Elimination Half-life Of Radioactivity Research Articles

Excretion and Distribution of the 60-kDa PEG Moiety Used in BAY 94-9027 in Male Wistar Rats

Introduction: PEGylation is a widely used method to prolong the half-life of therapeutic proteins. Long-acting factor VIII (FVIII) products developed through PEGylation may potentially reduce the burden associated with prophylaxis in patients with hemophilia A. BAY 94-9027 is a prolonged-half-life FVIII product modified through site-specific addition of a 60-kDa (2 × 30-kDa branched) PEG via a maleimide linker to a cysteine amino acid. BAY 1025662 is the 60-kDa PEG moiety used for PEGylation including linker and cysteine (PEG-60-Mal-Cys). In toxicology studies, BAY 94-9027 and BAY 1025662 were not associated with any adverse events or PEG-related cellular vacuolation (Ivens et al. Haemophilia. 2013;19:11-20). The rate-limiting clearance of the PEG part of PEGylated proteins after metabolism is expected to be similar to that when the corresponding PEG is administered alone (Baumann et al. Drug Discov Today . 2014;19:1623-1631). The study objective was to investigate the pharmacokinetics and mass balance of total radioactivity in male Wistar rats after a single intravenous (IV) administration of [14C]-labeled BAY 1025662, including size exclusion chromatography profiles of urine at selected time points.Methods: Radiolabeled BAY 1025662 ([prop-14C]BAY 1025662) was synthesized using a 2-step process resulting in a maleimide linker bearing the [14C] label at the propionic acid moiety. Radioactivity following a single IV dose of 11 mg/kg (the estimated maximal human PEG dose over ~30 years' treatment with BAY 94-9027) was determined in body fluids, organs and tissues, and in excreta by liquid scintillation counting after appropriate sample preparation and by quantitative whole-body autoradiography during and at the end of the study.Results: Single-dose mass balance studies using [prop-14C]BAY 1025662 showed that 30.4% of administered radioactivity was excreted within 1 week (23.7% in urine and 6.3% in feces); cumulative excretion at day 168 via urine and feces was 82.6% of the administered dose (68.4% via urine, 13.8% via feces). High-performance liquid chromatography profiling analysis of rat urine suggested that BAY 1025662 is excreted nearly unchanged (74% of total radioactivity, corresponding to 17.6% of dose, present unchanged in urine in the 0- to 168-hour interval). Radioactivity was continuously, albeit slowly, eliminated throughout the study; elimination half-life was 23 and 24 days in blood and plasma, respectively. The corresponding elimination half-lives of radioactivity were 33, 31, 39, 54, and 68 days in the liver, skin, carcass, testes, and kidneys, respectively. Elimination was almost complete at the end of experiment, with a total recovery of radioactivity (cumulative excretion plus residues in animals) of 89% on day 168. Following [prop-14C]BAY 1025662 administration, radioactivity was slowly distributed from blood to peripheral organs, reaching maximum concentration 2 hours postdose; highest maximum concentration was observed in blood, followed by lung and liver. At day 168, only ~4% of the administered radioactive dose was still present in the animal body, partially localized in endocrine/exocrine glands and lymphatic organs. No residual radioactivity was observed in the brain, indicating no crossing of the blood-brain barrier.Conclusions: Following single-dose administration of [prop-14C]BAY 1025662, elimination was almost complete by the end of the experiment on day 168. These results suggest that there are excretion processes in place for high-molecular-weight PEGs such as the PEG 60 moiety used in BAY 94-9027. Two clearance processes are proposed for large PEGs (>30 kDa), as indicated by a faster initial excretion over the first 1-2 weeks, followed by a nonspecific uptake into cells by pinocytosis leading to a longer elimination half-life. The PEG moiety can be recycled from inside the cells back to the plasma, possibly by exocytosis, to then undergo further (mainly renal) excretion (Baumann et al. Drug Discov Today . 2014;19:1623-1631). DisclosuresBaumann:Bayer AG: Employment. Schwarz:Bayer AG: Employment. Hucke:Bayer AG: Employment. Piel:Bayer AG: Employment. Sandmann:Bayer AG: Employment.

