Kinship--king's social harmonisation project. Pilot phase of a social network for use in higher education (HE)

Students entering Higher Education are increasingly information and communications technology literate. Many students (graduates and undergraduates) arrive as "digital residents", who are adept with social media and technologically fluent. The informal use of social media for learning is becoming increasingly evident, along with the potentially detrimental effects of a poor digital profile on employment prospects. This paper describes the creation of Kinship (King's Social Harmonisation Project), a university hosted, members only social network, which is currently being piloted in the Medical School at King's College London. Along with a number of other teaching and learning resources, it is intended to use Kinship to establish an informal code of conduct by modelling and moderating appropriate professional online behaviour. Kinship was developed using an open source Elgg platform, thanks to funding of £20,000 from the College Teaching Fund under the mentorship of Brighton University (1). This educational research project, led by Medicine, was proposed to select, customise and evaluate a social networking platform in order to provide functionality that would enhance new and existing e-learning resources, support group interaction, participation and sharing and meet the diverse needs of three academic schools: Medicine, the Dental Institute and two separate Departments, the Modern Languages Centre and the Department of English from Arts & Humanities, as a pilot for wider College deployment. Student involvement is central to the project, from conducting the evaluation to moulding and customising the functionality and look of Kinship, in order to ensure that the site is authentic and evolves in response to their wishes and requirements. Formal evaluation of Kinship commences summer 2012.

Pharmacokinetics and metabolism of the anti-oestrogen droloxifene in female human subjects

1. Single oral doses of a solution formulation of (14)C-droloxifene citrate (141 mg) appeared to be rapidly and well absorbed in four post-menopausal female subjects. Peak plasma concentrations (C(max)) of total (14)C (1260 ng eq. ml(-1)), droloxifene (196 ng ml(-1)) and the major metabolite droloxifene glucuronide (851 ng eq. ml(-1)) occurred at 0.9-1.1 h (T(max)) and declined bi-exponentially with terminal half-lives of 45.0, 31.6 and 32.0 h respectively. The mean AUCs of droloxifene and the major metabolite were 21 and 37% respectively that of total (14)C. 2. Total (14)C was excreted slowly, mainly in the faeces. Mean totals of 6.6 and 90.3% of the dose were excreted in the urine and faeces respectively during 11 days. The data were consistent with biliary excretion and enterohepatic circulation of the major metabolite, droloxifene glucuronide. 3. GC-MS showed that the major (14)C-components in 0-24-h urine were droloxifene (mean 0.4% dose) and its glucuronide (2.3% dose), and in faeces were droloxifene (60.2% dose) and N- desmethyldroloxifene (4.2% dose). Other components in faeces corresponded chromatographically to reference standards, droloxifene N-oxide (1.9% dose), side-chain hydroxylated droloxifene (dimethylamine moiety of droloxifene side-chain replaced by hydroxyl, 1.3% dose) and droloxifene glucuronide (10.7% dose). The latter was resistant to enzymic hydrolysis by the beta-glucuronidase used. 4. Intersubject variability in the pharmacokinetics of droloxifene in this study was relatively low (CV < 20% for AUC and half-life).

Species differences in the pharmacokinetics and metabolism of reparixin in rat and dog

The pharmacokinetics and metabolism of reparixin (formerly repertaxin), a potent and specific inhibitor of the chemokine CXCL8, were investigated in rats and dogs after intravenous administration of [14C]-reparixin L-lysine salt. Protein binding of reparixin was investigated in vitro in rat, dog, rabbit, cynomolgus monkey and human plasma. Plasma protein binding of reparixin was >99% in the laboratory animals and humans up to 50 microg ml-1, but lower at higher concentrations. Although radioactivity was rapidly distributed into rat tissues, Vss was low (about 0.15 l kg-1) in both rat and dog. Nevertheless, reparixin was more rapidly eliminated in rats (t1/2 approximately 0.5 h) than in dogs (t1/2 approximately 10 h). Systemic exposure in dog was due primarily to parent drug, but metabolites played a more prominent role in rat. Oxidation of the isobutyl side-chain was the major metabolic pathway in rat, whereas hydrolysis of the amide bond predominated in dog. Urinary excretion, which accounted for 80-82% of the radioactive dose, was the major route of elimination in both species, and biotransformation of reparixin was complete before excretion.

