bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of 1-Anilino-8-napthalenesulphonate as an Ion Probe for the Potentiometric Study of the Binding of Sulphonamides to Bovine Serum Albumin and Plasma
Authors: Angelakou A , Valsami G , Koupparis M , Macheras P
Published: April 2011

The binding of sulphafurazole, sulphamethizole and sulphamethoxazole to bovine serum albumin (BSA) and human plasma has been studied in-vitro by potentiometry using an electrode selective for the ion probe 1-anilino-8-napthalenesulphonate (ANS). The method requires two separate potentiometric titrations of the binder solution with ANS in the absence and in the presence of sulphonamides. ANS displaced sulphonamides from the first-class of binding sites of both binders. The binding constants for sulphonamide-BSA interactions were higher than those for sulphonamide-human plasma. The expansion of the least linear limit of the response curve of the electrode down to 10−7  m in the presence of BSA was also demonstrated. The reverse reaction, i.e. the displacement of the probe from the binding sites induced by the sulphonamides, was also explored. The proposed method is suitable for studying competitive binding interactions in biological specimens.
Different Mechanism of Relaxation Induced by Aporphine Alkaloids in Rat Uterus
Authors: Ivorra M Dolores , Martinez Francisco , Serrano Angel , D’Ocon Pilar
Published: April 2011

We have examined the uterine relaxant action of three aporphine molecules (S-glaucine, S-boldine and R-apomorphine) in two experimental conditions, with and without calcium in the bathing solution, and compared these effects with those obtained with the calcium antagonists verapamil and diltiazem. The present study shows that the alkaloids relax the uterine muscle but with different mechanisms of action. In Ca2+-containing solution all three alkaloids relaxed the uterus previously contracted by KCl or acetylcholine, but in Ca2+-free medium only R-apomorphine was able to relax oxytocin-induced contraction. The calcium antagonists, verapamil and diltiazem, relaxed KCl- or acetylcholine-induced contraction in Ca2+-containing solution, whereas they only relaxed oxytocin-induced contraction in Ca2+-free medium at much higher doses. These results suggest that glaucine and boldine behave as specific calcium entry blockers without affecting the contractile machinery or intracellular Ca2+ levels as apomorphine does. The absolute configuration (S-glaucine and S-boldine vs R-apomorphine) may account for this different action.
Inhibitory Activity of Camptothecin Derivatives Against Acetylcholinesterase in Dogs and Their Binding Activity to Acetylcholine Receptors in Rats
Authors: Kawato Yasuyoshi , Sekiguchi Masayasu , Akahane Kouichi , Tsutomi Yumi , Hirota Yasuhide , Kuga Hiroshi , Suzuki Wataru , Hakusui Hideo , Sato Reiki
Published: April 2011

A camptothecin derivative, 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11), shows a potent antitumour activity in experimental tumour models and in clinical trials. However, CPT-11 induced early diarrhoea and vomiting at high dose levels in clinical studies and showed an acetylcholine-like action on the guinea-pig ileum and trachea. In the present study, we investigated the activities of camptothecin derivatives in inhibiting acetylcholinesterase (AChE) and in binding to muscarinic acetylcholine receptors (AChR). CPT-11 inhibited AChE and binding of the specific ligand to AChR with respective 50% inhibition concentrations of 0·2 and 5 μm. These inhibitions were induced by camptothecin derivatives having an amino group at the C-10 position (or the C-4 position of hexacyclic derivatives), but were not or were only slightly induced by the others. Early defecation and vomiting in dogs were observed after intravenous injection of DU-6596 and DU-6888, two hexacyclic derivatives having the aminomethyl group at the C-4 position, and of CPT-11. DU-6174, however, which has a hydroxy group at this position, induced no early defecation and little vomiting. Plasma concentrations of CPT-11, DU-6596 and DU-6888 after intravenous treatment at doses causing such early adverse effects were maintained for 1 h or longer at levels sufficient to inhibit AChE. These results suggest that the inhibition of AChE by camptothecin derivatives with an amino group at the C-10 position (or the C-4 position) relates to the early defecation or diarrhoea and vomiting.
Inhibition of Endogenous Acetylcholine Release by Blockade of Voltage-dependent Calcium Channels in Enteric Neurons of the Guinea-pig Colon
Authors: Marino Franca , Marcoli Manuela , De Ponti Fabrizio , Lecchini Sergio , Castelletti Carlo Maria , Frigo Gian Mario
Published: April 2011

The effects on acetylcholine release from the guinea-pig colon of the N-type calcium channel blocker ω-conotoxin GVIA (ω-conotoxin), the L-type calcium channel blocker nifedipine and the putative blocker of T-type channels, flunarizine, have been investigated. Endogenous basal acetylcholine release and electrically (1 Hz, 1 ms, 450 mA)-evoked overflow in the presence of cholinesterase inhibitor were studied. ω-Conotoxin (1–10 nM) and nifedipine (0·03–3 μm) dose-dependently inhibited basal and electrically-evoked acetylcholine release. Maximal inhibition of basal or electrically-evoked acetylcholine release was about 40% for nifedipine and about 75% for ω-conotoxin. The potency of nifedipine was inversely related to the external calcium concentration: its EC50 value in low-calcium medium (0·5 Mm) was as low as 12 Nm. Flunarizine inhibited acetylcholine release only at concentrations higher than 0·2 μm. Our results are consistent with an involvement of N- and L-type calcium channels in the control of the endogenous acetylcholine release from the guinea-pig colon.
Effect of Hepatotoxic Doses of Paracetamol and Carbon Tetrachloride on the Serum and Hepatic Carboxylesterase Activity in Mice
Authors: Huang Tien L , Villalobos Sergio A , Hammock Bruce D
Published: April 2011

