Content of Botulinum Neurotoxin in Botox?/Vistabel?, Dysport?/Azzalure?, and Xeomin?/Bocouture?

Background: Botulinum neurotoxin type A (BoNT/A) is the active substance in preparations used for the highly effective treatment of neurologic disorders such as cervical dystonia, blepharospasm, or spasticity, as well as other indications such as axillary and palmar hyperhidrosis, and urologic disorders.Objective: To determine the amount of BoNT/A protein present in pharmaceutical preparations of Botox®, Dysport®, and Xeomin®, which are identical with Vistabel®, Azzalure®, and Bocouture®, respectively.Methods: Rabbit and guinea pig antibodies raised against the 150kD BoNT/A neurotoxin purified from Clostridium botulinum type A, strain ATCC 3502 (‘Hall strain’), were used in a sensitive sandwich ELISA to determine the overall mean concentration of the 150kD neurotoxin present in four batches of Botox® (C2344C3, C2384C3, C2419, and C2385), two batches of Dysport® (678F and 689X) and three batches of Xeomin® (61111, 70604, and 81 208). The specific neurotoxin potency, defined as the potency or biologic activity (units) per mass of neurotoxin protein (ng), was calculated based on the overall mean concentration of BoNT/A neurotoxin.Results: Overall, the mean concentration of BoNT/A neurotoxin in Botox® was 0.73 ng per 100 unit vial (coefficient of variation [CV] = 3.5%), 3.24 ng per 500 unit vial of Dysport®, corresponding to 0.65 ng in 100 units (CV = 11.4%), and 0.44 ng per 100 unit vial of Xeomin® (CV = 1.9%). The specific potency of the 150kD BoNT/A neurotoxin was calculated as 137 units/ng for Botox®, 154 units/ng Dysport®, and 227 units/ng Xeomin®.Conclusions: The current study has shown that of the three products, Xeomin® contains the highest specific neurotoxin activity, followed by Dysport®, with Botox® having the lowest specific activity. This result suggests that Xeomin® contains only active neurotoxin in contrast with Botox®, which is likely to contain additional denatured/inactive neurotoxin.     

Biotransformation and pharmacokinetics of sulfinpyrazone (Anturan®) in man

Summary The absorption, biotransformation and elimination of sulfinpyrazone, 1,2-diphenyl-3,5-dioxo-4-(2-phenylsufinylethyl)-pyrazolidine, have been studied by administration of single 200 mg oral doses of a¹⁴C-labelled preparation to two male volunteers. Absorption from the gastro-intestinal tract was rapid and complete and the plasma concentration of unchanged drug reached maximum values of 22.67 and 13.04 µg/ml, respectively, after 1 – 2 hours. The elimination half-life in the two subjects, calculated from the decline between 3 and 8 hours, was 2.7 and 2.2 hours. The integrated concentration of unchanged sulfinpyrazone in plasma, estimated from the area under the concentration curves (AUC), was almost as high as that of total¹⁴C-substances, so the proportion of metabolized drug in plasma was low. In no case did the AUC of the three specifically determined metabolites, i.e. the sulphone G 31 442, the para-hydroxy-compound G 32 642 and the 4-hydroxy-compound GP 52 097, exceed 4% of the sulfinpyrazone value. More than 95% of whole blood radioactivity was confined to plasma. The oral dose was rapidly and completely excreted, since within 4 days more than 95% was recovered, 85% from urine and 10% from faeces. A large proportion of the dose was excreted as unchanged drug in the two volunteers: 51 and 54% of total urinary radioactivity was present as sulfinpyrazone; 8.2 and 8.8% was present as para-hydroxy-metabolite, 2.7 and 3.0% as sulphone-metabolite, and 0.6 and 0.8% as 4-hydroxy-metabolite. About 30% of urinary radioactivity consisted of highly polar metabolites. Spectroscopy of them showed that they were the C--glucuronides of sulfinpyrazone (28%) and the corresponding sulfone (2%). In these metabolites the C(4) of the pyrazolidine ring was directly attached to glucuronic acid, and thus they represent a new type of biosynthetic conjugate.     

