Conversion and pharmacokinetics profiles of a novel pro-drug of 3-n-butylphthalide, potassium 2-(1-hydroxypentyl)-benzoate, in rats and dogs.

Potassium 2-(1-hydroxypentyl)-benzoate (dl-PHPB) is a novel pro-drug of 3-n-butylphthalide (dl-NBP) that is used to treat ischemic stroke. Currently, dl-PHPB is in phase II-III clinical trials in China. In this study, we investigated the conversion and pharmacokinetics profiles of dl-PHPB in vitro and in vivo. The conversion of dl-PHPB to dl-NBP was pH- and calcium-dependent, and paraoxonase was identified as a major enzyme for the conversion in rat plasma. The pharmacokinetics, tissue distribution and excretion of dl-PHPB were studied and compared with equal-molar doses of dl-NBP in rats and dogs. The in vivo studies showed that dl-PHPB could be quickly and completely converted to dl-NBP. The plasma concentration-time course of converted dl-NBP after intravenous dl-PHPB administration was nearly the same as that after equal-molar dl-NBP. The Cmax and AUC of dl-NBP after oral dl-PHPB administration in rats and dogs were higher by 60% and 170%, respectively, than those after oral dl-NBP administration. Analysis of the tissue distribution of dl-PHPB revealed that converted dl-NBP was primarily distributed in fat, the brain and the stomach. In the brain, the levels of dl-NBP were relatively higher after dl-PHPB treatment by orally than after treatment with equal-molar dl-NBP. Approximately 3%-4% of dl-NBP was excreted within 72 h after dosing with dl-PHPB or dl-NBP, but no dl-PHPB was detected in urine or feces excrements. Our results demonstrate that the conversion of dl-PHPB is fast after oral or intravenous administration. Furthermore, the bioavailability of dl-PHPB was obviously better than that of dl-NBP.

Thermo-sensitive isopentane aerification for mucosal lift during endoscopic resection in animal models (with video).

BACKGROUND AND AIMS: Mucosal lift is critical for successful endoscopic treatment. Normal saline (NS) solution is widely used as the submucosal filler, but its short persistency restricts clinical endoscopic submucosal dissection (ESD). In this study, thermo-sensitive isopentane was introduced for submucosal injection. With a boiling point at 27.8°C, liquid isopentane can be easily applied, and gasification inflation can provide great support for submucosal lifting at body temperature. The feasibility and efficiency of isopentane were evaluated in this study. METHODS: Porcine stomachs were used for in vitro evaluation. A 37°C water bath was used to mimic body temperature. Compared with NS, isopentane was studied for its lifting performance, including injection dosage, persistence of lifting strength, and efficacy for assisting submucosal dissection. The changes in submucosal tissue were also compared. For in vivo evaluation, rats were used to further compare the differences between isopentane and NS, including lifting efficacy, pathologic effect, and safety. RESULTS: Compared with NS, the maximum lifting height was achieved with less isopentane (2% NS volume). Longer persistency and faster operation for submucosal dissection were also recorded for isopentane during the in vitro study. Aerification resulted in vacuolization of submucosal connective tissue, which facilitates EMR and postoperative recovery. The same results were confirmed in the rat model. With the same dosage, isopentane produced better mucosal elevation and larger range than NS. According to the histologic examination, no tissue injury was observed with isopentane application. CONCLUSIONS: As a submucosal injection agent, the feasibility, efficacy, and safety of isopentane has been demonstrated. Thermo-sensitive aerification may be a promising approach to facilitate ESD.

A thermoplastic elastomer patch matrix for traditional Chinese medicine: design and evaluation.

OBJECTIVE: To design and evaluate a novel pressure sensitive adhesive (PSA) patch containing traditional Chinese medicine (TCM) using styrene-isoprene-styrene (SIS) copolymer. METHOD: A mixture D-optimal design with ternary response surface diagram was employed in the optimization process. The proportions of SIS copolymer, tackifying resin and plasticizer were selected as the independent variables while tack force, peel strength of the patch and skin penetrability of methyl salicylate were selected as the dependent variables. The optimized patch was then evaluated including in vivo absorption, pharmacological activities and skin irritation, by comparing with a commercial patch based on natural rubber. RESULTS: The optimized patch, which comprised 30.0% SIS copolymer, 26.6% tackifying resin and 43.4% plasticizer, was superior to commercial patch in skin permeation, pharmacological activities and skin biocompatibility. CONCLUSION: SIS copolymer was a suitable substitute to natural rubber in producing patches containing TCM formula.

