The pharmacokinetics of lipoyl vildagliptin, a novel dipeptidyl peptidase IV (DPP IV) inhibitor, was studied in rats after oral administration for developing it as an antidiabetic agent.
A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed to determine lipoyl vildagliptin in rat plasma. After an overnight fasting, rats were orally given lipoyl vildagliptin. Following a single oral dose of 25, 50, and 100?mg·kg?1, Tmax values were from 1.25 to 1.84?h, CL/F values were around 100?l h?1 kg?1. In the dose range, Cmax values (63.9–296?μg·l?1) and AUC0–∞values (260–1214?μg·h·l?1) were proportional to the doses.
In conclusion, this LC-MS/MS method for the determination of lipoyl vildagliptin in rat plasma was selective and sensitive. In rats, lipoyl vildagliptin displayed linear pharmacokinetics after a single oral dose in the range of 25–100?mg·kg?1. Lipoyl vildagliptin might have very high CL/F values and Vd/F values, which indicated that the bioavailability of this drug might be low or lipoyl vildagliptin might distribute extensively or accumulate in tissues in view of its high liposolubility.
AMG 900 is a small molecule being developed as an orally administered, highly potent, and selective pan-aurora kinase inhibitor. The aim of the investigations was to characterize in vitro and in vivo pharmacokinetic (PK) properties of AMG 900 in preclinical species.
AMG 900 was rapidly metabolized in liver microsomes and highly bound to plasma proteins in the species tested. It was a weak Pgp substrate with good passive permeability.
AMG 900 exhibited a low-to-moderate clearance and a small volume of distribution. Its terminal elimination half-life ranged from 0.6 to 2.4?h. AMG 900 was well-absorbed in fasted animals with an oral bioavailability of 31% to 107%. Food intake had an effect on rate (rats) or extent (dogs) of AMG 900 oral absorption.
The clearance and volume of distribution at steady state in humans were predicted to be 27.3?mL/h/kg and 93.9?mL/kg, respectively.
AMG 900 exhibited acceptable PK properties in preclinical species and was predicted to have low clearance in humans. AMG 900 is currently in Phase I clinical testing as a treatment for solid tumours. Preliminary human PK results appear to be consistent with the predictions.
Domperidone was evaluated in direct and time-dependent cytochrome P450 (CYP) 3A inhibition assays in human liver microsomes with midazolam and testosterone as probe substrates.
Domperidone was found to be a modest mechanism-based inhibitor of human and rat CYP3A. For human CYP3A, the inactivation constant (KI) is 12 μM, and the maximum inactivation rate (kinact) is 0.037?min?1.
A rat interaction study was conducted between midazolam and either a single dose or five daily doses of domperidone. Although a single oral dose of 10?mg kg?1 domperidone did not affect the pharmacokinetics of 10?mg kg?1 oral midazolam, five daily oral doses of domperidone almost doubled the area under the plasma concentration versus time curve (AUC) of midazolam, and increased the maximum plasma concentration (Cmax) of midazolam by 72%.
Based on the simulation and rat in vitro–in vivo extrapolation, it is predicted that co-administration of domperidone in humans could modestly increase (approximately 50%) the exposure of drugs that are primarily cleared by CYP3A.
The pharmacokinetics and disposition of GDC-0879, a small molecule B-RAF kinase inhibitor, was characterized in mouse, rat, dog, and monkey.
In mouse and monkey, clearance (CL) of GDC-0879 was moderate (18.7–24.3 and 14.5?±?2.1?ml min?1 kg?1, respectively), low in dog (5.84?±?1.06?ml min?1 kg?1) and high in rat (86.9?±?14.2?ml min?1 kg?1). The volume of distribution across species ranged from 0.49 to 1.9?l kg?1. Mean terminal half-life values ranged from 0.28?h in rats to 2.97?h in dogs. Absolute oral bioavailability ranged from 18% in dog to 65% in mouse.
Plasma protein binding of GDC-0879 in mouse, rat, dog, monkey, and humans ranged from 68.8% to 81.9%.
In dog, the major ketone metabolite (G-030748) of GDC-0879 appeared to be formation rate-limited.
Based on assessment in dogs, the absorption of GDC-0879 appeared to be sensitive to changes in gut pH, food and salt form (solubililty), with approximately three- to four-fold change in areas under the curve (AUCs) observed.