Pharmacokinetics and Excretion of 14C-Labeled Polyethylene Glycol (60 kDa) in Rats

Introduction: Although there is no evidence for PEG-related safety issues with PEGylated proteins in the clinic, questions relating to the pharmacokinetics including disposition and excretion of PEG are being raised more frequently by health authorities nowadays, particularly for PEGylated proteins used chronically and/or in the pediatric population (http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2012/11/WC500135123.pdf).BAY 94-9027, a B-domain–deleted recombinant FVIII with a 60-kDa branched PEG molecule attached via a maleimide linker to an amino acid using site-specific PEGylation, is in clinical development for acute and prophylactic intravenous treatment of hemophilia A. The objective of this study was to investigate the pharmacokinetics and excretion of radioactivity (unchanged compound and radioactive metabolites) after single intravenous administration of 14C-labeled BAY 1025662 (cysteine linker-[60-kDa] PEG part of BAY 94-9027 with the 14C label covalently integrated in the linker) in male Wistar rats.Methods: The administered dose was 11 mg/kg body weight related to BAY 1025662 (approximated human lifetime dose of PEG 60 kDa resulting from treatment with BAY 94-9027). The concentrations and amounts of radioactivity in urine, feces, blood, plasma, and selected organs and tissues were investigated in order to determine the excretion via urine and feces, and the pharmacokinetics of total radioactivity and radioactive residues in the animal body.Results: After single intravenous administration of 14C-BAY 1025662 to rats, a fast initial elimination of 14C radioactivity was observed; 63.2% of administered radioactivity was excreted within the first 24 hours (51.4% in urine, 11.8% in feces). Up to day 7, 75.6% of administered radioactivity was excreted predominantly via urine. The balance/recovery of radioactivity on day 7 amounted to 99.0% in relation to the administered radioactive dose. The radioactive residue in the animals amounted to 23.4% of administered dose. The majority of the residual radioactivity was recovered in the carcass and skin, followed by liver and kidneys. The excretion of radioactivity continued at steadily decreasing levels until the end of the study. The daily radioactivity excretion decreased from 2.1% at 72 hours to 0.013% of dose at 6 months after administration of 14C-BAY 1025662. The cumulative excretion of radioactivity via urine and feces was calculated (partly interpolated) to 92.2% of the administered radioactive dose by the end of the experiment on day 168 (74.5% via urine, 17.4% via feces, and 0.294% recovered in the cage wash). The radioactivity was continuously albeit slowly eliminated from the investigated organs and tissues. The elimination half-life of radioactivity was 26 and 23 days in blood and plasma, respectively. The corresponding elimination half-lives of radioactivity were 35, 41, and 31 days in the liver, carcass, and skin, respectively. Radioactivity elimination from kidneys was biphasic with a terminal half-life of 92 days. The radioactive residues in the animals excluding the gastrointestinal tract decreased during the study from 22.5% on day 7 to 1.79% of dose at the end of the study on day 168. There was no indication for any retention or irreversible binding of radioactivity in the animal body. The total recovery of radioactivity (cumulative excretion plus residues in the animals) was 94% in relation to the administered dose at the end of the experiment on day 168.Conclusions: In this study, nearly complete excretion of the 60-kDa PEG molecule (measured as total radioactivity) could be observed, with a fast initial elimination in the first few days and a subsequent considerably slower process until the end of the observation period (6 months). These results are in agreement with recently proposed fast and slow processes for the renal excretion of large PEG and PEG proteins (Baumann, A. et al. Drug Discov Today. 2014:[Epub ahead of print, http://dx.doi.org/10.1016/j.drudis.2014.06.002]). DisclosuresBaumann:Bayer Pharma AG: Employment. Schwarz:Bayer Pharma AG: Employment. Seidel:Bayer Pharma AG: Employment. Hucke:Bayer Pharma AG: Employment. Steinke:Bayer Pharma AG: Employment. Buehner:Bayer Pharma AG: Employment.

