Antinociceptive Effect of Liposomal Bupivacaine Formulations After Intrathecal Administration in Rats

Background/aim: Based on our previous in vitro study with multilamellar liposomal bupivacaine (MLB) versus bupivacaine alone in artificial cerebrospinal fluid, we aimed to investigate in vivo antinociceptive effect of intrathecal MLB by determining tail flick latency (TFL) time after thermal stimulation in rats. Materials and methods: After preparing MLB and high-yield drug entrapment in liposome (HYDEL) bupivacaine, 18 female Wistar rats were assigned to 3 groups as control (bupivacaine) and study groups (MLB and HYDEL bupivacaine) including 6 rats in each group to administer these drugs intrathecally. Antinociceptive activity was determined in terms of TFL time after thermal stimulation. Maximum possible effect (MPE) calculated from TFL times and rats with motor block were documented. Results: TFL times after intrathecal injection of HYDEL bupivacaine were significantly longer than that of the control and MLB groups (P < 0.05) and returned to baseline 180 min after intrathecal injection. MPE (100%) with intrathecal HYDEL bupivacaine occurred between 10 to 45 min. Afterwards, MPEs were 70% and 50% for the control and MLB groups, respectively. Motor block disappeared after 20 min in the study groups while it lasted 75 min in the control. Conclusion: Intrathecal administration of MLB and HYDEL bupivacaine in rats resulted in longer duration of antinociceptive activity with shorter motor block duration.

Multiwalled Carbon Nanotube-Chitosan Scaffold: Cytotoxic, Apoptoti c, and Necrotic Effects on Chondrocyte Cell Lines.

BACKGROUND: Carbon nanotubes (CNTs) have been considered highly successful and proficient in terms of their mechanical, thermal and electrical functionalization and biocompatibility. In regards to their significant extent in bone regeneration, it has been determined that CNTs hold the capability to endure clinical applications through bone tissue engineering and orthopedic procedures. In the present study, we report on a composite preparation, involving the use of CNT-chitosan as scaffold for bone repair and regeneration. Through the use of water-soluble tetrazolium salt (WST-1) and double staining methods, the cytotoxic, necrotic, and apoptotic effects of chitosan-multiwalled carbon nanotube nanocomposites on the chondrocyte ATTC cell line have been exhibited. METHODS: The chitosan-multiwalled carbon nanotube scaffolds were prepared. Chondrocytes differentiation tool (ATCC) cell line was prepared. WST-1 assay for cytotoxicity studies were performed by using chondrocytes cells in 12.5-200 µL concentration range. The samples of membranes (chitosan- multiwalled carbon nanotube scaffold) were measured at 2 mg/mL and further prepared amongst chitosan- multiwalled carbon nanotube scaffold's which were placed into separate wells. While in the process of incubation, in the four-hour time range, the plates were immediately read in an Elisa microplate Reader. To predict the number of apoptotic and necrotic cells in culture, the technique of double staining with Hoechst dye was performed with PI on the basis of scoring cell nuclei. The mechanical properties such as tensile strength and elongation at break values of the chitosan only and chitosan/CNT scaffolds were evaluated on Texture Analyzer. RESULTS: Based on the results of the WST-1 assay procedure, the amount of cell viability was not significantly affected by nanocomposite concentrations and the lowest mortality rate of cells was obtained at a concentration of 12.5 µg/mL, whereas the highest mortality rate was obtained at a rate of 200 µg/mL. In addition, the effects of chitosan-CNT nanocomposites were not found to cytotoxic on chondrocyte cells. The double staining method has been able to determine the apoptotic and necrotic effects of chitosan MWCNT nanocomposites. The apoptotic and necrotic effects of the combined compounds had varied within the concentrations. In a similar manner to the outcome of the control groups, apoptosis was obtained at a percentage of 2.67%. Under a fluorescent inverted microscope, the apoptotic cell nuclei were stained with a stronger blue fluorescence in comparison to non-apoptotic cells, which may have had an effect. We also compared the strain-stress curve measurements results. The results indicated that the mechanical properties of scaffold were not different. Elongation at break values increased by addition of CNT. CONCLUSION: CNTs as a biomaterial hold the potential to be used for applications in future regenerative medicine. By using the components of chondrocytes (ATTC) cell lines, the cytotoxicity evaluations were made for the chitosan-multiwalled carbon nanotube scaffold. The chitosan-MWCNT nanocomposites do not seem to induce drastic cytotoxicity to the chondrocyte cells.

Evaluation of neuroprotective and anti-fatigue effects of sildenafil.