The carboxylesterase activity in the serum and liver of untreated Swiss-Webster mice, and in mice administered hepatotoxic doses of either CCl4 or paracetamol was studied. In addition to p-nitrophenyl acetate (p-NpAc) and diethylsuccinate, a sensitive, spectrophotometric substrate, methyl β-(1-pentylthio) propiothioate was used to determine the esterase activity. At 24 h after treatment with CCl4 (1 mL kg−1), the liver esterase activity in the soluble fraction acting on p-NpAc was increased 1·7-fold whereas the microsomal esterase activity decreased by one-half. The serum esterase activity increased 2·4- to 3·4-fold depending upon the substrate used. Esterase activity assays of sliced gels from isoelectric focusing (IEF) of serum from mice treated with CCl4 indicated the presence of at least three additional esterase peaks when compared with serum of control mice. These peaks correlated with esterase bands visualized after staining the IEF gel with 1-naphthyl acetate. Furthermore, these esterase bands matched closely the esterase bands from microsomes of normal mice. The serum esterase activity was analysed at 4, 8, 12 and 24 h after paracetamol (400 mg kg−1) treatment. Serum esterase activity remained unchanged or decreased marginally depending on the treatment time and substrate used. Serum glutamic oxalacetic transaminase levels in CCl4- and paracetamol-treated mice, however, were significantly elevated compared with control mice. These results suggest that acute liver damage might cause the release of carboxylesterase activity to the soluble intracellular and extracellular compartments, including blood serum, with some but not all toxicants. The results also indicate that the different modes of action of the two chemicals may account for the difference in the serum carboxylesterase activity of the experimental animals.
Evaluation of the Inhibitory Activity on Serine and Aspartic Proteases of 4-Amino-4H-1,2,4-triazole and 5-Aminothiazole Derivatives Structurally Related to β-Lactam Antibiotics
Authors: Vilain Anne-Cécile , Pirotte Bernard , Vergely Isabelle , Boggetto Nicole , Masereel Bernard , Schynts Marc , Delarge Jacques , Reboud-Ravaux Michèle
Published: April 2011

Twenty new derivatives of 4-amino-4H-1,2,4-triazole and 5-aminothiazole have been examined for their inhibitory potential towards serine and aspartic proteases. Upon prolonged incubation with enzyme, the phenylacetylaminothiazolium salts exhibit progressive, time-dependent inhibition of chymotrypsin according to a first-order process. The formation of a tetrahedral transition state-like complex by attack of the active-site serine at the C2-position of the pseudobase form of the thiazolium may be responsible for the observed effect. Triazolium salts appeared to be simple competitive inhibitors of this enzyme, effective in the Mm range concentration. Poor inhibitions of trypsin and pepsin were also obtained in the triazolium series. In spite of their structural analogy with β-lactams, the selected derivatives failed to inhibit human leucocyte elastase.
Mesulergine antagonism towards the fluoxetine anti-immobility effect in the forced swimming test in mice
Authors: Cesana R , Ceci A , Ciprandi C , Borsini F
Published: April 2011

The anti-immobility effect of fluoxetine (40 mg kg−1) in the forced swimming test in mice was antagonized by the 5-HT1c/2 antagonist mesulergine (7·5 mg kg−1) and the dopamine D2 antagonist (±)-sulpiride (12.5 mg kg−1) but not by the 5-HT2/1C antagonist ritanserine (2 mg kg−1), the 5-HT1A/1B antagonist (–)-propranolol (20 mg kg−1) or the 5-HT3 antagonist DAU 6215 (0·1 mg kg−1). All compounds were administered intraperitoneally (i.p.) 6 min before fluoxetine, given i.p. 30 min before testing. The anti-immobility effect of fluoxetine was also prevented by pretreat-ment with p-chlorophenylalanine (300 mg kg−1 twice daily for 3 days) which produced an 80% reduction of 5-HT in brain. The results suggest that fluoxetine reduces immobility time in mice forced to swim, by acting indirectly through a mesulergine-sensitive site, probably the 5-HT1C receptor.
Modulation of (–)-sulpiride-induced increase in electrically-evoked release of dopamine from rat striatal slices
Authors: Yamada Shigeto , Yokoo Hideyasu , Nishi Syogoro
Published: April 2011

(–)-Sulpiride (10 Nm-10 μm) in the superfusate, dose-dependently increased the electrically-evoked release of dopamine from rat striatal slices. (+)-Sulpiride had little effect on evoked release of dopamine up to 10 μm. Apomorphine inhibited electrically evoked release of dopamine, and this effect of apomorphine was antagonized by (–)-sulpiride. SCH23390 and forskolin had no effect on the (–)-sulpiride-induced increase in evoked release of dopamine. Treatment with the irreversible dopamine-receptor antagonist N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline caused a significant increase in evoked release of dopamine and prevented the (–)-sulpiride-induced increase in the evoked release of dopamine. These results indicate that the (–)-sulpiride-induced increase in evoked release of dopamine is due to antagonism of the activation of dopamine autoreceptors by endogenously released dopamine.
Effect of chlorpromazine on mouse ambulatory activity sensitization caused by (+)-amphetamine
Authors: Hirabayashi Makizo , Tadokoro Sakutaro
Published: April 2011

The development of sensitization to the ambulation-increasing effect of (+)-amphetamine (2·5 mg kg−1) was found to be dose-dependently inhibited when 1 or 2 mg kg−1 chlorpromazine was administered concomitantly, and the sensitization to (+)-amphetamine was almost completely suppressed when co-administered with 4 mg kg−1 chlorpromazine. Following a challenge dose of 2·5 mg kg−1 (+)-amphetamine, mice pretreated with (+)-amphetamine alone or with (+)-amphetamine plus 1 or 2 mg kg−1 chlorpromazine showed similar marked enhancement of the sensitization. However, mice that had been given (+)-amphetamine plus 4 mg kg−1 chlorpromazine displayed only slight enhancement of the effect compared with the activity level in saline-pretreated mice.
Chemical and Physicochemical Characterization of Petrolatums Used in Eye Ointment Formulations
Authors: De Muynck C , Lalljie S P D , Sandra P , De Rudder D , Van Aerde P , Remon J P
Published: April 2011

