Study on the metabolic fate of catena-(S)-[mu-N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 3rd communication: transfer into fetus and milk in rats.

Studies on the transfer into the fetus and the milk were performed after administration of 14C-Z-103 and 65Zn-Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]- zinc], CAS 107667-60-7) to rats. After oral administration of 14C-Z-103 to pregnant rats, the transfer of radioactivity to the fetus was studied by means of whole body autoradiography (ARG) and measurement of radioactivity in the fetus. The concentration of radioactivity in the fetus was approximately the same as those in the blood and the placenta of the maternal animal. The transfer of radioactivity into the milk was demonstrated after administration of 14C-Z-103 to lactating rats. Radioactivity in the fetus and milk are considered to be due to metabolites of L-carnosine of Z-103, such as amino acid or protein. The distribution of radioactivity in the fetus was also observed after administration of 65Zn-Z-103 to pregnant rats. However, after administration of non-radioactive Z-103 to pregnant rats, the zinc level in the fetus was found to be almost the same level as that in the fetus of the untreated rats. The transfer of radioactivity to the milk was studied after administration of 65Zn-Z-103 to the lactating rats, and it was seen that the concentration of radioactive zinc in the milk was much lower than the endogenous level of zinc in the milk at any of the time points investigated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Study on the metabolic fate of catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 1st communication: absorption, distribution, metabolism and excretion after single administration to rats.

Studies on the absorption, distribution, metabolism and excretion of 14C-Z-103 and 65Zn-Z-103 (catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) were performed after oral administration to rats. After oral administration of 14C-Z-103 and 65Zn-Z-103, the blood concentrations of 14C-radioactivity were 30- to 40-fold higher than those of 65Zn-radioactivity. The 14C-radioactivity showed a dose-dependent increase of Cmax and AUC values in the dose range from 13.1 mg/kg to 100 mg/kg, and remained longer in the blood. In contrast, no dose-dependent increase of AUC was observed with 65Zn-radioactivity, suggesting saturation of absorption at doses more than 30 mg/kg of 65Zn-Z-103. The major route of excretion of 14C-radioactivity was by excretion into the expired air, amounting to 38.8% of the administered dose, while the urinary and fecal excretions were low values at 4.1% and 13.3%, respectively. The radioactivity remaining in the carcass accounted for 39.3% of the dose. On the other hand, in the case of 65Zn-radioactivity, 85.0% of the administered dose was excreted into the feces and 10.5% of the dose remained in the carcass. Both 14C- and 65Zn-radioactivities were distributed to the whole body, while 14C-radioactivity showed higher concentrations in the body, and was retained longer than the 65Zn-radioactivity. When the plasma and the liver and kidney homogenates, from rats received 14C-Z-103, were treated with trichloroacetic acid (TCA), the radioactivities in the TCA-insoluble fraction increased as a function of time. Following the treatment of the homogenates with protease, the radioactivities in the TCA-insoluble fraction decreased. In vitro study was showed that L-carnosine of 14C-Z-103 added to the homogenates of liver and small intestine was metabolized to L-histidine. The results suggest that the remaining radioactivities in tissues and organs caused the incorporation of the metabolites of 14C-Z-103 into endogenous high molecular substances.     

Study on the metabolic fate of catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 4th communication: disposition of zinc and amino acids in rats, dogs and monkeys.

The time course of the zinc plasma concentrations in rats, dogs and monkeys and the metabolic fate of L-carnosine were investigated after oral administration of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7). There was no intradiurnal variation in the plasma concentrations of endogenous zinc in rats, dogs and monkeys. The plasma concentrations of endogenous zinc in dogs and monkeys were approximately the same as that in humans, whereas the plasma concentration of zinc in rats was 2.2-fold higher than that in man. After administration of Z-103 to non-fasted dogs at 100 mg/kg, the plasma concentration of zinc reached Cmax at 0.5 h after administration (1.7-fold higher than endogenous zinc level), while the plasma concentration was the lowest in comparison with other animal species. After administration to fasting rats at 50 mg/kg, the plasma concentration of zinc reached Cmax at 1 h after administration (2.5-fold higher than endogenous zinc level) and decreased thereafter, returning to the endogenous level at 8 h after administration. After oral administration to monkeys at 10 mg/kg and 50 mg/kg, the Cmax values were 4.1-fold and 6.8-fold higher than the endogenous level, respectively. The Tmax values were achieved at 4-6 h and 8 h after each administration, respectively, showing slower absorption in comparison with other animal species.(ABSTRACT TRUNCATED AT 250 WORDS)     

Antigenicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]

The antigenicity of Z-103 (catena-(S)-[mu[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was evaluated using the following assay procedures: 1. active systemic anaphylaxis (ASA) in guinea pigs. 2. passive cutaneous anaphylaxis (PCA) in guinea pigs with serum from guinea pigs sensitized with Z-103, 3. delayed type skin reaction (Maximization Test) in guinea pigs, 4. passive cutaneous anaphylaxis (PCA) in rats with serum from mice sensitized with Z-103 and 5. passive hemagglutination (PHA) with serum from mice sensitized with Z-103. In each test except for Maximization Test, the sera obtained 1 or 6 h (hereinafter designated as 1-h-sera or 6-h-sera) after a single oral administration of 500 mg/kg of Z-103 to the unused rats, guinea pigs or rabbits, were used as the challenge antigen. 1. ASA in guinea pigs: No anaphylaxis reaction was observed in any of the sensitized guinea pigs by elicitation with challenge antigen. 2. PCA in guinea pigs: PCA titer of sera from all the sensitized animals was less than 1 in elicitation with the challenge antigen. 3. Delayed type skin reaction test: No skin reaction was observed in sensitized guinea pigs after intradermal injection or dermal application of Z-103. 4. PCA in rats: PCA titer of sera from BALB/c and C3H/He mice sensitized with Z-103 was less than 5 in elicitation with the challenge antigen. 5. PHA reaction: When erythrocytes coated with challenge antigen were added to sensitized sera, the hemagglutination titer was less than 1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive and developmental toxicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc]

To evaluate the effects of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) on the reproductive performance of male and female rats, the general toxicity of dams, and the development, physical growth and reproductive performance of the next generation, Z-103 was administered to rats prior to, and in the early stages of pregnancy, during the period of fetal organogenesis, and during the perinatal and lactation periods, and to rabbits during the period of fetal organogenesis at the appropriate doses for each study. At the administration of Z-103 prior to and in the early stages of pregnancy in rats, no dose-related abnormalities were observed in the reproductive performance of either sex. Furthermore, there were no death or evidence of teratogenicity or repressive effect on growth in fetuses. Administration of Z-103 during the period of fetal organogenesis in rats affected the growth of embryos and fetuses at 1200 mg/kg. At 600 mg/kg or less, however, there were no death, teratogenicity or repressive effect on growth in fetuses, and furthermore, no dose-related abnormalities were observed in growth, physical development, behavior and reproductive performance in offspring. Administration of Z-103 during the period of fetal organogenesis in rabbits caused a decrease in the number of live fetuses at 300 mg/kg suggesting that 300 mg/kg of Z-103 may have a lethal effect on fetuses. There were, however, neither teratogenicity nor any repressive effect on the growth of fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mutagenicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]

Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was examined in the bacterial mutation test, a chromosomal aberration test with mammalian cells in culture and the micronucleus test using male mice. 1. Z-103 did not increase the number of revertants in Escherichia coli WP2 uvrA when tested at up to 5000 micrograms/plate in the presence or absence of metabolic activation. And Z-103 did not increase mutants in Salmonella typhimurium SD 100 (streptomycin dependent strain) or in Salmonella typhimurium TM677 (8-azaguanine sensitive strain) when tested at up to 5000 micrograms/ml in the presence or absence of metabolic activation. 2. The chromosomal aberration test was carried out with cultured Chinese hamster lung cells (CHL). For the direct assay procedure, the cells were treated with 3.3 x 10(-4)-3.3 x 10(-6) mol/l Z-103 for 24 or 48 h, after which time chromosome preparations were made. For the metabolic activation assay procedure, the cells were treated with 1.0 x 10(-3)-3.3 x 10(-6) mol/l of Z-103 for 6 h in the presence or absence of metabolic activation, and the chromosome preparations were made after a further 18-h incubation in the absence of Z-103 and metabolic activation. Z-103 did not cause chromosome aberrations either in the presence or in the absence of metabolic activation. 3. The micronucleus test was performed in ddY male mice. Z-103 was administered orally to mice at a dose of 400, 200 or 100 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics and disposition of a new antitumor antibiotic (2'R)-4'-O-tetrahydropyranyladriamycin in rats. Distribution and excretion after multiple administration

