Pharmacokinetics and absorption mechanism of tandospirone citrate

Tandospirone citrate (TDS) is commonly used for the treatment of patients with generalized anxiety disorder in clinical practice, and several studies are developing new indications for TDS. However, the in vivo processes and absorption properties of TDS have not been systematically investigated. In this work, we conducted a comprehensive investigation using in vivo, in vitro, and ex vivo approaches, involving animal and cellular models, to examine the pharmacokinetic properties and absorption mechanisms of TDS. The results of in vivo studies revealed that the half-life (t 1/2) of TDS was 1.380 ± 0.46 h and 1.224 ± 0.39 h following intragastric (i.g.) and intravenous (i.v.) administration of 20 mg/kg TDS, respectively. This indicates that TDS is rapidly eliminated in rats. The area under the curve (AUC) of TDS after i.g. and i.v. administration was 114.7 ± 40 ng/mL*h and 48,400 ± 19,110 ng/mL*h, respectively, and the absolute bioavailability of TDS was found to be low (0.24%). Furthermore, TDS was extensively metabolized in rats, with the AUC of the major active metabolite [1-[2-pyrimidyl]-piperazine] being approximately 16.38-fold higher than that of TDS after i.g. administration. The results from the in vitro Caco-2 cell model and ex vivo everted gut sac experiment demonstrated that TDS exhibited good permeability, and its transport was influenced by concentration, temperature, and pH. Passive diffusion was identified as the main absorption mechanism. In conclusion, TDS is classified as a Biopharmaceutics Classification System (BCS) class I drug, characterized by high solubility and permeability. The low absolute bioavailability of TDS may be attributed to its rapid metabolism. The pharmacokinetic data and absorption characteristics obtained in this study provide fundamental information for the further development and utilization of TDS.

Investigation of the potential of Glycyrrhiza glabra as a bioavailability enhancer of Vitamin B12

Vitamin B12 deficiency is prevalent among individuals globally. Inadequate consumption of B12 rich diet and low bioavailability (due to diet based/physiological factors) are linked to the deficiency of Vitamin B12 inside the body. Bioavailability enhancers augment the bioavailability of an ingested substance (drug/nutrient) thus increasing their concentration inside the body and maximizing their therapeutic benefits. In traditional medicine, Licorice (Glycyrrhiza glabra) finds utility in the treatment of various health conditions. Thus, the present study aimed to examine the potential of ethanolic extract obtained from G. glabra roots to enhance the bioavailability of Vitamin B12. The effect of ethanolic extract of G. glabra (GgEtOH) on intestinal absorption enhancement of B12 was assessed in vitro on Caco-2 and ex-vivo everted gut sac models. The influence of extract on the pharmacokinetics of Vitamin B12 was determined in vivo in Swiss albino mice. GgEtOH significantly enhanced the permeation (Papp) of B12 by 2-5 fold in vitro (25, 50, and 100 μg/ml concentrations) and ex-vivo (250 and 500 μg/ml concentrations). The pharmacokinetic parameters of B12 such as Cmax, AUC, Tmax, etc. were also significantly elevated in vivo upon oral administration of B12 (1 mg/kg dose) in combination with GgEtOH (100 and 1,000 mg/kg dose). These preliminary findings indicate that the ethanolic extract of G. glabra is capable of enhancing the bioavailability of Vitamin B12. To the best of our knowledge, this is the first report to demonstrate herbal extract-mediated enhancement of Vitamin B12 bioavailability through in vitro, ex vivo, and in vivo assays.

Oral nanoparticles based on gellan gum/pectin for colon-targeted delivery of resveratrol

Nanoparticles based on gellan gum/pectin blends were designed for colon-targeted release of resveratrol (RES). Their impact on drug release rates and permeability were evaluated using Caco-2 cell model and mucus secreting triple co-culture model. Polymeric nanoparticles (PNP) were successfully prepared by nebulization/ionotropic gelation, achieving high drug loading (>80%). PNP were spherical with a low positive charge density (+5mV) and exhibited diameters of around 330 nm. Developed PNP were able to promote effective modulation of drug release rates, so that only 3% of RES was released in acidic media over 2 h, and, in pH 6.8, the drug was released in a sustained manner, reaching 85% in 30 h. The permeability of RES-loaded PNP in the Caco-2 model was 0.15%, while in the triple co-culture model, in the presence of mucus, it reached 5.5%. The everted gut sac experiment corroborated the low permeability of RES-loaded PNP in the presence or absence of mucus and highlighted their high ability to interact with the intestinal tissue. Results indicate that the novel PNP developed in this work are safe and promising carriers for controlled delivery of RES at the colon.