Biotransformation and pharmacokinetics of acenocoumarol (Sintrom®) in man

Summary The absorption, biotransformation and elimination of the anticoagulant acenocoumarol, 3-[- (4-nitrophenyl)--acetylethyl]-4-hydroxycoumarin, have been studied by oral administration of 12 mg of a¹⁴C-labelled preparation to two male volunteers. Absorption from the gastro-intestinal tract was rapid and the plasma concentration of unchanged drug reached a maximum of 169 and 412 ng/ml, respectively, after 3 hours. The elimination half-life in the two subjects, calculated from the decline between 6 and 24 h, was 8.7 and 8.2 hours. A constant proportion of 98.7% of the drug was bound in vitro to serum proteins over a concentration range of 0.021–8.34 µg/ml, with little interindividual variation. The major portion of the binding was to human serum albumin (97.5%) at two classes of binding sites: association constant K₁=1.04×10⁵ l/mole (n₁=1) and K₂=5.55×10³ l/mole (n₂=4). In addition to unchanged acenocoumarol, four metabolites were determined in plasma by isotope dilution techniques: the amino-, acetamido-, alcohol₁- and alcohol₂-metabolites. Of them, the amino-metabolite showed the highest concentration, namely 278 ng/ml, after 6 h in Subject A, and 163 ng/ml after 10 hours in Subject B. Judged from the integrated concentrations, the compounds analyzed accounted for 76 and 89%, respectively, of the total radioactivity in plasma. All the metabolites detected in plasma showed anticoagulant activity when tested in mice. The quantities of the metabolites excreted in urine from 0–120 hours were (Subject A/Subject B): acenocoumarol 0.3/0.2%, amino-metabolite 12.3/7.7%, acetamido-metabolite 19.0/11.1%, alcohol₁-metabolite 4.6/9.0%, alcohol₂-metabolite 1.7/4.4%, 6-hydroxy-metabolite 6.9/18.3% and 7-hydroxy-metabolite 14.0/22.2%.     

Safety,Toxicokinetics and Tissue Distribution of Long-Term Intravenous Liposomal Amphotericin B (ambisome®): A 91-day Study in Rats

Purpose. Amphotericin B in small, unilamellar liposomes (AmBisome) is safer and produces higher plasma concentrations than other formulations. Because liposomes may increase and prolong tissue exposures, the potential for drug accumulation or delayed toxicity after chronic AmBisome was investigated. Methods. Rats (174/sex) received intravenous AmBisome (1, 4, or 12 mg/kg), dextrose, or empty liposomes for 91 days with a 30-day recovery. Safety (including clinical and microscopic pathology) and toxicokinetics in plasma and tissues were evaluated. Results. Chemical and histopathologic changes demonstrated that the kidneys and liver were the target organs for chronic AmBisome toxicity. Nephrotoxicity was moderate (urean nitrogen [BUN] 51 mg/dl; creatinine unchanged). Liposome-related changes (vacuolated macrophages and hypercholesterolemia) were also observed. Although plasma and tissue accumulation was nonlinear and progressive (clearance and volume decreased, half-life increased with dose and time), most toxic changes occurred early, stabilized by the end of dosing, and reversed during recovery. There were no delayed toxicities. Concentrations in liver and spleen greatly exceeded those in plasma; kidney and lung concentrations were similar to those in plasma. Elimination half-lives were 1-4 weeks in all tissues. Conclusions. Despite nonlinear accumulation, AmBisome revealed predictable hepatic and renal toxicities after 91 days, with no new or delayed effects after prolonged treatment at high doses that resulted in plasma levels >200 g/ml and tissue levels >3000 g/g.     