The accumulation of (2'R)-4'-O-tetrahydropyranyladriamycin (THP) was studied in rats received intravenous administration of 14C-THP at a dose of 0.5 mg/kg/day for 14 consecutive days by determining blood and tissue levels and the excretion of the radioactivity. The radioactivity levels in plasma and blood cells after the multiple administration were higher than those after single administration. The half-life of the radioactivity after the multiple administration was longer in the blood cells but not in the plasma than the half-life after a single administration. Tissue levels of the radioactivity after the multiple injection were 2 to 4 times as high as the levels after a single injection except for the brain and testes in which a large accumulation of the radioactivity was observed. However, little accumulation of unlabeled THP was found in most tissues when determined by HPLC. The accumulation of radioactivity in tissues, therefore, was due to metabolites of THP. The disposition of 14C-THP was also examined in rats which had previously received unlabeled THP (0.5 mg/kg/day) for 13 days. The pretreatment did not affect the disposition of 14C-THP seriously, although the pretreatment raised tissue levels slightly and a rebound of plasma level of 14C-THP, and lowered the fecal excretion ratio. No induction of hepatic drug metabolizing enzymes was observed in rats after repeated administrations of THP for consecutive 14 days.     

Repeated dose toxicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc] in rats.

Thirteen- and 52-week oral toxicity studies of Z-103 (catena-(S)-[mu- [N alpha-(3-aminopropionyl) histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) were carried out in rats. In a 13-week repeated dose toxicity study (37.5, 75, 150, 300, 600 or 1200 mg/kg/d), deterioration of the general condition was observed at 300 mg/kg/d or more, a decrease in body weight gain at 600 mg/kg/d or more. Approximately 40% of the animals were found dead or sacrificed in a moribund state at 1200 mg/kg/d. Furthermore, in the 600 mg/kg group changes in urine volume, blood urea nitrogen and weight of kidneys were observed, suggesting that Z-103 may have had adverse effects on the kidney. No sex difference was noted. From these results the no-effect dose level was estimated to be 150 mg/kg/d under the conditions of this experiment. In a 52-week repeated dose toxicity study (18.75, 37.5, 75 or 150 mg/kg/d), proliferation of small duct and atrophy of acinar cells in the pancreas were observed in both sexes of the 150 mg/kg/d group. No other dose-related changes were observed throughout the administration period. Therefore, the no-effect dose level was estimated to be 75 mg/kg/d under this condition.     

Distribution to and elimination from tissues following a single or repeated administration of 14C-(+-)-3-(benzyl-methylamino)-2,2-dimethylpropyl methyl 4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedica rbo xylate hydrochloride in rats.