Distribution of perospirone to melanin in pigmented rats

Following the administration of [Carbonyl-14C]perospirone ([CO-14C]perospirone) and [isothiazolyl-3-14C]perospirone ([TH-14C]perospirone) to male-pigmented rats at a single oral dose of 10 mg/kg, serum radioactivity reached maxima of 499 ng eq./g and 446 ng eq./g, respectively, at 1 hour, then decreased rapidly to below 2 ng eq./g at 168 hours, and radioactivity in eyeballs reached maxima of 576 ng eq./g and 3449 ng eq./g, respectively, at 24 hours, then decreasing slowly to become 120 ng eq./g and 314 ng eq./g at 26 weeks. Apparent elimination half-lives of radioactivity in eyeballs were 197 and 126 days for [CO-14C]perospirone and [TH-14C]perospirone, respectively. With radioluminograms, radioactivity was detected specifically in the uvea, reaching maxima at 168 hours for [CO-14C]perospirone and at 24 hours for [TH-14C]perospirone. In addition to unchanged compound, many metabolites were found in serum and eyeballs, but those were also detectable in SD albino rats and cynomolgus monkeys. Among radioactive components in eyeballs after administration of [CO-14C]perospirone, ratios of ID-15036 and MX11 followed by unchanged compound and MX9 are high. After administration of [TH-14C]perospirone, ID-11614 accounted for nearly half of the radioactivity. Values decreased in line with radioactivity in eyeballs over time and 26 weeks only a few polar metabolites could be detected.

In vivo pharmacokinetics of pyribenzoxim in rats.

Pyribenzoxim, benzophenone O-[2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoyl]oxime, is a new post-emergence herbicide providing broad-spectrum weed control in rice fields. [14C]Pyribenzoxim was used to study the pharmacokinetics of the compound after oral administration of a dose of 1000 mg kg-1 to male Sprague-Dawley rats. The material balance ranged from 97.3 to 99.7% of the administered dose and urinary and fecal recovery accounted for 97.1%, with the majority of radioactivity recovered in feces (88.6%) by 168 h after treatment. Elimination as volatile products or as carbon dioxide was negligible. The following values were obtained for the compound in the blood: AUC0-168 h, 28,400 micrograms equiv hg-1; Tmax, 12 h; Cmax, 372 micrograms equiv g-1; half-life, 53 h. Radioactivity in tissue decreased from 96.1% of applied radiocarbon at 6 h to 0.4% at 168 h and the highest concentration of radioactivity among the tissues was observed in liver while the lowest residues were found in brain. The elimination half-lives of radioactivity from tissues was in the range of 7 to 77 h and Tmax values of 12, 24 and 12 h were observed for blood, liver and kidney, respectively. Except for that in the digestive tract, the tissue-to-blood ratio (TBR) was highest in the liver.

Metabolic Fate of NKH477. (1). Blood and Plasma Concentrations, Distribution and Excretion in Rats and Dogs after a Single Intravenous Administration.

The pharmacokinetics, distribution and excretion of NKH477, a novel water-soluble forskolin derivative, improving acute cardiac failure, were investigated in rats and dogs after a single intravenous administration of 14C-labeled NKH477 and unlabeled NKH477. 1. After intravenous bolus administration of 14C-NKH477 (0.011 ?? 0.3 mg/kg) to male rats, the elimination half life of radioactivity in the blood ranged from 70.67 to 118.23 hr. The elimination half life of radioactivity in the blood was prolonged compared with that in the plasma, which should be attributed to binding of the radioactivity to blood cells. 2. After intravenous bolus dosing of NKH477 to male rats, plasma concentrations of unchanged NKH477 and active metabolite, M-1, declined rapidly with half lives of 0.23 and 0.25 hr, respectively. The AUC of M-1 was markedly lower than that of unchanged NKH477. 3. In dogs, the radioactivity levels in the blood and plasma declined two-exponentially following administration, and the slow elimination of the blood radioactivity, but less compared to rats, was also observed. 4. Following intravenous infusion of NKH477 for 2 hours to male dogs under anesthesia at doses ranging from 0.15 to 0.60 mg/kg/min, plasma concentrations of unchanged NKH477 and M-1 decreased with the elimination half lives of 1.57 ?? 2.36 hr. The AUC of M-1 was half as much as that of unchanged NKH477. 5. After administration to male rats, the radioactivity was rapidly and extensively distributed to the tissues except those belonging to the central nervous system. The liver showed much higher concentration of radioactivity than the other tissues. The radioactivity declined rapidly from most tissues, except the heart, blood, spleen and adrenal gland. 6. After dosing to male rats, excretion of the radioactivity in urine and feces within 144 hr was 6.4 and 90.2% of dose, respectively. In bile duct-cannulated rats, biliary and urinary excretion of radioactivity was 77.1 and 7.8% of the dose, respectively within 72 hr after administration, suggesting that the main excretory route of 14C-NKH477 is feces through bile. 7. In dogs, 78.2% of the dose was excreted into feces during 144 hr after dosing.