Pharmacokinetics and Metabolism of the Prodrug DB289 (2,5-Bis[4-(N-methoxyamidino)phenyl]furan Monomaleate) in Rat and Monkey and Its Conversion to the Antiprotozoal/Antifungal Drug DB75 (2,5-Bis(4-guanylphenyl)furan Dihydrochloride)

DB289 (pafuramidine maleate; 2,5-bis[4-(N-methoxyamidino)phenyl]furan monomaleate) is a prodrug of DB75 (furamidine dihydrochloride; 2,5-bis(4-guanylphenyl)furan dihydrochloride), an aromatic dication related to pentamidine that has demonstrated good efficacy against African trypanosomiasis, Pneumocystis carinii pneumonia, and malaria, but lacks adequate oral availability. The pharmacokinetics and metabolism of 14C-DB289 have been investigated in rat and monkey after oral and intravenous administration. Oral doses were well absorbed (approximately 50-70%) and effectively converted to DB75 in both species but subject to first-pass metabolism and hepatic retention, limiting its systemic bioavailability to 10 to 20%. Clearance of DB289 approximated the liver plasma flow and its large volume of distribution was consistent with extensive tissue binding. Plasma protein binding of DB289 was 97 to 99% in four animal species and humans, but that of DB75 was noticeably less and more species- and concentration-dependent. Together, prodrug and active metabolite accounted for less than 20% of the plasma radioactivity after an oral dose, but DB75 was the major radiochemical component in key organs such as brain and liver and was largely responsible for the persistence of 14C in the body. The predominant route of excretion of radioactivity was via the feces, although biliary secretion was not particularly extensive. High-performance liquid chromatography and liquid chromatography-mass spectrometry investigations showed that the formation of DB75 from the prodrug involved the sequential loss of the two N-methoxy groups, either directly or by O-demethylation followed by reduction of the resulting oxime to the amidine. It was estimated that almost half of an oral dose of DB289 to rats and about one-third of that to monkeys was metabolized to DB75.

Absorption, distribution and excretion of 14C-pilocarpine following oral administration to rats

The absorption, distribution and excretion of pilocarpine (CAS 92-13-7) were studied after single oral doses of 14C-pilocarpine hydrochloride (CAS 54-71-7) to the Sprague-Dawley rat, administered in aqueous solution mainly at a dose level of 0.3 mg/kg. Rats also received single intravenous doses at 0.3 mg/kg so as to compare 14C pharmacokinetics and excretion. The oral 14C-dose was rapidly and almost completely absorbed from the duodenum and small intestine within 30 min in the male rat and 14C concentrations in plasma declined biexponentially with a terminal half-life of about 9 h. Over the oral dosage range studied, i.e. 0.1-1.0 mg/kg, there was no evidence of significant non-proportionality for Cmax of 14C, whereas there was some such evidence for AUG24. Tissue 14C concentrations in male and pregnant female (Day 18) rats peaked at 0.5 h and mostly declined in parallel with those in the plasma. Excluding tissues concerned with drug absorption and elimination, 14C concentrations in most tissues were similar to, or lower than, those in the plasma. The extent of placental transfer of 14C was small and less than 0.09% of a maternal dose reached a foetus. 14C diffused into maternal milk at concentrations similar to those in the plasma. The 14C-dose was rapidly excreted in male rats, mostly in the urine (about 80%) during 6 h post dose. Recoveries of 14C in mass balance (excretion) studies were in the range 96-100%. There were no apparent gender differences in the disposition of 14C-pilocarpine in the rat.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the dog