Permeability Behavior of Nanocrystalline Solid Dispersion of Dipyridamole Generated Using NanoCrySP Technology

Nanocrystals research has been an area of significant interest lately, providing oral bioavailability benefits to solubility- and/or dissolution rate-limited drugs. Drug nanocrystals are generated using top-down or bottom-up technologies. Combination technologies (Nanoedge, Nanopure XP and SmartCrystal) have been recently developed to generate nanocrystals of improved properties. Our lab has also contributed in this field by providing a ‘novel’ platform technology, NanoCrySP, for the generation of nanocrystals. NanoCrySP-generated nanocrystals have improved the oral bioavailability of various molecules. In this study, we aim to assess the permeability behavior of nanocrystals generated by NanoCrySP. Three samples of Dipyridamole (DPM) drug were used in this study: (1) DPM (micron-sized powder), (2) nanocrystals of DPM (NS), generated by media milling (as control) and, (3) nanocrystalline solid dispersion containing DPM (NSD) in the matrix of mannitol (MAN), generated using NanoCrySP technology. In vitro (Caco-2 cell lines) and ex vivo (everted gut sac) studies were conducted in this work. Cellular permeability (P_app) from apical-to-basolateral side in Caco-2 cell monolayer was found to be in the order NS > NSD > DPM, which was the same as their apparent solubility values. Higher P_app from a basolateral-to-apical side suggested a significant contribution of the P-gp efflux transport for DPM, while NS exhibited much higher inhibition of the efflux mechanism than NSD. Both NS and NSD showed higher permeation from the jejunum region in the ex vivo everted gut sac study. Interestingly, P_app of NSD was similar to NS in ex vivo everted gut sac model, however, NSD showed higher mucoadhesion than NS and DPM in this study.

Attenuation of Oxidative Damage by Coenzyme Q10 Loaded Nanoemulsion Through Oral Route for the Management of Parkinson's Disease

Coenzyme Q₁₀ (CoQ₁₀) is a well-known antioxidant molecule which is used in the treatment of neurodegenerative disorders, but due to poor solubility it suffers with the drawback of low oral bioavailability. The aim of present study was to prepare and characterize CoQ₁₀ loaded nanoemulsion to improve the oral bioavailability. Prepared formulation was studied for droplet size, polydispersity index (PDI), percentage transmittance, refractive index, viscosity, zeta potential, surface morphology by transmission electron microscopy, and in vitro release study. Optimized formulation (A10) showed spherical droplets with mean diameter of 60.00 ± 15 nm, PDI of 0.121 ± 0.053, and zeta potential values of -24.40 ± 0.16 mV. Prepared nanoemulsion exhibited good transmittance (100.50% ± 0.86%), refractive index (1.41 ± 0.02), and viscosity (30.54 ± 2.86 cP). Various behavioral tests like forced swimming test, locomotor activity test, catalepsy, muscle coordination test, and akinesia test performed in haloperidol challenged rats and treated with CoQ₁₀ nanoemulsion significantly improved the behavioral activities in comparison to CoQ₁₀ suspension by reducing nigrostriatal dopamine depletion and thereby helping in the treatment of Parkinson's disease. Biochemical estimation data showed that CoQ₁₀ nanoemulsion was helpful in elevating the decreased content of glutathione and reducing the increased content of thiobarbituric acid reactive substances. Improved CoQ₁₀ release was obtained with nanoemulsions. Pharmacokinetic study results revealed that nanoemulsion exhibited 1.81 times enhancement in bioavailability in comparison to CoQ₁₀ suspension.

Liquid Chromatographic Method for Irinotecan Estimation: Screening of P-gp Modulators

The present work is aimed to develop a simple, sensitive, robust and reliable HPLC method for the estimation of irinotecan in the physiological media in order to assess the permeability profile of irinotecan, using the everted gut sac, in the presence of various P-gp modulators. Separation was achieved using, C18 column with mobile phase consisting of acetonitrile and 0.045 µM sodium dihydrogen phosphate dihydrate buffer containing ion pair agent heptane sulphonic acid sodium salt (0.0054 µM), pH 3. The flow rate was maintained at 1 ml/min and analysis was performed at 254.9 nm using PDA detector. Calibration data showed an excellent linear relationship between peak-area verses drug concentration (r², 0.9999). Linearity was found to be in the range of 0.060-10.0 µg/ml. Limits of detection and quantification were found to ~0.020 µg/ml and ~0.060 µg/ml, respectively. The developed method was found to be precise (RSD < 1.5%, for repeatability and <2.55% for intermediate precision, acceptable ranges of precision), accurate (The recovered content of irinotecan in the presence of various P-gp modulators varied from 96.11-101.51%, within acceptable range, 80-120%), specific and robust (% RSD < 2). Developed method has been applied successfully for the evaluation of eleven P-gp modulators from diverse chemical class.