Petrolatums from different manufacturers were characterized by viscosity measurements, oil number and ratio of low to high mol. wt components (capillary gas chromatography). Viscosity measurements and oil numbers of original materials did not correlate with the viscosity of the processed material in eye ointments. The ratio of high carbon number components to the low carbon number components was a reliable predictor for the viscosity of the formulation.
Pulmonary Uptake of Liposome-associated α-Tocopherol Following Intratracheal Instillation in Rats
Authors: Suntres Z E , Hepworth S R , Shek P N
Published: April 2011

This study examined the uptake and subcellular distribution of α-tocopherol in the lung following intratracheal instillation of liposome-associated α-tocopherol in rats. The liposomal suspension was composed of dipalmitoylphosphatidylcholine (DPPC) and α-tocopherol (molar ratio 7:3), labelled with [3H]α-tocopherol and [14C]cholesterol. Following intratracheal administration of the liposomal preparation (2 mg α-tocopherol/animal), the recovery of [3H]α-tocopherol in the lung was maximal (87% of initial dose) 1 h after treatment; thereafter, α-tocopherol levels remained relatively high (no less than 73% of initial dose) for the rest of the 72-h experimental period. This treatment effect resulted in a 16-fold increase in pulmonary total α-tocopherol concentration 72 h post-instillation. No radioactivity was detected in the blood, liver, kidney, pancreas, spleen and heart of animals during the 72-h experimental period. [3H]α-Tocopherol was recovered largely from cytosolic (45%) and nuclear (36%) fractions of lung and to a lesser extent, from microsomal (11%) and mitochondrial (9%) fractions. Chromatographic analysis of the subcellular fractions revealed that [3H]α-tocopherol was co-eluted with 14C-labelled liposomal lipids. Our in-vitro study, involving the incubation of Fe3+-ADP (a pro-oxidant) with mitochondrial or microsomal fractions isolated from lung tissues of animals treated with liposome-associated α-tocopherol, provided evidence that α-tocopherol levels present in the membranes of these subcellular fractions were sufficient to protect against oxidant-induced lipid peroxidation. α-Tocopherol in the rat lung can be greatly increased by the intratracheal instillation of α-tocopherol entrapped in DPPC-liposomes, suggesting that this liposomal preparation may be used as an effective prophylactic agent against oxidant-induced lung injury.
Effects of Long-term Oral Administration of NZ-105, a Novel Calcium Antagonist, With or Without Propranolol in Spontaneously Hypertensive Rats
Authors: Shudo Chizuru , Masuda Yukinori , Sakai Toshinori , Tanaka Sakuya , Shigenobu Koki , Kasuya Yutaka
Published: April 2011

A new calcium antagonist, NZ-105 ((±)-2-[benzyl(phenyl)amino]ethyl 1,4-dihydro-2,6-dimethyl-5- (5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl)-3-pyridinecarboxylate hydrochloride ethanol) (10 mg kg−1, p.o.), showed slow-onset hypotensive effect in spontaneously hypertensive rats (SHRs). The tachycardia evoked by NZ-105 was completely prevented when combined with a β-adrenoceptor blocker, propranolol (20 mg kg−1), which did not affect the hypotensive response to NZ-105. In long-term administration experiments for 12 weeks with SHRs, the systolic blood pressure in the control group increased with age and the heart rate was stable throughout the period. NZ-105 (10 mg kg−1 day−1) alone and its combined treatment with propranolol (20 mg kg−1 day−1) maintained the systolic blood pressure and heart rate at a low level compared with the control group. The hypotensive action of NZ-105 was reproducible after repeated dosing for 12 weeks. Long-term administration of propranolol affected neither the elevation of the systolic blood pressure nor the heart rate substantially. The heart weight per body weight was significantly reduced after the chronic combination of both drugs, suggesting that the cardiac hypertrophy accompanying hypertension was prevented.
The Existence of Conformationally Labile (Preformed) Drug Binding Sites in Human Serum Albumin as Evidenced by Optical Rotation Measurements
Authors: Walji F , Rosen A , Hider R C
Published: April 2011

The ability of certain drugs to induce conformational changes in human serum albumin has been examined by differential optical rotation measurements at 233 nm. At drug: protein molar ratios ([D]/[P]) of unity, the optical rotation increased, decreased or remained the same depending on the drug used. The change in the optical rotatory dispersion (ORD) signal was investigated as a function of the drug concentration. Drug-protein interactions were relatively specific. There exists at least one, and possibly more, stable preformed high affinity sites for the binding of drugs to albumin. At low [D]/[P] ratios, the ORD titration curves suggest that the high affinity sites are conformationally labile and that the albumin molecule is flexible.
Application of the WATR Technique for Water Suppression in 1H NMR Spectroscopy in Determination of The Kinetics of Hydrolysis of Neostigmine Bromide in Aqueous Solution
Authors: Ferdous Abu J , Waigh Roger D
Published: April 2011

