1. Ornidazole, labelled with 14C in the imidazole ring, administered orally to rats, dogs and men was largely excreted in the urine, predominantly as metabolites, with less than 4% of the drug being excreted unchanged. Free and conjugated metabolites were found in the ratio of approx. 1 : 2. 2. The pattern of free ornidazole and metabolites was different in the three species: while ornidazole predominated in man, ornidazole and metabolite M1 in the dog, the most extensive metabolic pattern was found in the rat. 3. The following metabolites were identified: M1, 1-chlorlo-3-(2-hydroxymethyl-5-nitro-1-imidazolyl)-2-propanol; M2, 2-methyl-5-nitroimidazole; M3, N-(3-chloro-2-hydroxypropyl)acetamide: M4, 3-(-2-methyl-5-nitro-1-imidazolyl)-1, 2-propanediol; M5, acetamide. 4. The formation of metabolite M3 and M5 indicated cleavage of the imidazole ring between N-1/C-5 and C-2/C-3. Other ring scissions were not observed. Metabolites carrying a free amino group were not detected. On the basis of the structures identified, a scheme is suggested for the metabolism of ornidazole.
Introduction
Currently, there is no consensus on the indication of prophylactic surgery of the nodal compartments in the treatment of medullary thyroid carcinoma (MTC). The aim of our study was to perform a correlation study between preoperative calcitonin (basalCT) values and lymph node involvement to establish a criterion on which to base prophylactic surgery in these patients.
Material and Methods
We conducted an observational, retrospective and multicentre study with 29 hospitals. Patients over 18 years of age with a diagnosis of MTC with a pre-surgical calcitonin registry were included. The minimum surgery in all patients had to have been total thyroidectomy (TT) with central compartment lymph node dissection (CCLND). Receiver operating characteristic (ROC) curve analysis was used to establish basalCT cut-off values as predictors of postoperative lymph node involvement.
Results
A total of 244 patients were included. Baseline calcitonin (basalCT) was a good predictor of nodal involvement (AUC 0.718 and 95%CI 0.66–0.978). Heritability was identified as a preoperative factor correlated with baseline tumour CT values (p = 0.000). With a probability of lymph node involvement below 10%, new cut-off points were established. A prophylactic bilateral lateral lymph node dissection in sporadic tumours should be performed at a basalCT > 600 pg/mL; in the case of RET-mutated tumours this value would be 200 pg/mL.
Conclusion
The baseline CT value is a good predictor of postoperative lymph node involvement in MTC, however, cut-off points should depent on the hereditary nature of the tumour.
The pharmacokinetics of aditoprim, a new dihydrofolate reductase (DHFR) inhibitor, and trimethoprim (TMP) were studied in heifers following a single intravenous injection of a 10rng/kg b. w. dose. Aditoprim had a larger volume of distribution at steady state (6.5 k 0.6 Pkg) than TMP (1.1 +_ 0.1 I/kg) and this probably reflects a better tissue penetration than TMP. Both antimicrobials had the same high plasma clearance (5.0 k 1 .O Urnin). Accordingly, aditoprim exhibited a longer halflife (4-6.711) than TMP which was 1.3h, as reported by several authors. Moreover, the plasma concentrations of the new antimicrobial were higher than those of TMP, starting from 4 hours after the drug was injected. For these reasons, the duration of the in vivo bacteriostatic activity of aditoprim should be significantly longer than that of TMP.Aditoprim was also injected intravenously into heifers in combination with either sulphadimidine (SDM) or sulphamerazine (SMR) in a 5:l w/w sulphonamide/aditoprim ratio. The dose was 15 mg of the combination/kg b. w. The pharmacokinetics of the two combinations showed no significant differences. The half-lives of SDM and SMR were both 4 hours, and the pharmacokinetic parameters of aditoprim did not differ significantly from those found when the drug was injected alone. Thus, the half-life of the new DHFR inhibitor appeared to be in the same range as that of the sulphonamides commonly used in veterinary medicine, while its antimicrobial activity was considerably higher. The use of aditoprim as a single drug could thus be envisaged as well as in combination with a sulphonamide.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.