Post-drug Administration Research Articles

Urinary and Blood Concentrations of β2-Agonists in Trained Subjects: Comparison between Routes of Use

We aimed to assess the plasma and urine concentrations of beta2-agonists and evaluate the difference between three routes of administration in trained adults in order to distinguish doping from prevention of exercise-induced asthma. Ten young healthy Caucasian male subjects received during a four treatment period study: 1) inhaled salbutamol (S(I)) 2 x 100 microg t.i.d. for 3 days, 2) inhaled formoterol (F(I)) 2 x 12 microg b.i.d. for 3 days, 3) a single subcutaneous injection of salbutamol (S(S)) 0.5 mg, and 4) salbutamol 2 x 2 mg t.i.d. orally for 3 days (S(O)). Blood samples were taken during the first and the third day of experimentation at baseline, 30 min, 1 h, 2 h, 4 h and 6 h after administration; additional blood samples were drawn at 15 min for S(I), S(S) and F(I) and at 12 h for F(I). Urinary samples were collected at baseline, 2 h, 4 h, 6 h and 12 h after administration. Urinary concentrations were 20 to almost 50 times higher after S(O) than after S(I). Mean urinary concentration after S(O) increased to above 800 ng.mL(-1) within the two hours and above 1000 ng.mL(-1) at 6 to 12 hours post-drug administration. Urinary concentrations after S(S) were maximal during the first 2 hours (mean: 340 +/- 172 ng.mL(-1)). Plasma concentrations were very low, whatever the routes of administration. Results showed that we could eliminate the use of S(I) (authorized) and S(S) administration when individual urinary concentrations are higher than 230 ng.mL(-1) and 615 ng.mL(-1), respectively. Therefore, at rest, the cut-off value used to discriminate therapeutic from doping salbutamol intake could be fixed at 250 ng.mL(-1) instead of the 1000 ng.mL(-1) still authorized by international committees.

Design, synthesis, and biological evaluation of linear 1-(4-, 3- or 2-methylsulfonylphenyl)-2-phenylacetylenes: A novel class of cyclooxygenase-2 inhibitors

A group of regioisomeric 1-(methylsulfonylphenyl)-2-phenylacetylenes possessing a COX-2 SO 2Me pharmacophore at the para-, meta- or ortho-position of the C-1 phenyl ring, in conjunction with a C-2 phenyl or substituted-phenyl ring substituent (3-F, 3-OMe, 3-OH, 3-OAc, 4-Me), were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. These target linear 1,2-diarylacetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction followed by oxidation of the respective 1-(methylthiophenyl)-2-phenylacetylene intermediate. In vitro COX-1/COX-2 isozyme inhibition structure–activity studies identified 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene ( 12d) as a potent COX-2 inhibitor (IC 50 = 0.32 μM) with a high COX-2 selectivity index (SI > 320) comparable to the reference compound rofecoxib (COX-2 IC 50 = 0.50 μM; COX-2 SI > 200). A molecular modeling study where ( 12d) was docked in the binding site of COX-2 showed that the MeSO 2 COX-2 pharmacophore was positioned in the vicinity of the secondary COX-2 binding site near Val 523. The 1-(4-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene ( 11f, COX-1 IC 50 = 1.00 μM; COX-2 IC 50 = 0.06 μM; COX-2 SI = 16.7) and 1-(3-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene ( 12f, COX-1 IC 50 = 6.5 μM; COX-2 IC 50 = 0.05 μM; COX-2 SI = 130) regioisomers exhibited comparable COX-2 inhibition, and moderately lower selective COX-2 selectivity, relative to the reference drug celecoxib (COX-1 IC 50 = 33.1 μM; COX-2 IC 50 = 0.07 μM; COX-2 SI = 472). The most potent anti-inflammatory agent 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene ( 12d) exhibited moderate oral anti-inflammatory activity (ED 50 = 129 mg/kg) at 3 h postdrug administration relative to the reference drug celecoxib (ED 50 = 10.8 mg/kg) in a carrageenan-induced rat paw edema assay. The structure–activity data acquired indicate that the acetylene moiety constitutes a suitable scaffold (template) to design novel acyclic 1,2-diarylacetylenes with selective COX-2, or dual COX-1/COX-2, inhibitory activities.