Both ammonium chloride and guanidinium chloride were used to secure water suppression in 1H NMR spectra using the ‘Water Attenuation by T2 Relaxation’ (WATR) technique. The effect of phosphate buffer in the suppression was investigated over a range of pH values at 80 MHz. The spin-spin relaxation time of water protons at 80 MHz was found to reach a minimum at pH 7·3 in the presence of 0·1 m phosphate buffer and 1 m guanidinium chloride; these conditions were therefore chosen for subsequent use of the WATR technique in a study of the kinetics of hydrolysis of neostigmine bromide. The method was found to be very convenient for studies of the hydrolysis of this representative amide.
Comparative study of the rat uterine smooth muscle relaxant activity of three bisbenzyltetrahydroisoquinolines with tetrandrine
Authors: Zafra-Polo M Carmen , Tormos M José , Cortes Diego , Anselmi Elsa
Published: April 2011

The relaxant activity of three bisbenzyltetrahydroisoquinolines—obaberine, popisonine and lindoldhamine—was examined in rat isolated uterus and their inhibitory potencies were compared with that of tetrandrine. All alkaloids tested relaxed KCl-depolarized rat uterus and totally or partially inhibited oxytocin-induced rhythmic contractions. The degree of methylation of the free phenolic hydroxy groups and the loss of one diarylether bridge influence the potency of relaxant action of these alkaloids. Only alkaloids with absolute configuration 1R,1′S or 1R1′R acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca2+-free medium.
The effect of therapeutic doses of paracetamol on liver function in the rat perfused liver
Authors: Khedun S M , Maharaj B , Leary W P , Naicker T
Published: April 2011

The isolated liver perfusion technique was used to study the effect of therapeutic doses of paracetamol on hepatic gluconeogenesis and bromosulphthalein clearance from the perfusate and biliary excretion of the dye in the rat. Six groups of rats were studied; those in the three experimental groups were given 0·02 g kg−1 paracetamol daily for ninety days. The livers of animals in the control group and in one of the experimental groups were perfused with a medium containing pyruvate. The animals in the second experimental and control group were perfused with a medium containing bromosulphthalein (10 mg/100 mL). The livers of the third experimental and control group were subjected to histological examination. The rate of glucose formation and glucose concentrations were decreased, while, lactate levels and lactate: pyruvate ratios were increased in paracetamol-treated rats. The mean concentration of bromosulphthalein in the perfusate and biliary excretion of the dye were decreased. Macro and micro vesicular fatty change was present in the livers of paracetamol-treated rats. This study demonstrates that chronic administration of therapeutic doses of paracetamol to rats adversely affects liver function, as evidenced by impaired gluconeogenesis and bromosulphthalein clearance from the perfusate, and excretion of the dye into the bile, and provides histological evidence of hepatic damage in rats.
Dopamine depresses non-adrenergic, non-cholinergic neurotransmission in the rat bladder
Authors: Lot Theodore Y
Published: April 2011

The effects of dopamine on non-adrenergic, non-cholinergic (NANC) neurotransmission have been investigated using rat bladder strips in-vitro. Dopamine administered alone did not produce any effect on the bladder but it depressed responses to NANC nerve stimulation in a dose-related fashion. All doses of dopamine employed depressed KCl-evoked contractions of the bladder to similar extents. The depressant action of dopamine on NANC transmission was not mediated by blockade of purinergic receptors, but was partially reversed by haloperidol. It is suggested that depression of NANC neurotransmission induced by dopamine in the rat bladder is partly mediated by dopaminergic receptors.
Comparison of the effects of KRN2391 and other coronary dilators on porcine isolated coronary arteries of different sizes
Authors: Kasai Hideo , Jinno Yasuhiro , Kaneta Soichiro , Fukata Yuzo , Fukushima Hideaki , Ogawa Nobuyuki
Published: April 2011

The present study was performed to determine whether KRN2391 (N-cyano-N′-(2-nitroxyethyl)-3-pyridinecarboximidamide monomethanesulphonate), a novel vasodilator, shows different effects on porcine isolated coronary arteries of different sizes. The vasodilating effects of KRN2391 on porcine large (2·5–3·0 mm outer diam.) and small (0·8–1·0 mm) coronary arteries were also compared with those of cromakalim, nicorandil, nifedipine, nitroglycerin and adenosine. The relaxant effects of these drugs were examined in coronary arteries contracted by 25 Mm KCl. Nitroglycerin caused greater relaxation in large vessels than in small vessels. In contrast, adenosine, nifedipine and cromakalim caused greater relaxation in small vessels. However, there was no difference between large and small vessels in the relaxing effects of KRN2391 and nicorandil. These unique features of KRN2391 and nicorandil appear to be beneficial in ischaemic heart disease.
Intra-articular therapy of experimental arthritis with a derivative of triamcinolone acetonide incorporated in liposomes
Authors: LóPez-García Francisco , Vázquez-Autón Iosé M , Oil Francisco , Latoore Rafael , Moreno Francisco , Villalaín José , Gómez-Fernández Juan C
Published: April 2011

Triamcinolone acetonide-21-palmitate was synthesized and incorporated into liposomes for intra-articular treatment of an experimentally-induced arthritis in the knee joints of rabbits. The liposomal formulation was more efficient than free triamcinolone acetonide in solution in suppressing the arthritis. Using radioactive tracers, it was found that triamcinolone acetonide-21-palmitate incorporated into liposomes was retained in the articular cavity, together with the liposomal lipids, for a much longer period than free triamcinolone acetonide, and this correlated with its anti-inflammatory effect.
Effect of Alginate and Alginate-cimetidine Combination Therapy on Stimulated Postprandial Gastro-oesophageal Reflux
Authors: Washington N , Denton G
Published: April 2011

This randomized, single-blind cross-over study compared the effectiveness of a conventional alginate reflux barrier formulation (20 mL single dose of Liquid Gaviscon; sodium alginate, sodium bicarbonate, calcium carbonate) with a 20 mL single dose of an alginate-cimetidine combination formulation (Algitec Suspension; sodium alginate, cimetidine) in the suppression of food and acid reflux into the oesophagus after a test meal in 12 healthy volunteers.