Studies on the Metabolic Fate of Neutrophil Elastase Inhibitor ONO-5046Na (1): Plasma Concentration-profile, Distribution and Excretion after Single Intravenous Administration to Rats.

The plasma concentration-time profile, distribution and excretion after a single intravenous administration of 14C-ONO-5046·Na were investigated in rats. 1. After intravenous bolus administration of 14C-ONO-5046·Na (0.1 ?? 100 mg/kg) to male rats, the elimination half life of radioactivity ranged from 163.61 to 192.72 min. AUC0-∞ increased in dose-dependent manner up to 1 mg/kg. Sex-related difference in pharmacokinetic parameter was not clearly observed at dose range of 0.1 ?? 100 mg/kg. 2. During 3 hr intravenous infusion of 14C-ONO-5046·Na at the doses of 0.1, land 10 mg/kg/hr to male rats, the plasma levels of radioactivity reached the steady-state levels within 1.5 hr. Plasma levels of radioactivity in the steady-state increased in dose-dependent manner, and the elimination half life ranged from 232.29 to 631.63 min. 3. At 30 min after intravenous bolus administration at the dose of 1 mg/kg to male and female rats, the radioactivity was distributed in whole body. Kidney, intestine and its contents, were the tissues highly concentrating radioactivity. Then radioactivity decreased to the level below detection limit in most tissues at 24 hr, and no marked residue in any tissue was found. 4. Within 24 hr after intravenous bolus ad ministration of 14C-ONO-5046·Na at the dose of 1 mg/kg to male rats, 24.0% and 73.1% of administered radioactivity were excreted into urine and feces, respectively. Total excretion rates into urine and feces within 72 hr was 99.4%. Within 24 hr after intravenous administration of 14C-ONO-5046·Na in female rats, the excretion rates into urine and feces were 90.2% and 8.2%, respectively. Sex-related difference was observed. 5. Within 2 hr after intravenous bolu s administration of 14C-ONO-5046·Na at the dose of 1 mg/kg, 33.0% and 14.0% of administered radioactivity were excreted into bile in male and female, respectively. Sex-related difference was observed. Cumulative excretion rates until 48 hr after administration were 35.9% and 15.4%, respectively. Almost all of radioactivity in bile was excreted until 2 hr after administration. 6. Re-absorption rate obtained from urinary and biliary excretion rate of recipient rats after administration to duodenum of the bile, which excreted after intravenous bolus administration of 14C-ONO-5046·Na at the dose of 1 mg/kg, were 38.9% in male rats, and 42.5% in female rats.

Metabolic Fate of (.+-.)-2-((2-(isobutylmethylamino)benzyl)sulfinyl)-1H-benzimidazole (NC-1300-O-3). (1): Absorption, Distribution and Excretion after Single Oral Administration to Rats and Dogs.