An evaluation of the sensitivity of the standardised field sobriety tests to detect the presence of amphetamine

The Standardised Field Sobriety Tests (SFSTs), designed and validated to assess impairment associated with alcohol intoxication, are currently being employed by the Victoria Police (Australia) for the identification of driving impairment associated with drugs other than alcohol. The aim of this study was to evaluate whether the SFSTs are a sensitive measure for identifying the presence of dexamphetamine and methamphetamine. Three studies each employed a repeated-measures, counterbalanced, double-blind placebo-controlled design. In each study, 20 healthy volunteers completed two treatment conditions: either 0.42 mg/kg d,l-dexamphetamine and placebo, 0.42 mg/kg d,l-methamphetamine and placebo, or 0.42 mg/kg d-methamphetamine and placebo. Performance was assessed using the SFSTs, consisting of the Horizontal Gaze Nystagmus test, the Walk and Turn test, and the One Leg Stand test. Blood and saliva samples were obtained before and immediately after the administration of the SFSTs (120 and 170 min post drug administration). At 120 and 170 min post drug administration, d,l-dexamphetamine blood levels were 83.16 and 98.42 ng/ml, respectively; d,l-methamphetamine levels were 90 and 95 ng/ml, respectively; and d-methamphetamine blood levels were 72 and 67 ng/ml, respectively. None of the three amphetamine doses impaired performance on the SFSTs. Using the SFSTs, the presence of dexamphetamine was identified in 5% of cases, d-methamphetamine in 5%, and d,l-methamphetamine in 0% of cases. Under these conditions, the SFSTs are not a sensitive measure for detecting the presence of low levels of amphetamine.

Dynamic manganese-enhanced MRI signal intensity processing based on nonlinear mixed modeling to study changes in neuronal activity

We analyze data on the impact of testosterone on the dynamics of Mn2+ accumulation measured by magnetic resonance imaging in three songbird brain areas: the nucleus robustus arcopallii (RA), area X, and the high vocal center (HVC). Birds with and without testosterone were included in the experiment, and repeated measurements were available in both a preand post-drug administration period. We formulate a nonlinear modeling strategy, allowing for the incorporation of (1) within-bird correlation, (2) the nonlinearity of the profiles, and (3) the effect of treatment. For two of the outcomes (RA and area X), biological theory suggests a parametric form, but for HVC this is not the case. Because the HVC outcome bears some resemblance with the two-compartment model known from pharmacokinetics, this model was considered a sensible choice. We use a different model, based on fractional polynomials, as a sensitivity analysis for the latter. All methods used provide good fits to the data, confirm results from previous, simple analyses undertaken in the literature, but were able to detect additional effects of treatment that had so far gone undetected. The fractional polynomial and two-compartment models provide similar substantive conclusions; the two together can be seen as a form of sensitivity analysis.

Functional effects of single dose first- and second-generation antipsychotic administration in subjects with schizophrenia

Using PET with 15O water, we characterized the time course of functional brain changes following the acute administration of a first- and a second-generation antipsychotic. Volunteers with schizophrenia were scanned while drug-free (baseline) and after single dose administration of haloperidol ( n = 6) or olanzapine ( n = 6) during a time course adapted to their plasma kinetics. To obtain brain location information, we contrasted each post-drug scan to baseline-acquired scans. We plotted the regional cerebral blood flow (rCBF) extracted in these locations and calculated the kinetic characteristics of the curves. Further, we compared and contrasted the rCBF changes induced by the drugs over the first 4 h post-drug administration. Dorsal and ventral striatum, thalamus and anterior cingulate cortex were activated with haloperidol, while frontal, temporal and cerebellum regions evidenced reduced flow. With olanzapine, ventral striatum, anterior cingulate and temporal cortices evidenced increases, and thalamus and lingual cortex decreases, in rCBF. Both drugs activated the caudate nucleus. Haloperidol induced greater activation of the dorsal striatum than did olanzapine. These data reveal important differences in patterns of brain activation between the drugs. Differences in the involvement in basal ganglia parallel known differences between the drugs in the emergence of acute EPS upon emergency administration.