Subjects were fasted overnight before the study. A pH electrode and gamma detector were accurately positioned 5 cm above the cardia. The volunteers received a 99mTc-labelled meal designed to provoke reflux and then either remained untreated, or 30 min later were given either Algitec Suspension or Liquid Gaviscon. Reflux of both food and acid into the oesophagus was measured for 3 h. There was a seven day wash-out period between each treatment.

Food reflux in the control group was 22 878 ± 14 385 counts × 103 and this was significantly suppressed by both Liquid Gaviscon (174 ± 128 (s.e.) counts × 103; P = 0.003); however, although the reduction of food reflux to 3812 ± 2322 counts × 103 observed after Algitec treatment was considerable, this did not reach statistical significance (P>0.05) due to the large intersubject variation. Liquid Gaviscon was significantly better at reducing food reflux than Algitec (P = 0.001). Gaviscon also significantly reduced acid reflux when compared with the control group (1.08 ± 0.73 vs 5.87 ± 3.27% recording time oesophageal pH < 4, respectively) (P = 0.03). The slight reduction in acid reflux after Algitec treatment (3.25 ± 1.82% recording time oesophageal pH < 4) also did not reach statistical significance. The difference between Algitec and Gaviscon treatment was also not significant.
Percutaneous Absorption of Salicylates from Some Commercially Available Topical Products Containing Methyl Salicylate or Salicylate Salts in Rats
Authors: Megwa S A , Benson H A E , Roberts M S
Published: April 2011

Studies to determine the extent of local tissue penetration of topically applied, commercially available salicylate esters and salts were conducted in male Wistar rats.

The salicylate concentrations in the deeper tissues approached concentrations observed in the contralateral tissues suggesting that salicylate present in these tissues was due to the systemic blood supply.

The salicylate concentration in plasma, tissues underlying the site of drug application, and similar tissues on the contralateral (control) side were measured. The plasma and tissue salicylate levels suggest that direct penetration of salicylate was predominant to the top muscle level on the treated site. Results also suggest that the drugs were first absorbed into the bloodstream and subsequently distributed to both the deeper tissues on the treated site and the contralateral tissues. The topical application of formulations of ester methyl salicylate and salts triethanolamine salicylate and diethylamine salicylate containing comparable salicylate concentrations yielded similar salicylate concentrations in the various tissues.
Effect of 2-Hydroxypropyl-β-cyclodextrin on Percutaneous Absorption of Methyl Paraben
Authors: Tanaka Muneo , Iwata Yuhei , Kouzuki Yuichi , Taniguchi Kazuyo , Matsuda Hajime , Arima Hidetoshi , Tsuchiya Seishi
Published: April 2011

A potential use of 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) to solubilize methyl paraben and to suppress its percutaneous absorption was examined, and compared with nonionic surfactant HCO-60.

HP-β-CyD significantly increased the solubility of methyl paraben in water, where the apparent 1:1 stability constant of the soluble complex was determined to be 2150 M−1. The in-vitro cutaneous permeability of methyl paraben through an isolated skin of hairless mouse was suppressed by HP-β-CyD, thus promoting the bioconversion of methyl paraben to the less toxic metabolite, p-hydroxybenzoic acid (p-HBA) in the epidermis. These effects of HP-β-CyD were greater than those of HCO-60. HP-β-CyD (2% w/v) reduced the in-vivo percutaneous absorption of methyl paraben by 66% 24 h after the topical application of a solution containing [14C]methyl paraben to hairless mouse skin. Additionally, the percutaneous absorption of [14C]HP-β-CyD was confirmed to be extremely low.

These results suggest that HP-β-CyD is useful in liquid preparations of methyl paraben for topical application.
Involvement of NK1 and NK2 Receptors in Pulmonary Responses Elicited by Non-adrenergic, Non-cholinergic Vagal Stimulation in Guinea-pigs
Authors: Savoie Chantal , Tousignant Christine , Rodger Ian W , Chan Chi-Chung
Published: April 2011

Previous studies from our laboratory using exogenously administered neurokinin (NK) agonists have shown that both NK1- and NK2-receptor subtypes are involved in plasma extravasation in the guinea-pig airways. In the present study, we have extended these observations using antidromic vagal stimulation to stimulate sensory c-fibres as a means of eliciting the release of endogenous tachykinins in propranolol- and atropine-treated guinea-pigs.

Antidromic vagal stimulation (5 ms, 30 s) induced frequency-dependent (1–10 Hz) bronchoconstriction that was completely abolished by co-administration of the NK1-selective antagonist CP-99,994 ((2s-methoxy-benzyl)-(2-phenyl-piperidin-3s-yl)-amine), and the NK2-selective antagonist SR-48,968 ((S)-N-methyl-N-[4-(4-acetylamino-4-phenyl piperidino)-2-(3,4-dichlorophenyl) butyl]benzamide), each at a dose sufficient to block NK1 and NK2 receptors, respectively (each at 0.3 mg kg−1, i.v.). In contrast, SR-48,968 when given alone only partially blocked the vagal stimulation-induced bronchospasm, whereas CP-99,994 had no effect. Significant increases (2–3-fold) in plasma extravasation of [125I]fibrinogen in the trachea, main bronchi, distal airways and oesophagus following vagal stimulation (5 Hz, 5 min, 10 V, 5 ms) were observed. Pretreatment with the neutral endopeptidase inhibitor, thiorphan (1 mg kg−1, i.v.), and the angiotensin-converting enzyme inhibitor, enalapril (1 mg kg−1, i.v.), potentiated both vagal stimulation-induced bronchoconstriction and plasma leakage in all tissues examined. This potentiation was due to reduced metabolism of endogenously released tachykinins since enhanced plasma overflow of immuno-reactive substance P was observed following vagal stimulation in thiorphan- and enalapril-treated guinea-pigs. CP-99,994 substantially blocked plasma leakage in all parts of the airways and in the oesophagus. In comparison, SR-48,968 had no significant effect in the trachea and the oesophagus but partially inhibited plasma leakage in the main bronchi and distal airways. Co-administration of both CP-99,994 and SR-48,968 abolished the residual plasma leakage in these two regions.