Dermal peptide delivery using enhancer molecules and colloidal carrier systems--part I: carnosine.

Due to the lipophilic properties of the uppermost skin layer of the stratum corneum (SC), it is highly challenging to attain therapeutic concentrations of active substances; hydrophilic drugs, in particular, penetrate poorly. The purpose of this study was the improvement of the topical bioavailability of the hydrophilic dipeptides L-carnosine and its related compound N-acetyl-L-carnosine. Different strategies were investigated. On the one hand, an enhancer molecule, 1,2-pentylene glycol (PG), was added to a standard preparation, and on the other hand, a microemulsion (ME-PG) system was developed. Both were compared to the standard formulation without an enhancer molecule. For all 3 preparations, the penetration of the peptides in ex vivo human skin was investigated. This allows statements to be made regarding dermal penetration, localization and distribution of the active substances in each skin layer as well as the influence of vehicle variations, in this case, the addition of PG or the incorporation of N-acetyl-L-carnosine in an ME-PG system. For L-carnosine and N-acetyl-L-carnosine, the use of the standard preparation with PG resulted in a significant increase of the substance within the SC. Approximately 6-fold and higher dipeptide concentrations in the SC and in the viable skin layers were detected at all experimental periods compared to the formulation without the enhancer molecule and the ME-PG. High concentrations of the compounds were found after a short period of time in the viable skin layers after applying the enhancer molecule, even in concentrations of 5%. The application of the colloidal carrier system did not lead to a higher penetration rate of N-acetyl-L-carnosine in comparison to both standard preparations, although it must be said that the microstructure of the investigated ME-PG might not have been optimal for the hydrophilic properties of the dipeptide.

Safety assessment of 1,2-glycols as used in cosmetics.

Caprylyl glycol and related 1,2-glycols are used mostly as skin and hair conditioning agents and viscosity agents in cosmetic products, and caprylyl glycol and pentylene glycol also function as cosmetic preservatives. The Cosmetic Ingredient Review (CIR) Expert Panel noted that, while these ingredients are dermally absorbed, modeling data predicted decreased skin penetration of longer chain 1,2-glycols. Because the negative oral toxicity data on shorter chain 1,2-glycols and genotoxicity data support the safety of the 1,2-glycols reviewed in this safety assessment, the Panel concluded that these ingredients are safe in the present practices of use and concentration described in this safety assessment.

Evaluation of Microparticulate (S)-4,5-Dihydroxy-2,3-pentanedione (DPD) as a Potential Vaccine Adjuvant.

Adjuvants potentiate the immune response against co-inoculated antigens in the vaccine formulation. Based on the mechanism of action, the adjuvants are classified as immunostimulatory adjuvants and vaccine delivery systems. (S)-4,5-Dihydroxy-2,3-pentanedione (DPD) is the precursor of bacterial quorum sensing molecule, autoinducer (AI)-2. We tested the immunogenicity and adjuvant potential of microparticulate formulation of (S)-DPD via in vitro evaluation. By formulating the microparticles of (S)-DPD, we consolidated the advantages of both the classes of adjuvants. The microparticulate (S)-DPD was tested for its immunogenicity and cytotoxicity. We further tested its adjuvant effect by combining it with particulate vaccines for measles and gonorrhea and compared the adjuvant effect observed with the microparticulate formulations of the FDA-approved adjuvants alum, MPL A®, and MF59®. Microparticulate (S)-DPD was found to be non-cytotoxic towards the antigen-presenting cells and had an adjuvant effect with microparticulate gonorrhea vaccine. Further studies with additional bacterial vaccines and the in vivo evaluation will confirm the potential of microparticulate (S)-DPD as a probable vaccine adjuvant candidate.

Comparing the effects of brushing with a new gel-to-foam dentifrice to brushing with regular fluoride control dentifrices on viable bacteria levels in saliva.