DISPOSITION KINETICS OF DIFLOXACIN IN NORMAL AND EXPERIMENTALLY INFECTED CHICKENS WITH MYCOPLASMA GALLISEPTICUM

The pharmacokinetic properties of difloxacin were investigated follo-wing intravenous, intramuscular and oral administration of 10 mg/kg body weight, in non-infected and experimentally mycoplasma infected chickens. Serum concentrations of difloxacin were assayed microbial-ogically after intravenous, intramuscular and oral administrations. difl-oxacin residues were detected in chicken tissues following repeated oral administrations in non-infected and infected chickens. Following a single intravenous injection, the serum difloxacin level was best approximated to follow a two-compartment open model. The elimination half-life (t0.5b) was 4.58 + 0.008 h. The volume of distri-bution at steady-state (Vdss) was 2.12 + 0.07 L/kg and the mean resid-ence time (MRT) was 3.91 + 0.07 h. Following a single oral administration of 10 mg/kg b.wt difloxacin,the recorded results revealed that serum level of difloxacin was higher in infected chickens than non infected chickens. Serum concentrations peaked one hour post-drug administration with half lifes of absorption (t0.5ab) of 0.48 + 0.02 and 0.37 + 0.02 hour in non infected and myc-oplasma infected chickens, respectively. The extent of serum protein binding of difloxacin in non-infected chickens was 15.44 + 1.24%. Systemic bioavailability after oral and intramuscular administration of difloxacininnon-infectedchickenswas75.87and 93.03%,respectively. Following oral and intramuscular administration of 10 mg difloxacin / kg b.wt once daily for 5 consecutive days in infected and non infected chic-kens, the drug could be detected in all tested tissue up to 48 hours after last oral and intramuscular dose in non infected and infected chickens.

Effects of sildenafil on rat irritable bowel syndrome

Background: Irritable bowel syndrome (IBS) is a disorder with unknown pathophysiology, although it would appear that stress of different types plays an important role in the onset and development of the disorder. It affects 10-15% of the general population. Currently, anticholinergics and prokinetics are the main therapies. Objective: The objective of this study was to examine the effects of sildenafil in an animal model of IBS. Methods: IBS was induced in rats using the wrap-restraint method and sildenafil was administered intragastrically by gavage at doses of 0.5, 1 and 5mg/kg. Gastric emptying, small bowel transit and fecal excretion (index of large intestine motility) as well as concentrations of cyclic nucleotides (cGMP and cAMP) and total antioxidant capacity in the large intestine were determined. Results: Sildenafil at all doses used (0.5, 1 and 5mg/kg) significantly reduced gastric emptying up to 120min postdrug administration. All doses (0.5, 1 and 5mg/kg) of sildenafil dose-dependently reduced...

Enhancement of Radiation Effect by <i>Aphanamixis polystachya</i> in Mice Transplanted with Ehrlich Ascites Carcinoma

The effect of radiation on tumor tissue can be optimized by adding radiosensitizing agents, in order to achieve a greater degree of tumor damage than expected from the use of either treatment alone. The ethanolic extract of Aphanamixis polystachya (APE) was tested in Swiss albino mice transplanted with Ehrlich ascites carcinoma (EAC) and exposed to various doses of gamma-radiation. EAC mice received 0, 10, 25, 50, 75, 100, 150 or 200 mg/kg body wt APE before exposure to 6 Gy gamma-radiation followed by once daily administration for another 8 consecutive days post-irradiation. The optimum radiosensitizing dose was found to be 50 mg/kg APE that was further tested in EAC mice exposed to 0, 1, 2, 4, 6 or 8 Gy hemi body gamma-radiation. The best effect of APE and radiation was observed for 6 Gy gamma-radiation. The splitting of 50 mg into two equal fractions of 25 mg and administering the split dose with a gap of 8 h on 1, 3, 5, 7 or 9 d of tumor inoculation resulted in an increased survival even when the drug was administered at late stages (day 5) of tumor development. The APE treatment before irradiation elevated lipid peroxidation followed by a reduction in the glutathione contents. Treatment of tumor bearing mice with APE before irradiation further reduced the activities of various antioxidant enzymes like glutathione peroxidase, glutathione-s-transferase, superoxide dismutase and catalase at different post last drug administration (PLDA) times.

The effects of dexamphetamine on simulated driving performance

The number of road fatalities related to the presence of amphetamines in drivers has been relatively constant over the past 10 years. However, there remains uncertainty as to the extent that these drugs induce driving impairment, and whether any such impairments translate to an increase in road fatalities. To examine the acute effects of 0.42 mg/kg dexamphetamine on simulated driving performance, and to establish which, if any, simulated driving abilities become impaired following dexamphetamine administration. A repeated-measures, counter-balanced, double-blind, placebo-controlled design was employed. Twenty healthy volunteers completed two treatment conditions-0.42 mg/kg dexamphetamine and placebo. Performance was assessed using a driving simulator task. Blood and saliva samples were obtained prior to the driving tasks and immediately after task completion (120 min and 170 min post-drug administration, respectively). Mean dexamphetamine blood concentrations were 83 ng/ml and 98 ng/ml at 120 min and 170 min, respectively. Results indicated a decrease in overall simulated driving ability following dexamphetamine administration during the day-time but not the night-time scenario tasks. Contributing to this performance reduction, "incorrect signalling", "failing to stop at a red traffic light" and "slow reaction times" were the behaviours most strongly affected by dexamphetamine. The decrease in simulated driving ability observed during the day-time driving tasks are consistent with the perceptual narrowing or tunnel vision that is associated with dexamphetamine consumption.