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in dogs and also eliminated rapidly with a short half-life. Following single intravenous doses, dexloxiglumide was characterised as a drug having a high clearance (30.7 and 27.0 ml/min/kg in males and females respectively), a low volume of distribution (Vss, 0.34 and 0.27 L/kg in males and females respectively) and a moderate systemic availability (about 33%). It was extensively bound to plasma proteins (89%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the kidney, liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. 14C concentrations generally peaked at 0.25h and declined rapidly during 24h being present only in a few tissues (such as the kidney, liver and gastrointestinal tract) at 24h. Single intravenous or oral doses were mainly excreted in the faeces (77-89%), mostly during 24h. Urine contained up to 7.5% dose. Mean recoveries during 7 days ranged between 93-97%. Biliary excretion of 14C was prominent (64% dose during 24h) in the disposition of 14C which was probably also subjected to some limited enterohepatic circulation. Unchanged dexloxiglumide was the major component in plasma. Urine and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. about 55% dose in faeces). LC-MS/MS of urine and bile extracts showed that dexloxiglumide was metabolised mainly by O-demethylation and by conjugation with glucuronic acid.

In Vitro/in Vivo Correlation for14C-Methylated Lysozyme Release from Poly(Ether-Ester) Microspheres

PURPOSE

The purpose of this study was to obtain an in vitro/in vivo correlation for the sustained release of a protein from poly(ethylene glycol) terephthalate (PEGT)/poly(butylene terephthalate) (PBT) microspheres.

METHODS

Radiolabeled lysozyme was encapsulated in PEGT/PBT microspheres via a water-in-oil-in-water emulsion. Three microsphere formulations varying in copolymer composition were administered subcutaneously to rats. The blood plasma was analyzed for radioactivity content representing released lysozyme at various time points post-dose. The in vitro release was studied in phosphate-buffered saline.

RESULTS

The encapsulation efficiency, calculated from the radioactivity in the outer water phase of the emulsion, varied from 60-87%. Depending on the PEG segment length and wt% PEGT, the lysozyme was released completely in vitro within 14 to 28 days without initial burst. 14C-methylated lysozyme could be detected in the plasma over the same time courses. The in vitro/in vivo correlation coefficients obtained from point-to-point analysis were greater than 0.96 for all microsphere formulations. In addition, less then 10% of administered radioactivity remained at dose site at 28 days for the microsphere formulations, indicating no notable retention of the protein at the injection site.

CONCLUSION

The in vitro release in phosphate-buffered saline and the in vivo release in rats showed an excellent congruence independent of the release rate of 14C-methylated lysozyme from PEGT/PBT microspheres.

Absorption, distribution, metabolism and excretion of the cholecystokinin-1 antagonist dexloxiglumide in the rat

Single oral doses of 14C-dexloxiglumide were rapidly and extensively absorbed in rats, and eliminated more slowly by females than by males. The respective half-lives were about 4.9 and 2.1 h. Following single intravenous doses, dexloxiglumide was characterised as a drug having a low clearance (6.01 and about 1.96 ml/min/kg in males and females respectively), a moderate volume of distribution (Vss, 0.98 and about 1.1 L/kg in males and females respectively) and a high systemic availability. It was extensively bound to plasma proteins (97%). Dexloxiglumide is mainly cleared by the liver. Its renal clearance was minor. In only the liver and gastrointestinal tract, were concentrations of 14C generally greater than those in plasma. Peak 14C concentrations generally occurred at 1-2 h in males and at 2-4 h in females. Tissue 14C concentrations then declined by severalfold during 24 h although still present in most tissues at 24 h but only in a few tissues (such as the liver and gastrointestinal tract) at 168 h. Decline of 14C was less rapid in the tissues of females than in those of males. Single intravenous or oral doses were mainly excreted in the faeces (87-92%), mostly during 24 h and more slowly from females than from males. Urines contained less than 11% dose. Mean recoveries during 7 days when 14C was not detectable in the carcass except in one female rat ranged between 93-101%. Biliary excretion of 14C was prominent (84-91% dose during 24 h) in the disposition of 14C which was also subjected to facile enterohepatic circulation (74% dose). Metabolite profiles in plasma and selected tissues differed. In the former, unchanged dexloxiglumide was the major component whereas in the latter, a polar component was dominant. Urine, bile and faeces contained several 14C-components amongst which unchanged dexloxiglumide was the most important (eg. up to 63% dose in bile). LC-MS/MS showed that dexloxiglumide was metabolised mainly by hydroxylation in the N-(3-methoxypropyl)pentyl sidechain and by O-demethylation followed by subsequent oxidation of the resulting alcohol to a carboxylic acid.