A newly synthesized calcium antagonist, TC-81((+-)-3-benzylmethylamino)-2,2-dimethylpropyl methyl-4-(2-fluoro-5-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5- pyridinedicarboxylate hydrochloride, CAS 96515-74-1) was administered to adult male rats, pregnant and lactating rats with a single oral dose or with repeated doses of 0.3 mg/kg for 2 weeks. The distribution to tissues, placental transfer and secretion of the radioactive drug into milk was studied using whole body autoradiography methods and quantitative determination of total radioactivity after autopsy. 14C-TC-81 was distributed rapidly but disproportionately to the tissues after single administration. The highest concentration of radioactivity was observed in the liver. The radioactivity in the various tissues declined slowly comparing to the plasma but at 96 h after dosing the radioactivity was detected only in the liver. The radioactivity penetrated the blood-placental barrier to a low extent after oral administration of 14C-TC-81 to pregnant rats. When 14C-TC-81 was administered to lactating rats, the radioactivity was secreted into the milk with the maximum concentration of radioactivity, 86% of the corresponding plasma concentration. Following 14-day oral treatments of male rats the equivalent concentration in the plasma was increased 1.5 fold as compared to the single treatment. In all tissues, the AUC0-24 h after 1, 7, and 14 days treatment were gradually increased, but these increases were almost the same as or even less than the rise observed in the plasma. After the last dosing, the radioactivity declined slowly with time in most of the tissues.(ABSTRACT TRUNCATED AT 250 WORDS)     

Single dose toxicity study on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc] in mice and rats.

The toxicity of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was evaluated in mice and rats after single administration. LD50 values in mice were 1269 mg/kg for males and 1331 mg/kg for females by the oral route, 220 mg/kg for males and 165 mg/kg for females by the intraperitoneal route, and 758 mg/kg for males and 874 mg/kg for females by the subcutaneous route. LD50 values in rats were 8441 mg/kg for males and 7375 mg/kg for females by the oral route, 405 mg/kg for males and 422 mg/kg for females by the intraperitoneal route and more than 5000 mg/kg for both sexes by the subcutaneous route. No sex differences were observed. A decrease in locomotor activity, ventral posture, crouching, hypothermia and respiratory depression were observed in both mice and rats as the main clinical signs. In addition to these changes, induration, swelling and crust formation were observed at the subcutaneous injection site.     

Studies on absorption, distribution and excretion of 14C labeled pivaloyloxymethyl (+)-(6R,7R)- 7-[(Z)-2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]- 3-[(5-methyl-2H-tetrazol-2-yl)methyl]-8-oxo-5-thia- 1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate (14C-T-2588) in rats and mice

Absorption, distribution and excretion of T-2588 were studied in rats and mice using (aminothiazole-2-14C) T-2588 and (pivaloyloxymethyl-14C) T-2588. Results are summarized below. The binding rate of 14C-T-2525, an activated form of 14C-T-2588 in vivo, to serum protein was 90 approximately 100% in rats and mice after an oral administration of (aminothiazole-2-14C) T-2588. Blood levels of radioactivity reached to the highest concentration at 1 hour after an oral administration of (aminothiazole-2-14C) T-2588 to rats, and then gradually diminished. After an oral administration of (aminothiazole-2-14C) T-2588 to rats and mice, the highest radioactivity distribution was found in kidney among all the organs except stomach, intestine and bladder. Radioactivity was widely distributed into other organs such as adrenal, lung, liver, heart and pancreas. But little radioactivity was found in the brain. In new born rats, tissue levels of radioactivity were lower and diminished slower than those of adult rats. After an oral administration of (aminothiazole-2-14C) T-2588 to rats and mice, urinary excretion of radioactivity was about 26% and 35% of the dosed radioactivity in rats and mice, respectively, and fecal excretion was about 76% and 63% of the dosed radioactivity in rats and mice, respectively. Urinary and fecal excretion patterns of radioactivity after multiple oral administration of (aminothiazole-2-14C) T-2588 for 7 days to mice were similar to those after a single administration. This result suggests that T-2588 did not accumulate in the body. After an oral administration of (pivaloyloxymethyl-14C) T-2588 to rats and mice, urinary excretion was both about 8% of the dosed radioactivity, and fecal excretion was both about 6%. Then excretion of 14CO2 into respiratory air was about 55% and 66% of the dosed radioactivity in rats and mice, respectively. Biliary excretion was about 6.5% of the dosed radioactivity after an oral administration of (aminothiazole-2-14C) T-2588 to rats. Small amount of radioactivity was secreted to the milk after intravenous administration of (aminothiazole-2-14C) T-2525 to nursing rats. After an administration of (aminothiazole-2-14C) T-2588 to pregnant mice, radioactivity hardly transferred into the fetus.     