Phase I trial of oblimersen (Genasense®) and gemcitabine in refractory and advanced malignancies

Background: Overexpression of Bcl-2 is associated with worse prognosis for a number of cancer types. The present study was designed to determine the maximum tolerated dose (MTD) of oblimersen (antisense Bcl-2) and gemcitabine when administered to patients with refractory malignancies. Materials and methods: Sixteen patients with advanced solid tumors refractory to standard therapies were treated with escalating doses of oblimersen continuous, 120-h intravenous infusion given every 14 days, with a fixed-dose-rate intravenous infusion of gemcitabine administered on day 5 of each cycle. Serial plasma samples were collected to calculate the pharmacokinetics of oblimersen and gemcitabine, and also to measure the effect of oblimersen on Bcl-2 expression. Results: 7 women and 9 men, median age 55 years (range 35–74 years), received a 5-day infusion of oblimersen at dose levels of 5 mg/kg/day (n = 4) or 7 mg/kg/day (n = 12). On the 5th day of the infusion, gemcitabine was given at 10 mg/m²/h for a total dose of 1,000 mg/m² (n = 7; cohorts I and II), 1,200 mg/m² (n = 3; cohort III), or 1,500 mg/m² (n = 6; cohort IV). Edema was the dose-limiting toxicity (DLT), necessitating expansion of cohort IV. No subsequent DLTs were noted. Thus, the maximum planned doses were well tolerated, and a formal MTD was not determined. Most hematologic toxicities were grade 1 or 2. There was low-grade fatigue, nausea/vomiting, and myalgias/arthralgias. Oblimersen C_ss and AUC increased in relation to the dose escalation, but gemcitabine triphosphate levels did not correlate well with dose. There were no objective responses, though 5 patients had stable disease. A >75% reduction in Bcl-2 expression in peripheral blood mononuclear leucocytes was seen more frequently in patients who achieved stable disease than in progressing patients. Conclusions: The maximal planned dose levels of oblimersen and gemcitabine in combination were well tolerated. Only one DLT (edema) occurred. There was a correlation between Bcl-2 reduction and stable disease. The recommended doses of the drugs for future studies are 7 mg/kg/day of oblimersen on days 1–5, and gemcitabine 1,500 mg/m² on day 5, every two weeks.     

Dextranomer in stabilized sodium hyaluronate (Solesta®): in adults with faecal incontinence

Dextranomer in stabilized sodium hyaluronate, hereafter referred to as dextranomer/hyaluronic acid, is a biocompatible bulking agent administered by submucosal injection. It is hypothesized to expand the submucosal layer of the proximal anal canal, thereby augmenting bowel control. Treatment with dextranomer/hyaluronic acid was associated with symptomatic improvements in adult patients with faecal incontinence participating in a randomized, double-blind, sham-controlled, multinational study and a noncomparative, multinational study. In the double-blind study, patients in the dextranomer/hyaluronic acid group met the primary efficacy objective in that a significantly higher proportion of patients responded to treatment (≥50% reduction from baseline in the number of incontinence episodes) at the 6-month post-treatment timepoint than in the sham group (two of three primary response criteria), with the durability of the treatment response (≥25% reduction from baseline in the number of incontinence episodes) confirmed at the 12-month post-treatment timepoint (third primary response criterion). For the most part, dextranomer/hyaluronic acid did not significantly differ from the sham treatment in terms of quality of life and various other symptomatic endpoints at 6 months post-treatment in the double-blind study, although there were significant improvements from baseline in various parameters, such as the mean number of incontinence-free days, the median number of incontinence episodes and mean Faecal Incontinence Quality of Life domain scores, at 12 months post-treatment. In general, dextranomer/hyaluronic acid was well tolerated for up to 18 months post-treatment, with the majority of treatment-related adverse events considered mild or moderate in intensity.     

Omega-3 Carboxylic Acids (Epanova®): A Review of Its Use in Patients with Severe Hypertriglyceridemia

Omega-3 carboxylic acids (Epanova^®) [OM3-CA] is the first free fatty acid form of long-chain marine omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid being the most abundant) to be approved by the US FDA as an adjunct to diet to lower triglyceride levels in patients with severe hypertriglyceridemia (≥500 mg/dL). Oral OM3-CA has greater bioavailability than ethyl ester forms of omega-3 and, unlike omega-3 acid ethyl esters, does not require co-ingestion of a high-fat meal, as it does not need pancreatic enzyme activity for absorption. In the 12-week EpanoVa fOr Lowering Very high triglyceridEs (EVOLVE) trial, OM3-CA 2 or 4 g/day significantly reduced serum triglyceride levels relative to placebo. Other lipid parameters, including non-high-density lipoprotein cholesterol (non-HDL-C), total cholesterol, and very low-density lipoprotein cholesterol (VLDL-C) levels, were also reduced significantly with OM3-CA relative to placebo. Low-density lipoprotein cholesterol levels were increased significantly with OM3-CA relative to placebo; however, these increases were not accompanied by increases in the circulating concentrations of non-HDL-C, VLDL-C, or apolipoprotein B. OM3-CA was generally well tolerated in this study, with most adverse events being of mild or moderate severity. Although additional comparative data are needed to position OM3-CA with respect to other formulations of omega-3 fatty acids, current evidence suggests that OM3-CA is a useful addition to the treatment options available for patients with severe hypertriglyceridemia.     