These results support the hypothesis that both NK1 and NK2 receptors are involved in tachykinin-induced pulmonary responses in the airways.
Pre- and Postjunctional Effects of Diadenosine Polyphosphates in the Guinea-pig Vas Deferens
Authors: Hoyle Charles H V , Postorino Alessandra , Burnstock Geoffrey
Published: April 2011

The pre- and postjunctional activities of a number of diadenosine polyphosphates were examined in the guinea-pig isolated vas deferens at the level of the membrane-potential, using a modified sucrose-gap technique.

P1,P3-Di(adenosine 5′)triphosphate (Ap3A), P1,P4-di(adenosine 5′)tetraphosphate (Ap4A) and P1,P5-di(adenosine 5′)pentaphosphate (Ap5 A) all caused concentration-dependent depolarization of the smooth muscle membrane. The potency order was: Ap5A > Ap4A. Ap3A. P1, P2-Di(adenosine 5′)pyrophosphate (Ap2A) did not evoke depolarization even at the highest concentration tested (1 mM). All the dinucleotides caused a reduction in the amplitude of evoked excitatory junction potentials (e.j.ps). The potency order was: Ap5A = Ap4A > Ap3A > Ap2A. The depolarizations evoked by the dinucleotides were markedly reduced by the selective P2X-purinoceptor antagonist, pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS, 10 μM), as was the amplitude of the fully facilitated e.j.p. The inhibition of the e.j.p. evoked by Ap3A and Ap2A was reduced by the P1-purinoceptor antagonist, 8-p-sulphophenyltheophylline (8-pSPT, 50 μM), but that evoked by Ap5A and Ap4A was not.

Thus, Ap3A, Ap4A and Ap5 A evoke depolarization of the guinea-pig vas deferens via P2X-purinoceptors, and additionally Ap2A and Ap3A exert a prejunctional effect via P1-purinoceptors. The prejunctional activity of Ap4A and Ap5A is mediated via an undefined purinoceptor, which is neither P1 nor P2X.
The Effect of Co-administered Drugs on Oxaprozin Binding to Human Serum Albumin
Authors: Aubry Anne-Françoise , Markoglou Nektaria , Adams Marijke H , Longstreth James , Wainer Irving W
Published: April 2011

The binding of the non-steroidal anti-inflammatory drug oxaprozin to human serum albumin was studied by bioaffinity high-performance liquid chromatography using a column based on immobilized human serum albumin.

Displacement studies using marker compounds for the major drug binding sites showed that oxaprozin has a high affinity for the benzodiazepine/indole site and binds to the warfarin site but with a significantly lower affinity.

Biochromatography and ultrafiltration techniques were used to screen for possible competition and allosteric interactions between oxaprozin and potential co-administered drugs including non-steroidal anti-inflammatory drugs, antipyretics, hypoglycaemics, inhibitors of angiotensin-converting enzyme, anaesthetics, metal ions and anticancer agents. Competition occurred mainly with drugs bound at the benzodiazepine site (benzodiazepines, various non-steroidal anti-inflammatories).
Bioavailability of Phenytoin Following Oral Administration of Phenytoin-lipid Conjugates to Rats
Authors: Scriba Gerhard K E , Lambert Didier M , Poupaert Jacques H
Published: April 2011

The bioavailability of phenytoin was evaluated in rats upon oral administration of phenytoin-lipid conjugates obtained by covalent binding of 3-hydroxymethylphenytoin to 1,3-dimyristoylglyceride via a succinidyl linkage, to 2-(1,3-dimyristoyl-2-glyceryl)butyric acid and to 3-myristoyloxy-2-myristoyloxy-methylpropionic acid.

Despite differences of the phenytoin plasma concentrations all three compounds approximately doubled the AUC compared with the dosing of phenytoin itself. The early onset and the long duration of the anticonvulsant activity after administration of the triglyceride-derived conjugate could be correlated to the increased phenytoin plasma levels.

It is concluded that drug-lipid conjugates may be useful prodrugs for the oral delivery of poorly watersoluble drugs.
Metabolism of Quinine in Man: Identification of a Major Metabolite, and Effects of Smoking and Rifampicin Pretreatment
Authors: Wanwimolruk Sompon , Wong Suk-Ming , Zhang Hu , Coville Peter F , Walker Robert J
Published: April 2011

Our previous studies have shown that cigarette smoking and rifampicin pretreatment enhance the elimination of quinine, metabolism assumed, by analogy with quinidine, to be carried out by CYP3A (P450IIIA). This finding is unexpected since it has been shown that smoking induces the CYP1A rather than the CYP3A enzyme family, suggesting that the metabolism of quinine may be catalysed by CYP1A. Therefore, we conducted this study to identify possible quinine metabolites in human urine and to determine which metabolic pathway is induced by cigarette smoking and rifampicin pretreatment. A specific HPLC procedure was employed to identify metabolites of quinine in urine samples collected from healthy volunteers after an oral dose of 600 mg quinine sulphate.

The results showed that there were at least seven possible metabolites of quinine detected in human urine. Three of these were identified as 2′-oxoquininone, quinine glucuronide and 3-hydroxyquinine. The 3-hydroxyquinine appeared to be a major metabolite of quinine in urine samples from every subject who took an oral dose of quinine.

