bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of ZNC-2381, a New Oral Compound, on Several Hepatic Injury Models and on Hepatocellular Apoptosis in Mice and Rats
Authors: Itokazu Yoshihiko , Segawa Yoshihide , Omata Takeshi , Inoue Naonori , Tsuzuike Naoki , Nagasawa Masaaki , Nishioka Hiroyasu , Kobayashi Tadashi , Nakano Yoshihisa , Kanda Takashi
Published: October 2002

The hepatoprotective effect of ZNC-2381 (1-(4-aminophenyl) methyl-3-(3-nitrophenyl)-1,3-dihydroimidazo[4,5-b]pyridine-2-one), a novel 2-one dihydroimidazopyridine derivative, has been evaluated in several experimental models of hepatic injury.

In mice, oral ZNC-2381, administered at doses of 3, 10 or 30 mg kg−1, 1 h before induction of hepatic injury with concanavalin A, dose-dependently inhibited increases in serum alanine aminotransferase (ALT) activity. Apoptosis of liver cells, as indicated by DNA fragmentation (nucleosome assay) and DNA-ladder formation (electrophoresis), was also inhibited dose-dependently. ZNC-2381 dose-dependently inhibited concanavalin A-induced increases in serum tumour necrosis factor (TNF)-α levels, and TNF-α mRNA expression in the liver. Oral ZNC-2381 also dose-dependently inhibited increases in serum ALT activity in mice with hepatic injury induced by Propionibacterium acnes and a bacterial lipopolysaccharide (LPS) or d-galactosamine-LPS, and in rats with d-galactosamine-induced hepatic injury.

These results indicate that oral ZNC-2381 inhibits cytokine (TNF-α) production and cytokine-related hepatocellular apoptosis, and might thus prevent different types of hepatic injury.
Influence of Immunogenicity on the Pharmacokinetics of BMS-191352, a Pseudomonas Exotoxin Immunoconjugate, in Rats and Dogs
Authors: Damle Bharat , Tay Lee , Comereski Charles , Warner William , Kaul Sanjeev
Published: October 2002

BMS-191352 is an immunotoxin construct of modified Pseudomonas exotoxin conjugated to a fragment of the BR96 monoclonal antibody. We have investigated the potential for immunogenicity of BMS-191352 and its influence on the pharmacokinetics in rats and dogs.

BMS-191352 was administered intravenously at doses of 0.75, 1.5, and 3 mg m−2 once every two days for a total of five doses in rats, and 1.2, 2.4, and 4.8 mg m−2 once every three days for a total of five doses in dogs. Blood samples were collected on days 1 and 9 in rats, and on days 1, 7, and 13 in dogs to monitor pharmacokinetics and anti-BMS-191352 immune response. Plasma concentrations of BMS-191352 and serum anti-BMS-191352 antibody titre were determined using ELISA assays. Pharmacokinetics were assessed using a non-compartmental method.

Anti-BMS-191352 antibodies were not observed in rats within the drug administration interval. In all dogs, except one, markedly higher anti-BMS-191352 antibody titres were observed on day 13 compared with days 1 and 7, and its magnitude was independent of BMS-191352 dose. The single dose kinetics of BMS-191352 in rats and dogs were linear and the drug exposures were generally dose proportional. Mean half-life, total body clearance, and volume of distribution were 1.74 h, 3.35 mL min−1 m−2, and 0.27 L m−2 in rats, respectively, and 4.27 h, 6.28 mL min−1 m−2, 1.19 L m−2 in dogs, respectively. The multiple-dose (day 9) kinetics in rats were similar to the single-dose kinetics. In dogs, the disposition of BMS-191352 on day 7 was similar to that on day 1; however, there was a precipitous reduction in the systemic drug exposure (by 5- to 110-fold) and marked increase in drug clearance on day 13. These changes in the kinetics of BMS-191352 were attributed to the generation of anti-BMS-191352 antibodies. In the one dog that did not develop anti-BMS-191352 antibodies, the pharmacokinetics were unchanged.

The pharmacokinetics of BMS-191352 may be perturbed due to an immune response thus restricting the therapeutic utility of the immunotoxin.
Ranolazine Attenuates Palmitoyl-l-carnitine-induced Mechanical and Metabolic Derangement in the Isolated, Perfused Rat Heart
Authors: Maruyama Kazuyasu , Hara Akiyoshi , Hashizume Hiroko , Ushikubi Fumitaka , Abiko Yasushi
Published: October 2002

The effect of ranolazine, a novel anti-ischaemic drug that stimulates the activity of pyruvate dehydrogenase, on palmitoyl-l-carnitine-induced mechanical dysfunction and metabolic derangement in isolated perfused rat hearts has been studied and compared with the effect of dichloroacetate, an activator of pyruvate dehydrogenase. Rat hearts paced electrically were perfused aerobically at constant flow by the Langendorff technique. Palmitoyl-l-carnitine (4 μm) increased left ventricular end-diastolic pressure and reduced left ventricular developed pressure (i.e. induced mechanical dysfunction); it also reduced tissue levels of adenosine triphosphate and increased tissue levels of adenosine monophosphate (i.e. induced metabolic derangement). These functional and metabolic alterations induced by palmitoyl-l-carnitine were attenuated by ranolazine (5, 10, and 20 μm) in a concentration-dependent manner. In contrast, dichloroacetate (1 and 10 mm) did not attenuate palmitoyl-l-carnitine-induced mechanical and metabolic derangement. In the normal (palmitoyl-l-carnitine-untreated) heart, however, ranolazine did not modify mechanical function and energy metabolism.