Influence of the A and B subunits of cholera toxin (CT) and Escherichia coli toxin (LT) on TNF-α release from macrophages

In this study an in vitro model was developed with the aim of investigating the modulatory effect of cholera toxin (CT) and its counterpart the heat labile toxin of Escherichia coli (LT) on TNF-α release induced by murine macrophages and primary human monocytes. Previous studies have demonstrated that the enzymatic activity of CT and LT molecules can inhibit TNF-α release by macrophages. The results obtained in this study showed that CT and LT are both, in a dose dependent manner, able either to induce or inhibit TNF-α release by murine macrophages and primary human monocytes. The results also showed that recombinant B subunits of CT and LT in the absence of their A subunit induce high levels of TNF-α release by macrophages and, in addition, increase the level of TNF-α release induced by LPS. The ability of both B subunits (CTB and LTB) in inducing TNF-α release by macrophages is not related to the level of LPS contamination, since direct measurements of LPS made in the samples employed in this study showed only traces of LPS (3.4 × 10⁻⁸ EU/ml) which is in our system does not induce TNF-α release by macrophages. In contrast to the results obtained with the B subunits, incubation of cells with the A subunit of CT (CTA) inhibit TNF-α release induced by native CT, native LT, recombinant LTB and LPS. This inhibitory effect must be related to the activity of the A subunit since viability tests performed in terms of metabolic rate demonstrated that high concentrations of CTA are not toxic to the cells. The data presented herein demonstrate that the A subunits of CT and LT have an inhibitory effect on TNF-α release in macrophages, whereas their B subunits have a stimulatory effect on TNF-α. The results also suggest that the dose dependent bi-modal effect of native CT and native LT on TNF-α release by macrophages is a result of the combined effect of their individual A and B subunits.     

Population pharmacokinetics of recombinant factor VIII:C (ReFacto®) in adult HIV-negative and HIV-positive haemophilia patients

Purpose

The aim of this study was to explore possible differences in the pharmacokinetics (PK) of recombinant factor VIII:C (ReFacto® - ReFacto ) in HIV+ vs. HIV– patients and also differences in the chromogenic substrate bioassay (CHS) and one-stage clotting (OSC) methods.

Methods

Twenty-eight haemophilia A adults (20 HIV– and eight HIV+) were assayed with both the CHS and OSC methods. An average of two and six samples were collected per patient for HIV–/+, respectively, after one, and occasionally two more, prophylactic doses (mean 2,003 IU; range 1,000–4,300 IU). The observations were analysed with the mixed-effects (population) compartmental PK modelling package NONMEM (nonlinear mixed-effects modelling) and the FOCE (first-order conditional estimation) method. Base modelling was performed independently for the CHS and OSC bioassays for comparison, and covariate models and simulation tests were done only for the commonly used OSC bioassay. The final covariate model was validated using the bootstrap method. Monte Carlo simulations were used to estimate the expected probability of exceeding 20%, 40% or 60% of normal factor VIII:C in plasma after a single dose, corresponding to required levels for preventing mild, moderate and life-threatening haemorrhages.

Results

One-compartment base-model population PK parameters were [mean parameter (interpatient variability %)] for CHS: clearance (CL)?=?2.56 dl h^?1 (33.2%); volume of distribution (V)?=?34.8 dl (12.8%); and for OSC: CL?=?3.83 dl h^?1 (47.8%), V?=?53.7 dl (22.4%). The volumes differed significantly between the CHS and OSC methods (p?1/2?=?l n (2) × V/CL) were similar for CHS and OSC, [(mean ± standard deviation (SD)], 9.5 ± 3 h and 10.2 ± 4 h, respectively. In covariate modelling with the OSC-derived model, HIV status (VIR) was a significant categorical predictor (p?

