Cyclodextrin Reduces Intravenous Toxicity of a Model Compound

Solubilization of new chemical entities for toxicity assessment must use excipients that do not negatively impact drug pharmacokinetics and toxicology. In this study, we investigated the tolerability of a model freebase compound, GDC-0152, solubilized by pH adjustment with succinic acid and complexation with hydroxypropyl-β-cyclodextrin (HP-β-CD) to enable intravenous use. Solubility, critical micelle concentration, and association constant with HP-β-CD were determined. Blood compatibility and potential for hemolysis were assessed in vitro. Local tolerability was assessed after intravenous and subcutaneous injections in rats. A pharmacokinetic study was conducted in rats after intravenous bolus administration.GDC-0152 exhibited pH-dependent solubility that was influenced by self-association. The presence of succinic acid increased solubility in a concentration-dependent manner. HP-β-CD alone also increased solubility, but the extent of solubility enhancement was significantly lower than succinic acid alone. Inclusion of HP-β-CD in the solution of GDC-0152 improved blood compatibility, reduced hemolytic potential by ～20-fold in vitro, and increased the maximum tolerated dose to 80 mg/kg.     

Effects of Various Pharmaceutical Excipients on the Intestinal Transport and Absorption of Sulfasalazine,a Typical Substrate of Breast Cancer Resistance Protein Transporter

Breast cancer resistance protein (BCRP) transporter is an efflux transporter that utilizes energy from adenosine triphosphate hydrolysis to push its substrates, regardless of the concentration gradient. Its presence on the apical membrane of the intestinal mucosa is a major obstacle for the intestinal absorption of its substrates. In this study, we examined the effects of various pharmaceutical excipients on the intestinal transport and absorption of sulfasalazine, a BCRP substrate. Four excipients, including 0.05% and 0.075% BL-9EX, 0.01% and 0.05% Brij 97, 0.075% Labrasol, and 0.05% and 0.1% Tween 20 decreased the secretory transport of sulfasalazine in an in vitro diffusion chamber. Further investigation in an in situ closed loop experiment in rats showed that 0.05% and 0.1% BL-9EX and 0.1% Brij 97 effectively enhanced the intestinal absorption of sulfasalazine while maintaining minimal toxicity to the intestinal mucosa. However, 0.1% Brij 97 also increased the intestinal absorption of 5(6)-carboxyfluorescein, a paracellular marker compound. These findings suggest that BL-9EX might effectively inhibit the BCRP-mediated efflux of sulfasalazine in vivo, indicating that BL-9EX could improve the intestinal absorption of sulfasalazine and other BCRP substrates.     

复方丹参脉冲控释滴丸的制备及其体外释放度考察

目的 制备复方丹参脉冲控释滴丸,并考察其体外释放度.方法 以复方丹参滴丸为载药丸芯,对包衣材料配比及包衣材料用量进行选择,对控释滴丸体外释药情况进行考察.结果 溶胀层的种类与包衣增重、控释层的包衣增重对药物的释放影响显著,采用交联羧甲基纤维素钠（CMC-Na）作为溶胀层材料,乙基纤维素水分散体作为控释层材料,溶胀层包衣增重12％,控释层包衣增重20％,所制备的微丸时滞时间为4h左右,时滞后3h内累积释药达到80％.结论 制备的复方丹参脉冲控释滴丸体外释放可达到脉冲控释效果.     

Ultrapure alginate anti-adhesion gel does not impair colon anastomotic strength

Background

Ultrapure alginate gel is promising in terms of adhesion prevention. Because anti-adhesive barriers have been shown to disturb healing of bowel anastomoses, the effect of ultrapure alginate gel on the repair of colon anastomoses was studied.

Materials and methods

In 102 male Wistar rats, a 0.5-cm segment was resected from the descending colon and continuity was restored by an inverted single-layer end-to-end anastomosis. Animals were randomized into a control, an alginate gel, and a sodium hyaluronate carboxymethyl cellulose film group, each n = 34. Half of each group was sacrificed at day 3 and 7 postoperatively. Anastomotic strength was assessed by measuring both bursting pressure and breaking strength. Hydroxyproline content was measured and histologic analysis was performed. The incidence of adhesion and abscess formation was scored at sacrifice.