These results suggest that ranolazine attenuates palmitoyl-l-carnitine-induced mechanical and metabolic derangement in the rat heart, and that the beneficial action of ranolazine is not because of the energy-sparing effect or activation of pyruvate dehydrogenase.
N-Methyl-d-aspartate Receptor Antagonists Enhance the Head-twitch Response, a 5-Hydroxytryptamine2 Receptor-mediated Behaviour, in Reserpine-treated Mice
Authors: Kim Hack-Seang , Park In-Sook , Lim Hwa-Kyung , Choi Hong-Serck , Oh Seikwan , Park Woo-Kyu , Jang Choon-Gon , Kim Seung-Hwan , Chang Myung-Jei
Published: October 2002

In this study, N-methyl-d-aspartate (NMDA)-receptor antagonists enhanced the head-twitch response induced by 5-hydroxytryptamine (5-HT) in reserpine-treated mice.

To minimize the risk of any indirect involvement of NMDA-receptor antagonists (d(-)-2-amino-5-phosphonopentanoic acid (AP-5), l(-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP), (+)-5-methyl-10,11-dihydroxy-5H-dibenzo-[a,d]-cyclohepten-5,10-imine (MK-801), ketamine, dextrorphan and dextromethorphan) with 5-HT neurones, vesicle stores of monoamines, especially 5-HT, were depleted with reserpine. In addition, the enhancement of 5-HT-induced head-twitch response was inhibited by apomorphine and NMDA as well as ritanserin in reserpine-treated mice.

These results support our previous conclusion that NMDA receptors play important roles in the glutamatergic modulation of 5-HTergic function at the postsynaptic 5-HT2 receptors in mice.
Gelatin Microspheres as a Pulmonary Delivery System: Evaluation of Salmon Calcitonin Absorption
Authors: Morimoto Kazuhiro , Katsumata Hideyuki , Yabuta Toshiyuki , Iwanaga Kazunori , Kakemi Masawo , Tabata Yasuhiko , Ikada Yoshito
Published: October 2002

The use of negatively and positively charged gelatin microspheres for pulmonary delivery of salmon calcitonin was examined in rats. The microspheres were prepared using acidic gelatin (isoelectric point (IEP):, 5.0) and basic gelatin (IEP, 9.0) for the negatively and positively charged microspheres, respectively. The average diameters of positively charged gelatin microspheres in the dry state were 3.4, 11.2, 22.5 and 71.5 μm, and that of negatively charged gelatin microspheres was 10.9 μm. Neither positively nor negatively charged gelatin microspheres underwent any degradation in pH 7.0 PBS and there was less than 8% degradation in bronchoalveolar lavage fluid (BALF) after 8 h. In in-vitro release studies in pH 7.0 PBS, salmon calcitonin was rapidly released from positively charged gelatin microspheres within 2 h, and its cumulative release was approximately 85%. In addition, the release profiles were not influenced by particle sizes. The release rates of salmon calcitonin from negatively charged gelatin microspheres were lower than that from positively charged gelatin microspheres. The cumulative release was approximately 40% after 2 h, but there was no evidence of any sustained release.

The pulmonary absorption of salmon calcitonin from gelatin microspheres was estimated by measuring its hypocalcaemic effect in rats. The pharmacological availability after administration of salmon calcitonin in positively and negatively charged gelatin microspheres was significantly higher than that in pH 7.0 PBS. The pharmacological availability after administration of salmon calcitonin in positively charged gelatin microspheres was significantly higher than that in negatively charged gelatin microspheres. Administration of salmon calcitonin in positively charged gelatin microspheres with smaller particle sizes led to a higher pharmacological availability. The pharmacological availability after pulmonary administration of salmon calcitonin in positively charged gelatin microspheres with particle sizes of 3.4 and 11.2 μm was approximately 50%.

In conclusion, the gelatin microspheres have been shown to be a useful vehicle for pulmonary delivery of salmon calcitonin.
Preclinical Study of an Oral Controlled Release Naltrexone Complex in Mice
Authors: Alvarez-Fuentes J , Rojas-Corrales M O , Holgado M A , Caraballo I , Micó J A , Fernández-Arévalo M
Published: October 2002

Naltrexone, a long-acting, orally effective, opioid antagonist which blocks opioid effects as well as the development of physical dependence, would appear to be a drug ideally suited to addiction treatment. An optimal dosage regimen is critical for the treatment patient compliance in ambulatory opiate detoxification programs. The ideal dosage regimen would be an oral controlled-release system of naltrexone that allowed once-a-day administration providing stable plasma levels.

A naltrexone-Eudragit L complex was produced in aqueous medium from naltrexone hydrochloride solution and Eudragit L30D (30% w/v) previously diluted (6% w/v) and partially neutralized. The antagonistic activity of naltrexone-Eudragit L on morphine-induced thermal antinociception, in comparison with conventional naltrexone, was evaluated, using the mouse hot-plate model. Mice were administered 10 mg kg−1 morphine subcutaneously, 10 min before test, and the antagonist products, either naltrexone-Eudragit L or naltrexone hydrochloride, were administered orally at 0.5, 1, 2, 4, 6, 8, 10, 12, 14 and 16 h before the test.

The results showed that the antagonism induced by naltrexone-Eudragit L was effective until 12 h after drug administration, while that induced by naltrexone hydrochloride disappeared 10 h after its administration. A 23.47% increase of the area under curve was obtained when naltrexone-Eudragit L was administered, compared with that induced by conventional naltrexone. The time taken to decrease the inhibition of analgesic activity to 50% was delayed by 51.80%.

This complexation technique can be considered as a useful tool in the design of oral controlled-release systems capable of inducing a long-lasting effect in-vivo.
Tocolytic Effects of a Long-acting β2-Adrenoceptor Agonist, Formoterol, in Rats
Authors: Shinkai Norihiro , Takayama Satoshi
Published: October 2002

We have assessed the tocolytic activity of formoterol, a novel long-acting and potent β2-adrenoceptor agonist, through its production of cyclic adenosine monophosphate, in comparison with ritodrine, a β2-adrenoceptor agonist used clinically to counter premature delivery.