Conclusions

Both HIV– and HIV+ patients showed 100% success with the 20% threshold at doses >20 IU/kg. HIV– patients receiving >50 IU/kg had a 100% expected chance of success for all thresholds. HIV+ patients for moderate or life-threatening haemorrhage treatment need 10 IU/kg more than the HIV– patient equivalent to have the same probability of success.

     

Comparison of Zafirlukast (Accolate®) Absorption After Oral and Colonic Administration in Humans

Purpose. This study characterized the gastrointestinal (GI) absorptionof zafirlukast after oral and colonic administration in humans. Methods. Five healthy subjects received zafirlukast solution (40 mg)orally and via an oroenteric tube into the colon in a randomized,crossover fashion. Two additional subjects were dosed into the distalileum. Serial blood samples were obtained and plasma concentrationswere quantitated by HPLC. Results. Mean ± SD pharmacokinetic parameters after oral vs. colonicadministration were: AUC of 2076 ± 548 vs. 602 ± 373 ng*h/mL,respectively, and C_max of 697 ± 314 vs. 194 ± 316 ng/mL, respectively.Mean colon:oral AUC and C_max were 0.29 and 0.30, respectively.Median t_max values were 2.0 and 1.35 hr after oral and colonicadministration. First-order absorption rate constants (K_a and K_ac) wereestimated from a two-compartment model with first-order elimination.K_ac:K_a was <0.5 in 4 of the 5 subjects dosed in the colon. Conclusions. Zafirlukast was absorbed at multiple sites in the GI tract.The rate and extent of zafirlukast absorption was less after colonicthan oral administration. Zafirlukast was significantly absorbed in thedistal ileum. This study demonstrated that gamma scintigraphy, digitalradiography, and fluoroscopy can be used to track the movement andconfirm the location of the oroenteric tube in the GI tract.     

A pharmacokinetic–pharmacodynamic model for intrathecal baclofen in patients with severe spasticity

Aims

Intrathecal baclofen (ITB) has proven to be an effective and safe treatment for severe spasticity. However, although ITB is used extensively, clinical decisions are based on very scarce pharmacokinetic–pharmacodynamic (PKPD) data. The aim of this study was to measure baclofen CSF concentrations and clinical effects after administration of various ITB boluses in patients with spasticity and to create a PKPD model for ITB.

Methods

Twelve patients with severe spasticity received four different bolus doses of ITB (0, 25, 50, 75 μg and an optional dose of 100 μg), administered via a catheter with the tip at thoracic level (Th) 10. After each bolus, 10 CSF samples were taken at fixed time intervals, using a catheter with the tip located at Th12. Clinical effect was assessed by measuring spasticity with the Modified Ashworth Scale (MAS). These data were used to develop a PKPD model.

Results

All patients achieved an adequate spasmolytic effect with ITB doses varying from 50 to 100 μg. No serious side effects were observed. CSF baclofen concentrations, as well as the clinical effects, correlated significantly with ITB doses. The PK model predicted a steep spinal concentration gradient of ITB along the spinal axis. The clinical effect could be predicted using a delayed‐effect model.

Conclusions

ITB is an effective and safe therapy with, however, a steep concentration gradient along the spinal axis. This means that the administered baclofen is staying mainly around the catheter tip, which stresses the importance to position the ITB catheter tip closely to the targeted spinal level.     

