Bi-polymeric Spongy Matrices Through Cross-linking Polymerization: Synthesized and Evaluated for Solubility Enhancement of Acyclovir.

In this study, two hydrophilic polymers hydroxypropyl methyl cellulose and beta-cyclodextrin (ß-CD) are used to synthesize highly responsive and spongy polymeric matrices. Porous and stimulus-responsive polymeric network was developed to improve the solubility of acyclovir (ACV) at significant level. Grafting was successfully carried out by free radical polymerization technique. Spongy matrices were characterized by percentage entrapment efficiency, drug loading, solubility studies, FTIR, powder X-ray diffraction, TGA, DSC, XRD, SEM, swelling studies, and in vitro studies. Acute oral toxicity studies were conducted to determine the safety of oral administration of prepared HPMC-ßCD-g-poly(AMPS) formulation. Porous and spongy structures were depicted in SEM images. Complex formation and thermal stability of constituents and drug (ACV) were analyzed by FTIR, TGA, and DSC spectra. XRD analysis revealed reduction in acyclovir crystallinity in spongy matrices. Particle size of optimized formulation was found in the range of 197 ± 2.55 nm. The momentous difference with reference product committed that drug solubility and release characteristics were markedly enhanced by the developed spongy matrices. Toxicity studies endorsed that developed spongy matrices were non-toxic and compatible to biological system. The efficient method of preparation, enhanced solubility, excellent physico-chemical characteristics, high dissolution, and non-toxic HPMC-ßCD-g-poly(AMPS) spongy matrices may be a promising approach for oral delivery of poorly soluble drugs.

Emergence of Nanotechnology to Fight HIV Sexual Transmission: The Trip of G2-S16 Polyanionic Carbosilane Dendrimer to Possible Pre-Clinical Trials.

Development of new, safe, and effective microbicides to prevent human immunodeficiency virus HIV sexual transmission is needed. Unfortunately, most microbicides proved ineffective to prevent the risk of HIV-infection in clinical trials. We are working with G2-S16 polyanionic carbosilane dendrimer (PCD) as a new possible vaginal topical microbicide, based on its short reaction times, wide availability, high reproducibility, and quantitative yields of reaction. G2-S16 PCD exerts anti-HIV activity at an early stage of viral replication, by blocking gp120/CD4/CCR5 interaction, and providing a barrier against infection for long periods of time. G2-S16 PCD was stable at different pH values, as well as in the presence of seminal fluids. It maintained the anti-HIV activity against R5/X4 HIV over time, did not generate any type of drug resistance, and retained the anti-HIV effect when exposed to semen-enhanced viral infection. Importantly, G2-S16 PCD did not modify vaginal microbiota neither in vitro or in vivo. Histopathological examination did not show vaginal irritation, inflammation, lesions, or damage in the vaginal mucosa, after administration of G2-S16 PCD at different concentrations and times in female mice and rabbit animal models. Based on these promising data, G2-S16 PCD could become a good, safe, and readily available candidate to use as a topical vaginal microbicide against HIV.

NPY1R-targeted peptide-mediated delivery of a dual PPARα/γ agonist to adipocytes enhances adipogenesis and prevents diabetes progression.

OBJECTIVE: PPARα/γ dual agonists have been in clinical development for the treatment of metabolic diseases including type 2 diabetes and dyslipidemia. However, severe adverse side effects led to complications in clinical trials. As most of the beneficial effects rely on the compound activity in adipocytes, the selective targeting of this cell type is a cutting-edge strategy to develop safe anti-diabetic drugs. The goal of this study was to strengthen the adipocyte-specific uptake of the PPARα/γ agonist tesaglitazar via NPY1R-mediated internalization. METHODS: NPY1R-preferring peptide tesaglitazar-[F7, P34]-NPY (tesa-NPY) was synthesized by a combination of automated SPPS and manual couplings. Following molecular and functional analyses for proof of concept, cell culture experiments were conducted to monitor the effects on adipogenesis. Mice treated with peptide drug conjugates or vehicle either by gavage or intraperitoneal injection were characterized phenotypically and metabolically. Histological analysis and transcriptional profiling of the adipose tissue were performed. RESULTS: In vitro studies revealed that the tesaglitazar-[F7, P34]-NPY conjugate selectively activates PPARγ in NPY1R-expressing cells and enhances adipocyte differentiation and adiponectin expression in adipocyte precursor cells. In vivo studies using db/db mice demonstrated that the anti-diabetic activity of the peptide conjugate is as efficient as that of systemically administered tesaglitazar. Additionally, tesa-NPY induces adipocyte differentiation in vivo. CONCLUSIONS: The use of the tesaglitazar-[F7, P34]-NPY conjugate is a promising strategy to apply the beneficial PPARα/γ effects in adipocytes while potentially omitting adverse effects in other tissues.

