| As well as Metronidazole, Tinidazole and Ornidazole, Morinidazole(MNZ) is a 5’-nitroimidazole homologue. In vitro study showed that:Mirinidazole have a strong antibacterial effect against anaerobic gram-negative nonspore-bearing bacillus and gram-positive coccus isolated from clinical strains. To Clostridium perfringens, Bacillus fragilis and Veillonella, the antibacterial activity of Morinidazole, well as Ornidazole’s, is 2 to 8 times stronger than metronidazole’s and tinidazole’s. Morinidazole have strong antibacterial action against Bacteroides distasonis oval Bacteroides, Bacteroides vulgatus, and bacteroides melanogenicus, same to ornidazole, and 2-4 times stronger than metronidazole and tinidazole. In vivo study showed that:Morinidazole have stronger antibacterial activity than Metronidazole, Tinidazole and Ornidazole. The protective effect of intravenous administration is better than oral administration. The primarily elimination path of Morinidazole in rats is by metabolism, followed by excretion in urine. The safe dose range showed in phase I clinical trial of Morinidazole injection is 2.5 to 24 mg/Kg, and in the 10 to 24 mg/kg dose range the elimination of Minidazole presents linear dynamics, the terminal half-life of Morinidazole (t1/2β) is 5.70 h～ 6.651h, the Cav of multiple doses is 11.22±0.90) μg · mL-1, AUCss is (89.77±7.17) ug·h· mL-1. In human the ratio of Minidazole eliminated from urine in prototype is 18.9-41.1%,and M2, one of the metabolites, eliminated from urine amount to 1.0-3.6%. Animal experiments and clinical trial I studies indicated that Morinidazole eliminated through hepatic metabolism mainly. Liver dysfunction may change pharmacokinetics of the drug, and thus affect the drug’s safety and pharmacodynamics. In view of the efficacy and safety of Morinidazole, it is approved to conduct the special groups (liver and kidney dysfunction) Pharmacokinetics study in phase III clinical trial of Morinidazole by State Food and Drug Administration (SFDA) in China, based on the results of pharmacokinetics studies of the injection of low and high dose (300 mg, bid,500 mg, bid) studies in phase II clinical trials. The objective of this project is to examine the pharmacokinetic characteristics of Morinidazole in subjects with hepatic dysfunction, compared with the healthy subjects’, and the dosing regimen may be recommended in patients with hepatic impairment of MNZ. This study includes two parts:Part 1 Development and validation of the Method for the Determination of Morinidazole and its metabolite M2 in Human Plasma and Urine Using LC-MS/MSA high performance liquid chromatographic-tandem mass spectrometric (HPLC-MS/MS) method was developed to determine the MNZ and M2 concentration both in the plasma and urine samples collected from the pharmacokinetics studies. Waters Alliance 2690 series HPLC instrument and Finnigan TSQ Quantum Discovery Max tandem mass spectrometer apparatus was applicated in the determination. MNZ and M2 was separated using a Shiseido MGII CAPCELL PAK column (2.0 by 50mm,3μm) with mobile phase of 0.1% methanoic acid and acetonitrile(contained 0.1% formic acid) (97:3) to determine the plasma and urine samples respectively. A rapid sensitive convenient LC-MS/MS method was developed, in which the biological specimens of plasma and urine were pretreated by directed protein precipitation. The internal standard (IS) was Ornidazole. The lower limit of quantification for MNZ and M2 in plasma and urine were both 0.01μg/mL. For plasma and urine samples, the recoveries of MNZ were 101.0% and 100.3%, the intra-batch precision (RSD)≤7.0% and<7.9%, and the intra-batch accuracy ranged from 90.0% to 103.0% and 96.8% to 105.0%, respectively; the inter- batch precision (RSD)≤7.1% and ≤4.7%, and the inter-batch accuracy ranged from 91.7% to 99.9% and 95.5% to 108.3%, respectively; the intra-week precision (RSD)≤10.0% and ≤6.7%, and the intra- week accuracy ranged from 95.0% to 103.3% and 96.8% to 103.3%, respectively. For M2 in plasma and urine samples, the recoveries were 105.6% and 112.6%, the intra- batch precision (RSD)≤8.9% and ≤7.8%, and the intra- batch accuracy ranged from 100.0% to 106.3% and 90.2% to102.2%, respectively; the inter- batch precision (RSD)≤8.1% and ≤5.2%, and the inter-batch accuracy ranged from 97.8% to 105.0% and 91.7% to 106.7%, respectively; the intra-week precision (RSD)≤6.4% and ≤11.9%, and the intra- week accuracy ranged from 96.9% to 113.3% and 92.3% to 103.3%, respectively. In room temperature, MNZ and M2 kept stable over 6 h in plasma and urine samples before pretreatment, and also stable over 48 h in the post-preparative plasma and urine samples. MNZ and M2 were stable in plasma over three cycles of freeze (-80℃) and thawing (room temperature). The Dilution-recovery of MNZ and M2 in plasma samples were 111.4%-118.6% and 112.1%～117.4%, respectively, after 2 to 10 times dilution. In urine samples the Dilution-recovery were 94.5%～100.8% and 100.7%-101.1%, respectively, after 10 to 100 times dilution. The matrix effect of MNZ, M2 and IS in plasma were (106.2±8.9)%, (107.7±6.5)% and (110.0±8.6)%, respectively; in urine were (89.1±5.8)%, (91.5±7.4)% and (60.1±4.0)%, respectively. The method was accorded with the demands of the relevant documents released by SFDA drug evaluation.Part 2 Pharmacokinetic Study of Morinidazole in Human Subjects with Impaired Hepatic FunctionDetermining the pharmacokinetics.and safety of Morinidazole in subjects with hepatic impairment, a single-centre, open-label, parallel-group