Pharmacokinetics and metabolism of the cholecystokinin antagonist dexloxiglumide in male human subjects

1. Mean concentrations of total (14)C and of dexloxiglumide at the end of single 20-min infusion doses of (14)C-dexloxiglumide (200 mg) to four healthy male subjects were 18.5 microg eq x ml(-1) and 19.5 microg ml(-1) respectively. The mean plasma clearance (0.22 l h(-1) x kg(-1)) and mean volume of distribution (V(ss) = 0.18 l kg(-1)) were low. 2. Single oral doses of a solid formulation of (14)C-dexloxiglumide (200 mg) to the same subjects appeared to be rapidly and well absorbed. Mean peak plasma concentrations (C(max)) of total (14)C (2.8 microg eq x ml(-1)) and of dexloxiglumide (2.2 microg x ml(-1)) occurred at about 1.5 h. Systemic availabilities of the oral dose based on total (14)C and dexloxiglumide were 70 and 48%, respectively. Thus, a proportion of an oral dose was subjected to presystemic elimination and the absorbed dose mainly eliminated by metabolism. Binding of dexloxiglumide to plasma proteins was extensive (96.6-99.2%). 3. Total (14)C was excreted mainly in the faeces. Mass balance of (14)C excretion was almost complete within 7 days when a mean of > 93% of the dose had been recovered. After the intravenous (i.v.) dose, mean totals of 23.7 and 69.8% of the dose were excreted in urine and faeces, respectively, during 7 days, and 19.5 and 73.7% of the dose, respectively, after the oral dose. The data were consistent with biliary excretion and perhaps some enterohepatic circulation of conjugates of dexloxiglumide and at least one of its metabolites. 4. LC-MS/MS of urine extracts showed that dexloxiglumide was metabolized by oxidation and conjugation. The former included at least two metabolites formed by monohydroxylation in the N-(3-methoxypropyl) pentyl side chain, and O-demethylation of this side chain followed by subsequent oxidation of the resultant alcohol to the dicarboxylic acid. At least one glucuronide was also present in urine. The main components in faeces appeared to be dexloxiglumide and a dicarboxylic metabolite formed by O-demethylation followed by oxidation of the N-(3-methoxypropyl) side chain. Both compounds were identified as their corresponding methyl esters formed because acid and methanol were used in the extraction procedure. Dexloxiglumide and the dicarboxylic acid were presumably excreted in bile as the glucuronic acid conjugates.

The pharmacokinetics and metabolism of sucralose in the mouse

The excretion and metabolism of (14)C-sucralose has been investigated in mice following intravenous and oral administration. A 20mg/kg intravenous dose was rapidly excreted mainly in the urine (80% in 5 days). After 100, 1500 and 3000mg/kg oral doses of (14)C-sucralose, means of 23%, 15% and 16% of the dose, respectively, were excreted in the urine during 5 days. Comparison with the intravenous dose indicated that 20-30% of the oral doses was absorbed. Sucralose was excreted almost entirely unchanged and represented more than 80-90% of the radioactivity in all urine and faeces samples. Only two minor metabolites were detected, representing 2-8% of urine radioactivity.

The pharmacokinetics and metabolism of sucralose in the dog

The pharmacokinetics and metabolism of sucralose were investigated in dogs following intravenous or oral administration. Oral doses of (14)C-sucralose were rapidly absorbed, although there was some variation in the extent of absorption (range 18-48% of the dose). After intravenous or oral administration, radioactivity excreted in the urine was associated mainly with unchanged sucralose. One urinary metabolite was detected after both intravenous and oral doses and was identified by mass spectrometry as a glucuronic acid conjugate of sucralose. This metabolite accounted for about 15-20% of the intravenous dose but for only about 2-8% of the oral dose.