Pharmacokinetics of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist. 4th communication: tissue distribution, placental transfer and milk secretion of radioactivity in rats after a single oral administration of 14C-NS-49, and effects of repeated administration on its pharmacokinetics.

The tissue distribution, placental transfer and milk secretion of 14C-NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoro-methanesulfonanilide hydrochloride, CAS 137431-04-0), a phenethylamine class alpha 1A-adrenoceptor agonist, have been studied after a single oral administration (1 mg/kg) of a suspension formulation to rats. Radioactivity concentrations in tissues were generally highest 1 or 4 h, and for most tissues, exceeded those in the corresponding plasma. Concentrations were generally similar in male and female rats and persisted for at least 24 h. Radioactivity concentrations in most tissues declined in parallel with those in plasma. Placental transfer of radioactivity was low accounting for < 0.1% of the maternal dose. In milk, concentrations were of a similar order to those in the plasma but reached a peak later: the data implied that 14C-NS-49 readily diffused from the plasma into the milk. The absorption, distribution and excretion of 14C-NS-49 have been studied after the repeated administration (1 mg/kg) of a suspension formulation to rats for up to 21 days. At 21 days, radioactivity concentrations in plasma reached a peak 1 h and declined with a terminal half-life of 67 h. Steady state concentrations were reached during 14 days. Peak concentrations in tissues occurred 1 h and, in most tissues exceeded the plasma value. Radioactivity concentrations in tissues appeared to reach steady state during the 21-day dosing period. Tissue and blood cell concentrations declined more slowly than those in the plasma. Radioactivity excretion was relatively constant during the repeated administration and similar in urine (mean 45.8% total dose) and feces (mean 48.2% total dose). At 7 days after the last of 21 daily oral doses, only 0.2% of the total dose remained in the body, indicating that there is no marked accumulation of radioactivity in the tissues. The results obtained in these studies indicated that rats receiving NS-49 at 24 h intervals during chronic and reproductive toxicity studies would be continually exposed to the parent compound and/or its metabolites.     

Pharmacokinetics of NS-105, a novel cognition enhancer. 2nd communication: distribution and transfer into fetus and milk after single administration, and effects of repeated administration on pharmacokinetics and hepatic drug-metabolizing enzyme activities in rats

The tissue distribution and transfer into the fetus and milk of NS-105 ((+)-5-oxo-D-prolinepiperidinamide monohydrate, CAS 110958-19-5), a novel cognition enhancer, were investigated in rats after single oral administration of 14C-NS-105. The effects of repeated oral administration on the pharmacokinetics of NS-105 and hepatic drug-metabolizing enzyme activities also were investigated in rats. The radioactivity concentration in most tissues of male rats reached a maximum of 0.5 h after the single oral administration of 14C-NS-105, indicating rapid absorption and distribution, 0.5 h after the administration, the highest concentrations were present in the kidney and stomach, and the lowest in the white fat. The concentrations in the remaining tissues were moderately lower than the plasma value. The radioactivity concentrations in all the tissues tested decreased along with the plasma concentration, and were below or near the detection limit 24 h after the administration. Most of the radioactivity in the plasma, liver, kidney and cerebrum was due to unchanged NS-105. The tissue distribution patterns of radioactivity in female (non-pregnant) and pregnant rats after the oral administration of 14C-NS-105 did not differ from the pattern in male rats, revealing neither sex- nor pregnancy-related differences in NS-105 distribution. In pregnant rats, the maximum concentration in the fetus was 66% of that in the maternal plasma. In lactating rats, the radioactivity concentration in the milk was similar to that in the plasma. During and after the repeated oral administration of 14C-NS-105, the plasma concentrations and cumulative urinary and fecal excretions of radioactivity did not change with the number of administrations and were similar to the corresponding values after the single administration. The radioactivity concentrations in most tissues 8 h after the 7th, 14th and 21st administrations were about twice the corresponding values after the single administration, indicating that there is no marked accumulation of radioactivity in the tissues and that a steady state level was reached within 1 week. Repeated oral administration of NS-105 (10 mg/kg) to male rats did not affect hepatic drug-metabolizing enzyme activities.     