Formoterol and ritodrine inhibited the amplitude and frequency of rat uterine contraction, with IC50 values of 3.8 times 10−10 and 4.7 times 10−7 M, respectively. Intravenous administration of formoterol or ritodrine caused inhibition of uterine motility and increased heart rate in a dose-dependent manner. Inhibition of uterine motility by oral administration of formoterol (0.3 and 1 mg kg−1) continued for at least 60 min, whereas that with ritodrine (100 mg kg−1) persisted for 15 min with rapid recovery thereafter in pregnant rats. The β-adrenoceptor binding of [125I]iodopindolol to the myometrium of pregnant rats was competitive with formoterol and ritodrine, with Ki values of 0.04 and 6.10 nM, respectively. Formoterol (10−6 — 10−4 M) and ritodrine (10−6 — 10−4 M) increased the level of cyclic adenosine monophosphate in lymphocytes in a dose-dependent manner.

The results suggested that formoterol caused relaxation of uterine motility through production of cyclic adenosine monophosphate. Thus, formoterol may be useful as a treatment to counter premature delivery.
The Anxiolytic Effect of Two Oriental Herbal Drugs in Japan Attributed to Honokiol from Magnolia Bark
Authors: Kuribara Hisashi , Kishi Eiko , Hattori Naoko , Okada Minoru , Maruyama Yuji
Published: October 2002

An improved elevated plus-maze test in mice revealed that seven daily treatments with two differnt traditional Chinese medicines, known as Kampo medicines in Japan, Hange-koboku-to (composed of extracts of 5 plants) and Saiboku-to (composed of extracts of 10 plants), produced an anxiolytic effect, and the effect was mainly due to the presence of honokiol derived from magnolia. This study was carried out to evaluate the anxiolytic potential of honokiol, Hange-koboku-to and Saiboku-to, which were prescribed with two different magnolia samples: Kara-koboku (Magnoliae officinalis) (KA) or Wa-koboku (Magnoliae obovata) (WA).

The doses of test samples were adjusted to ensure a constant dose of honokiol at 0.2 mg kg−1. Although the doses of magnolol (an isomer of honokiol), as well as those of undetermined chemicals, varied among samples, the seven daily treatments with 9 out of 10 test samples produced an anxiolytic effect almost equivalent to that produced by 0.2 mg kg−1 honokiol. The only exception was the sample containing the lowest amount of honokiol. Magnolia-free preparations of Hange-koboku-to or Saiboku-to did not have any anxiolytic effect.

These results confirm that honokiol derived from magnolia is the causal chemical of the anxiolytic effect of Hange-koboku-to and Saiboku-to.
In-vivo Drug Delivery of 5-Fluorouracil using Poly(2-hydroxyethyl methacrylate-co-acrylamide) Hydrogels
Authors: Blanco M D , Garcia O , Gomez C , Sastre R L , Teijon J M
Published: October 2002

Poly(2-hydroxyethyl methacrylate-co-acrylamide) hydrogels crosslinked with ethylen glycol dimethacrylate were used as devices for the in-vivo drug release of 5-fluorouracil (5-FU).

Drug-loaded hydrogels were subcutaneously implanted in the back of Wistar rats. All hydrogel discs reached an equilibrium swelling degree, which was slightly larger than that determined in-vitro. After 30 days of implantation, the hydrogel discs were transparent, and without fracture or apparent degradation. In addition, a fibrous capsule was not detected around the hydrogels that had greater hydration degrees. Release of 5-FU from these hydrogels allows the drug to remain in the plasma from 1 to 5 days, in spite of its short plasma half-life (15 min). This was an improvement of up to 98-times compared with the intraperitoneal drug administration.

Administration of 5-FU by implantation of 2-hydroxyethylmethacrylate-co-acrylamide copolymeric hydrogels seems to be a good candidate for 5-FU therapy, since the drug released results in a therapeutically suitable plasma concentration of 5-FU for an extended period of time, despite the short half-life of the drug.
Gastrointestinal First-pass Effect of Furosemide in Rats
Authors: Kim Eun Jung , Han Kye Soo , Lee Myung Gull
Published: October 2002

The first-pass effect of furosemide was investigated in rats. Furosemide intravenous solution (20 mgkg−1 Lasix), was administered via the jugular vein and the portal vein, orally, and instilled directly into the duodenum of rats. The first-pass effects of furosemide by lung, heart, and liver seemed to be negligible in rats. The absolute bioavailability of furosemide was 28.9 and 48.3% after oral and intraduodenal administration, respectively. Based on the gastrointestinal (GI) recovery study, 68.3 and 69.5% of furosemide were found to have disappeared mainly due to absorption and/or metabolism from rat GI tract after oral and intraduodenal administration, respectively.

The results indicate that gastrointestinal and intestinal first-pass effects of furosemide were approximately 40% (68.3–28.9%) and 20% (69.5–48.3%) of the dose, respectively.
Determination of the Salivary Retention of Hexetidine In-vivo by High-performance Liquid Chromatography
Authors: McCoy Colin P , Jones David S , McGovern James G , Gorman Sean P , Woolfson A David
Published: October 2002

The non-antibiotic antimicrobial agent hexetidine is widely used at a concentration of 0–1% w/v as an oral rinse to reduce the number of viable microorganisms within the oral cavity. However, following use, the available concentration of hexetidine in the oral cavity declines with time, thus compromising the resultant antimicrobial activity. It is, therefore, desirable to determine the persistence of the agent in the oral cavity by quantification of the drug concentration in saliva, thus enabling prediction of its antimicrobial activity in the oral environment.

A rapid reverse-phase HPLC method was therefore developed and validated for hexetidine in aqueous solution (Oraldene) and in saliva samples collected from volunteers post-rinsing with 15 mL of hexetidine oral rinse for 30 s. The HPLC assay was sufficiently sensitive to accurately detect hexetidine in saliva up to 25 min after in-vivo use of a commercial oral rinse. Furthermore, it was possible to detect hexetidine below the published minimum inhibitory concentrations (MICs) for a selection of microorganisms. From these data a first-order elimination rate constant of hexetidine from the oral cavity was determined post-rinsing in each of six volunteers.