In vivo measurements of the cerebral perfusion and cardiovascular effects of the novel guanidine ME10092 in the non-human primate, Papio ursinus

The novel guanidines N-(3,4-dimethoxy-2-chlorobenzylideneamino)-guanidine (ME 10092) and N-(3,4-dimethoxy-2-chlorobenzylideneamino)-N 1-hydroxyguanidine (PR5) were recently reported to exhibit promising cardioprotective activities in myocardial ischaemia and reperfusion in rats. The current study investigated for the first time pharmacological effects of ME10092 in the primate, viz. the Cape baboon Papio ursinus. The effects of ME10092 (1 and 2 mg/kg doses) on the cerebral blood flow, heart rates and the systolic and diastolic blood pressure were investigated after intravenous injection to the baboon under anaesthesia. The cerebral perfusion effects of ME10092 were assessed using Single Photon Emission Computed Tomography according to the split-dose approach and 99mTc-hexamethyl-propylene amine oxime as brain perfusion tracer. The observation that the recovery times from the anaesthesia were unacceptably prolonged excluded doses beyond 2 mg/kg. The data indicate that no cerebral perfusion changes were induced at both the 1 and 2 mg/kg doses of ME10092. Both these doses of ME10092 showed blood pressure and heart rate effects, with the latter being more significant. Decreases in heart rate were seen directly after ME10092 administration reaching levels of about 20% for the 2 mg/kg dose and about 15% for the 1 mg/kg dose at around 6 min post drug administration. A transient decrease in both systolic and diastolic blood pressure was observed for the higher dose. The blood pressure data further suggest an attenuation of the anaesthesia induced increase in pressure usually present in non-intervention studies. ME10092 clearly exhibits mycocardial effects in the non-human primate, similar to the effects previously observed in the ischaemia-reperfusion rat model, where ME10092 showed strong protection.

Combretastatin family member OXI4503 induces tumor vascular collapse through the induction of endothelial apoptosis.

The mechanism of tumor cell killing by OXI4503 was investigated by studying vascular functional and morphological changes post drug administration. SCID mice bearing MHEC5-T hemangioendothelioma were given a single dose of OXI4503 at 100 mg/kg. Tumor blood flow, measured by microsphere fluorescence, was reduced by 50% at 1 hr, and reached a maximum level 6-24 hr post drug treatment. Tumor vascular permeability, measured by Evan's blue and hemoglobin, increased significantly from 3 hr and peaked at 18 hr. The elevated tumor vessel permeability was accompanied by an increase in vascular endothelial growth factor (VEGF) from 1 hr post drug treatment. Immunohistochemical staining for CD31 and laminin showed that tumor blood vessels were affected as early as 3 hr but more prominent from 6 hr. From 12 hr, the vessel structure was completely destroyed. Histopathological and double immunohistochemical staining showed morphological change and induction of apoptosis in endothelial cells at 1-3 hr, followed by tumor cell necrosis from 6-72 hr. There were no statistically significant changes of Evan's blue and hemoglobin contents in liver tissue over the time course. These results suggest that OXI4503 selectively targets tumor blood vessels, and induces blood flow shutdown while it enhances tumor blood vessel permeability. The early induction of endothelial cell apoptosis leads to functional changes of tumor blood vessels and finally to the collapse of tumor vasculature, resulting in massive tumor cell necrosis. The time course of the tumor vascular response observed with OXI4503 treatment supports this drug for development as a stand alone therapy, and also lends support for the use of the drug in combination with other cancer therapies.