GDC-0449 (2-chloro-N-(4-chloro-3-(pyridin-2-yl)phenyl)-4-(methylsulfonyl)benzamide) is a potent, selective Hedgehog (Hh) signalling pathway inhibitor being developed for the treatment of various cancers.
The in vivo clearance of GDC-0449 was estimated to be 23.0, 4.65, 0.338, and 19.3?ml min?1 kg?1 in mouse, rat, dog and monkeys, respectively. The volume of distribution ranged from 0.490 in rats to 1.68 l kg?1 in mice. Oral bioavailability ranged from 13% in monkeys to 53% in dogs. Predicted human clearance using allometry was 0.096–0.649?ml min?1 kg?1 and the predicted volume of distribution was 0.766 l kg?1.
Protein binding was extensive with an unbound fraction less than or equal to 6%, and the blood-to-plasma partition ratio ranged from 0.6 to 0.8 in all species tested. GDC-0449 was metabolically stable in mouse, rat, dog and human hepatocytes and had a more rapid turnover in monkey hepatocytes.
Proposed metabolites from exploratory metabolite identification in vitro (rat, dog and human liver microsomes) and in vivo (dog and rat urine) include three primary oxidative metabolites (M1–M3) and three sequential glucuronides (M4–M6). Oxidative metabolites identified in microsomes M1 and M3 were formed primarily by P4503A4/5 (M1) and P4502C9 (M3).
GDC-0449 was not a potent inhibitor of P4501A2, P4502B6, P4502D6, and P4503A4/5 with IC50 estimates greater than 20?μM. Ki’s estimated for P4502C8, P4502C9 and P4502C19 and were 6.0, 5.4 and 24?μM, respectively. An evaluation with Simcyp® suggests that GDC-0449 has a low potential of inhibiting P4502C8 and P4502C9. Furthermore, GDC-0449 (15?μM) was not a potent P-glycoprotein/ABCB1 inhibitor in MDR1-MDCK cells.
Overall, GDC-0449 has an attractive preclinical profile and is currently in Phase II clinical trials.
Bupropion is metabolized extensively in humans by oxidative and reductive processes. CYP2B6 mediates oxidation of bupropion to hydroxybupropion, but the enzyme(s) catalyzing carbonyl reduction of bupropion to erythro- and threohydrobupropion in human liver is unknown. The objective of this study was to examine the enzyme kinetics of bupropion reduction in human liver.
In human liver cytosol, the reduction of bupropion to erythro-and threohydrobupropion was NADPH dependent with Clint values of 0.08 and 0.60 µL·min?1mg?1 protein, respectively. Bupropion reduction in liver microsomes was also NADPH dependent with Clint values of 10.4 and 280 µL·min?1mg?1 protein, respectively. Formation of erythro-and threohydrobupropion in microsomes exceeded that in cytosol by 70 and 170 fold, respectively.
Menadione, an inhibitor of cytosolic carbonyl reducing enzymes (e.g. CBRs), inhibited erythro-and threohydrobupropion formation in cytosol with IC50 of 30 and 54 µM, respectively. In microsomes 18β-glycyrrhetinic acid, an inhibitor of microsomal carbonyl reductases (e.g. 11β-HSDs), inhibited their formation with IC50 of 25 and 26?nM, respectively.
Our findings, in agreement with recent human placental studies, show that carbonyl reducing enzymes in hepatic microsomes are significant players in bupropion reduction. Contrary to past studies, we found that threohydrobupropion (not hydroxybupropion) is the major microsomal generated hepatic metabolite of bupropion.
Valspodar is a P-glycoprotein inhibitor widely used in preclinical and clinical studies for overcoming multidrug resistance. Despite this, the pharmacokinetics of valspodar in rat, a commonly used animal model, have not been reported. Here, we report on the pharmacokinetics of valspodar in Sprague–Dawley rats following intravenous and oral administration of its Cremophor EL formulation, which has been used for humans in clinical trials.
After intravenous doses, valspodar displayed properties of slow clearance and a large volume of distribution. Its plasma unbound fraction was around 15% in the Cremophor EL formulation used in the study. After 10?mg kg?1 orally it was rapidly absorbed with an average maximal plasma concentration of 1.48?mg l?1 within approximately 2?h. The mean bioavailability of valspodar was 42.8%.