The pharmacokinetics and metabolism of sucralose in the rabbit

The excretion and metabolism of (14)C-sucralose has been investigated in non-pregnant and pregnant rabbits after administration of single 10mg/kg oral doses. Means of 22% and 55% of the dose were excreted in urine and faeces, respectively, by non-pregnant animals during 5 days. Excretion was similar in pregnant animals with means of 22% and 65% of the dose in urine and faeces, respectively, during the same time. Following a single oral dose, a mean of approximately 7% of the dose was still being excreted during the 96-120-hr collection period. Only one major radioactive component was detected in urine samples which corresponded to unchanged sucralose.

Metabolism, disposition, excretion, and pharmacokinetics of levormeloxifene, a selective estrogen receptor modulator, in the rat

The tissue distribution, pharmacokinetics, metabolism, and excretion of the selective estrogen receptor modulator levormeloxifene have been investigated after oral administration of [(14)C]-levormeloxifene to male and female Sprague-Dawley rats. The quantitative distribution of radiolabeled levormeloxifene and/or metabolites was confirmed by whole body autoradiography. Levormeloxifene was absorbed from the gastrointestinal tract and was widely distributed into tissues, with peak radioactive concentrations generally being observed 4 h after administration in the intestine, liver, lung, kidney, spleen, pancreas, adrenals, and ovary (females). Fecal elimination was the major excretion route of radioactivity. In a separate pharmacokinetic study, plasma C(max) was generally observed 6 h after dose administration and the half-life of elimination was long (24 h) and a doubling in dose resulted in an approximate doubling in exposure. The majority of the drug was excreted as norlevormeloxifene; the 7-desmethyl metabolite of levormeloxifene, via the formation of phase II metabolites (glucuronides) and excretion into the bile. Unchanged drug was also excreted, mainly from 0 to 24 h, and accounted for about 6 to 12% of the dose. Together these two components accounted for approximately 50% of the radioactivity excreted. Additional metabolites isolated and identified by liquid chromatography-tandem mass spectrometry, and accounting for 1 to 5% of the excreted radioactivity in rat feces during the first 24 h, included two monohydroxylevormeloxifene species, a pyrrolidinone ring-opened metabolite of levormeloxifene, and desmethylnorlevormeloxifene.

Metabolism of the anti-psoriatic agent 5-methoxypsoralen in humans: comparison with rat and dog

1. Single oral doses of 14C-5-methoxypsoralen (5-MOP) to human subjects (50 mg), rats (1 mg/kg) and dogs (1 mg/kg) were fairly well absorbed but subjected to extensive first-pass metabolism, at least in rat and human. Means of 62, 51 and 40% dose in urine and 31, 38 and 48% dose in faeces, were excreted by humans (during 5 days), rats (3 days) and dogs (1 day), respectively. In dogs, faecal 14C was probably derived, in part, from biliary excreted material. 2. Total 14C in human plasma reached peak concentrations after 2 h (mean 235 ng 5-MOP equivalent/ml) and declined relatively slowly, to about 60% of this value within 24 h. Unchanged 5-MOP was not detected in plasma using h.p.l.c. (< 5 ng/ml). 3. Tissue concentrations of 14C were generally greater in dogs than rats and reached peak levels at 1 h in dogs but at 24 h in rats. Apart from liver and bile, dog tissue 14C concentrations were lower than those in the corresponding plasma, whereas in rat they were lower only until the time of peak concentrations, after which they were generally greater. 4. 5-MOP was extensively metabolized in all three species. The major 14C-components in human and dog urine were glucuronic acid conjugates, mainly of an arylacetic acid and arylalcohols, resulting from initial oxidative metabolism of the furan ring of 5-MOP. In rat, these metabolites were excreted mainly unconjugated. An unusual metabolite was formed by reduction of the lactone moiety of 5-MOP, probably by the gut flora, giving rise to an arylpropionic acid, excreted as a glucuronic acid conjugate in the urine of all three species. 5. Unchanged drug was a very minor component of human and rat plasma, but a major component of dog plasma. In all three species, circulating 14C-metabolites were similar to those in the urine but were present mainly unconjugated. On the basis of these data, the metabolic fate of 5-MOP in humans was more similar to that in dog than to that in rat, although humans appeared to metabolize 5-MOP more rapidly than did dog.