Oral ketamine as a positive control in abuse liability studies

Background NMDA receptor antagonists are currently being developed for the treatment of several neurodegenerative disorders including Alzheimer's disease, Parkinson's disease and neuropathic pain conditions. Some high affinity NMDA receptor antagonists (e.g. phencyclidine and ketamine) have dissociative properties and are established agents of abuse. Other NMDA receptor antagonists such as memantine, amantadine or dextromethorphan do not exhibit significant potential for abuse. Therefore based on the pre-clinical and/or clinical pharmacological profiles, a clinical abuse potential evaluation may be required for a new NMDA receptor antagonist or a new formulation of an existing NMDA receptor antagonist. Positive (abused) control drugs such as ketamine are required in the conduct of human abuse liability studies. Most published studies have evaluated intravenous ketamine as a comparator drug. Purpose The present study was designed to assess the subjective effects of oral ketamine. Methods Twenty-nine healthy, experienced recreational drug users were given d-amphetamine (d-AMP) 20 mg p.o. in a single-blinded within-day qualifying day in which they could receive three doses of placebo and one dose of d-AMP. Sixteen subjects reliably reported liking d-AMP and 11 subjects (9 males, 2 females) entered a single-blind controlled dose escalating study in which they received ketamine 65 mg, 100 mg or 150 mg (intravenous formulation dissolved in juice) or placebo-juice orally. Subjective and physiologic measures were evaluated for up to 8 hours post-drug administration. Results Graded dose related effects and differences from placebo were reported across a wide range of abuse measures (e.g. VAS feeling high, VAS liking, subjective price value, Cole ARCI euphoria). Pharmacologic effect characteristics of the class (e.g. floating, confusion) were also found. Ketamine 65 mg was readily distinguished from placebo on most measures. Doses of 150 mg were well tolerated in the 4 subjects who received this dose. Conclusions These pharmacological data suggest that oral doses of ketamine (60 -150 mg) can be used as positive controls for studies for NMDA receptor antagonist mediated effects. Clinical Pharmacology & Therapeutics (2004) 75, P72–P72; doi: 10.1016/j.clpt.2003.11.271

Impact of racemic albuterol compared to levalbuterol on objective measures of hyperactivity and inattentiveness in children with asthma

Rationale Levalbuterol (LEV) 0.63 mg produces clinically comparable bronchodilation compared with racemic albuterol (RAC) 2.5 mg, but with fewer beta-mediated side effects. Parents complain of increases in hyperactivity and restlessness following treatment with racemic albuterol (White and Sander, JACI 1999). This study quantified and compared the effects of LEV, RAC, and placebo (PLA) on measures of hyperactivity and attentiveness in children with asthma. Methods Randomized, double-blind, 3-way crossover study. Either PLA, LEV 0.63 mg and RAC 2.5 mg were administered to 16 children (12 to 16 years old) on three separate visits. Attention and activity were measured using an FDA-approved test (McLean Motion and Attention Test) focused on two of the primary symptoms of ADHD, namely hyperactivity and inattention (15-min computer-driven vigilance task coupled to a high precision motion analysis system that tracks patient movement, performed at baseline and 15-min post drug administration). Objective measures included time spent immobile, spatial scaling (complexity of movement patterns), temporal scaling (index of time spent moving) and heart rate. Results Measures were significantly better following treatment with LEV compared with RAC (p≤0.007), indicating that RAC produced less time spent immobile, a higher index of time spent moving and more complex movements. Additionally, RAC resulted in significant changes in time spent immobile versus placebo (p=0.03). RAC, but not LEV, resulted in a significant increase in heart rate (p≤0.014 versus LEV and placebo). Conclusions In this study, treatment with RAC 2.5 mg significantly increased objective measures of hyperactivity and inattentiveness in asthmatic children compared with LEV 0.63 mg.

Design, synthesis, and biological evaluation of 6-substituted-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones: a novel class of diarylheterocyclic selective cyclooxygenase-2 inhibitors.

A group of 6-alkyl (alkoxy or alkylthio)-4-aryl-3-(4-methanesulfonylphenyl)pyran-2-ones (14a-v), possessing either a H or F substituent at the para-position of the C-4 phenyl ring, were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo antiinflammatory-analgesic activities. Although 6-ethylthio-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (14s) exhibited a very high in vitro COX-2 inhibitory potency (IC(50) = 0.0032 muM) and COX-2 selectivity (SI > 120 000), 14s exhibited moderate antiinflammatory activity compared to celecoxib in a carrageenan-induced rat paw edema assay. In contrast, the less potent (IC(50) = 0.10 muM), and less selective (SI = 2880) COX-2 inhibitor 6-ethoxy-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (14i) exhibited good antiinflammatory activity where a 1 mg/kg oral dose reduced inflammation 32 and 67% at 3 and 5 h postdrug administration relative to the reference drug celecoxib where a 50 mg/kg oral dose reduced inflammation by 79 and 58% at the respective 3 and 5 h time periods. Molecular modeling studies, where 14i was docked in the active site of both COX-1 and COX-2, reveals that the C-6 ethoxy substituent orients the pyran-2-one ring to position the SO(2)Me pharmacophore in the vicinity of the secondary pocket in COX-2. The absence of this COX-2 secondary pocket in the COX-1 binding site is due to the presence of the bulky Ile(523) in COX-1 such that access to the amino acid residues (Ile(517), Phe(518), Gln(192), and His(90)), which line the COX-2 secondary pocket with which the SO(2)Me pharmacophore could interact, is hindered. The six-membered pyran-2-one ring system is a suitable central template to design selective COX-2 inhibitors.