In rat, valspodar showed properties of low hepatic extraction and wide distribution, similar to that of its structural analogue cyclosporine A.
5-{2-[4-(3,4-Difluorophenoxy)-phenyl]-ethylsulfamoyl}-2-methyl-benzoic acid (1) is a novel, potent, and selective agonist of the peroxisome proliferator-activated receptor alpha (PPAR-α).
In preclinical species, compound 1 demonstrated generally favourable pharmacokinetic properties. Systemic plasma clearance (CLp) after intravenous administration was low in Sprague–Dawley rats (3.2?±?1.4?ml min?1 kg?1) and cynomolgus monkeys (6.1?±?1.6?ml min?1 kg?1) resulting in plasma half-lives of 7.1?±?0.7?h and 9.4?±?0.8?h, respectively. Moderate bioavailability in rats (64%) and monkeys (55%) was observed after oral dosing. In rats, oral pharmacokinetics were dose-dependent over the dose range examined (10 and 50?mg kg?1).
In vitro metabolism studies on 1 in cryopreserved rat, monkey, and human hepatocytes revealed that 1 was metabolized via oxidation and phase II glucuronidation pathways. In rats, a percentage of the dose (approximately 19%) was eliminated via biliary excretion in the unchanged form.
Studies using recombinant human CYP isozymes established that the rate-limiting step in the oxidative metabolism of 1 to the major primary alcohol metabolite M1 was catalysed by CYP3A4.
Compound 1 was greater than 99% bound to plasma proteins in rat, monkey, mouse, and human.
No competitive inhibition of the five major cytochrome P450 enzymes, namely CYP1A2, P4502C9, P4502C19, P4502D6 and P4503A4 (IC50’s?>?30 μM) was discerned with 1.
Because of insignificant turnover of 1 in human liver microsomes and hepatocytes, human clearance was predicted using rat single-species allometric scaling from in vivo data. The steady-state volume was also scaled from rat volume after normalization for protein-binding differences. As such, these estimates were used to predict an efficacious human dose required for 30% lowering of triglycerides.
In order to aid human dose projections, pharmacokinetic/pharmacodynamic relationships for triglyceride lowering by 1 were first established in mice, which allowed an insight into the efficacious concentrations required for maximal triglyceride lowering. Assuming that the pharmacology translated in a quantitative fashion from mouse to human, dose projections were made for humans using mouse pharmacodynamic parameters and the predicted human pharmacokinetic estimates.
First-in-human clinical studies on 1 following oral administration suggested that the human pharmacokinetics/dose predictions were in the range that yielded a favourable pharmacodynamic response.
The transport and metabolism of the antitumour drug candidate 2′-benzoyloxycinnamaldehyde (BCA) was characterized in Caco-2 cells.
BCA disappeared rapidly from the donor side without being transported to the receiver side during its absorptive transport across Caco-2 cells. Its metabolites 2′-hydroxycinnamaldehyde (HCA) and o-coumaric acid (OCA) were formed in both the donor and the receiver sides.
HCA, in a separate study, also disappeared rapidly from the donor side, mostly being converted to its oxidative metabolite OCA during its absorptive transport across Caco-2 cells.
OCA was transported rapidly in the absorptive direction across Caco-2 cells with a Papp of 25.4?±?1.0?×?10?6?cm s?1 (mean?±?standard deviation (SD), n?=?3). OCA was fully recovered from both the donor and the receiver side throughout the time-course of this study.
Formation of HCA from BCA was inhibited almost completely by bis(p-nitrophenyl)phosphate (BNPP), a selective inhibitor of carboxylesterases (CES), and phenylmethylsulfonyl fluoride (PMSF), a broad specificity inhibitor of esterases in Caco-2 cells, suggesting that this hydrolytic biotransformation was likely mediated predominantly by CES. Conversion of HCA to OCA was inhibited significantly by isovanillin, a selective inhibitor of aldehyde oxidase (AO). Inhibitors for xanthine oxidase (XO) and aldehyde dehydrogenase (ALDH), which are known to be involved in the oxidation of aldehydes to carboxylic acids, did not have a significant effect on the biotransformation of HCA to OCA in Caco-2 cells.
