supplement combination over a range of concentrations was conducted in human liver microsomes and the decrease in the rate of active metabolite formation was monitored using high-performance liquid chromatography tandem mass spectrometry. Data was analysed using non-linear regression analysis and Dixon plots to determine the dominant mechanism of inhibition and to estimate the Ki and IC50 values of the commercial supplements. KEY FINDINGS: The data suggest that black cohosh was the strongest inhibitor tested in this study for both CYP450 and carboxyesterase mediated biotransformation of tamoxifen and irinotecan, respectively, to their active metabolites. St John's wort was a stronger inhibitor compared with ginger root extract for tamoxifen (CYP mediated pathway), while ginger root extract was a stronger inhibitor compared with St John's wort for the carboxyesterase mediated pathway. CONCLUSIONS: Commercially available supplements are widely used by patients and their potential impact on the efficacy of the chemotherapy is often unknown. The clinical significance of these results needs to be evaluated in a comprehensive clinical trial.

The effect of Rho-associated kinase inhibition on the ocular penetration of timolol maleate.

PURPOSE: To assess the effects of Rho-associated kinase (ROCK) inhibition on the intraocular penetration of timolol maleate. METHODS: Ex vivo porcine corneal penetration of timolol maleate, sotalol hydrochloride, or brinzolamide incubated with or without Y-27632 was determined in vertical Franz diffusion cells. The effect of ROCK inhibition on the vasodilation of porcine conjunctival vasculature was assessed by scanning electron microscopy (SEM) and immunohistochemical staining with subsequent laser-scanning confocal microscopy (LSCM). Experiments were conducted in New Zealand White (NZW) rabbits to assess the effect of ROCK inhibition on the intraocular distribution of timolol maleate. RESULTS: ROCK inhibition resulted in minimal alteration of ex vivo porcine corneal drug penetration of timolol, sotalol, or brinzolamide. SEM and LSCM experiments conducted with conjunctiva and sclera tissue in Franz diffusion cells suggested vasodilation in the conjunctival vasculature in the presence of Y-27632. Pretreatment of the eyes of NZW rabbits with Y-27632 resulted in aggregate fold reductions (1 hour, 0.25-fold; 4 hours, 0.45-fold) of timolol maleate drug concentrations in intraocular tissues (aqueous humor, lens, and iris) versus eyes not receiving Y-27632 pretreatment. Pretreatment with a vasoconstrictor, phenylephrine, resulted in a reversal of the effect of Y-27632 on diminished timolol maleate intraocular penetration in NZW rabbits. CONCLUSIONS: ROCK inhibition reduced the intraocular penetration of administered timolol maleate presumably due to increased systemic elimination through the conjunctival vasculature. It is anticipated that care in order and timing of ROCK inhibitor administration will be warranted for those patients who may be on a multiple topical drug regimen for primary open-angle glaucoma.

Comparative pharmacokinetics of perfluorohexanesulfonate (PFHxS) in rats, mice, and monkeys.

Perfluorohexanesulfonate (PFHxS) has been found in biological samples from wildlife and humans. The human geometric mean serum PFHxS elimination half-life has been estimated to be 2665days. A series of studies was undertaken to establish pharmacokinetic parameters for PFHxS in rats, mice, and monkeys after single administration with pharmacokinetic parameters determined by WinNonlin(®) software. Rats and mice appeared to be more effective at eliminating PFHxS than monkeys. With the exception of female rats, which had serum PFHxS elimination half-life of approximately 2 days, the serum elimination half-lives in the rodent species and monkeys approximated 1month and 4months, respectively, when followed over extended time periods (10-24weeks). Collectively, these studies provide valuable insight for human health risk assessment regarding the potential for accumulation of PFHxS in humans.

Distribution of perfluorooctanesulfonate and perfluorooctanoate into human plasma lipoprotein fractions.

Some cross-sectional epidemiological studies have reported positive associations of serum concentrations of non-high density lipoprotein cholesterol with serum perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). However, the strength of the reported associations is inconsistent for exposure-response across three orders of magnitude of serum PFOS and/or PFOA concentrations. These positive associations are unexpected based on toxicological/mechanistic studies, suggesting that the associations may have a biological, rather than a causal, basis. This study tested the hypothesis that PFOS and PFOA distribute into serum lipoprotein fractions such that increases in serum lipoproteins would result in corresponding increases in serum concentrations of PFOS and PFOA. Based on observed binding of PFOS and PFOA to isolated ß-lipoproteins in physiological saline (96% and 40% bound, respectively) in preliminary experiments using ultrafiltration and LC-MS/MS methods, binding to human donor plasma lipoprotein fractions was investigated by two density gradient methods. The majority of PFOS and PFOA recovered masses were found in lipoprotein-depleted plasma. Plasma density gradient fractionation data suggested that maximally 9% of PFOS distributes to lipoprotein-containing fractions, yet only 1% or less of PFOA is so distributed. These data do not support a strong role for plasma lipoprotein fractions in explaining the inconsistent dose-response associations reported in cross-sectional epidemiological studies.

Comparative pharmacokinetics of perfluorooctanesulfonate (PFOS) in rats, mice, and monkeys.

Perfluorooctanesulfonate (PFOS) has been found in biological samples in wildlife and humans. The geometric mean half-life of serum elimination of PFOS in humans has been estimated to be 4.8 years (95% CI, 4.0-5.8). A series of studies was undertaken to establish pharmacokinetic parameters for PFOS in rats, mice, and monkeys after single oral and/or IV administration of K(+)PFOS. Animals were followed for up to 23 weeks, and pharmacokinetic parameters were determined by WinNonlin® software. Rats and mice appeared to be more effective at eliminating PFOS than monkeys. The serum elimination half-lives in the rodent species were on the order of 1-2 months; whereas, in monkeys, the serum elimination half lives approximated 4 months. Collectively, these studies provide valuable insight for human health risk assessment regarding the potential for accumulation of body burden in humans on repeated exposure to PFOS and PFOS-generating materials.