Effects of Pharmacologically Targeting Neuroimmune Pathways on Alcohol Drinking in Mice Selectively Bred to Drink to Intoxication.

BACKGROUND: Rodent models of high alcohol drinking offer opportunities to better understand factors for alcohol use disorders (AUD) and test potential treatments. Selective breeding was carried out to create 2 unique High Drinking in the Dark (HDID-1, HDID-2) mouse lines that represent models of genetic risk for binge-like drinking. A number of studies have indicated that neuroimmune genes are important for regulation of alcohol drinking. We tested whether compounds shown to reduce drinking in other models also reduce alcohol intake in these unique genetic lines. METHODS: We report tests of gabapentin, tesaglitazar, fenofibrate, caffeic acid phenethyl ester (CAPE), ibrutinib, and rolipram. Although these compounds have different mechanisms of action, they have all been shown to reduce inflammatory responses. We evaluated effects of these compounds on alcohol intake. In order to facilitate comparison with previously published findings for some compounds, we employed similar schedules that were previously used for that compound. RESULTS: Gabapentin increased ethanol (EtOH) binge-like alcohol drinking in female HDID-1 and HS/NPT mice. Tesaglitazar and fenofibrate did not alter 2-bottle choice (2BC) drinking in male HDID-1 or HS/NPT mice. However, tesaglitazar had no effect on DID EtOH intake but reduced blood alcohol levels (BAL), and fenofibrate increased DID intake with no effects on BAL. CAPE had no effect on EtOH intake. Ibrutinib reduced intake in female HDID-1 in initial testing, but did not reduce intake in a second week of testing. Rolipram reduced DID intake and BALs in male and female HDID-1, HDID-2, and HS/NPT mice. CONCLUSIONS: A number of compounds shown to reduce EtOH drinking in other models, and genotypes are not effective in HDID mice or their genetically heterogeneous founders, HS/NPT. The most promising compound was the PDE4 inhibitor, rolipram. These results highlight the importance of assessing generalizability when rigorously testing compounds for therapeutic development.

Efficacy and Safety of the Glucagon Receptor Antagonist RVT-1502 in Type 2 Diabetes Uncontrolled on Metformin Monotherapy: A 12-Week Dose-Ranging Study.

OBJECTIVE: Evaluate the safety and efficacy of RVT-1502, a novel oral glucagon receptor antagonist, in subjects with type 2 diabetes inadequately controlled on metformin. RESEARCH DESIGN AND METHODS: In a phase 2, double-blind, randomized, placebo-controlled study, subjects with type 2 diabetes (n = 166) on a stable dose of metformin were randomized (1:1:1:1) to placebo or RVT-1502 5, 10, or 15 mg once daily for 12 weeks. The primary end point was change from baseline in HbA1c for each dose of RVT-1502 compared with placebo. Secondary end points included change from baseline in fasting plasma glucose (FPG) and safety assessments. RESULTS: Over 12 weeks, RVT-1502 significantly reduced HbA1c relative to placebo by 0.74%, 0.76%, and 1.05% in the 5-, 10-, and 15-mg groups (P < 0.001), respectively, and FPG decreased by 2.1, 2.2, and 2.6 mmol/L (P < 0.001). The proportions of subjects achieving an HbA1c <7.0% were 19.5%, 39.5%, 39.5%, and 45.0% with placebo and RVT-1502 5, 10, and 15 mg (P ≤ 0.02 vs. placebo). The frequency of hypoglycemia was low, and no episodes were severe. Mild increases in mean aminotransferase levels remaining below the upper limit of normal were observed with RVT-1502 but were reversible and did not appear to be dose related, with no other liver parameter changes. Weight and lipid changes were similar between RVT-1502 and placebo. RVT-1502-associated mild increases in blood pressure were not dose related or consistent across time. CONCLUSIONS: Glucagon receptor antagonism with RVT-1502 significantly lowers HbA1c and FPG, with a safety profile that supports further clinical development with longer-duration studies (NCT02851849).