The validated HPLC assay method presented is useful for the assay of hexetidine in the oral cavity both at and below MICs. The first-order elimination rate constant shows significant variation between volunteers.
Effects of Ba2+ on SK&F 96365-sensitive Sustained Contraction of Rat Pulmonary Artery
Authors: Uchida Kohsuke , Saito Kyoko , Kitajima Toshimitsu , Kamikawa Yuichiro
Published: October 2002

The effects of Ba2+ on receptor-mediated sustained contraction of rat pulmonary artery and guinea-pig oesophageal muscularis mucosae were studied in-vitro.

In rat isolated pulmonary artery, sustained contraction induced by noradrenaline (1 μm) was resistant to nicardipine (1 μm), but this same sustained contraction was completely inhibited by SK&F 96365 (30 μm), a blocker of voltage-dependent L-type Ca2+ channels and receptor-activated Ca2+ influx. The SK&F 96365-sensitive sustained contraction induced by noradrenaline (1 μM) may be due primarily to Ca2+ influx through receptor-activated Ca2+ channels resistant to nicardipine. Cumulatively applied BaCl2 (0.1 — 10 mM) increased the noradrenaline (1 μM)-induced sustained contraction of the pulmonary arterial preparation in the absence of nicardipine, but in the presence of nicardipine (1 μM), BaCl2 (0.1 — 3 mM) did not affect this contraction. A higher concentration of BaCl2 (10 mM), however, weakly inhibited the noradrenaline (1 μM)-induced tone. In addition, BaCl2 (3–10 mM) increased the tone induced by KCl (60 mM), and the BaCl2-elevated KCl tone was markedly inhibited by nicardipine (1 μM) treatment.

In the guinea-pig isolated oesophageal muscularis mucosae, sustained contraction induced by acetylcholine (3 μM) was resistant to nicardipine (1 μM) but was returned to its basal level by SK&F 96365 (30–60 μM). The SK&F 96365-sensitive, acetylcholine-induced sustained contraction of the oesophageal muscularis mucosae is also likely to link with receptor-activated Ca2+ channels resistant to nicardipine. In contrast to the rat pulmonary artery, cumulatively applied BaCl2 (0.3–10 mM) inhibited the acetylcholine (3 μM)-induced sustained contraction of the oesophageal muscularis mucosae in a concentration-dependent manner in the presence of nicardipine (1 μM).

In conclusion, Ba2+ presumably activates voltage-dependent Ca2+ channels by depolarizing plasma membrane and also passes through voltage-dependent Ca2+ channels to contract the pulmonary artery in the absence of nicardipine, and Ba2+ also has a minor effect on the nicardipine-resistant, SK&F 96365-sensitive sustained contraction induced by noradrenaline in rat isolated pulmonary artery.
Electron-microscopic Study of the Bactericidal Effect of OPB-2045, a New Disinfectant Produced from Biguanide Group Compounds, Against Methicillin-resistant Staphylococcus aureus
Authors: Sakagami Yoshikazu , Kajimura Keiji , Nishimura Hiroshi
Published: October 2002

The bactericidal effect of OPB-2045, a new disinfectant produced from biguanide group compounds, against methicillin-resistant Staphylococcus aureus (MRSA), MRSA IID 1677, was investigated by transmission electron microscopy.

OPB-2045 showed strong bactericidal activity against MRSA. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of OPB-2045 against the test strain were 0.78 and 1.56 μg mL−1, respectively. The test bacteria were incubated in the presence of OPB-2045 at 1/2 MIC (0.39 μg mL−1), 1 MIC (0.78 μg mL−1), 2 MIC (1 MBC, 1.56 μg mL−1), 4 MIC (2 MBC, 3.13 μg mL−1) or 10 MIC (5 MBC, 7.8 μg mL−1) at 37°C for 30 s, 3 min, 30 min or 6h. The morphology of the cells was examined by transmission electron microscopy.

The cell damage observed after 30-min or 6-h incubation in the presence of OPB-2045 at 1/2 or 1 MIC was the same as that at 2, 4 or 10 MIC. The numbers of damaged MRSA cells increased according to the increase in concentration of added disinfectant, and the image of bacteriolysis was observed, too.

After treatment at 1/2 or 1 MIC, a few leaking cells were recognized, but no destroyed cells were found. No morphological changes were observed after treatment at 1 or 2 MIC for 30 s, 3 min or 30 min. When the incubation time was extended to 6 h, morphological changes in the MRSA cells treated at 1 or 2 MIC were observed.

When examining the relationship between the numbers of surviving bacteria and the MIC (MBC) values in soybean casein digest broth, no decrease in MRSA cell numbers was recognized in the untreated control or at 1/2 MIC, but a marked decrease in MRSA cell numbers was recognized as the OPB-2045 concentration was increased.

The new disinfectant OPB-2045 would make a useful contribution to the medical field for the prevention of infections caused by pathogenic bacteria such as MRSA.
Balicalin, the Predominant Flavone Glucuronide of Scutellariae Radix, is Absorbed from the Rat Gastrointestinal Tract as the Aglycone and Restored to its Original Form
Authors: Akao Teruaki , Kawabata Kiyoshi , Yanagisawa Erika , Ishihara Kazuhisa , Mizuhara Yasuharu , Wakui Yoko , Sakashita Yoko , Kobashi Kyoichi
Published: October 2002

When baicalin was orally administered to conventional rats, it was detected in their plasma for 24 h after administration, but baicalein, the aglycone of baicalin, was not detected. However, when baicalin was given to germ-free rats, only a small amount of baicalin was detected in their plasma within 2 h after the administration, its AUC0-lim (the area under the concentration-time curve from 0 to last determination time) being 12.0% of that in conventional rats. Subsequently, a considerable amount (55.1 ± 6.2%) of baicalin was recovered from the gastrointestinal tract even 4 h after administration. When baicalein was orally administered to conventional rats, however, baicalin appeared rapidly in their plasma at an AUC0-lim value similar to that obtained after oral administration of baicalin, despite the absence of baicalein in plasma. When intestinal absorption was evaluated by the rat jejunal loop method, baicalein was absorbed readily, but only traces of baicalin were absorbed. Moreover, in conventional rats a small amount (13.4 ± 3.1%) of baicalin and an appreciable amount (21.9 ± 3.4%) of baicalein were recovered from the gastrointestinal tract even 4 h after oral administration of baicalin, but only a small amount (3.93 ± 1.43%) of baicalein was detected in the intestinal tract 1 h after administration of baicalein.