Disposition of timiperone, 4-fluoro-4-[4-(2-thioxo-1-benzimidazolinyl)piperidino]butyrophenone,a neuroleptic,in the rat on repeated oral dosage

1. The metabolic disposition of [¹⁴C]timiperone was studied in male Wistar strain rats receiving an oral dose of 0.5?mg kg consecutively daily for 21 days.

2. Blood concentrations of ¹⁴C indicate that absorption of [¹⁴C]timiperone on repeated dosage may be similar to that after a single dose.

3. Tissue levels of ¹⁴C after repeated doses were increased to up to double those after a single dose, but the decline of tissue concentrations after the 21st dose was similar to that after a single dose. Thus, no rat tissues show accumulation.

4. Repeated administration did not affect the metabolism of timiperone.

5. Excretion of ¹⁴C on the third day of repeated medication was urine, 44.7% and faeces 52.4% of the cumulative dose, and total daily excretions were more than approx. 97% of the cumulative dose in days 3.21 of the repeat dosage schedule.     

Metabolism of 8-chloro-6-(o-chlorophenyl)-1-methyl-4H-s-triazolo [4,3-alpha] [1,4] benzodiazepine, triazolam, a new central depressant. I. Absorption, distribution and excretion in rats, dogs and monkeys.

1. Peak radioactivity in the blood was reached at 30 min after i.p. and 1 h after oral dosing of [14C]triazolam to rats. In dogs, peak blood level was observed at 30 min after oral dosing. 2. Daily dosing of triazolam to male rats for 21 days caused a gradual increase in blood level, with peak at 1 h after dosing. 3. The rate of binding of triazolam plus its metabolites to plasma protein of rats was about 30% at 15 min and 6 h. 4. In rats, the majority of the activity of the intra-intestinally administered [14C]triazolam was found in the small intestines in 6 h. 5. About 58% of the oral dose and 77% of the i.p. dose were recovered in the bile of rats in 48 h after dosing. When the bile from one rat was introduced into the duodenum of a second rat, approximately 37% was recovered in the bile of the second animal in 24 h. 6. In male rats, high radioactivity was seen in the liver, kidneys, adrenals and heart, and low in the CNS. By 96 h after dosing, radioactivity in the liver, blood and kidneys was very low, and was undetectable in other tissues and organs. Radioactivity levels in tissues after daily dosing for 7, 14 and 21 days did not differ appreciably from single administration. 7. In monkeys, activity was high in the liver, kidneys and skin following oral administration and low in the CNS. 8. After oral administration of [14C]triazolam to pregnant rats, the activity in the uterus and placenta was higher than that in the maternal blood. The activity in the foetus was low. 9. In rats given [14C]triazolam orally or i.p., 85% and 12% of the oral dose, and 82% and 14% of the i.p. dose were recovered in the faeces and urine, respectively, in 96 h. The rate of cumulative faecal and urinary excretion after repeated dosing was similar to the single dosing with 80% and 14% of the activity recovered, respectively, in faeces and urine in 6 days. In dogs, 50% of the oral dose was found in the faeces and 40% in the urine. 10. Radioactivity in the milk of rats was maximal at 4 h after oral dosing. It declined to 34% of the peak level 48 h later.     

Metabolism and disposition of (RS)-2-methoxy-3-(octadecylcarbamoyloxy)propyl 2-(3-thiazolio)ethyl phosphate (MOTP) in rats and dogs