Limits of stimulation of proliferation and differentiation of bone marrow cells of mice treated with swainsonine

The limits of stimulation of the immunomodulatory alkaloid swainsonine (8αβ-indolizidine-1α,2α,8β-triol) were studied in inbred C57BL/6 mice for potential support of intense high dose cancer chemotherapy and/or radiation because of its attractive pharmacologic profile on the hematopoietic system. Specifically, the effects of swainsonine on bone marrow cellularity and on in vitro progenitor cell proliferation to total colony forming units (CFU) and differentiation to different lineages were studied as a function of number of days post drug administration. The lineages evaluated were colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFU-e) and CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM or CFU-Mix). Groups of mice were treated with swainsonine or plain vehicle, phosphate buffered saline for 10 consecutive days. The effects of these agents on the hematopoietic system were studied up to 60 days following their discontinuation. The magnitude of the effects of swainsonine on bone marrow system gradually declined with increasing duration of days following its discontinuation. Nevertheless, its residual stimulatory effects on bone marrow cellularity, total CFU, CFU-GM, BFU-e and CFU-Mix continued to be significant ( P<0.0001) up to 45, 50, 50, 55 and 50 days, respectively, compared to those of diluent buffer or untreated controls. Since cancer chemotherapeutic agents or radiation are normally given in schedules and/or cycles, these results strongly suggest that swainsonine effects are sustained long enough to potentially support and facilitate hematopoietic recovery during anti-cancer cytotoxic treatment.

Inhibition of baboon platelet aggregation in vitro and in vivo by the garlic derivative, ajoene.

The infusion of pig growth factor-mobilized peripheral blood leukocytes (containing 1 to 2% progenitor cells) (pPBPC) into baboons is associated with a thrombotic microangiopathy, which results from a direct effect of these pig cells on platelet aggregation. Ajoene is a synthetic derivative of garlic that inhibits aggregation of human platelets induced by all known agents. To assess its potential use in models of xenotransplantation, this agent was tested for its effect on baboon platelet aggregation in vitro and in vivo. Baboon platelet aggregation assays, using adenosine diphosphate (ADP) (20 or 40 microm) or collagen (12.5 microg/ml), were performed after incubation with ajoene (0 to 150 microg/ml) or dipyridamole (0 to 200 microg/ml). Platelets were also incubated with pPBPC (5 x 10(6) cells) without or with ajoene in the absence of a known agonist. In vivo studies: Baboons received either a single intravenous dose of ajoene (10 to 25 mg/kg) or dipyridamole (0.8 mg/kg), or repeated doses of both agents at 2 to 3 h intervals. Platelet-rich plasma was obtained for platelet aggregation assays at time points up to 4 h post-drug administration. In vitro, platelet aggregation was inhibited by 95% (ADP assay) and 89% (collagen assay) by ajoene at concentrations of > or =75 microg/ml. Dipyridamole had no effect at concentrations of <100 microg/ml, but inhibited aggregation almost completely at higher concentrations. Ajoene inhibited the aggregation caused by pPBPC by 33 to 50%. In vivo, platelet aggregation was completely inhibited for 2 h by ajoene at 25 mg/kg. Dipyridamole at 0.8 mg/kg reduced aggregation by 20% for 15 min, but the effect was lost by 60 min. In combination, the two agents prolonged inhibition marginally. Repeated doses of both agents at 2 h intervals maintained complete inhibition of aggregation, but did not do so when the interval between doses was extended to 2.5 or 3 h. Combined therapy was not associated with any bleeding complications. Although ajoene is a powerful inhibitor of platelet aggregation, the need for repeated administration and its partial effect on pPBPC-induced platelet aggregation would suggest that it may be of only limited value in preventing the thrombotic microangiopathy that develops when pPBPC are infused into baboons. However, it would seem worthy of further investigation when used in combination with other agents.

Influence of age on the enantiomeric disposition of ibuprofen in healthy volunteers.