Facile Synthesis of Chitosan Based-(AMPS-co-AA) Semi-IPNs as a Potential Drug Carrier: Enzymatic Degradation, Cytotoxicity, and Preliminary Safety Evaluation.

OBJECTIVE: The study describes the development of chitosan-based (AMPS-co-AA) semi-IPN hydrogels using free radical polymerization technique. METHODS: The resulting hydrogels were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The successful crosslinking of chitosan, 2- Acrylamido-2-Methylpropane Sulfonic Acid (AMPS), and Acrylic Acid (AA) was confirmed by FT IR. Unloaded and drug-loaded hydrogels exhibited higher thermal stability after crosslinking compared to the individual components. XRD confirmed the decrease in crystallinity after hydrogel formation and molecular dispersion of Oxaliplatin (OXP) in the polymeric network. SEM showed rough, vague and nebulous surface resulting from crosslinking and loading of OXP. RESULTS: The experimental results revealed that swelling and drug release were influenced by the pH of the medium being low at acidic pH and higher at basic pH. Increasing the concentration of chitosan and AA enhanced the swelling, drug loading and drug release while AMPS was found to act inversely. CONCLUSION: It was confirmed that the hydrogels were degraded more by specific enzyme lysozyme as compared to the non-specific enzyme collagenase. In-vitro cytotoxicity suggested that the unloaded hydrogels were non-cytotoxic while crude drug and drug-loaded hydrogel exhibited dose-dependent cytotoxicity against HCT-116 and MCF-7. Results of acute oral toxicity on rabbits demonstrated that the hydrogels are non-toxic up to 3900 mg/kg after oral administration, as no toxicity or histopathological changes were observed in comparison to control rabbits. These pH-sensitive hydrogels appear to provide an ideal basis as a safe carrier for oral drug delivery.

Development of a novel sulfonate ester-based prodrug strategy.

A self-immolative γ-aminopropylsulfonate linker was investigated for use in the development of prodrugs that are reactive to various chemical or biological stimuli. To demonstrate their utility, a leucine-conjugated prodrug of 5-chloroquinolin-8-ol (5-Cl-8-HQ), which is a potent inhibitor against aminopeptidase from Aeromonas proteolytica (AAP), was synthesized. The sulfonate prodrug was considerably stable under physiological conditions, with only enzyme-mediated hydrolysis of leucine triggering the subsequent intramolecular cyclization to simultaneously release 5-Cl-8-HQ and form γ-sultam. It was also confirmed that this γ-aminopropylsulfonate linker was applicable for prodrugs of not only 8-HQ derivatives but also other drugs bearing a phenolic hydroxy group.

Prevention vaginally of HIV-1 transmission in humanized BLT mice and mode of antiviral action of polyanionic carbosilane dendrimer G2-S16.