Although cigarette smoking and rifampicin pretreatment were shown to cause a marked increase in the elimination of quinine there were no significant changes in the formation of 3-hydroxyquinine as measured in the urine samples. This suggests that the effects of smoking and rifampicin are more complicated than we expected and require further investigation.
A Clinical Study to Evaluate the Efficacy of the Antihistamine Doxylamine Succinate in the Relief of Runny Nose and Sneezing Associated with Upper Respiratory Tract Infection
Authors: Eccles R , Van Cauwenberge P , Tetzloff W , Borum P
Published: April 2011

Antihistamines are widely used in common cold medications, although the role of histamine in the development of common cold symptoms is unclear and the use of antihistamines for the treatment of common cold is controversial. It is clear that antihistamines do not offer a cure for common cold but they may alleviate symptoms of sneezing and runny nose. The present study was designed to investigate the efficacy of an antihistamine, doxylamine, on the symptoms of runny nose and sneezing associated with common cold.

We conducted a randomized double-blind study in cold sufferers. One thousand and one volunteers with cold symptoms were screened in four centres (UK, Denmark, Belgium, Germany) and 688 satisfied the entry criteria of the study. The main reasons for excluding subjects were a low nasal secretion weight (secretion weight < 0.2 g, 72%) and a low subjective rhinorrhoea score (24%). Volunteers were randomized to receive either doxylamine succinate 7.5 mg by mouth four times a day up to nine doses (n = 345) or placebo (n = 343). The principal measurements were prospectively defined as runny nose and sneezing symptom scores. Data were analysed on an intention-to-treat basis, using Cochran-Mantel-Haenszel statistics controlling for baseline symptom scores.

A between-group comparison showed that doxylamine-treated volunteers benefited from a significantly greater reduction in runny nose scores (P < 0.01) and sneezing scores (P < 0.001), than those volunteers in the placebo group. Doxylamine therapy was well tolerated; the incidence of unexpected side-effects was comparable with placebo. Of the expected side-effects, 13.3% of doxylamine-treated patients reported drowsiness. The incidence of sedative effects was lower than has been reported for other commonly used first-generation antihistamines.
Effects of Amitriptyline on Rat Plasma and Brain Content of Monoamine Precursors and Other Large Neutral Amino Acids
Authors: Eriksson Tomas , Eriksson Thomas E
Published: April 2011

Amitriptyline caused decreased concentrations in rat plasma of the amino acids tyrosine and tryptophan, which are precursors to monoaminergic neurotransmitters, and also of those other large neutral amino acids (LNAAs) (valine, phenylalanine, leucine and isoleucine) with which tyrosine and tryptophan compete for the carrier-mediated transport from plasma into the brain.

The various LNAAs were, however, not decreased to the same extent. Thus, the relative concentrations, calculated as the ratio of each one of them to the total concentration of LNAAs, were also influenced by amitriptyline. The relative concentrations of tryptophan were decreased while the relative concentrations of phenylalanine and leucine were increased. Those of tyrosine, valine and isoleucine were not influenced by amitriptyline. The relative concentrations of the LNAAs in plasma are considered to be of importance to how much of each of them that will be transported into the brain. Based on this assumption one would have expected that the amitriptyline-induced changes in the relationships between different LNAAs would have caused changes in their brain concentrations in accordance with their relative concentrations in plasma. However, amitriptyline caused decreased concentrations of all LNAAs in rat whole brain.

This finding cannot be explained by altered relationships between the LNAAs but must be explained by other mechanisms. Nevertheless, this effect of amitriptyline on brain LNAA concentrations might be of importance to monoamine function.
In-vitro Platelet Responses to Arachidonic Acid in the Rat
Authors: Rodríguez-Liñares Belén , Cano Ernesto
Published: April 2011

Using both the turbidimetric and the conductive methods to study aggregation of platelets, we found that arachidonic acid stimulated rat washed platelets in a dose-dependent manner (40 μM-0.5mM).

Although a high concentration of arachidonic acid (0.5 mM) produced an increase in light transmission both in the presence of 2 mM CaCl2 and EGTA (45.8 ± 2.8 and 50.4 ± 0.8% respectively) no changes in impedance were detected. Lysis caused by this concentration of arachidonic acid was very high at all the concentrations of calcium used (mean of 81.3%). In addition, the turbidimetric response induced by 0.5 mM arachidonic acid implied an initial decrease in light transmission but did not correlate with a real shape change. Forty micromolar arachidonic acid induced a calcium-dependent aggregation measured both by aggregometry and impedance. Morphology of aggregates induced by both concentrations was also studied.

These results suggest that the optimal concentration for studying rat platelet activation by arachidonic acid is 40 μM; high concentrations (0.5 mM) cause aspecific effects not correlated to a physiological activation response.
Mechanisms in Inhibitory Action of Aclarubicin on Contractility of Rat Aorta
Authors: Wakabayashi Ichiro , Hatake Katsuhiko , Masui Hidehisa , Sakamoto Kunihiro
Published: April 2011

The effects of aclarubicin on vasocontractile response and 45Ca2+ influx were investigated using rat isolated aorta.

KCl-induced contractile force in medium containing 2.5 mM calcium and calcium-induced contractile force in high K+ (60 mM)-depolarized aorta were both markedly attenuated by aclarubicin (70 μM) pretreatment. 45Ca2+ influx stimulated by 60 mM KCl was significantly lower in the aclarubicin (70 μM)-pretreated aorta compared with the control. Aclarubicin pretreatment attenuated phorbol 12, 13-dibutyrate (1 μM)-induced contraction both in the presence and absence of calcium in the medium. Aclarubicin pretreatment also attenuated caffeine (20 mM)-induced transient contraction.

