The absorption, excretion and metabolism of SNI-2011, a novel muscarinic acetylcholine receptor agonist developed as an agent improving the symptoms of dry mouth or dry eye caused by Sjögren's syndrome, were studied in dogs. 1. After a single oral administration of 14C-SNI-2011 to male dogs, blood and plasma level of radioactivity reached the maximum at approximately 1 hour, and declined by the bi-exponential manner. Blood and plasma half-lives of radioactivity in α phase were similar, however, blood half-life in β phase was longer than that observed in plasma. The distribution of radioactivity in blood cell was 27-54% up to 8 hours, and then increased with time reaching the values of more than 80% at 24 hours. 2. Cumulative excretion rates of radioactivity in urine and feces were approximately 95% and 0.7%, respectively, within 168 hours after administration, indicating that the main elimination route is the urinary tract. 3. Plasma concentrations of SNI-2011 N-oxide (SNI-NO) were 32 and 23 times higher in male and female dogs, respectively, than those of unchanged form. Main metabolite found in dog's urine was also SNI-NO. 4. There was no sex-related difference in blood and plasma concentration, excretion and metabolism of SNI-2011 in dogs after a single oral administration.
The pharmacokinetics and metabolism of SNI-2011 ((±)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine]monohydrochloride hemihydrate, cevimeline, CAS 153504-70-2), a novel muscarinic acetylcholine receptor agonist developed for the treatment of Sjögren's syndrome, were investigated in six healthy volunteers after a single oral administration of 14C-SNI-2011. After administration, plasma concentrations of the radioactivity and SNI-2011 reached to Cmax at approximately 2 h, and then decreased with t1/2 of 9 and 4 h, respectively.Cmax and AUC0–∞ of the radioactivity in plasma were 2.2 and 5.0 times higher than those of SNI-2011, respectively. The main excretion route of the radioactivity was urine, and 97.3 % of the dose excreted in urine within 168 h, indicating that 14C-SNI-2011 was completely absorbed. The mean recoveries of the metabolites in urine at 24 h after administration were 16.0 % for SNI-2011, 35.8 % for SNI-2011 trans-sulfoxide (SNI-t-SO), 8.7 % for SNI-2011 cis-sulfoxide, 4.1 % for SNI-2011 N- oxide, furthermore, two unknown metabolites, UK-1 and UK-2, were detected 14.6 % and 7.7 %, respectively. LC/MS analysis and hydrolysis studies revealed that UK-1 and UK-2 were glucuronic acid conjugates of SNI-2011 and SNI-t-SO, respectively.
The absorption, distribution, metabolism, excretion and plasma protein binding of SNI-2011, a novel muscarinic acetylcholine receptor agonist developed as an agent improving the symptoms of dry mouth or dry eye caused by Sjögren's syndrome, were studied in rats. 1. After a single oral administration of 14C-SNI-2011 to male rats, plasma level of radioactivity reached the maximum at approximately 30 minutes, and declined by the bi-exponential manner. Oral absorption rate of radioactivity was 94%. Plasma level and pharmacokinetic parameters of radioactivity in female rats were comparable with those of male rats. 14C-SNI-2011 was considerably absorbed from duodenum, jejunum, ileum and colon. Plasma level of radioactivity at 8hr after daily oral administration of 14C-SNI-2011 increased with the number of dosing, and reached a steady state by the 3rd day. 2. After a single oral administration of 14C-SNI-2011 to male or female rats, radioactivity was distributed rapidly in whole body, and then eliminated rapidly. Tissue levels of radioactivity in male rats at 8hr after daily oral administration increased with the number of doses reaching approximately 4 times higher levels than those after the 1st administration. In pregnant rats on the 18th day of gestation, radioactivity was transferred into fetal tissues, and then decreased similarly as from maternal plasma. 3. SNI-2011 trans-sulfoxide (SNI-t-SO), SNI-2011 cis-sulfoxide (SNI-c-SO), SNI-2011 sulfone (SNI-SO2) and SNI-2011 N-oxide (SNI-NO) were identified in rat urine. As judged from the result on TLC/ radioluminography of plasma and urine samples, SNI-t-SO appeared to be the main metabolite in rats. Plasma concentration and urinary excretion rates of the unchanged SNI-2011 in female rats were higher than those in male rats. Repeated administration of SNI-2011 had no effect on liver weight, microsomal protein contents and activities of hepatic drug-metabolizing enzymes. 4. Main excretion route of 14C-SNI-2011 was urine in both of male and female rats, and approximately 100% of the dose was excreted in urine within 168 hours after administration. Fecal excretion rate of radioactivity was below 1% of the administered dose. Residual radioactivity in carcass accounted only for 0.1% of the dose. Daily urinary and fecal excretion rates of radioactivity in the period and after repeated oral administration were almost constant, and these rates were similar to those after a single administration. Radioactivity in the milk was 3.0 to 4.7 times higher than that in plasma. 5. Plasma protein binding rates of 14C-SNI-2011 in rats, dogs and human in vitro were relatively low (15.2 to 20.6%), and the binding rate was not affected by drug concentration or test species.