The development of a safe, effective, and low-priced topical microbicide to prevent HIV-1 sexual transmission is urgently needed. The emerging field of nanotechnology plays an important role in addressing this challenge. We demonstrate that topical vaginal administration of 3% G2-S16 prevents HIV-1JR-CSF transmission in humanized (h)-BLT mice in 84% with no presence of HIV-1 RNA and vaginal lesions. Second-generation polyanionic carbosilane dendrimer G2-S16 with silica core and 16 sulfonate end-groups exerts anti-HIV-1 activity at an early stage of viral replication, blocking the gp120/CD4 interaction, acting on the virus, and inhibiting the cell-to-cell HIV-1 transmission, confirming its multifactorial and non-specific ability. This study represents the first demonstration that transmission of HIV-1 can be efficiently blocked by vaginally applied G2-S16 in h-BLT mice. These findings provide a step forward in the development of G2-S16-based vaginal microbicides to prevent vaginal HIV-1 transmission in humans. FROM THE CLINICAL EDITOR: HIV infections remain a significant problem worldwide and the major route of transmission is through sexual activity. In this article, the authors developed an antiviral agent containing polyanionic carbosilane dendrimer with silica core and 16 sulfonate end-groups. When applied vaginally, this was shown to exert anti-HIV protection. These positive findings may offer hope in the fight against the spread of HIV epidemic.

Convergent translational evidence of a role for anandamide in amygdala-mediated fear extinction, threat processing and stress-reactivity.

Endocannabinoids are released 'on-demand' on the basis of physiological need, and can be pharmacologically augmented by inhibiting their catabolic degradation. The endocannabinoid anandamide is degraded by the catabolic enzyme fatty acid amide hydrolase (FAAH). Anandamide is implicated in the mediation of fear behaviors, including fear extinction, suggesting that selectively elevating brain anandamide could modulate plastic changes in fear. Here we first tested this hypothesis with preclinical experiments employing a novel, potent and selective FAAH inhibitor, AM3506 (5-(4-hydroxyphenyl)pentanesulfonyl fluoride). Systemic AM3506 administration before extinction decreased fear during a retrieval test in a mouse model of impaired extinction. AM3506 had no effects on fear in the absence of extinction training, or on various non-fear-related measures. Anandamide levels in the basolateral amygdala were increased by extinction training and augmented by systemic AM3506, whereas application of AM3506 to amygdala slices promoted long-term depression of inhibitory transmission, a form of synaptic plasticity linked to extinction. Further supporting the amygdala as effect-locus, the fear-reducing effects of systemic AM3506 were blocked by intra-amygdala infusion of a CB1 receptor antagonist and were fully recapitulated by intra-amygdala infusion of AM3506. On the basis of these preclinical findings, we hypothesized that variation in the human FAAH gene would predict individual differences in amygdala threat-processing and stress-coping traits. Consistent with this, carriers of a low-expressing FAAH variant (385A allele; rs324420) exhibited quicker habituation of amygdala reactivity to threat, and had lower scores on the personality trait of stress-reactivity. Our findings show that augmenting amygdala anandamide enables extinction-driven reductions in fear in mouse and may promote stress-coping in humans.

Nanostructured lipid carriers as delivery system for the phopholipase A2 inhibitors PX-18 and PX-13 for dermal application.

PX-18 and PX-13 are secretory phospholipase A2-IIA (sPLA2-IIA) inhibitors. An increased expression of sPLA2 in psoriatic skin has been reported. The selective inhibition of this enzyme is a new therapeutic approach. For dermal application PX-18 and PX-13 have been loaded to Nanostructured lipid carriers (NLC). The PX-18-loaded and PX-13-loaded NLC possessed an average particles size of about 250 nm, a narrow particle size distribution (PI < 0.2), a high entrapment efficiency as well as a good physical stability, as already indicated by their high zeta potential. Both NLC formulations have been incorporated into a hydroxyethyl cellulose gel and an o/w cream. In the gel and in the o/w cream PX-18-loaded and PX-13-loaded NLC showed a good physical stability. Neither aggregation nor dissolution of NLC took place.

Photochemically and electrochemically triggered Au nanoparticles "sponges".

Stimuli-triggered wettability of surfaces and controlled uptake and release of substrates by "smart" materials are essential for drug delivery and microfluidic control. A composite "sponge" consisting of bis-aniline-bridged Au nanoparticles (NPs), functionalized with photoisomerizable nitrospiropyran/nitromerocyanine that includes selective imprinted molecular recognition sites for N,N'-bis(3-sulfonatopropyl)-4,4'-bipyridinium (PVS) was electropolymerized on a Au electrode. The system is triggered by photonic and/or electrical signals to yield four different states exhibiting variable binding/release capacities for PVS and controlled wettability of the surface. The electrical/optical uptake and release of PVS to and from the Au NPs "sponge", respectively, is followed by CdSe/ZnS quantum dots, acting as an auxiliary photonic label.