The metabolism and pharmacokinetics of 14C-cetirizine in humans

This study investigated the metabolism and pharmacokinetics of cetirizine, a new H1-receptor antagonist. Single oral doses of 14C-cetirizine dihydrochloride (10 mg) in aqueous solution were administered to six healthy male volunteers. The drug was rapidly absorbed: The peak mean concentration of radioactivity (359 ng-equivalents/mL) and of unchanged drug (341 ng/mL) were achieved within one hour. Mean concentrations of cetirizine declined biexponentially and had a mean elimination half-life of 7.4 hours. The drug was excreted quite rapidly, with 60% of the dose recovered in the 24-hour urine. An additional 10% was excreted in urine over the next four days. Approximately 10% of the dose was excreted in feces over the five-day study period. The dose was excreted mainly as the unchanged drug. Examination of the radioactive compounds present in the plasma, and excreted in the urine and feces indicate that there is little metabolism of cetirizine. One minor metabolite, formed by oxidative O-dealkylation of the cetirizine side chain, was detected in plasma and feces.

Metabolic fate of the thrombolytic agent benzarone in man: comparison with the rat and dog

1. The metabolic fate of 14C-benzarone in the rat and dog has been compared to that in human subjects. An oral dose was well-absorbed in all three species. However, the 14C excretion patterns differed: humans (100 mg) excreted means of 73 and 19% dose in the urine and faeces respectively, whereas the rat (2 mg/kg) and dog (0.5 mg/kg) excreted greater than 80% in the faeces, mostly during the first 48 h. 2. Much of the faecal 14C was attributable to 14C excreted in the bile which amounted to 59% in the 7 h bile collected from an intravenously dosed dog, and a mean of 72% in the 24 h bile of orally dosed rats. Enterohepatic circulation of 14C was demonstrated in rats. 3. Total 14C in human plasma reached peak concentrations between 1-2 h and declined relatively rapidly, to about 10% of this value within 24 h. Unchanged benzarone was not detected in plasma (less than 25 ng/ml), even after a 400 mg dose, but conjugated benzarone was--accounting for about 10% of the peak concentration of 14C. In the dog, by contrast, conjugated benzarone accounted for about 50% of the peak concentration of 14C of 0.96 microgram equiv./ml at 1 h. The extent of binding of benzarone to human plasma proteins (greater than 99%; in vitro was slightly greater than that (greater than 96%) of total 14C (ex vivo, representing metabolites). 4. Examination of metabolite profiles by h.p.l.c. suggested that in the rat and dog, at least 70% absorbed dose was eliminated by direct conjugation, whereas in humans at least 70% was hydroxylated before conjugation, mainly with glucuronic acid. Hydroxylation occurred in the benzofuran ring and/or the ethyl side-chain. The principal urinary metabolite in humans was the conjugate(s) of the 1-hydroxylated ethyl side-chain derivative (mean 26% dose).

Pharmacokinetics and metabolism of 14C-tinidazole in humans

Following intravenous infusion of 800 mg of 14C-tinidazole during 30 min to two human subjects, a mean of 44% of the dose was excreted in urine during the first 24 h, increasing to 63% of the dose during five days: 12% of the dose was excreted in the faeces, indicating the possible involvement of biliary excretion and other secretory processes in the disposition of tinidazole. At 6 min after the end of the infusion, the mean plasma tinidazole concentration was 12 mg/l. Tinidazole was a major component in 0-120 h urine (about 32% of urinary 14C): the major metabolite in the 0-12 h urine examined was ethyl 2-(5-hydroxy-2-methyl-4-nitro-1-imidazolyl)ethyl sulphone (about 30% urinary 14C), the product of hydroxylation and nitro-group migration. These compounds were also present in the faeces. A minor urinary metabolite was 2-hydroxymethyltinidazole (about 9% urinary 14C), which was also present in plasma. The mean pharmacokinetic parameters obtained for tinidazole were similar to those reported in the literature; total clearance 51 ml/min, renal clearance 10 ml/min, volume of distribution 501 and half-life 11.6 h.