In vitro studies were conducted to identify human drug-metabolizing enzymes involved in the metabolism of SNI-2011 ((+/-)-cis-2-methylspiro [1,3-oxathiolane-5,3'-quinuclidine] monohydrochloride hemihydrate, cevimeline hydrochloride hydrate). When 14C-SNI-2011 was incubated with human liver microsomes, SNI-2011 trans-sulfoxide and cis-sulfoxide were detected as major metabolites. These oxidations required NADPH, and were markedly inhibited by SKF-525A, indicating that cytochrome P450 (CYP) was involved. In a chemical inhibition study, metabolism of SNI-2011 in liver microsomes was inhibited (35-65%) by CYP3A4 inhibitors (ketoconazole and troleandomycin) and CYP2D6 inhibitors (quinidine and chlorpromazine). Furthermore, using microsomes containing cDNA-expressed CYPs, it was found that high rates of sulfoxidation activities were observed with CYP2D6 and CYP3A4. On the other hand, when 14C-SNI-2011 was incubated with human kidney microsomes, SNI-2011 N-oxide was identified as a major metabolite. This N-oxidation required NADPH, and was completely inhibited by thiourea, indicating that flavin-containing monooxygenase (FMO) was involved. In addition, microsomes containing cDNA-expressed FMO1, a major isoform in human kidney, mainly catalyzed N-oxidation of SNI-2011, but microsomes containing FMO3, a major isoform in adult human liver, did not. These results suggest that SNI-2011 is mainly catalyzed to sulfoxides and N-oxide by CYP2D6/3A4 in liver and FMOI in kidney, respectively.
In the present study a highly specific and sensitive method by gas chromatography-mass spectrometry has been established for the determination of the blood levels of four metabolites of 5,7,3',4'-tetrahydroxyflavonol-3-rutinoside (rutoside, rutin), i.e. 3,4-dihydroxytoluene (DHT), 3-hydroxyphenylacetic acid (mPHAA), 3,4-dihydroxyphenylacetic acid (DHPAA), and 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid, HVA) after the oral administration of rutoside to healthy volunteers. By the established method the pharmacokinetics in the blood and the urinary excretion of those metabolites were investigated. Blood levels of DHT, mHPAA, DHPAA, and HVA started to increase at 4 to 8 h after the oral dosage of the rutoside formulation, Esberiven (further active ingredient: coumarin). At 8 to 12 h post-administration, blood levels reached a maximum level which was 2- to 3-fold the time 0 level. Blood levels decreased gradually afterwards and returned to the original level at 20 to 35 h. The sum of the four metabolites was at a maximum value at 8 h which then returned to the initial levels at 35 h yielding a half-life of 11 h. Total urinary excretion of metabolites was 50.5% of the dose in 48 h.
In this study, the pharmacokinetics of SNI-2011 ((±)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine]monohydrochloride hemihydrate, cevimeline, CAS 153504-70-2), a novel muscarinic acetylcholine receptor agonist developed for the treatment of Sjögren's syndrome, in rats and dogs were determined following intravenous or oral administration using liquid chromatography/mass spectrometry (LC/MS). The in vitro metabolism of SNI-2011 was also evaluated with rat and dog liver microsomes. After oral administration, plasma concentrations of SNI-2011 reached to Cmax within 1 h in both species, suggesting that SNI-2011 was quickly absorbed, and then decreased with a t1/2 of 0.4–1.1 h. The bioavailability was approximately 50 % and 30 % in rats and dogs, respectively. Major metabolites in plasma were both S- and N-oxidized metabolites in rats and only N-oxidized metabolite in dogs, indicating that a large species difference was observed in the metabolism of SNI 2011. Sex difference was also observed in the pharmacokinetics of SNI-2011 in rats, but not in dogs. In the in vitro study, chemical inhibition and pH-dependent studies revealed that the sulfoxidation and N-oxidation of SNI-2011 were mediated by cytochrome P450 (CYP) and flavin-containing monooxygenase (FMO), respectively, in both species. In addition, CYP2D and CYP3A were mainly responsible for the sulfoxidation in rat liver microsomes.