Design and application of esterase-labile sulfonate protecting groups.

Three esterase-labile, but chemically-stable sulfonate protecting groups have been designed and synthesized. One of these sulfonate esters allowed the cytoplasmic delivery and unmasking of a sulfonated dye in live cells.

Evaluation and prediction of pharmacokinetics of PFOA and PFOS in the monkey and human using a PBPK model.

Perfluoroalkyl acid carboxylates and sulfonates (PFAAs) have many consumer and industrial applications. The persistence and widespread distribution of these compounds in humans have brought them under intense scrutiny. Limited pharmacokinetic data is available in humans; however, human data exists for two communities with drinking water contaminated by PFAAs. Also, there is toxicological and pharmacokinetic data for monkeys, which can be quite useful for cross-species extrapolation to humans. The goal of this research was to develop a physiologically-based pharmacokinetic (PBPK) model for PFOA and PFOS for monkeys and then scale this model to humans in order to describe available human drinking water data. The monkey model simulations were consistent with available PK data for monkeys. The monkey model was then extrapolated to the human and then used to successfully simulate the data collected from residents of two communities exposed to PFOA in drinking water. Human PFOS data is minimal; however, using the half-life estimated from occupational exposure, our model exhibits reasonable agreement with the available human serum PFOS data. It is envisioned that our PBPK model will be useful in supporting human health risk assessments for PFOA and PFOS by aiding in understanding of human pharmacokinetics.

Tesaglitazar, a dual peroxisome proliferator-activated receptor alpha/gamma agonist, improves apolipoprotein levels in non-diabetic subjects with insulin resistance.

AIM: To determine the effects of the peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist tesaglitazar on serum levels of apolipoprotein (apo) A-I, apoB, and apoCIII in non-diabetic insulin-resistant subjects. METHODS: This randomized, double-blind, multicentre, placebo-controlled trial examined the effect of tesaglitazar (0.1, 0.25, 0.5, and 1mg) once daily for 12 weeks on apolipoprotein levels in 390 abdominally obese subjects with hypertriglyceridaemia. RESULTS: Tesaglitazar dose-dependently increased serum concentrations of apoA-I (p<0.009) and decreased concentrations of apoB (p<0.0001), the apoB/apoA-I ratio (p<0.0001), and apoCIII (p<0.0001). Similar improvements were observed in all subgroups of subjects, where individuals were grouped according to age, gender, baseline body mass index, serum triglycerides and high-density lipoprotein cholesterol levels. Low-density lipoprotein particle concentrations were also dose-dependently reduced by tesaglitazar (p<0.0001). CONCLUSION: Although tesaglitazar is no longer in clinical development, these data indicate that dual PPARalpha/gamma agonism may be a useful pharmacological approach to improve the atherogenic dyslipidaemia associated with insulin resistance.

The dual peroxisome proliferator-activated receptor alpha/gamma agonist tesaglitazar further improves the lipid profile in dyslipidemic subjects treated with atorvastatin.