PURPOSE: To compare the effects of a new gel-to-foam dentifrice to two standard fluoride control dentifrices on foam generation, levels of total viable anaerobes and total viable volatile sulfur compound (VSC)-producing bacteria in expectorate after brushing. METHODS: 36 subjects participated in this investigator-blind, randomized, crossover study. After a 1-week wash-out period prior to each product use, participants reported to the test site having refrained from oral hygiene, eating and drinking on the morning prior to the visit. Subjects brushed with a full ribbon of assigned dentifrice (Aquafresh Iso-active, Aquafresh Extreme Clean or Aquafresh Fresh & Minty), then expectorated the slurry into a collection vessel after 30 and 60 seconds of supervised brushing. Total foam volume was immediately measured. Subjects then rinsed with sterile water for 10 seconds and expectorated into the same vessel, which was processed for microbiological analysis. Total viable anaerobes and total viable VSC-producing bacteria were enumerated using appropriate selective media. RESULTS: No statistically significant difference was indicated between the gel-to-foam dentifrice and either of the control dentifrices with respect to the level of total viable anaerobes (P > 0.05). The level of total viable VSC-producing bacteria was statistically significantly lower for the gel-to-foam dentifrice (Aquafresh Iso-active) than for one of the control dentifrices (Aquafresh Fresh & Minty) (P < 0.05), and numerically lower for the gel-to-foam dentifrice than for the other control dentifrice (Aquafresh Extreme Clean) (P = 0.0526). Use of the gel-to-foam dentifrice resulted in statistically significantly greater (P < 0.05) foam generation than the two control dentifrices.

Pharmacokinetics and tissue distribution of N-(2-hydroxyphenyl)-2-propylpentanamide in Wistar Rats and its binding properties to human serum albumin.

N-(2-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA) is a novel valproic acid derivative that has shown anti-proliferative activity against epitheloid cervix carcinoma (HeLa), rhabdomyosarcoma (A204), and several breast cancer cell lines. The aim of this research was to evaluate the pharmacokinetic profile and tissue distribution of HO-AAVPA in Wistar rats, as well as its human serum albumin binding potential by experimental and in silico methods. A single dose of HO-AAVPA was given to male rats by intravenous, intragastric or intraperitoneal routes at doses of 25, 100, and 100 mg/kg, respectively. Then, blood samples were drawn at predetermined intervals of time, and the HO-AAVPA concentration in the plasma was quantified with a validated HPLC method. The elimination half-life (t1/2) was approximately 222 min, and the systemic clearance (CL) and apparent volume of distribution (Vd) were 2.20 mL/min/kg and 0.70 L/kg, respectively. The absolute oral bioavailability of HO-AAVPA was 33.8%, and the binding rate of HO-AAVPA with rat plasma proteins was between 66.2% and 83.0%. Additionally, in silico, UV and Raman spectroscopy data showed weak interactions between the test compound and human serum albumin. Thus, the results that were obtained demonstrated that despite its low oral bioavailability, the potential anticancer agent HO-AAVPA exhibits acceptable pharmacokinetic properties that would allow it to reach its site of action and exert its pharmacological effect in Wistar Rats, and it has a convenient profile for future assays to evaluate its human applications.

Potassium 2-(1-hydroxypentyl)-benzoate inhibits ADP-induced rat platelet aggregation through P2Y1-PLC signaling pathways.

Potassium 2-(1-hydroxypenty1)-benzoate (dl-PHPB) is a new drug candidate for treatment of ischemic stroke with antiplatelet effect. In this study, we investigated the mechanisms of dl-PHPB in inhibiting platelet aggregation. The ADP-activated P2Y1-Gq-PLC and P2Y12-Gi-AC pathways were observed, respectively. Intravenous injection of dl-PHPB (1.3, 3.9, 12.9 mg/kg) significantly inhibited ADP-, collagen-, and arachidonic acid-induced rat platelet aggregation in a dose-dependent manner, and dl-PHPB had a relatively more potent inhibitory effect on ADP-induced rat platelet aggregation than other agonists. Dl-PHPB also showed a decreased expression of CD62P (a marker for platelet activation) mediated by ADP. Both dl-PHPB and ticlopidine (P2Y12 receptor antagonist) decreased cytoplasmic Ca(2+) concentration. But, dl-PHPB did not reverse the inhibition of PGE1-induced platelet cAMP formation by ADP, which was different from ticlopidine. Further, dl-PHPB instead of ticlopidine showed increasing phospholipase C-ß phosphorylation (ser(1105)). The m-3M3FBS, a phospholipase C activator, attenuated the inhibitory effect of dl-PHPB on ADP-induced platelet aggregation and enhanced IP1 accumulation in rat platelets. Dl-PHPB decreased IP1 accumulation induced by ADP but had no effect on IP1 level enhanced by m-3M3FBS. Our results suggest that dl-PHPB has a potent antiplatelet effect, which is mainly through blockade of P2Y1 receptor-PLC-IP3 pathway and decreasing cytoplasmic calcium.