In summary, the present work demonstrates that BCA is hydrolysed rapidly to HCA, followed by subsequent oxidation to OCA, in Caco-2 cells. The results provide a mechanistic understanding of the poor absorption and low bioavailability of BCA after oral administration.
Prediction of biliary excretion is a challenge for drug discovery scientists due to the lack of in vitro assays. This study explores the possibility of establishing a simple assay to predict in vivo biliary excretion via the mrp2 transport system.
In vitro mrp2 activity was determined by measuring the ATP-dependent uptake of 5(6)-carboxy-2′,7′-dichlorofluorescein (CDCF) in canalicular plasma membrane vesicles (cLPM) from rat livers. The CDCF uptake was time- and concentration-dependent (Km of 2.2?±?0.3 µM and Vmax of 115?±?26 pmol/mg/min) and strongly inhibited by the mrp2 inhibitors, benzbromarone, MK-571, and cyclosporine A, with IC50 values ≤ 1.1 µM.
Low inhibition of CDCF uptake by taurocholate (BSEP inhibitor; 57 µM) and digoxin (P-gp inhibitor; 101 µM) demonstrated assay specificity towards mrp2.
A highly significant correlation (r2?=?0.959) between the in vitro IC50 values from the described mrp2 assay and in vivo biliary excretion in rats was observed using 10 literature compounds.
This study demonstrated, for the first time, that a high throughput assay could be established with the capability of predicting biliary excretion in the rat using CDCF as a substrate.
The metabolism, pharmacokinetics and excretion of a hypoxically activating prodrug developed for the treatment of cancer, TH-302, were studied in rats following intravenous administration of 50?mg/kg [14C]-TH-302.
The pharmacokinetics of TH-302 was characterized by a short half-life of 12.3?min, a high clearance of 2.29?L/h/kg and a volume of distribution of 0.627?L/kg.
In intact and bile duct-cannulated rats, TH-302 was extensively metabolized with total recovery in excreta of 68.1% and 85.8%, respectively, with equal amounts excreted through urine and bile.
Quantitative whole body autoradiography showed rapid distribution of [14C]-TH-302 associated radioactivity with the highest concentrations in the kidney and small intestinal content, suggesting significant biliary excretion and/or gut secretion.
TH-302 was metabolized via (i) hydrolysis to form 2-bromoethyl amine RM3 (7.5%); (ii) monoglutathione conjugation and subsequently to the mercapturic acid RM13 (7.5%); and (iii) diglutathione conjugation followed by hydrolysis to form the dicysteine conjugate RM5 (6.5%).
A large percentage (19.7%) of the dose in the excreta was associated with unidentified polar metabolites RM1 and RM2.
TH-302 was the predominant circulating component in plasma and the two major metabolites in plasma were the cysteine conjugate RM8 and mercapturic acid RM13.
The mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) pathway is a key signalling pathway that regulates cell proliferation. G-573 is an allosteric inhibitor of MEK that is both potent and selective.
The objectives of these studies were to characterize the disposition of G-573 in preclinical species and to determine the relationship of G-573 plasma concentrations to pERK (phosphorylated ERK) and to tumour growth inhibition in HCT116 and H2122 mouse xenograft models.
The clearance of G-573 was low in mouse (7.7?ml/min/kg), rat (2.24?ml/min/kg), dog (10?ml/min/kg), and cynomolgus monkey (0.754?ml/min/kg) while volumes of distribution (0.114–1.77?l/kg) was low to moderate, resulting in moderate half-lives across species (~2–9?h).
Indirect response models were used to characterize the relationship between plasma concentration of G-573 to both pERK inhibition and tumour growth inhibition. The IC50 value for pERK inhibition in HCT116 tumours by G-573 was estimated to be 0.406?μM. The IC50 values for tumour growth inhibition in HCT116 and H2122 were estimated to be 3.43 and 2.56?μM, respectively. ED50 estimates in HCT116 and H2122 mouse xenograft models were estimated to be ~4.6 and 1.9?mg/kg/day, respectively. The information from these studies provides useful information when characterizing candidates for potential further clinical testing.
Tissue distribution, metabolism, and disposition of oral (0.2–20?mg/kg) and intravenous (0.2?mg/kg) doses of [2-14C]dibromoacetonitrile (DBAN) were investigated in male rats and mice.