Tesaglitazar (GALIDA; AstraZeneca, Wilmington, DE) is a dual peroxisome proliferator-activated receptor alpha/gamma agonist previously in clinical development for the treatment of glucose and lipid abnormalities associated with type 2 diabetes mellitus and insulin resistance. This study compared the efficacy of tesaglitazar with that of pioglitazone as adjunctive therapy to atorvastatin in subjects with abdominal obesity and dyslipidemia. In this open-label, 3-way crossover study, 58 subjects received atorvastatin 10 mg once daily in a 6-week run-in period, followed by tesaglitazar 3 mg, pioglitazone 45 mg, or placebo, as adjunctive therapy to atorvastatin, in a randomized sequence for 6 weeks each. Serum triglycerides and other lipids, apolipoproteins, glucose, and insulin concentrations were compared between treatments. Tesaglitazar adjunctive therapy reduced serum triglycerides significantly more from baseline (-1.07 mmol/L) than pioglitazone (-0.33 mmol/L; P = .007) or placebo (-0.09 mmol/L; P < .0001). Tesaglitazar also resulted in significantly greater improvements in free fatty acids, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio, low-density lipoprotein particle size, apolipoprotein (apo) B, apo C-III, and the apo B/apo A-I ratio compared with pioglitazone or placebo. Tesaglitazar adjunctive therapy also reduced fasting plasma glucose, fasting plasma insulin, and insulin resistance (homeostasis model assessment index) significantly more than pioglitazone or placebo (P < .0001 for all comparisons). Tesaglitazar was generally well tolerated in combination with atorvastatin, but hemoglobin and absolute neutrophil count decreased and serum creatinine increased more with tesaglitazar than with pioglitazone or placebo. These effects, also shown in previous trials, led to the discontinuation of the clinical development of the drug. In conclusion, the addition of tesaglitazar to a background of atorvastatin therapy further improved the dyslipidemia associated with insulin resistance.

Tesaglitazar, a dual PPAR{alpha}/{gamma} agonist, ameliorates glucose and lipid intolerance in obese Zucker rats.

Insulin resistance, impaired glucose tolerance, high circulating levels of free fatty acids (FFA), and postprandial hyperlipidemia are associated with the metabolic syndrome, which has been linked to increased risk of cardiovascular disease. We studied the metabolic responses to an oral glucose/triglyceride (TG) (1.7/2.0 g/kg lean body mass) load in three groups of conscious 7-h fasted Zucker rats: lean healthy controls, obese insulin-resistant/dyslipidemic controls, and obese rats treated with the dual peroxisome proliferator-activated receptor alpha/gamma agonist, tesaglitazar, 3 mumol.kg(-1).day(-1) for 4 wk. Untreated obese Zucker rats displayed marked insulin resistance, as well as glucose and lipid intolerance in response to the glucose/TG load. The 2-h postload area under the curve values were greater for glucose (+19%), insulin (+849%), FFA (+53%), and TG (+413%) compared with untreated lean controls. Treatment with tesaglitazar lowered fasting plasma glucose, improved glucose tolerance, substantially reduced fasting and postload insulin levels, and markedly lowered fasting TG and improved lipid tolerance. Fasting FFA were not affected, but postprandial FFA suppression was restored to levels seen in lean controls. Mechanisms of tesaglitazar-induced lowering of plasma TG were studied separately using the Triton WR1339 method. In anesthetized, 5-h fasted, obese Zucker rats, tesaglitazar reduced hepatic TG secretion by 47%, increased plasma TG clearance by 490%, and reduced very low-density lipoprotein (VLDL) apolipoprotein CIII content by 86%, compared with obese controls. In conclusion, the glucose/lipid tolerance test in obese Zucker rats appears to be a useful model of the metabolic syndrome that can be used to evaluate therapeutic effects on impaired postprandial glucose and lipid metabolism. The present work demonstrates that tesaglitazar ameliorates these abnormalities and enhances insulin sensitivity in this animal model.

Pharmacokinetics and metabolism of tesaglitazar, a novel dual-acting peroxisome proliferator-activated receptor alpha/gamma agonist, after a single oral and intravenous dose in humans.