A novel liquefied gas based oral controlled release drug delivery system for liquid drug formulations.

A novel liquefied gas based drug delivery system for the oral delivery of liquid and semi-solid drug formulations is presented. The capsule-shaped system is equipped with a capillary as an element controlling the release rate. The delivery mechanism is based on a constant vapor pressure produced by isopentane as a low-boiling liquefied gas. The liquid drug valproic acid (VA) was used as a model compound. The viscosity was increased by the addition of povidone (PVP). The VA-PVP gel exhibited pseudoplastic rheological properties, the shear rate was above 0.1s(-1), similar to a Newtonian liquid. The gels tested in the gas based delivery system provided near-zero-order release kinetics. The longest delivery time was up to ca. 8h. The system is characterized by high flexibility of the delivery rate, which can be achieved by adjusting system parameters such as the diameter and length of the capillary, the vapor pressure of the propellant and the viscosity of the drug formulation.

2-(1-Hydroxypentyl)-benzoate increases cerebral blood flow and reduces infarct volume in rats model of transient focal cerebral ischemia.

2-(1-Hydroxypentyl)-benzoate (dl-PHPB), a derivate of 3-n-butylphthalide (dl-NBP), is a novel drug candidate used for treatment of cerebral ischemia. The goal of the present study was to investigate the effects of dl-PHPB on infarct volume, neurological function, and cerebral blood flow (CBF) in transient focal cerebral ischemia. Therefore, an animal model of 2-h middle cerebral artery occlusion (MCAO) followed by 24-h reperfusion was used. Rats received dl-PHPB (1.3, 3.9, or 12.9 mg/kg) intravenously 10 min after the onset of MCAO. Compared with the vehicle control group (37.4%), infarct volume in dl-PHPB-treated groups was reduced significantly and dose-dependently to 25.4, 17.4, and 13.7%, respectively. The changes in neurological deficient were also observed in neurobehavioral test in a dose-dependent manner, and the neuronal score was improved significantly from the vehicle control of 3.2 to 2.7, 2.1, and 1.8, respectively. At the highest dose, the potency of dl-PHPB was similar to those of dl-NBP. CBF was quantified by using laser-Doppler flowmetry. During the ischemia, the regional CBF values of dl-PHPB groups were significantly higher than that of vehicle group. In addition, our study showed that dl-PHPB converted into dl-NBP very quickly in blood in vitro. Approximately 70% of dl-PHPB converted into dl-NBP in 5 min when dl-PHPB was added into plasma at final concentrations of 6, 30, and 60 mug/ml. This result demonstrated that the neuronal protection effects of dl-PHPB were mainly induced by dl-NBP, an active compound converted from its precursor, dl-PHPB. In conclusion, dl-PHPB can reduce infarct volume and improve neurobehavioral deficits in a rat model of transient MCAO. Those effects may partially be due to an increase in CBF by the active metabolite (dl-NBP) of dl-PHPB. Therefore, our results suggest that dl-PHPB may be useful for treatment of ischemia stroke.

Repeated exposure inhalation study of pentane in rats.

Pentane (CAS No. 109-66-0) is a chemical being used as a co-solvent in a polymer production facility with potential for inhalation exposure in humans. To assess the toxicity of pentane, groups of 10 male rats each were exposed by inhalation, 6 hr/day, 5 days/week for 2 weeks to either 0 (control), 1,000, 3,000 or 10,000 ppm. Five rats per group were killed following the 10th exposure; the remaining 5/group were killed after a 14-day post-exposure recovery period. Parameters investigated were clinical signs of toxicity, functional behavior, body weights, clinical pathology, and gross and microscopic pathology including organ weights. No unusual clinical observations were seen in the pentane-treated rats, and body weights were not altered. Test rats generally exhibited normal behavioral responses in the functional observational battery. Increases in serum calcium and phosphorus concentrations were seen in rats exposed to either 3,000 or 10,000 ppm. These were reversible during the 2-week recovery period. No other clinical pathology changes were observed and no pentane-related tissue pathology was seen in any of the groups. The no-observed-adverse-effect level was 1,000 ppm with reversible clinical pathology changes produced at 3,000 and 10,000 ppm.