Baicalin was transformed to baicalein readily by the rat gastric and caecal contents. When baicalin was administered orally to conventional rats, an appreciable amount of baicalein was recovered in their gastrointestinal tracts. Moreover, baicalein was efficiently conjugated to baicalin in rat intestinal and hepatic microsomes.

These results indicate that baicalin itself is poorly absorbed from the rat gut, but is hydrolysed to baicalein by intestinal bacteria and then restored to its original form from the absorbed baicalein in the body.
Transdermal Delivery of the Potent Analgesic Dihydroetorphine: Kinetic Analysis of Skin Permeation and Analgesic Effect in the Hairless Rat
Authors: Ohmori Satoshi , Hayashi Teruaki , Kawase Masami , Saito Setsuo , Sugibayashi Kenji , Morimoto Yasunori
Published: October 2002

Dihydroetorphine is an extraordinarily strong opioid analgesic. To assess its effectiveness after topical application in hairless rats we have examined the kinetic analysis of skin permeation through excised skin and the in-vitro reservoir effect of skin, and have investigated the predictability of plasma concentration and analgesic effect following in-vivo transdermal application.

Dihydroetorphine was moderately permeable from an aqueous suspension through excised hairless rat skin. Dihydroetorphine flux from drug-dispersed pressure-sensitive adhesive tape was threefold that from the applied aqueous suspension. The fluxes through the abdominal and the dorsal skin during tape application fitted the Fickian diffusion equation well after the tape was removed peeling off the outer layer of the stratum corneum. The relationship between the plasma concentration and the analgesic effect was examined for four different rates of infusion of dihydroetorphine. A non-linear pharmacokinetic disposition was observed. Following abdominal (0.28 cm2, 20μg) and dorsal (0.50 cm2, 35μg) applications of the dihydroetorphine tape, plasma concentration (0.2-0.8 ng mL−1) and analgesic effect were maintained at a suitable level, for more than 8h, until removal of the tape. These profiles were predictable using the combined equation for percutaneous absorption, disposition and the analgesic effect, but the analgesic effect was slightly lower than the predicted value.

The results show that it was possible to control the plasma concentration and the analgesic effect of dihydroetorphine by topical application of the analgesic using pressure-sensitive adhesive tape in the hairless rat. It was possible to predict the result using mathematical modelling.
Different Effects of Amitriptyline and Imipramine on the Pharmacokinetics and Metabolism of Perazine in Rats
Authors: Daniel Wladyslawa A , Syrek Maciej , Haduch Anna , Wójcikowski Jacek
Published: October 2002

The aim of this study was to search for possible effects of imipramine and amitriptyline on the pharmacokinetics and metabolism of perazine at steady state in rats. Perazine (10 mg kg−1, i.p.) was administered to rats twice daily for two weeks, alone or jointly with imipramine or amitriptyline (10 mg kg−1 i.p.). Concentrations of perazine and its two main metabolites (5-sulphoxide and N-desmethylperazine) in the plasma and brain were measured at 30 min (Cmax), 6h and 12h (slow disposition phase) after the last dose of the drugs. Liver microsomes were prepared 24 h after withdrawal of the drugs.

Amitriptyline increased the plasma and brain concentrations of perazine (up to 300% of the control) and N-desmethylperazine, while not affecting those of 5-sulphoxide. Imipramine only tended to increase the neuroleptic concentration in the plasma and brain. Studies with control liver microsomes showed that amitriptyline and imipramine added to the incubation mixture in-vitro, competitively inhibited N-demethylation (Ki (inhibition constant) = 16 μM and 164 μM, respectively) and 5-sulphoxidation (Ki = 57 μM and 86 μM, respectively) of perazine, amitriptyline being a more potent inhibitor of perazine metabolism, especially with respect to N-demethylation. Studies with microsomes of rats treated chronically with perazine or tricyclic antidepressants, or both, did not show significant differences in the rate of perazine metabolism between perazine- and perazine+antidepressant-treated rats. The data obtained were compared with the results of analogous experiments with promazine and thioridazine.

It was concluded that elevations of perazine concentration were caused by direct inhibition of the neuroleptic metabolism by the antidepressants. Similar interactions, possibly leading to exacerbation of the pharmacological action of perazine, may be expected in man. Since the interactions between phenothiazines and tricyclic antidepressants may proceed in two directions, reduced doses of both the neuroleptic and the antidepressant are recommended when the drugs are administered jointly.
Effects of Interferons on Cortisol Production in Bovine Adrenal Fasciculata Cells Stimulated by Adrenocorticotropin
Authors: Tachikawa Eiichi , Itho Koji , Kudo Kenzo , Harada Kazuho , Kashimoto Takeshi , Hirota Yoshikazu
Published: October 2002

The effects of interferons (IFNs) IFN-α, IFN-β and IFN-γ on the production of cortisol in bovine adrenal fasciculata cells have been investigated.

Pretreatment of the fasciculata cells with recombinant interferon-α-2b from man (over 300 units mL−1), but not with fibroblast IFN-β or recombinant IFN-γ from man, reduced the production of cortisol in cells stimulated with adrenocorticotropin (ACTH) (1 nM). IFN-α-2b inhibited ACTH-induced cortisol production in a concentration- (300-15 000 units mL−1) and time- (2–24 h) dependent manner. The inhibitory effect of IFN-α-2b on the production was abolished when the cells were simultaneously treated with anti-IFN-α antibody, and it was reversible. IFN-α-2b also inhibited dibutyryl cyclic AMP-induced production of cortisol but not pregnenolone-induced production. The effect of IFN-α-2b was not influenced by increases in external ACTH and Ca2+ concentrations and IFN-α-2b did not affect the ACTH-induced increase in cyclic AMP level in the cells.