Sildenafil, a phosphodiesterase-5 inhibitor is widely used for the treatment of erectile dysfunction. Recently, the FDA approved the use of sildenafil in the therapeutic treatment of pulmonary arterial hypertension. Sildenafil crosses the blood-brain barrier and has been shown to enhance memory. Tremor, rigidity and akinesia are the most common symptoms seen in Parkinson's disease. Fatigue and sexual dysfunction are the other prominent features seen in Parkinson's disease. Interestingly, sildenafil is used therapeutically to treat sexual dysfunction in Parkinson's disease patients. Currently research on Parkinson's disease focuses on developing novel drug therapies for retarding the nigral dopaminergic neurodegeneration. Hence, we investigated the anti-fatigue and neuroprotective effects of sildenafil. In this study, the effect of sildenafil on fatigue was evaluated using forced swim test in mice. Sildenafil had no effect on fatigue as seen by the swim time. With regard to neuroprotective effects, we investigated the effects of sildenafil using two animal models of Parkinson's disease. In this study, 6-hydroxydopamine-lesioned (unilateral) rats and MPTP-treated mice were used as the animal models of Parkinson's disease. 6-Hydroxydopamine-lesioned rats were used to determine the effect of sildenafil on rotational behavior. Ipsilateral or contralateral rotational behavior can indicate the amphetamine-like activity or apomorphine-like activity of sildenafil. Sildenafil did not induce contralateral or ipsilateral rotations in 6-hydroxydopamine-lesioned rats. Sildenafil did not protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopamine depletion in the striatum.

Oral montelukast treatment of preschool-aged children with acute asthma.

BACKGROUND: Increased amounts of cysteinyl leukotrienes have been demonstrated in urine samples from asthmatic patients, particularly during exacerbations of asthma. Although the use of leukotriene receptor antagonists has been recommended in the treatment of chronic asthma, no guidelines are available regarding their use in the treatment of acute asthma. OBJECTIVE: To investigate the safety and effectiveness of a 4-mg tablet of oral montelukast in addition to short-acting beta2-agonist bronchodilator as the initial treatment in mild to moderate asthma exacerbations in children between 2 and 5 years old. METHODS: Fifty-one patients who were experiencing mild to moderate asthma exacerbation were included in a randomized, double-blind, placebo-controlled, parallel-group study. Each patient received either a 4-mg tablet of montelukast or placebo in addition to inhaled salbutamol and were followed up for 4 hours. The pulmonary index score, respiratory rate, and pulse were determined at baseline and throughout 4 hours after administration. RESULTS: Compared with placebo, the pulmonary index scores and respiratory rates were significantly lower in the montelukast group starting at 90 minutes (P = .01). This difference persisted at 120, 180, and 240 minutes of the study (P = .008, P = .02, and P = .048, respectively). At the end of the first hour of treatment, oral steroid need was 20.8% and 38.5% in patients randomized to the montelukast and placebo groups, respectively (P = .22). Hospitalization rates were not different between the 2 treatment groups. CONCLUSION: A single 4-mg tablet of montelukast had the potential to provide additive clinical benefit in mild to moderate acute asthma in preschool-aged children when administered concomitantly with short-acting beta2-agonist bronchodilators as the initial treatment.

A sustained release dosage form of acyclovir for buccal application: an experimental study in dogs.

Acyclovir is an antiviral agent and it has been particularly used for the treatment of herpes simplex infections. The treatment of infection in the oral cavity is often difficult, because of insufficient drug concentration in saliva when acyclovir is administered via the oral route in conventional tablet form for systemic uptake. Therefore, it was aimed to prepare a tablet for buccal administration and to investigate its effectiveness by performing in vitro and in vivo experiments.The solubility (1.559-4.584) and octanol/water partition coefficients ( - 2.176 to - 1.625) of the acyclovir were investigated at different pH conditions. A series of tablet formulations were prepared for buccal application and their dissolution properties were determined in artificial saliva medium. The effect of tablet ingredients on the release rate and mucoadhesion force was investigated. The dissolution properties of commercially available acyclovir tablets were also determined in the artificial gastric juice. Franz type diffusion cells were used to determine acyclovir penetration through buccal mucosa from prepared buccal tablets. Selected buccal tablets, commercial tablets and intravenous acyclovir solutions were administered to mongrel dogs and drug levels in the blood determined by HPLC.A pharmacokinetic model for buccal application was also developed and blood concentrations were calculated theoretically and compared with the experimental results. Prepared buccal tablets were found to be effective for the treatment of viral infections locally within the oral cavity and also for systemic treatment.

Rectal and vaginal administration of insulin-chitosan formulations: an experimental study in rabbits.

Insulin is a polypeptide drug and it is degraded by gastrointestinal enzymes, therefore, it cannot be used via oral route readily. There are only parenteral forms available in the market. The aim of this study was to investigate the effect of rectal and vaginal administration of various insulin gel formulations on the blood glucose level as alternative routes in rabbits. Chitosan gel (CH-gel) was used as a carrier; the penetration enhancing effect of sodium taurocholate and dimethyl-beta-cyclodextrin (DM-betaCD) was also investigated. CH-gel provided longer insulin release. The maximum decreasing effect on blood glucose level was observed with insulin-CH-gel containing 5% DM-betaCD. In conclusion, our results indicate that insulin may penetrate well through the rectal and vaginal mucosae from the CH-gel. DM-betaCD was also found to be a useful agent to enhance the penetration of insulin through rectal and vaginal membranes.