[14C]DBAN reacts rapidly with rat blood in vitro and binds covalently. Prior depletion of glutathione (GSH) markedly diminished loss of DBAN. Chemical reaction with GSH readily yielded glutathionylacetonitrile.
About 90% of the radioactivity from orally administered doses of [14C]DBAN was absorbed. After intravenous administration, 10% and 20% of the radioactivity was recovered in mouse and rat tissues, respectively, at 72?h. After oral dosing, three to four times less radioactivity was recovered, but radioactivity in stomach was mostly covalently bound.
Excretion of radioactivity into urine exceeded that in feces; 9–15% was exhaled as labeled carbon dioxide and 1–3% as volatiles in 72?h.
The major urinary metabolites were identified by liquid chromatography-mass spectrometry, and included acetonitrile mercaptoacetate (mouse), acetonitrile mercapturate, and cysteinylacetonitrile.
The primary mode of DBAN metabolism is via reaction with GSH, and covalent binding may be due to reaction with tissue sulphydryls.
The aim was to identify the individual human cytochrome P450 (CYP) enzymes responsible for the in vitro N-demethylation of hydromorphone and to determine the potential effect of the inhibition of this metabolic pathway on the formation of other hydromorphone metabolites.
Hydromorphone was metabolized to norhydromorphone (apparent Km = 206?? 822?μM, Vmax = 104 ? 834?pmol?min?1?mg?1 protein) and dihydroisomorphine (apparent Km = 62 ? 557?μM, Vmax = 17 ? 122?pmol?min?1?mg?1 protein) by human liver microsomes.
In pooled human liver microsomes, troleandomycin, ketoconazole and sulfaphenazole reduced norhydromorphone formation by an average of 45, 50 and 25%, respectively, whereas furafylline, quinidine and omeprazole had no effect. In an individual liver microsome sample with a high CYP3A protein content, troleandomycin and ketoconazole inhibited norhydromorphone formation by 80%.
The reduction in norhydromorphone formation by troleandomycin and ketoconazole was accompanied by a stimulation in dihydroisomorphine production.
Recombinant CYP3A4, CYP3A5, CYP2C9 and CYP2D6, but not CYP1A2, catalysed norhydromorphone formation, whereas none of these enzymes was active in dihydroisomorphine formation.
In summary, CYP3A and, to a lesser extent, CYP2C9 catalysed hydromorphone N-demethylation in human liver microsomes. The inhibition of norhydromorphone formation by troleandomycin and ketoconazole resulted in a stimulation of microsomal dihydroisomorphine formation.
The purpose was to investigate whether the pharmacokinetics and pharmacodynamics of prednisolone in the non-human primate was an appropriate surrogate for man.
After single intravenous doses of 0.03, 0.3, and 3?mg kg?1, prednisolone demonstrated a dose-dependent clearance and volume of distribution. When corrected for concentration-dependent protein binding, the free clearance was linear at the tested dose levels. The protein binding-corrected volume of distribution was similar across doses. The serum half-life was estimated as being between 2 and 4?h. Prednisolone exhibits near complete inhibition of the cytokines TNF-α, IL-1β, IL-6 and IL-8 with very similar IC50 estimates from 0.09 to 0.16 μg ml?1 (from 0.24 to 0.44 μM).
The monkey demonstrated a similar pharmacokinetics–pharmacodynamics profile of prednisolone when compared with man (from the literature).
We compared the intrinsic clearance (CLint) of a number of substrates in suspensions of fresh and cryopreserved human hepatocytes from seven donors.
CLint values for a cocktail incubation of phenacetin, diclofenac, diazepam, bufuralol, midazolam, and hydroxycoumarin were 4.9?±?3.4, 18?±?7.2, 5.1?±?4.9, 6.3?±?3.3, 9.8?±?5.8 and 22?±?14?μl min?1/106 cells, respectively, and they correlated well with corresponding CLint values using cryopreserved hepatocytes from 25 different donors.
CLint values of each cocktail substrate and 20 AstraZeneca new chemical entities were compared in fresh and cryopreserved hepatocytes from the same three donors. There was a statistically significant correlation between CLint in fresh and cryopreserved hepatocytes for each of the three livers (p?int values was 1.03.
In conclusion, the results add further support to the use of cryopreserved human hepatocytes as a screening model for the intrinsic clearance of new chemical entities.