These results strongly suggest that IFN-α-2b reduces ACTH-induced production of cortisol in bovine adrenal fasciculata cells by affecting the early process of cortisol synthesis. The results also indicate that IFNs might not directly affect steroidogenesis in the adrenal cortex in-vivo, because of the requirement of high concentrations of IFN-α-2b for inhibition, and because of the ineffectiveness of IFN-β and IFN-γ.
Effect of Plasma-calcium-level-responsive Oestradiol Release from Apatitic Bone Cement on Bone Mineral Density in Ovariectomized Rats
Authors: Otsuka Makoto , Yoneoka Kazuki , Matsuda Yoshihisa , Fox Jeffrey L , Higuchi William I
Published: October 2002

The effects of plasma calcium levels on oestradiol release from apatite bone cement and on the bone mineral density of ovariectomized rats have been investigated.

Apatite cement was prepared from an equimolar mixture of tetracalcium phosphate, dicalcium phosphate dihydrate and 0.5% β-oestradiol bulk powder. After subcutaneous implantation of the cement, oestradiol release in diseased rats (ovariectomized rats on a low-calcium diet) was significantly higher than in normal rats. The drug levels of recovery-model rats (ovariectomized, but on a high-calcium diet) were significantly lower than those of the diseased rats. Calcium levels in diseased rats remained low during drug release but the plasma calcium levels of the recovery-model rats increased. The areas under the plasma calcium concentration-time curves (Ca-AUCs) for the recovery-model rats were higher than those for the diseased-model rats. The plasma oestradiol concentration AUCs and the Ca-AUCs were linearly related. The body weight of the recovery-model rats increased after five days, but that of the diseased-model rats did not. The bone mass of the recovery-model rats was greater after the experiment than before.

The relationship between the bone mineral density and Ca-AUC of the diseased rats suggested that bone mineral density increased with increasing Ca-AUC. The results suggest that the severity of osteoporosis in this animal model is reduced by implantation of the oestradiol-loaded apatite cement.
Stability Study of Human Serum Albumin Pharmaceutical Preparations
Authors: Oliva Alexis , Santoveña Ana , Llabres Matias , Fariña Jose B
Published: October 2002

The influence of temperature on the stability of human serum albumin (HSA) pharmaceutical preparations has been studied by size-exclusion high-performance liquid chromatography with multi-angle laser-light-scattering detection and by particle-size analysis.

The behaviour of HSA in two pharmaceutical preparations stored at different temperatures (40, 55 and 70°C) followed the same pattern—an increase in the relative percentage of dimer (MW 132 000 Da) and aggregate (MW > 200 000 Da), and then a decrease in the concentration of all species and, finally, sudden protein coagulation. These results suggest a time- and temperature-dependent process. At 70°C, monomer only was detected for both preparations; the amount remaining was 83 and 72% for formulations A and B, respectively. Analysis of size-distribution curves also seems to confirm these results. Initially, three distributions were observed with length-volume mean diameters (dl,v)of 1.67, 10.6 and 57 μm. After 80 days at 55°C, only two distributions were observed, with dl,v of 3.07 and 76 μm. An additional study using pure HSA at different concentrations (0.3, 2.5, 5 and 10% w/v) and storage at 75°C was performed to determine the influence of the concentration of auxiliary substances and of the HSA. Only when the HSA concentration was 0.3% w/v did the remaining fraction of HSA fit a Prout-Thompkins nucleation model. Initially three distributions with mean sizes of 2, 20 and 40 μm were observed whereas at the end of the assay only one distribution, mean size 129 μm, was seen. The methodology used enabled us to separate the HSA degradation products and to determine the absolute molecular weight of albumin monomer and dimer.

It is possible to conclude that the degradation mechanism for the formulations studied is complex, and that it is possible to fit the degradation data to Prout-Thompkins kinetics only when the concentration of HSA is low enough (0.3% w/v).
Halofantrine Metabolism in Microsomes in Man: Major Role of CYP 3A4 and CYP 3A5
Authors: Baune B , Flinois J P , Furlan V , Gimenez F , Taburet A M , Becquemont L , Farinotti R
Published: October 2002

We have clarified the contribution of the different enzymes involved in the N-debutylation of halofantrine in liver microsomes in man. The effect of ketoconazole and cytochrome P450 (CYP) 3A substrates on halofantrine metabolism has also been studied.

The antimalarial drug halofantrine is metabolized into one major metabolite, N-debutylhalofantrine. In microsomes from nine livers from man, N-debutylation of halofantrine was highly variable with apparent Michaelis-Menten constant Vmax and Km values of 215 ± 172 pmol min−1 mg−1 and 48 ± 26/μmol L−1, respectively, (mean ± standard deviation). Formation of N-debutylhalofantrine was cytochrome P450 (CYP)-mediated. Studies using selective inhibitors of individual CYPs revealed the role of CYP 3As in the formation of N-debutylhalofantrine. α-Naphthoflavone, a CYP 3A activator, increased metabolite formation. In microsomes from 12 livers from man the rate of N-debutylation of halofantrine correlated strongly with CYP 3A4 relative levels (P = 0.002) and less strongly, but significantly, with CYP 2C8 levels (P = 0.025). To characterize CYP-mediated metabolism of halofantrine further, incubations were performed with yeast microsomes expressing specific CYP 3A4, CYP 3A5, CYP 2D6, CYP 2C8 and CYP 2C19 from man. The rate of formation of N-debutylhalofantrine was six- and twelvefold with CYP 3A4 than with CYP 3A5 and CYP 2C8, respectively. CYP 2D6 and CYP 2C19 did not mediate the N-debutylation of halofantrine, but, because in-vivo CYP 2C8 is present at lower concentrations than CYP 3A in the liver in man, the involvement of CYP 3As would be predominant. Diltiazem, erythromycin, nifedipine and cyclosporin (CYP 3A substrates) inhibited halofantrine metabolism. Similarly, ketoconazole inhibited, non-competitively, formation of N-debutylhalofantrine with an inhibition constant, Ki, of 0–05 μM. The theoretical percentage inhibition of halofantrine metabolism in-vivo by ketoconazole was estimated to be 99%.