Prediction of skin penetration using artificial neural network (ANN) modeling.

Artificial neural network (ANN) analysis was used to predict the skin permeability of selected xenobiotics. Permeability coefficients (log k(p)) were obtained from various literature sources. A previously reported equation, which was shown to be useful in the prediction of skin permeability, uses the partial charges of the penetrants, their molecular weight, and their calculated octanol water partition coefficient (log K(oct)). The equation was used to predict the skin permeability for the set of 40 compounds (r(2) = 0.672). A successful ANN was developed and the ANN produced log k(p) values that correlated well with the experimental ones(r(2) = 0.997). The penetration properties of a selection of compounds through human skin that have not been previously investigated, etodolac, famotidine, nimesulide, nizatidine, ranitidine, were investigated. Their permeability coefficients were determined. It was then possible to compare the experimental data with that predicted using the partial charge equation and the trained ANN. ANN modeling for predicting skin permeability was found to be useful for predicting skin permeability coefficients of compounds. In conclusion, the developed and described ANN model in this publication does not require any experimental parameters; it could potentially provide useful and precise prediction of skin penetration for new drugs or toxic penetrants.

The use of the corpus cavernosum for the administration of phenobarbital: an experimental study in dogs.

Status epilepticus (SE) is classically defined as a generalized tonic-clonic seizure lasting longer than 30 min. Prolonged seizure activity can be resulted in irreversible cerebral injury. In addition, the existence evidence suggests that the longer the duration of the seizure activity is less likely to be controlled. The intravenous (IV) access is frequently difficult during SE, especially in infants and neonates. On the other hand, it has been demonstrated that high volumes of fluid can be injected into the corpora cavernosa. In this study, phenobarbital (PB) was administered to dogs using both IV and intracavernous (IC) routes with a dose of 20 mg/kg. The time period required to establish the IC route was less than 5 s. The levels of PB in the blood were measured and all results were compared. There was no statistically significant difference between the IV and IC administration with regard of the blood PB levels. Within 48 h of the experiment, none of animals demonstrated any evidence of infection or disability. Our findings suggest that the IC route may be an alternative route for the administration of PB when venous access is not immediately available or if it is not possible to achieve.

The use of liposomal enrofloxacin for intracellular infections in Kangal dogs and visualization of phagocytosis of liposomes.

It is difficult to treat intracellular infections because of the intrinsic resistance of the microorganism to most antibiotics. Moreover, these microorganisms can survive in phagocytic cells (macrophages and neutrophils). In this study, our aims were to encapsulate an antibiotic in liposomes, which will be phagocytized as well as the microorganisms in the phagocytic cell (because liposomes were prepared using lipids which have an antigenic activity and they can be phagocytized, thus, the active substance can be transferred into the cell), and to visualise with microscopy the phagocytic activity of macrophages and neutrophils to liposomes. MLV (multilamellar vesicles) fluorescein-labeled liposomes were prepared and incubated with isolated Kangal shepherd dog macrophages and neutrophils. The phagocytosis of liposomes by monocytes was visualized step by step under the microscope. Liposomes were also observed phagocytized after incubation with neutrophils. Enrofloxacin was chosen as a model drug. Neutrophils and macrophages were isolated from Kangal shepherd dogs and infected with Staphylococcus aureus, and their phagocytic activities (PA) and microbicidal activities (MA) were determined. PA and MA values were redetermined and compared when enrofloxacin formulations were used. Liposomal enrofloxacin was found to be more effective.

Intracavernous application of diazepam: an alternative route of the seizure treatment--an experimental study in rabbits.

BACKGROUND: There is a general need to terminate seizures as soon as possible using anticonvulsant drugs via an intravenous (i.v.) route, but it is often difficult to achieve a secure i.v. line during the seizure, especially in children. However, it has been demonstrated that high volumes of fluid can be injected into the corpora cavernosa. The purpose of this study was to evaluate the absorption properties of diazepam (DZ) after intracavernous (i.c.) administration and whether therapeutically significant plasma concentrations can be obtained or not. METHODS: Diazepam was administered to rabbits using both the i.v. and i.c route with a dose of 1 mg/kg. Blood samples were collected from the saphenous vein for a time period of 30 min. The levels of DZ in the blood were analyzed by high performance liquid chromatography and their blood profiles were obtained and compared. RESULTS: The insertions of the needle using this method were successful in all cases. The average time of inserting the needle was less than 5 s. There was no statistically significant difference between the i.v. and i.c. administration with regard of the blood DZ levels. Within 48 h after the experiment, none of the animals demonstrated any evidence of infection or disability. CONCLUSION: Our results demonstrated that commercially available parenteral DZ can be absorbed rapidly by the i.c. route in rabbits. Further studies are needed on the feasibility of this method before it is evaluated in humans.