1. Metabolites (RS)-4-[(3-hydroxy-2-methoxy)propoxycarbonylamino]butanoic acid (I) and (RS)-2-[(3-hydroxy-2-methoxy)propoxycarbonylamino]acetic acid(II) were isolated from urine after i.v. administration of (RS)-2-methoxy-3-(octadecyl-[14C]carbamoyloxy)propyl 2-(3-thiazolio)ethyl phosphate (14C-MOTP) to rats and characterized by t.l.c., g.l.c.-mass spectrometry and p.m.r. spectrometry. 2. After i.v. administration of 14C-MOTP, the plasma concentration of the drug declined biphasically with half-lives of 0.22 and 3.94 h in rats, and 0.81 and 8.00 h in dogs. In rats and dogs, unchanged MOTP was the main 14C component in the plasma, together with a small amount of I and II. 14C-MOTP was highly bound to plasma protein of both animals. 3. Five min after i.v. administration of 14C-MOTP to rats, 14C was widely distributed in tissues, with the highest conc. in the lung and the lowest in the eye. The distribution of 14C was relatively slow in some tissues. In most tissues, 14C decreased to low levels at 96 h, except in the Harder's gland. 4. Elimination of 14C-MOTP was almost complete within 120 h in rats and 144 h in dogs. In both species, the administered 14C was excreted largely in the urine as I and II, with the remainder appearing in the faeces and the expired air. Biliary excretion and reabsorption of 14C were detected in rats. 5. During repeated i.v. administration of 14C-MOTP to rats for 7 days, the conc. of 14C in plasma and most tissues attained steady state within 5 days, except in Harder's gland, where the level rose gradually until the seventh day of dosing. Within 6 days after the last dosing, 96% of the injected dose was eliminated from the body.     

Absorption, distribution and excretion of a new thienodiazepine derivative (Y-7131) in rats and mice.

The synthesis of radioactive 6-(o-chlorophenyl)-8-ethyl-1-methyl-4H-s-triazolo[3,4-c]thieno[2,3-e][1,4]diazepine (Y-7131), a new psychotropic agent, is descirbed. The labelled compound was rapidly and completely absorbed following oral administration to rats and mice. The blood levels of radioactivity reached maximum at 0.5 h in rats, and 1 h in mice, respectively, and then declined rapidly with biological half-lives of about 1.5 h in both animals, although the level was higher in mice than in rats. Approximately 45% of the radioactivity in the serum was bound to the serum protein at 1 h after oral administration. The dosed radioactivity was almost completely excreted within 3 days. In rats, more radioactivity was excreted in feces than in urine, while the reverse was noted in mice. An extensive biliary excretion of radioactivity was evidenced in rats after oral dosing. The highest concentrations of radioactivity were found in the liver, kidney, and adrenals, while relatively low levels in the brain of rats. The distribution patterns of radioactivity in mice were similar to those in rats except for the serum and liver. No remarkable accumulation of radioactivity in rat tissues was observed by repeated oral doses of the labelled compound for periods up to 21 days. The metabolic pathways of Y-7131 were qualitatively similar in rats and mice, and one of them was demonstrated to be the hydroxylation at alpha-position in the ethyl side chain.     

Di-(2-ethylhexyl)adipate: absorption, autoradiographic distribution and elimination in mice and rats

Whole-body autoradiography was used to study the tissue distribution of the plasticizer di-(2-ethylhexyl) adipate (DEHA), labelled in the acid [carbonyl-14C] or alcohol [2-ethylhexyl-1-14C]moiety, after iv or ig administration to male mice and rats and pregnant mice. With both DEHA preparations, during the first 24 hr after administration high levels of radioactivity were observed particularly in the body fat, liver and kidneys (after iv and ig administration) and in the intestinal contents (after ig administration) of both species. After administration of [carbonyl-14C]DEHA, radioactivity was also registered in the adrenal cortex, corpora lutea of the ovary, bone marrow, forestomach mucosa, salivary glands and Harder's gland in both species. [2-ethylhexyl-1-14C]DEHA derived radioactivity was found in the bronchi in male mice. Radioactivity was observed in the foetal liver, intestine and bone marrow during the first 24 hr after iv or ig administration of [carbonyl-14C]DEHA to pregnant mice. There was very little accumulation of [2-ethylhexyl-1-14C]DEHA in the mouse foetus but some was found in the urinary bladder, liver and intestinal contents as well as in the amniotic fluid. In an absorption/elimination study in rats of doses of 25 microCi/kg body weight of [14C]DEHA administered ig, dissolved in corn oil or dimethylsulphoxide, blood levels of radioactivity increased somewhat faster and were two or three times higher when DMSO was the vehicle indicating poor absorption of DEHA from the corn oil solution which more accurately reflects human contact with DEHA. Little radioactivity from [carbonyl-14C]DEHA was recovered in the bile, whereas [2-ethylhexyl-1-14C]DEHA was excreted in the bile in significant amounts particularly when DMSO was the vehicle. There was evidence of enterohepatic circulation of DEHA. Radioactivity was also excreted in the urine. As shown by autoradiograms obtained 4 days after the administration of [14C]DEHA there was no retention of DEHA and/or its metabolites in the tissues of mice.     