The matabolic fate of NC-1300-O-3, a new proton pump inhibitor with potent cytoprotective effect on the gastric mucosa, was investigated after a single oral administration of 14C(Iz)-NC-1300-O-3 or 14C(Bz)-NC-1300-O-3 to rats and male beagle dogs. 1. The radioactivity in blood and plasma after administration of 14C(Iz)-NC-1300-O-3 to male rats at doses of 10, 30 and 100 mg/kg reached maxima within 5 hr and thereafter declined. The values of Cmax and AUC were proportional to administered doses, while the difference was observed in disappearance of radioactivity, the elimination half lives of radioactivity in the blood were prolonged compared with those in plasma. No marked differences in pharmacokinetic parameters were observed between male and female rats. In dogs, the levels of radioactivity in the blood and plasma reached maxima at 2 hr after administration of14C(Iz)-NC-1300-O-3 at a dose of 30 mg/kg and there after declined biphasecally, and the slow elimination half-life in blood radioactivity, but less compared to rats, was also observed. When the 14C(Bz)-NC-1300-O-3 was administered to male rats, the levels of radioactivity in the blood and plasma were 2-7 times lower than those following 14C(Iz)-NC-1300-O-3 administration at the same dose level. However there was almost no difference between the pharmacokinetic parameters derived from the blood and plasma. 2. High levels of radioactivity were observed in the liver, kidney and gastrointestinal tracts after administration of 14C-NC-1300-O-3 to male rats. When administered the 14C(Iz)-NC-1300-O-3, a high radioactivity in the thyroid was observed. However there was no evidence of an accumulation of radioactivity, excluding blood. 3. The protein binding of 14C(Iz)-NC-1300-O-3 in vitro was more than 98.8% in rat, dog and human plasma. The binding of radioactive substances tc plasma proteins after oral administration of 14C-NC-1300-O-3 was 72.8-87.4% in rats, 61.7-77.5% in dogs, respectively. 4. The ratio of blood to plasma concentration after addition of 14C-NC-1300-O-3 to rat blood was increased with time, but almost no changes were observed in the blood of dog, monkey and human. 5. Within 168 hr after oral administration of 14C(Iz)-NC-1300-O-3 to male rats, 69.7 and 26.8% of the dose were excreted into urine and feces, respectively. On the other hand, 30.6 and 67.7% of the dose were excreted into urine and feces in case of 14C (Bz)-NC-1300-O-3. After administration of 14C(Iz)-NC-1300-O-3 and 14C(Bz) -NC-1300-O-3 to bile duct-cannulated male rats, 41.1 and 77.0% of the dose were excreted to bile within 48 hr, respectively, and approximately 80% of excreted radioactivity to bile was reabsorbed by entero-hepatic circulation. In dogs, the main excretion route was feces, 64.0 or 91.2% of the dose was excreted into feces within 168 hr after administration of 14C(Iz)-NC-1300-O-3 or 14C(Bz)-NC-1300-O-3.

Absorption, Distribution and Excretion of a New Antiplatelet Drug, Ethyl 2-(4,5-bis(4-methoxyphenyl)thiazol-2-yl)pyrrol-1-ylacetate, (KBT-3022), after Single Oral Asministration in Mice.

The absorption, distribution and excretion of ethyl 2-[4, 5-bis (4-methoxyphenyl) thiazol-2-yl]pyrrol-1-ylacetate (KBT-3022) were studied after administration of 14C-KBT-3022 to mice. Maximum plasma levels (Cax) appeared at 0.5 hr after oral administration of 14C-KBT-3022 to fasted male mice and 14C-KBT-3022 was absorbed from small intestine, especially from jejunum. The radioactivity decreased with half-life of 5-6 hr. The Cmax and the area under the plasma concentration-time curve (AUC) were higher in unfasted mice than in fasted mice. The percentages of radioactivity excreted in urine and feces, whithin 96 hr after intravenous or oral administration of 14C-KBT-3022 to male mice, were below 1% and above 96% of dose, respectively. The percentages of radioactivity excreted in urine and feces after oral administration of 14C-KBT-3022 were similar both in male and female mice. The 14C-KBT-3022 probably is excreted mainly in bile. The radioactivities in the intestine and liver were higher than in plasma, however, radioactivities were rapidly eliminated from tissues so that no significant remaining was observed in the tissue. After oral administration of 14C-KBT-3022 to fasted mice, the radioactivites in the platelet and aorta were 2.4-15.7 times higher and about 0.5 times lower than that in plasma, respectively. The elimination half-life of radioactivity in the platelet was close to that in plasma. This result shows KBT-3022 is reversibly distributed in platelet.

The disposition of recombinant human erythropoietin (EPOCH) after subcutaneous administration. (2). The disposition of 125I-EPOCH after single subcutaneous administration in rats.