Safety and Toxicokinetics of Intravenous Liposomal Amphotericin B (AmBisome ®) in Beagle Dogs

Purpose. Amphotericin B (AmB) in small, unilamellar liposomes (AmBisome ^®) has an improved therapeutic index, and altered pharmacokinetics. The repeat-dose safety and toxicokinetic profiles of AmBisome were studied at clinically relevant doses. Methods. Beagle dogs (5/sex/group) received intravenous AmBisome (0.25, 1,4, 8, and 16 mg/kg/day), empty liposomes or vehicle for 30 days. AmB was determined in plasma on days 1, 14, and 30, and in tissues on day 31. Safety parameters included body weight, clinical chemistry, hematology and microscopic pathology. Results. Seventeen of twenty animals receiving 8 and 16 mg/kg were sacrificed early due to weight loss caused by reduced food intake. Dose-dependent renal tubular nephrosis, and other effects characteristic of conventional AmB occurred at 1 mg/kg/day or higher. Although empty liposomes and AmBisome increased plasma cholesterol, no toxicities unique to AmBisome were revealed. Plasma ultrafiltrates contained no AmB. AmBisome achieved plasma levels 100-fold higher than other AmB formulations. AmBisome kinetics were non-linear, with clearance and distribution volumes decreasing with increasing dose. This, and nonlinear tissue uptake, suggest AmBisome disposition was saturable. Conclusions. AmBisome has the same toxic effects as conventional AmB, but they appear at much higher plasma exposures. AmBisome's non-linear pharmacokinetics are not associated with increased risk, as toxicity increases linearly with dosage. Dogs tolerated AmBisome with minimal to moderate changes in renal function at doses (4 mg/kg/day) producing peak plasma concentrations of 18–94 µg/mL.     

A farnesylated G-protein suppresses Akt phosphorylation in INS 832/13 cells and normal rat islets: regulation by pertussis toxin and PGE₂

Protein isoprenylation constitutes incorporation of either 15-carbon farnesyl or 20-carbon geranylgeranyl derivative of mevalonic acid onto the C-terminal cysteine, culminating in increased hydrophobicity of the modified proteins for optimal membrane anchoring and interaction with their respective effectors. Emerging evidence confirms the participatory role of prenylated proteins in pancreatic β-cell function including insulin secretion. Herein, we investigated the putative regulatory roles of protein farnesylation in cell survival signaling pathways in insulin-secreting INS 832/13 cells and normal rodent islets, specifically at the level of protein kinase-B/Akt phosphorylation induced by insulin-like growth factor [IGF-1]. Selective inhibitors of farnesylation [e.g., FTI-277 or FTI-2628] or knockdown of the β-subunit of farnesyl transferase by siRNA significantly increased Akt activation under basal and IGF-1-stimulated conditions. Consequentially, the relative abundance of phosphorylated FoxO1 and Bad were increased implicating inactivation of critical components of the cell death machinery. In addition, FTI-induced Akt activation was attenuated by the PI3-kinase inhibitor, LY294002. Exposure of INS 832/13 cells to pertussis toxin [PTx] markedly potentiated Akt phosphorylation suggesting involvement of a PTx-sensitive G-protein in this signaling axis. Furthermore, prostaglandin E?, a known agonist of inhibitory G-proteins, significantly attenuated FTI-induced Akt phosphorylation. Taken together, our findings suggest expression of a farnesylated G-protein in INS 832/13 cells and normal rat islets, which appear to suppress Akt activation and subsequent cell survival signaling steps. Potential regulatory roles of the islet endogenous protein kinase-B inhibitory protein [Probin] in islet function are discussed.     

Study of the Complex Between the Contrast Agent lobitridol (Xenetix®) and Elastase (PPE): A Model for Hydrophobic Site Protection in Drug-Protein Interactions

Purpose. The concept of Hydrophilic Sphere Stabilization, or Hydrophobic Shielding, has been postulated in the synthesis of biocompatible contrast agents in vascular imaging. To improve the safety of these polyiodinated agents, interactions with protein hydrophobic sites in biomacromolecules should be kept as low as possible. In order to evaluate the level of interactions with proteins, we have selected the serine proteinase Elastase, in presence of Iobitridol (Xenetix^®), as a model. Methods. The complex between Iobitridol and Pancreatic Porcine Elastase was investigated by X-ray diffraction techniques, on saturated monocrystals, using the synchrotron radiation at 0.98. Results. In contrast to Iohexol, which displays several interactions including one in the active site, Iobitridol is unable to interact directly with elastase. Only one partially occupied site is found in between two molecules of the crystal packing. Conclusions. The validation of the 'hydrophobic shielding' concept, which was at the origin of the design of the Iobitridol molecule, has been proven to be an essential feature in minimizing in vivo protein interactions.     