To determine the influence of age on the enantioselective disposition of ibuprofen in humans. Healthy young (n = 16; aged 20-36 years) and elderly (n = 16; aged 66-84 years) volunteers were given a 400-mg oral dose of racemic ibuprofen, and blood and urine samples were collected for 24 h post drug administration. Serum concentrations, total and free, and urinary excretion of both enantiomers of ibuprofen together with the urinary excretion of the stereoisomers of the two major metabolites of the drug, both free and conjugated, were determined by high-performance liquid chromatography. Ageing had little effect on the distribution and metabolism of R-ibuprofen, unbound clearance of the R-enantiomer via inversion being approximately two-fold that via noninversion mechanisms in both age groups. In contrast, the free fraction of S-ibuprofen was significantly greater [33%; young 0.48 +/- 0.10%; elderly 0.64 +/- 0.20%] mean difference -0.16; 95% confidence interval (CI) -0.05, -0.27; P < 0.01; and the unbound clearance of the drug enantiomer was significantly lower (28%; young 15.9 +/- 2.2 l min-1; elderly 11.5 +/- 4.1 l min-1; mean difference 4.4; 95% CI 2.12, 6.68; P < 0.001) in the elderly. The metabolite formation clearances of S-ibuprofen via glucuronidation, and oxidation at the 2- and 3- positions of the isobutyl side chain decreased by 24, 28 and 30%, respectively, in the elderly compared with the young, the differences between the two age groups being significant in each case (P < 0.05). Following administration of racemic ibuprofen age-associated stereoselective alterations in drug disposition have been observed, with the elderly having increased free concentrations and lower unbound clearance of the S-enantiomer in comparison with the young. In contrast, the handling of the R-enantiomer is essentially unaltered with age. The results of this study indicate that the elderly have an increased exposure to the active ibuprofen enantiomer and thus some caution may be required when using this drug in this age group.

The modulatory effects of dopamine D1 and D2 receptor function on object working memory in humans

The role of dopamine D1 and D2 receptors in modulating object working memory in humans is poorly understood. The current study was designed to investigate the effects of D1 and D2 receptor modulation on object working memory. Twelve healthy subjects underwent testing under three conditions (0.05 mg pergolide (D1/D2 receptor agonist), 2.5 mg bromocriptine (D2 receptor agonist) and placebo] in a double-blind, placebo-controlled repeated measures design. Subjects performed the object working memory N-back task pre-drug and 1.5 h and 3 h post-drug administration. Neither pergolide nor bromocriptine had an effect on object working memory performance. These findings suggest that object working memory may not be modulated by D1 and D2 receptors in humans.

Distribution of Oxacillin in Serum and Milk of Treated and Untreated Quarters in Cows Following Intramammary Infusion*

Experience in the use of intramammary antibiotic therapy has indicated that antibiotics are absorbed from the treated quarters into systemic circulation; degrees of absorption and hence crossover of drug to untreated quarters being different for different antibiotics. To answer these questions, a study was conducted on the use of oxacillin in three lactating cows of German Black Pied breed. The health status of quarters was assessed as per IDF criteria. Two quarters of each cow were infused each with Injection Oxacillin (1000 mg of water free oxacillin sodium, from Virbac Tierarzeneimittel GmbH, Germany) two times at 24 hours interval. The milk and blood samples were collected and processed in pre-treatment phase to rule out any antibiotic contamination. In post-treatment phase milk samples were collected up to 11 regular milking, and blood samples at different time intervals starting from 10 minutes to 24 hours post-therapy. The estimation of drug in milk and serum was done by Charm II test (From Charm Sciences Inc., USA). The therapy produced a drug concentration in milk from treated quarters, of 53.21 µg/ml to 180.55 µg/ml at first milking post-drug administration. The milk drug levels at 2nd milking ranged between 0.95 and 3.83 µg/ml. In all cases, the concentration fell below the detectable level of 0.01 µg/ml at 6th milking in treated quarters, and at 4th milking in bucket milk, after last infusion. The drug passed to untreated quarters; highest drug concentration being 0.65 µg/ml, and crossover residue persisted for 24 to 36 h post-therapy. The total excretion of oxacillin in milk from treated quarters varied between 18.00 and 35.50% of the administered dose. The drug diffused very rapidly to the general circulation; peak serum drug levels were detected at 10 to 30 minutes post-therapy. The peak serum drug levels in different cows ranged from 0.56 µg/ml to 1.38 µg/ml. The serum drug activity of 0.02 to 0.03 µg/ml was still maintained at 24 h when a second infusion was made. Following second infusion, serum drug concentrations of 0.11 to 0.18 µg/ml at 12 h, and 0.02 to 0.04 µg/ml at 24 h were observed.