We studied the absorption, distribution, excretion and metabolism of 125I-EPOCH after single subcutaneous administration to rats. 1. The levels of immunoreactive rad ioactivity reached the maximum at 8 to 12 hours after dosing and declined monoexponentially with a half-life ranging from 5.77 to 7.47 hours at the doses of 0.5, 1, 5 and 25μg/kg. The MRT of immunoreactive radioactivity after sc dosing ranged from 13.83 to 17.01 hours at any dose levels. F value (AUCsc/AUCiv), which ranged from 0.31 to 0.48, tend to increase in proportion to the administered dose. 2. Most of tissues showed the highest level of total radioactivity at 10 hour after dosing. The level of radioactivity in tissues were lower, than that of serum, except the thyroid gland whose level was the highest. They declined parallel with disappearence of the radioactivity in serum. The level of radioactivity in brain was extremely low. The elimination half-life of radioactivity from the injection site was calculated to be 9h and 1.97% of the dose still remained there at 48 hour. 3. Until 96h after sc administration of 125I-EPOCH at the dose of 1μg/kg, urinary excretions of total, the TCA-precipitable and the immunoreactive radioactivity were 75.89%, 0.35%, 0.05%, respectively. Fecal excretion of total radioactivity was 2.97%, until 96h after dosing. 4. Gel filtration of the plasma showed that the radioactivity of low molecular weight was iodo ion, and that related to radioactivity of high molecular weight appeared mainly as an unchanged 125I-EPOCH.

The placental and mammary transport of [14C]menaquinone-4 in rats.

The transfer of menaquinone-4 (vitamin K2(20] to the fetus and milk was studied in pregnant and lactating rats, respectively, after oral administration (4 mg/kg) of [3'-14C]menaquinone-4. Intestinal absorption of menaquinone-4 was rapid and the highest level of radioactivity in each tissue except guts of fetal rats was observed at 4h after dosing. The level in the fetal homogenate was low. At that time, the concentration of menaquinone-4 in the fetal liver was 84 ng/g, corresponding to 9% of the value found in the placenta. Therefore, we conclude that the transfer of menaquinone-4 to the developing rat fetus is restricted by the blood-placenta barrier, but that a sufficient amount of menaquinone-4 (more than the essential amount of vitamin K to ensure full carboxylation) can be transferred into the fetal liver. It was also observed that the radioactivity was transferred to milk after oral administration to lactating rats. Milk/blood concentration ratios at 6 and 24h after dosing were 13.8 and 65.1, respectively. The elimination half-life of radioactivity in milk was about 17h. Eighty-four percent of milk of radioactivity was due to menaquinone-4. These results suggest that the prophylactic maternal oral administration of menaquinone-4 may be efficacious for a prophylaxis of neonatal and infantile vitamin K deficiency.

Studies on the metabolic disposition of ethyl eicosapentaenoate(EPA-E) in rats and dogs.

Plasma level, tissue distribution and excretion of ethyl eicosapentaenoate(EPA-E) were studied after oral administration of 14C-uniformly labelled EPA-E to rats and dogs and the following results were obtained. 1. The maximum concentration of radioactivity in plasma was obtained at 6-9 hr and at 24hr after dosing in rats and dogs, respectively. The elimination of radioactivity from plasma was biphasic. 2. The radioactivity administered to rats was mainly excreted in expired air. 3. The cumulative biliary excretion of radioactivity was 2.9 % of the dose within 24 hr. 4. The concentration of radioactivity in each tissue reached maximum at 9-24hr after dosing except for brain, fat, skin, muscle and aorta in which the concentration reached maximum at 1 week and subsequently decreased gradually. The elimination rate of radioactivity from each tissue was almost as same as that from plasma or a little slower. 5. Foeto-placental transfer of radioactivity in the pregnant rats at 12 and 19 days of gestation was observed but its extent was low. 6. The milk level of radioactivty in the lactating rats reached maximum at 24 hr and was 6-14 times higher than that in the maternal blood after 24hr. 7. Radioactive substances in plasma were mainly bound to plasma protein in rats and dogs. 8. During daily repeated administration to rats, the concentration of radioactivity in plasma at 24hr after every dosing reached plateau level within the 12 days but that in each tissue increased with increase in the number of doses. No remarkable difference in elimination half-lives of radioactivity in each tissue between the single and repeated dosing was observed.