These results suggest that aclarubicin attenuates vasoconstriction by inhibiting both Ca2+ entry through the voltage-dependent calcium channel and the intracellular contractile pathway after elevation of intracellular free calcium in vascular smooth muscle, in addition to the known mechanism of inhibition of phosphoinositides hydrolysis.
Inhibition of In-vitro Lymphocyte Transformation by the Isoquinoline Alkaloid Berberine
Authors: Ckless K , Schlottfeldt J L , Pasqual M , Moyna P , Henriques J A P , Wajner M
Published: April 2011

Berberine is an isoquinoline alkaloid with multiple pharmacological actions, including an anti-inflammatory activity. The effects of berberine on in-vitro cellular proliferation of human peripheral lymphocytes stimulated with phytohaemagglutinin, concanavalin A and pokeweed mitogen were studied. Mononuclear cells were cultured in flat-bottomed 96-well microplates at 37°C for 96–144 h in the presence of one mitogen at different concentrations and the alkaloid at doses of 2.5 to 20 μgmL−1. The mitogen-induced response of lymphocytes was evaluated from the extent of the incorporation of [3H]thymidine into cells in-vitro.

A consistent and progressive inhibitory influence of berberine with increasing concentrations in culture was identified with all mitogens and was more pronounced with pokeweed mitogen. The effect of berberine was observed in phytohaemagglutinin (PHA)- and concanavalin A-activated lymphocytes when the drug was added during the first 24 h of culture, whereas the same effect occurred throughout the incubation period in pokeweed mitogen-stimulated cells. The viability of lymphocytes following treatment with the drug, as assessed by the trypan blue exclusion test, revealed no change when compared with the same untreated lymphocytes, indicating no lymphocytotoxic activity.

We conclude that some effects of berberine, especially its anti-inflammatory action, may arise in part from the inhibition of DNA-synthesis in activated lymphocytes.
Absorption and Excretion of Paeoniflorin in Rats
Authors: Takeda Shuichi , Isono Tomoko , Wakui Yoko , Matsuzaki Yutaka , Sasaki Hiromi , Amagaya Sakae , Maruno Masao
Published: April 2011

The absorption and excretion of paeoniflorin after intravenous and oral administration was studied in rats to evaluate the significance of paeoniflorin in the pharmacological action of Paeony root.

The plasma concentration of paeoniflorin after intravenous administration at the doses of 0.5, 2.0 and 5.0 mg kg−1 rapidly decreased, simulated by a biexponential curve, with mean terminal half-lives of 11.0, 9.9 and 12. 6 min, respectively. The Vdss values were 0.332, 0.384 and 0.423 L kg−1 and the CLtot values were 26.1, 31.2 and 30.3 mL min−1 kg−1 at each dose. When given orally at the same doses, the absolute bioavailability values (F) determined by the AUC were 0.032, 0.033 and 0.038, respectively. The cumulative urinary and faecal excretions of paeoniflorin at the dose of 5 mg kg−1 after intravenous administration were 50.5 and 0.22% of the dose within 72 h, and 1.0 and 0.08% of the dose after oral administration within 48 h, respectively. Cumulative biliary excretion after intravenous or oral administration at a dose of 0.5 mg kg−1 was 6.9 and 1.3% of the dose within 24 h, respectively. The total CLR and CLB value after intravenous dosing was less than the CLtot value. These findings suggest that paeoniflorin is metabolized in other organs as well as in the liver.

We conclude that paeoniflorin absorbed is excreted mainly in urine, it has a low bioavailability and the metabolites may be involved in the pharmacological action of Paeony root.
A Feasibility Study of the Multiple-peak Approach for Pharmacokinetic Screening: Population-based Investigation of Valproic Acid Relative Clearance Using Routine Clinical Pharmacokinetic Data
Authors: Yukawa Eiji
Published: April 2011

The multiple-peak approach was used to evaluate the effect of age, body mass, dose and gender on the population estimates of valproic acid relative clearance.

Routine clinical pharmacokinetic data (n = 474) was collected from 250 patients receiving valproic acid and no other drug. The data was analysed according to a simple steady-state pharmacokinetic model using NONMEM, a computer program designed for population pharmacokinetic analysis allowing pooling of data.

The final regression model for relative clearance (CL, mL kg−1 h−1) was:

CL = 18.9 x body weight−0.276. daily dose0.142. gender

where gender = 1 for males, 0.877 for females.

NONMEM estimates suggested that the rate of valproic acid clearance decreased nonlinearly with increasing body weight in the maturation process, and increased nonlinearly with increasing valproic acid dose (mg kg−1 day−1). The clearance in females was about 11% less than in males. These estimates were similar to those detected from previous studies.
The Analysis of Drug Release from Diluted Water/oil/water Emulsions by a Model of the Rupture of Oil Membrane
Authors: Hino T , Takeuchi H , Niwa T , Kitagawa M , Kawashima Y
Published: April 2011

The release behaviour of theophylline encapsulated in the inner aqueous phase of a water/oil/water emulsion was investigated by two methods. A cellulose tube containing a sample of the emulsion was placed in a rotary basket and was stirred in a dissolution medium (Method A), or the w/o/w emulsion was dispersed in a dissolution medium and the system was stirred by a paddle, allowing the drug to permeate into a cellulose tube placed in the dispersing medium (Method B).

In Method A, the drug release rate from the emulsion decreased with increase in the concentration of sodium chloride co-formulated with the drug in the inner aqueous phase. The drug release rate in the dissolution test medium No. 1 or No. 2 of the JP XII was greater than that in purified water and was increased with the ionic strength of the dissolution medium. The drug was released more rapidly in Method B than in Method A, because the emulsion was destroyed more easily using the former method. As this destruction of emulsion structure occurred immediately after dilution with dissolution medium, the influence of the dissolution medium on the release profile could not be detected using Method B.

The experimental data of drug release were satisfactorily explained by the destruction model of the oil membranes of the water/oil/water emulsions.