Extent of vaginal absorption of sulphated polysaccharide from A-gen 53 in the rabbit

The vaginal absorption of a sulphated polysaccharide (SAEP), the active substance of A-gen 53+, was studied in rabbits using the 35S-labelled product. After intra-vaginal administration of 35S-SAEP, measurements of 35S in urine, faeces, plasma and tissues of the reticulo-endothelial system indicated that the small proportion of the dose (ca. 5%) absorbed from the vagina was associated mainly with inorganic material (i.e. 35S-sulphate), present as an impurity in the 35S-dose.

Metabolic fact of 14C-isosorbide 5-mononitrate in humans

Single oral doses of 20 mg of the carbon-14 labelled form of the antianginal drug isosorbide 5-mononitrate (5-ISMN, Elantan) were essentially completely absorbed and excreted fairly rapidly in the urine. Means of 24, 52, 78, 93 and 96% dose were excreted during 6, 12, 24, 48 and 120 h, respectively. Concentrations of 14C reached peak levels at about 1-2 h when about 86% of the 14C was associated with the parent drug, 5-ISMN (peak mean level 430 ng/ml), and the remainder mainly with the pharmacologically-inactive denitrated product isosorbide. Because the plasma (and urinary) half-life of isosorbide was longer (about 8-9 h) than that of 5-ISMN (about 4.5 h), the proportions of the former in plasma increased relative to the latter. Concentrations of 14C in whole-blood and plasma were similar, implying that 5-ISMN diffused into blood cells. Concentrations of 5-ISMN in saliva and plasma were almost identical, presumably because of the almost negligible plasma protein binding of the drug (less than 5%). At least five metabolites of 5-ISMN were detected in urine - these were isosorbide (about 37% dose), conjugated material (about 25% dose) presumably mainly 5-ISMN-glucuronide, sorbitol (about 7% dose), the parent drug 5-ISMN (about 2% dose) and two unidentified metabolites (about 7 and 4% dose, respectively). The conjugated material was excreted in the urine relatively more rapidly than the denitrated product, isosorbide.

The metabolism of the anti-inflammatory drug eterylate in rat, dog and man

Oral doses of 14C-eterylate were well absorbed by rat and man and excreted mainly in the urine (94% dose by rat in three days and 91% by man in five days). Oral doses to dogs were excreted in similar proportions in both the urine and faeces, although faecal 14C was probably derived in part, from biliary-excreted material. Peak plasma 14C and drug concn. were generally reached between one and three hours after oral doses. In humans, only two metabolites, salicylic acid and 4-acetamido-phenoxyacetic acid, were detected in plasma. The latter was cleared more rapidly than the former and hence plasma salicyclate concn. reached a peak (10.9 and 19.8 micrograms/ml in Subjects 1 and 2, respectively) and initially declined with a half-life of about two-three hours. Plasma 4-acetamidophenoxyacetic acid concn. reached a peak (4.3, 10.0 micrograms/ml, respectively) and declined with a half-life of about one hour. Tissue concn. of 14C were generally greater in dogs than in rats. Highest conc. occurred at three hours in dogs and at one hour in rats. Apart from those in the liver and kidneys, tissue concn. were lower than those in the corresponding plasma. Unchanged drug was not detected in urine or plasma of any species and was rapidly metabolized in human plasma. The major 14C components in human urine were identified as salicyluric acid and 4-acetamidophenoxyacetic acid; minor metabolites were salicylic acid, gentisic acid and paracetamol. These metabolites were also detected in rat urine albeit in different proportions to those in human urine. Dog urine contained less of these metabolites and a major proportion of the 14C was associated with relatively non-polar components. Although salicylic acid and 4-acetamidophenoxyacetic acid were the only major circulating metabolites in man and rat, dog plasma also contained the non-polar urine metabolites.