Design, syntheses, and evaluation of novel 1,1‐dihalo‐2,3‐diphenylcyclopropanes as potential cyclooxygenase‐2 (COX‐2) inhibitors with analgesic‐antiinflammatory activity

AbstractA group of (Z)‐ and (E)‐1,1‐dihalo‐2‐(4‐substituted‐phenyl)‐3‐phenylcyclopropane [(Z)‐10, (E)‐11] stereoisomers having a variety of substituents (H, Br, Cl, F, NO2, SO2Me) at the para‐position of the C‐2 phenyl ring in conjunction with either two chloro or bromo substituents at C‐1 were synthesized for in vivo evaluation as analgesic and antiinflammatory (AI) agents, and as potential selective cyclooxygenase‐2 (COX‐2) inhibitors. This group of compounds (10‐11) exhibited significant analgesic activity since 4% NaCl‐induced abdominal constriction was reduced by 44–73% at 30 min, and 48–77% at 60 min, post‐drug administration relative to the reference drugs aspirin and celecoxib (58 and 32% inhibition at 30 min post‐drug administration) for a 50 mg/kg intraperitoneal dose. In the 1,1‐dichloro group of compounds, a Cl or MeSO2 substituent at the para‐position of the C‐2 phenyl ring generally provided superior analgesic activity. The most active analgesic compound, (E)‐1,1‐dichloro‐2‐(4‐methanesufonylphenyl)‐3‐phenylcyclopropane (11h) inhibited abdominal constriction by 72 and 77% at 30 and 60 min post‐drug administration, respectively. AI activities, determined using the carrageenan‐induced rat paw edema assay, showed that this class of (Z)‐10 and (E)‐11 compounds exhibited AI activities in the inactive‐to‐moderate activity range (1.5–45% inhibition) for a 50 mg/kg oral dose. The AI potency order, with respect to the para‐substitutent on the C‐2 phenyl ring, for the (Z)‐10 compounds was NO2 &gt; MeSO2 ≈ H ≥ Cl, and for the (E)‐11 compounds was H ≥ MeSO2 &gt; Cl ≈ Br. (E)‐1,1‐dibromo‐2‐(4‐methanesufonylphenyl)‐3‐phenylcyclopropane (11l), which was the most active AI compound, reduced inflammation by 45 and 37% at 3 and 5 h post‐drug administration, respectively. The (E)‐11 stereoisomer was generally a more potent AI agent than the corresponding (Z)‐10 stereoisomer. In vitro COX‐1 and COX‐2 inhibition studies showed that (E)‐1,1‐dichloro‐2‐(4‐nitrophenyl)‐3‐phenylcyclopropane (11c) inhibited COX‐1 (IC50 = 278.8 μM) and COX‐2 (IC50 = 80.5 μM) for a COX‐2 selectivity index of 3.5, whereas (E)‐1,1‐dichloro‐2‐(4‐methanesulfonylphenyl)‐3‐phenylcyclopropane (11h) was a more potent inhibitor of COX‐1 and COX‐2, but it was more selective for COX‐1 (COX‐1 IC50 = 0.59 μM, COX‐2 IC50 = 3.04 μM). A molecular modeling (docking) study for (E)‐1,1‐dichloro‐2‐(4‐methanesulfonylphenyl)‐3‐phenylcyclopropane (11h) on the active site of the human COX‐2 isozyme shows it binds in the center of the active site with the 1,1‐dichloro substituents oriented in the direction of the mouth of the channel towards Arg120, and the C‐2 MeSO2 moiety oriented towards the apex of the active site with the S‐atom of the MeSO2 substituent positioned about 6.56 Å inside the entrance to the secondary pocket (Val523) of COX‐2. In contrast, the corresponding (Z)‐10h stereoisomer assumes a different position in the COX‐2 binding site where the S‐atom of the MeSO2 moiety is near (4.02 Å) the Ser530 OH, but a much greater distance from the COX‐2 secondary pocket (Val523). The results from these docking studies are consistent with the observation that (E)‐11h is an inhibitor of both COX isozymes, whereas the (Z)‐10h stereoisomer is an inactive COX inhibitor (COX‐1 IC50 &gt; 100 μM, COX‐2 IC50 &gt; 200 μM). Drug Dev. Res. 55:79–90, 2002. © 2002 Wiley‐Liss, Inc.