study was performed. In this study, twelve subjects with moderate hepatic impairment [defined as a Child-Pugh score of 7-9] and twelve gender-, age-and weight-matched healthy subjects were enrolled in the study(male: female=7:5). Blood and urine samples were collected for pharmacokinetic assessments. High performance liquid chromatography with tandem mass spectrometry was used for analyses of parent drug and metabolite concentrations in both plasma and urine samples. Pharmacokinetic parameters (primary:area under the plasma concentration-time curve from time 0 to infinity [AUC0-∞], terminal elimination half-life (T1/2) and maximum plasma concentration [Cmax]) and safety were evaluated for morinidazole and its metabolite M2. Noncompartmental and compartmental PK analysis was performed using Phoenix WinNonlin 6.0 (Pharsight Corp. USA). The t test and analysis of variance were employed for the statistical significance test (The AUC, T1/2 and Cmax values were logarithmically transformed and subjected to analysis of variance (ANOVA) to obtain 90% confidence intervals (CI) for the ratio of subjects with hepatic impairment to healthy subjects).The results showed that moderate hepatic insufficiency has an impact on the pharmacokinetics of original drug and the metabolite M2. In the period of 8-48h after intravenous infusion, the blood concentration, in patients with liver dysfunction, was significantly higher than healthy subjects’ (P<0.05), and the concentration of the metabolite M2 during the administration and 4h after administration in plasma was significantly higher than healthy subjects’, respectively. The variability and individual variation of blood concentration of monidazole and its metabolite M2 in moderate hepatic impairment are more significant than healthy subjects’.The vivo process of MNZ has a significant difference between moderate hepatic dysfunction subjects (defined as group A) and healthy subjects (defined as group B). Both mean AUC0-48h and mean AUCO-inf of group A are 1.59 times and 1.68 times than the scores of group B, respectively. In addition, the half-life of group A (T 1/2=9.5 h) increase by 63% compared with group B (T1/2=5.83 h). At the same time, MRT of the former (11.2 h) increase by 69% compared with the latter (7.18 h). The clearance of drug in the plasma of group A and group B are 4.75L/h and 7.23L/h, respectively. The rate of clearance in group A is slower than B up to 34%. These PK parameters such as AUC0-48h, AUCO-inf, T1/2, MRT and CLt showed above display a significant difference between these groups(P<0.05).Compared with healthy subjects, the T1/2 and MRT of monidazole in liver dysfunction increased by 63% and by 69%(P<0.01), respectively; clearance rate decreased by 34%(P<0.05), AUC0-∞ increased by 51%(P<0.05). Compartment model analysis showed that the T1/2 of monidazole in moderate liver dysfunction, compared with healthy subjects, increased by 50%(P<0.01), indicating that liver dysfunction can change pharmacokinetics of monidazole by attenuating its elimination mainly. Pharmacokinetic parameters of the metabolite M2 in plasma were different form parent drug such as Cmax and km parameter, and km (defined as metabolic rate) decreased significantly (0.86%vs 1.25%, P<0.05).The percentages of monidazole original drug and metabolite M2 excreted in urine over 48h were 21.2% and 1.6%, respectively,which hve no significant difference between the two-group. Compared with healthy subjects, the maximum excretion rate and renal clearance of monidazole in hepatic dysfunction were significantly lower (P<0.05), reduced by 30% and by 42%, respectively, while excretion parameters of M2 in urine have no significant difference subjects in both groups.There were no serious adverse events, significant adverse events nor withdrawal events reported in the clinical trial. Hepatic dysfunction group reported a total of 10 cases of drug-related adverse reactions (ADRs) reported by 6 subjects, including3 cases of clinical ADR in 2 subjects, as 2 cases of gastrointestinal reactions in 1 patient and 1 case of skin rash; laboratory abnormality ADRs, including 4 cases of liver dysfunction (ALT, AST and other increases) in 2 subjects,1 case of thrombocytopenia and 2 cases of urinary protein positive in 2 subjects. In healthy subjects group, there were 2 cases of total bilirubin, direct bilirubin increase occurred in 2 subjects reporded as ADR. The incidence of AE and ADR in both groups were significantly different (P<0.05), indicating the background of liver dysfunction in patients are important factors account to AE and ADRs.Conclusion:Compared with healthy subjects, the moderate hepatic insufficiency group after a single 500mg intravenous injection dose of monidazole, displayed a certain accumulation of drug in the body, the rate of elimination of monidazole in prototype and metabolite M2 decreased(CLt, CLr lower), the elimination half-life extension, causing the drug dose in the current setting (500mg) up to a certain extent,and the exposure of drug in the body increased(compared with healthy subjects the AUC of moderate hepatic dysfunction group increased to1.68-time). When monidazole is administrated in patients with hepatic dysfunction, a appropriate dose reduction is recommended, and the dosage adjustments still need to refer to the physiological disposition of monidazole’s primary metabolites (M6, M7), as metabolite M2 determined in this experiment dose not the major metabolite. |
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