Results

No difference in either anastomotic-bursting pressure or breaking strength was found between experimental groups and the controls at any time point. Both the incidence of adhesion formation (35% versus 71%, P = 0.007) and the adhesion score (0.38 versus 0.79, P = 0.009) were significantly lower in the alginate gel group than in the controls. The abscess rate was higher (46% versus 18%, P = 0.030) in the hyaluronate carboxymethyl cellulose group than in the controls and unchanged in the alginate gel group.

Conclusions

While reducing adhesion formation, ultrapure alginate gel does not interfere with the development of colonic anastomotic strength during the crucial early healing period.     

Corticomuscular coherence in acute and chronic stroke

ObjectiveMotor recovery after stroke is attributed to neuronal plasticity, however not all post-stroke neuronal changes relate to regaining fine motor control. Corticomuscular coherence (CMC) is a measure allowing to trace neuronal reorganizations which are functionally relevant for motor recovery. Contrary to previous studies which were performed only in chronic stage, we measured CMC in patients with stroke at both acute and chronic stroke stages.MethodsFor the detection of CMC we used multichannel EEG and EMG recordings along with an optimization algorithm for the detection of corticomuscular interactions.ResultsIn acute stroke, the CMC amplitude was larger on the unaffected side compared to the affected side and also larger compared to the unaffected side in the chronic period. Additionally, CMC peak frequencies on both sides decreased in the acute compared to the chronic period and to control subjects. In chronic stage, there were no inter-hemispheric or group differences in CMC amplitude or frequency.ConclusionsThe changes in CMC parameters in acute stroke could result from a temporary decrease in inhibition, which normalizes in the course of recovery. As all patients showed very good motor recovery, the modulation of CMC amplitude and frequency over time might thus reflect the process of motor recovery.SignificanceWe demonstrate for the first time the dynamical changes of corticomuscular interaction both at acute and chronic stage of stroke.     

Pharmacokinetic aspects and in vitro–in vivo correlation potential for lipid-based formulations

Lipid-based formulations have been an attractive choice among novel drug delivery systems for enhancing the solubility and bioavailability of poorly soluble drugs due to their ability to keep the drug in solubilized state in the gastrointestinal tract. These formulations offer multiple advantages such as reduction in food effect and inter-individual variability, ease of preparation, and the possibility of manufacturing using common excipients available in the market. Despite these advantages, very few products are available in the present market, perhaps due to limited knowledge in the in vitro tests (for prediction of in vivo fate) and lack of understanding of the mechanisms behind pharmacokinetic and biopharmaceutical aspects of lipid formulations after oral administration. The current review aims to provide a detailed understanding of the in vivo processing steps involved after oral administration of lipid formulations, their pharmacokinetic aspects and in vitro in vivo correlation (IVIVC) perspectives. Various pharmacokinetic and biopharmaceutical aspects such as formulation dispersion and lipid digestion, bioavailability enhancement mechanisms, impact of excipients on efflux transporters, and lymphatic transport are discussed with examples. In addition, various IVIVC approaches towards predicting in vivo data from in vitro dispersion/precipitation, in vitro lipolysis and ex vivo permeation studies are also discussed in detail with help of case studies.KEY WORDS: Pharmacokinetics, Lipolysis, IVIVC, Efflux transporters, Lymphatic delivery, Food effectAbbreviations: ADME, absorption/distribution/metabolism/elimination; AUC, area under the curve; BCS, biopharmaceutics classification system; BDDCS, biopharmaceutics drug disposition classification system; CACO, human epithelial colorectal adenocarcinoma cells; C_max, maximum plasma concentration; CMC, critical micellar concentration; CYP, cytochrome; DDS, drug delivery systems; FaSSGF, fasted-state simulated gastric fluid; FaSSIF, fasted-state simulated intestinal fluid; FeSSIF, fed-state simulated intestinal fluid; GIT, gastrointestinal tract; IVIVC, in vitro in vivo correlation; LCT, long chain triglyceride; LFCS, lipid formulation classification system; log P, n-octanol/water partition coefficient; MCT, medium chain triglyceride; MDCK, Madin–Darby canine kidney cells; NCE, new chemical entity; P-app, apparent permeability; P-gp, permeability glycoprotein; SCT, short chain triglyceride; SEDDS, self-emulsifying drug delivery system; SIF, simulated intestinal fluid; SMEDDS, self-microemulsifying drug delivery system; SNEDDS, self-nanoemulsifying drug delivery system; Vit E, vitamin E