These results indicate that both CYP 3A4 and CYP 3A5 metabolize halofantrine, with major involvement of CYP 3A4. In-vivo, the other CYPs have a minor role only. Moreover, strong inhibition, and consequently increased halofantrine cardiotoxicity, might occur with the association of ketoconazole or other CYP 3A4 substrates.
The Effect of Immunosuppressive Agents (FK-506, Rapamycin) on Renal P450 Systems in Rat Models
Authors: Yoshimura Rikio , Yoshimura Norio , Ohyama Akira , Ohmachi Tetsuji , Yamamoto Keisuke , Kishimoto Taketoshi , Wada Seiji
Published: October 2002

It is well known that cyclosporin, rapamycin and FK-506 (tacrolimus) are metabolized by the liver microsomal cytochrome P450 enzyme system. Although there have been reports of interaction between these drugs and the renal P450 enzyme system, differences among these immunosuppressants has not been comprehensively demonstrated. We have studied the individual capacities of these immunosuppressants to induce renal microsomal P450 enzymes similar to CYP2B4 and CYP4A2 by examining renal function in treated rats, and have correlated the results by means of biochemical, immunological and immunohistochemical assays of renal P450 enzymes.

Cyclosporin caused impairment of renal function with an increase in renal-specific P450 content, but FK-506 and rapamycin did not. Laurate ω- and (ω-1)-hydroxylase activity increased in rats treated with rapamycin but decreased in those treated with FK-506. Prostaglandin A1 (PGA1) ω-hydroxylase activity increased in rats treated with FK-506 but was reduced by treatment with cyclosporin. Aminopyrine N-demethylase activity increased in rats treated with cyclosporin or FK-506, but not in those treated with rapamycin. Western-blot analysis revealed significant induction of P450, (similar to CYP2B4 of the rabbit P450 isozyme) in kidneys from rats treated with cyclosporin but not in those from rats receiving FK-506 or rapamycin. Histochemical studies clearly demonstrated a form of P450 such as CYP4A2 in the proximal tubules of rats treated with cyclosporin, but not in those of rats treated with FK-506 or rapamycin.

These results show that although cyclosporin has a strong effect on renal P450 systems and induces such a system in kidney cortex (microsomal P450), FK-506 and rapamycin have no substantial effect on the induction of renal P450. These findings might clarify the nephrotoxicity induced by these immunosuppressive drugs.
Overlap in the Pharmacology of L-type Ca2+-channel Blockers and 5-HT2 Receptor Antagonists in Rat Aorta
Authors: Okoro E O
Published: October 2002

We have previously shown that elimination of buffer Ca2+ markedly reduced maximum 5-HT-induced contractions. We have now investigated the effect of L-type Ca2+-channel blockers and 5-HT2 receptor antagonists on 5-HT- and K+-induced contractions in rat aorta to explore the possibility of a relationship between blockade of L-type Ca2+ channels and 5-HT2 receptor antagonism.

Sodium nitroprusside, felodipine, nifedipine, diltiazem, cinnarizine, verapamil, ritanserin, cyproheptadine, ketanserin and mianserin inhibited 5-HT-induced contractions of rat aorta with mean IC50 values (concentration (M) resulting in 50% inhibition) of 2.2 × 10−11, 6.6 × 10−11, 1.5 × 10−9,1.7 × 10−9, 3.2 × 10−7, 5.4 × 10−7, 9.7 × 10−10, 1.9 × 10−8, 5.0 × 10−7 and 6.4 × 10−7, respectively. The same compounds antagonized K+-induced rat aortic contractions with the rank order of potency (mean IC50, M): felodipine (7.0 × 10−11) > nifedipine (4.8 × 10−9) > sodium nitroprusside (4.1 × 10−8) > verapamil (5.5 × 10−8) > cyproheptadine (6.2 × 10-8) > diltiazem (4.1 × 10−7) > cinnarizine (1.3 × 10−6) > ritansarin(1.8 × 10−6) > ketanserin (9.0 × 10−6) > mianserin (2.0 × 10−5).

These data are indicative of a highly significant correlation (r = 0.81, P = 0.03) between potency against 5-HT-induced contraction and that against contractile response to K+ depolarization, and suggest overlap of the pharmacology of L-type Ca2+-channel blockers and 5-HT2 receptor antagonists in rat aorta.
Evidence for a Neuroprotective Effect of Pyrid-3-yl-sulphonylurea in Photochemically Induced Focal Ischaemia in Rats: Magnetic Resonance Imaging Evaluation
Authors: Baudelet Christine , Demeure Roger , Frois Ana , Masereel Bernard , Goudemant Jean-François , Ritter Christian , Gallez Bernard
Published: October 2002

A neuroprotective effect can be obtained with N-[(4-cycloheptylaminopyrid-3-yl)sulphonyl]N′-cycloheptyl urea (BM27), a pyrid-3-yl-sulphonylurea structurally related to torasemide, a loop diuretic. We have investigated the neuroprotective effect of BM27 by magnetic resonance imaging and use of the photothrombotic model of cerebral infarction in the rat. This method enables non-invasive quantification of the extent of the cerebral oedema from T2-weighted spin-echo images.

This article reports the evolution of the extent of oedema with time (0.5, 1, 2, 4, 6, 24 and 48 h, 7 and 15 days and 1 month after induction of the lesion) in rats pretreated with 5mg kg−1 BM27 or an appropriate control. At all times, the rats treated with BM27 had, on average, smaller lesions than control rats (30% decrease between 2 h and 6 h).