Absorption, distribution, metabolism and excretion of 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(o-difluoromethoxyphenyl)- 1,4-dihydropyridine (PP-1466) in rats

In this experiment, the absorption, excretion, distribution and metabolism of 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(o-difluoromethoxyphenyl)-1, 4-dihydropyridine (PP-1466) were investigated following oral or intravenous administration, single dose or repeated dose administration using male SLC-Wistar rats and the results of this investigation were summarized as follows: After oral administration of 14C-PP-1466 to rats, the blood level reached the maximum at 1 h and decreased with the biological half-life of about 5 h. The unchanged drug concentration in plasma was 30% of total concentration in plasma and disappeared at 6 h. The high radioactivities in the liver, kidney, fat, lung and adrenal gland were observed after oral and intravenous administration. After oral and intravenous administrations, the excretion in feces and urine during 48 h was 63.0 and 32.4, 58.6 and 41.6%, respectively. Biliary excretion amounted to 57.6 and 46.2% during 48 h, respectively. Six metabolites were found in the urine of rats. Three of them were identified as 2,6-dimethyl-3-carbomethoxy-4-(2-difluoromethoxyphenyl)-5-carboxylic acid pyridine, 2-methyl-3-carbomethoxy-4-(2-difluoromethoxyphenyl)-5-carboxylic acid-6-hydroxymethyl pyridine and its lactonizing analogue. These three metabolites covered 54% of total urinary metabolites. After oral repeated administration for three weeks, the excretion ratio of radioactivity in urine and feces was constant during the administration and no accumulation was observed in rat tissues.     

Pharmacokinetic study of maleate acid of 2-(N,N-dimethylaminoethanol-14C1)-cyclohexylpropionate (cyprodenate) and of N,N-dimethylaminoethanol-14C1 in animals.

The localization, distribution, and elimination of maleate acid 2-(N,N-dimethylaminoethanol-14C1)-cyclohexylpropionate (14C-cyprodenate, Actebral) was studied in rats and pigs. Beside this, dimethylaminoethanol-14C (DMAE) was also administered to rats enabling a comparison of the pharmacokinetics of the two 14C-labelled molecules to be made. The study of the localization by autoradiography and the study of the quantitative distribution of the radioactivity showed that cyprodenate, a psychotonic drug, diffused more rapidly than DMAE through the hemo-encephalic barrier. However, it was also observed that the radioactivity found in the brain rises continually as a function of time, regardless of the product administered. The two labelled products were primarily excreted in the urine (30-35 per cent of the dose in 72 h in rats and 6 per cent of the dose in 48 h in pigs) following oral administration of cyprodenate. Radioactivity found in the feces was practically nil and in rats the biliary elimination of the drug was very weak. Thus, whichever animal is used, it was found that 14C-cyprodenate is totally absorbed. Radioactivity expired as 14CO2 was negligible (around 1 per cent of the administered dose in 8 h), however, this value increases as a function of time, becoming 4 per cent in 24 h. In rats the maximum radioactivity in the blood was found at 45 min to 1 h after oral administration of 14C-cyprodenate. These values decrease slowly until 3 h when they begin to increase again. The rising of the blood level values is practically the same for pigs, the maximum being attained at 1 h. Therefore, whatever route of administration, whichever dose or animal, we always found a progressive elevation of the protein binding to the plasma proteins for these two labelled products in vivo.