The Metabolites of Oxprenolol (Trasicor®) in man

Abstract

1. Two volunteers given a single oral dose of [³H]oxprenolol, excreted 70% and 95% of the radioactivity in the urine in 48 h. 78% and 71% of the urinary radioactivity is attributed to metabolites more polar than oxprenolol.

2. Metabolites, identified by mass spectrometry and isotope dilution analysis were as follows: I. the glucuronide of unchanged oxprenolol, II. a conjugate of a derivative of oxprenolol hydroxylated in the aromatic ring, III. unchanged oxprenolol, IV. the hydroxycarboxylic acid derived from oxprenolol by oxidative deamination, V. a carboxylic acid with the carboxyl group in the position of the former carbinol, VI. the monoallyl ether of catechol.     

Correlation of the intrinsic clearance of donepezil (Aricept®) between in vivo and in vitro studies in rat,dog and human

1. Donepezil hydrochloride (Aricept®) is used for the treatment of Alzheimer's disease. Here the correlation of the intrinsic clearance (Cl_int) of donepezil between the in vivo and in vitro states was studied in rat, dog and human. 2. In an experiment with ¹⁴C-donepezil and human microsomes the routes of metabolism were identified as N-dealkylation and O-demethylation, and no unknown metabolites were detected. 3. The Cl_int of donepezil in the male rat, female rat, dog and human liver microsomes were 33.7, 13.4, 37.0 and 6.35 μl/min/mg microsomal protein respectively, and sex difference in rat and interspecies difference in the estimated Cl_int were found. 4. After a single intravenous administration to the male rat, female rat and dog, total plasma clearance (Cl^P_total) was 78.6, 29.5 and 88.3 ml/min/kg respectively, and a sex difference was observed in rat. 5. After a single oral administration to the male rat, dog and healthy volunteer, Cl^P_total/F was 140, 105 and 2.35 ml/min/kg respectively, and remarkable differences were observed between animals and man. 6. The contribution of renal clearance to blood clearance (Cl_r) was low in all species. The predicted in vitro hepatic clearance (Cl_h-pre) was in the rank order: male rat (15.91 ml/min/kg) &gt; dog (7.96) &gt; female rat (7.67) &gt; human (1.04). Although Cl_h-pre was underestimated, Cl_h-pre was significantly correlated with that of ClBtotal in the different animal species and in man, indicating that the in vitro-in vivo ranking order was conserved.     

Comparison of octenidine dihydrochloride (Octenisept®), polihexanide (Prontosan®) and povidon iodine (Betadine®) for topical antibacterial effects in Pseudomonas aeruginosa-contaminated,full-skin thickness burn wounds in rats

Pseudomonas aeruginosa is one of the most frequently isolated organisms from infected burn wounds and a significant cause of nosocomial infection and septic mortality among burn patients. In this animal study, three antiseptic agents which were Octenidine dihydrochloride (Octenisept®, Schülke &; Mayr, Norderstedt, Germany), polyhexanide (Prontosan®, B. Braun, Melsungen AG, Germany) and povidon iodine (Betadine, Purdue Pharma L.P, Stamford, USA) were compared to assess the antiseptic effect of their applications on experimental burn wounds in in rats contaiminated with P. aeruginosa. All treatment modalities were effective against P. aeruginosa because there were significant differences between treatment groups and control groups. The mean eschar concentrations were not different between polyhexanide and povidon iodine groups, but there were significant differences between the octenidine dihydrochloride group and the other treatment groups, indicating that the Octenidine dihydrochloride significantly eliminated P. aeruginosa more effectively in the tissues compared to the to other agents. All treatment modalities were sufficient to prevent the P. aeruginosa invasion into the muscle and to cause systemic infection. In conclusion, Octenidine dihydrochloride is the most effective antiseptic agent in the treatment of the P. aeruginosa-contaminated burn wounds; Octenidine dihydrochloride can be considered as a treatment choice because of its peculiar ability of limit the frequency of replacing wound dressings.