The pharmacokinetics of tesaglitazar (GALIDA), a novel dual-acting peroxisome proliferator-activated receptor alpha and gamma agonist, were studied in eight healthy male subjects. The subjects initially received either a single oral or intravenous (i.v.) dose of 1 mg of [(14)C]tesaglitazar. After a washout period, they received 1 mg of nonlabeled tesaglitazar via the alternative administration route. Serial blood samples and complete urine and feces were collected until 336 h postdose. Tesaglitazar absorption was rapid, with maximum plasma concentration (C(max)) at approximately 1 h postdose, and the absolute bioavailability was approximately 100%, suggesting no, or negligible, first-pass metabolism. Mean plasma clearance was 0.16 l/h and the volume of distribution at steady state was 9.1 liters. After either route of administration, the plasma concentration-time profiles of radioactivity and tesaglitazar were virtually identical, indicating low systemic metabolite concentrations and formation rate limitation of metabolite elimination. The elimination half-life of radioactivity and tesaglitazar was approximately 45 h. Radioactivity recovery was complete in all subjects, with mean values of 99.9% (i.v.) and 99.6% (oral). Tesaglitazar was mainly metabolized before excretion, and most radioactivity (91%) was recovered in urine. Approximately 20% of the dose was recovered unchanged after either administration route, resulting in a renal clearance of 0.030 l/h. Most of the radioactivity in urine was identified as acyl glucuronide of tesaglitazar. Plasma protein binding of tesaglitazar was high ( approximately 99.9%), and the mean blood-plasma partitioning ratio was 0.66, suggesting low affinity for red blood cells. There was no indication of partial inversion of the (S)-enantiomer to the corresponding (R)-form. Tesaglitazar was well tolerated.

Hepatobiliary excretion of dipyrrinone sulfonates in Mrp2-deficient (TR(-)) rats.

The biliary excretion of the sodium salts of 8-(2-ethanesulfonic acid)-3-ethyl-2,7,9-trimethyl-1,10-dihydro-11H-dipyrrin-1-one (xanthosulfonic acid) and a fluorescent analogue (8-desethyl-N,N'-carbonyl-kryptopyrromethenone-8-sulfonic acid) was compared in Mrp2-deficient (TR(-)) and normal rats. Both organic anions were excreted rapidly in bile in Mrp2-deficient rats, but the biliary excretion of the fluorescent sulfonate was impaired relative to normal controls. The rat clearly has efficient Mrp2-independent mechanisms for biliary efflux of these anions that are not used by bilirubin or its mono- and diglucuronides.

The clinical pharmacology of alkylating agents in high-dose chemotherapy.

Alkylating agents are widely used in high-dose chemotherapy regimens in combination with hematological support. Knowledge about the pharmacokinetics and pharmacodynamics of these agents administered in high doses is critical for the safe and efficient use of these regimens. The aim of this review is to summarize the clinical pharmacology of the alkylating agents (including the platinum compounds) in high-dose chemotherapy. Differences between conventional and high doses will be discussed.

Chloroethylmethanesulfonate-induced effects on the epididymis seem unrelated to altered Leydig cell function.

Decades ago it was reported that when male rats were exposed to chloroethylmethanesulfonate (CEMS) for 5 days prior to weekly matings with untreated females, the second mating resulted in reduced litter size. Since fertility was not assessed at earlier time points, it was not possible to determine whether CEMS exerted any effects on sperm in the epididymis. In this study, we used a 4-day exposure and assessed multiple reproductive endpoints on Day 5 to characterize effects of CEMS exposure (6.25-25 mg/kg) on Leydig cells and the epididymis. Exposure to CEMS caused a dose-related decline in serum testosterone (T) levels. This occurred at a dose lower than that required to decrease T production in vitro by testicular parenchyma. The in vitro decline was not attributed to a decrease in maximal hCG-stimulated T production, but to a decrease in unstimulated T production. CEMS was 5-fold less sensitive than ethane dimethanesulfonate (EDS) in reducing maximal hCG-stimulated T production. To control for alterations in the epididymis resulting from decreased serum T alone, T was implanted in CEMS-treated animals to maintain serum T at a concentration similar to that found in normal rats. This exogenous T failed to prevent the CEMS-induced decrease in the weight of the caput/corpus epididymidis but did prevent the CEMS-induced decrease in seminal vesicle weight. Implantation of T failed to prevent the CEMS-induced reduction in sperm reserves in the cauda epididymidis, and it failed to prevent the CEMS-induced alterations in the histology of both the corpus and proximal cauda epididymidis. The height of the epithelium in both of these regions was increased, and clear cells disappeared from the proximal cauda epididymidis. These results demonstrate that CEMS might alter the ability of the Leydig cell to respond to LH stimulation in vivo, and that alterations in the structure and function of the epididymis occur even when the serum concentration of T is maintained.