This work aimed to investigate plasma pharmacokinetics and tissue distribution of a new acridine derivative 5-acridin-9-ylmethylene-3-(4-methyl-benzyl)-thiazolidine-2,4-dione (AC04) and its 1-oxo-AC04 metabolite disposition in Wistar rats.
After a single AC04 1.5?mg/kg intravenous (i.v.) bolus dose, blood samples were taken up to 120?h. Plasma samples were deproteinization, and AC04 and metabolite were quantified by validated liquid chromatography in tandem with mass spectrometry method. Protein binding was determined by ultrafiltration. AC04 tissue disposition was evaluated after i.v. bolus dose.
Individual AC04 concentration–time profiles were best fitted by a two-compartment model showing CLtot of 3.4?±?3.4?L/h/kg, VdSS of 137.9?±?91.4?L/kg, AUC0–∞ of 788?±?483 ng·h/mL and a t1/2 of 45.5?±?31.5?h. Protein binding was 98.1?±?1.6%. AC04 showed higher penetration into the lung, spleen and liver, with AUC0–96 of 798,443, 263,211 and 303,722 ng·h/mL, respectively. The 1-oxo-AC04 metabolite represented 10% of AC04 plasma concentration, showing a t1/2 of 23.2?±?10.4?h.
These results suggest that, despite the small free plasma fraction, AC04 penetrates extensively reaching high concentrations in most tissues residing for a long time, which is important for its activity on solid tumours. All results combined indicate that AC04 is potentially a good antitumour candidate.
O2′, O3′, O5′-tri-acetyl-N6-(3-hydroxylaniline)adenosine (WS070117), a new structure-type lipid regulator, is being developed in pre-clinical study. In order to monitor drug kinetics it is essential to understand pre-analytical factors that may affect drug assay.
In vitro stability and metabolism were investigated using high-performance liquid chromatography (HPLC) method in this study. The hydrolysis products were identified by HPLC–mass spectrometry (MS)/MS method. The esterases involved in WS070117 hydrolysis was assigned via inhibition rate assay.
It was found that WS070117 was chemically unstable in alkaline solutions compared to acidic and near neutral solutions. Enzymatic hydrolysis was even more rapid. Hydrolytic rate constants differ between species, being 4.24, 5.96?×?10?3 and 6.85?×?10?2 min?1 in rat, dog and human plasma at 37°C, respectively. The hydrolysis was catalyzed by plasma esterase because NaF (sodium fluoride: a general esterase inhibitor) inhibited WS070117 hydrolysis and metabolite production. Hydrolysis was fast in rat plasma and was catalysed by carboxylesterase and butyrylcholinesterase. In dog plasma, carboxylesterase, butyrylcholinesterase and paraoxonase were mainly responsible. Butyrylcholinesterase was the major esterase involved in WS070117 hydrolysis in human plasma. The WS070117 hydrolysis in plasma proceeded by gradual loss of acetyl groups.
The knowledge of in vitro drug stability and metabolic pathways identified in this study will be essential for future pre-clinical and clinical pharmacokinetics studies.
The purpose of the study was to evaluate the pharmacokinetic characteristics of a single, intravenous dose of antofloxacin hydrochloride in healthy Chinese male volunteers.
Twelve subjects were randomly assigned to groups that received a single, intravenous dose of 200, 300, or 400?mg antofloxacin hydrochloride in a three-way crossover design study. The serum and urine concentrations of antofloxacin were then assayed with high-performance liquid chromatography (HPLC). Major pharmacokinetic parameters and urine excretion were obtained up to 96?h after administration.
All three dosages were well tolerated. No clinically adverse reactions or abnormal laboratory results were detected.
After single-dose intravenous administration, antofloxacin hydrochloride exhibited linear pharmacokinetic characteristics with increasing dosages. The Cmax for groups treated with 200, 300, or 400?mg dosages were 2.05?±?0.38, 3.01?±?0.60, and 3.80?±?0.78?mg l?1, respectively; the areas under the curve from zero to infinity (AUC0–∞) were 25.14?±?2.95, 37.63?±?5.42, and 53.87?±?9.48?mg l?1·h, respectively. The t1/2β was around 20?h; and the urinary excretion was measured as being from 58% to 60% within 96?h.
Based on these results, 300?mg of antofloxacin hydrochloride administered once daily is the dose suggested for further investigation in multiple-dose administration studies.