These results strongly suggest a significant (P < 0.01) but modest neuroprotective effect of BM27 in ischaemic cerebral stroke. Further investigations should be performed to determine if BM27 or its analogues are of clinical interest.
Some Misconceptions in the Kinetic Analyses of Pharmaceutical Systems
Authors: Galwey Andrew K
Published: October 2002

Some problems encountered during the formulation of reaction mechanisms, by the interpretation of kinetic and other experimental observations, in studies of reactions that occur on heating reactants that are initially solid, are critically reviewed. The representative chemical changes selected for inclusion here appear to be relatively simple. It has been found, however, that the provision of acceptable representational models is less straightforward than might have been anticipated. Accordingly, it is concluded that, when interpreting kinetic data, it is essential to consider most carefully the significance of all experimental measurements in the context of the overall change.

Interpretational difficulties, recognised in the literature, that identify inconsistencies that may complicate kinetic analysis are illustrated through consideration of the following systems (and other examples): characterisation of the changes in reaction stoichiometry that result from the presence of a gaseous atmosphere during NiSO4.6H2O dehydration; the sensitivity of kinetic behaviour to reaction conditions during the dehydration of NiC2O4.2H2O and in the dissociation of CaCO3; the formation of intermediates and the possibility of melting during the decompositions of KMnO4 and of copper(II) malonate.

It is concluded that the formulation of reaction models through the interpretation of kinetic (with other) data for solid-state decomposition is more difficult than is sometimes acknowledged. It is not known how widely problems of the types described in this short review apply. These are mentioned here as types of behaviour that require more general consideration in kinetic and mechanistic studies of the changes that occur on heating reactants that are originally solid.
Prediction of Clearance, Volume of Distribution and Half-life by Allometric Scaling and by use of Plasma Concentrations Predicted from Pharmacokinetic Constants: a Comparative Study
Authors: Mahmood Iftekhar
Published: October 2002

Pharmacokinetic parameters (clearance, CL, volume of distribution in the central compartment, VdC, and elimination half-life, t½β) predicted by an empirical allometric approach have been compared with parameters predicted from plasma concentrations calculated by use of the pharmacokinetic constants A, B, α and β, where A and B are the intercepts on the Y axis of the plot of plasma concentration against time and α and β are the rate constants, both pairs of constants being for the distribution and elimination phases, respectively.

The pharmacokinetic parameters of cefpiramide, actisomide, troglitazone, procaterol, moxalactam and ciprofloxacin were scaled from animal data obtained from the literature. Three methods were used to generate plots for the prediction of clearance in man: dependence of clearance on body weight (simple allometric equation); dependence of the product of clearance and maximum life-span potential (MLP) on body weight; and dependence of the product of clearance and brain weight on body weight. Plasma concentrations of the drugs were predicted in man by use of A, B, α and β obtained from animal data. The predicted plasma concentrations were then used to calculate CL, VdC and t½β. The pharmacokinetic parameters predicted by use of both approaches were compared with measured values. The results indicate that simple allometry did not predict clearance satisfactorily for actisomide, troglitazone, procaterol and ciprofloxacin. Use of MLP or the product of clearance and brain weight improved the prediction of clearance for these four drugs. Except for troglitazone, VdC and t½β predicted for man by use of the allometric approach were comparable with measured values for the drugs studied. CL, VdCand t½β predicted by use of pharmacokinetic constants were comparable with values predicted by simple allometry. Thus, if simple allometry failed to predict clearance of a drug, so did the pharmacokinetic constant approach (except for actisomide).

The results of this study indicate that caution should be employed in interpreting plasma concentrations predicted for a drug in man by use of pharmacokinetic constants obtained in animals.
Microdialysis Study of Biliary Excretion of Chloramphenicol and its Glucuronide in the Rat
Authors: Tsai T H , Hung L C , Chen C F
Published: October 2002

The biliary excretion of chloramphenicol and its glucuronide has been evaluated by use of a microdialysis probe linked to automatic on-line microbore high-performance liquid chromatography.

The microdialysis probe was inserted into the bile duct between the liver and the duodenum; to avoid obstruction of the bile duct or bile salt waste, a shunt linear probe was used. After intravenous administration of chloramphenicol succinate (100 mg kg−1) the amounts of unbound chloramphenicol and its glucuronide in the bile microdialysate were recorded. According to the pharmacokinetic results disposition of chloramphenicol seems to fit a two-compartment model whereas that of chloramphenicol glucuronide fits a one-compartment model in rat bile. The area under the concentration-time curve for chloramphenicol glucuronide was twice that for chloramphenicol in rat bile duct.

Clearance of chloramphenicol glucuronide was significantly higher than that of chloramphenicol in biliary excretion, indicating that chloramphenicol and its glucuronide are actively excreted into the bile.
Inhibitory Effects of the Antihistamines Epinastine, Terfenadine, and Ebastine on Potassium Currents in Rat Ventricular Myocytes
Authors: Ohtani Hisakazu , Hanada Erika , Hirota Michiko , Sato Hitoshi , Kotaki Hajime , Sawada Yasufumi , Uemura Hiroko , Nakaya Haruaki , Iga Tatsuji
Published: October 2002

We examined and compared the inhibitory effects of three non-sedating antihistamines, terfenadine, ebastine, and epinastine, on delayed rectifier potassium current (IK) and transient outward potassium current (Ito) of rat isolated ventricular myocytes, using a patch clamp technique.

Terfenadine, ebastine and epinastine were found to inhibit IK with IC50 values of 5.96, 15.3 and 145 μM, respectively. Ito was suppressed by epinastine with an IC50 value of 69.5 μM. The order of arrhythmogenicity, assessed by the inhibition of IK, was ranked as terfenadine > ebastine > epinastine, consistent with that of the potencies of each drug for QT prolongation reported in rats.