Roopa S. Pai

Recent advances of resveratrol in nanostructured based delivery systems and in the management of HIV/AIDS

Resveratrol, a natural polyphenolic compound present in trees, in peanuts, in grapevines and exhibited multiple pharmacological activities. Extensive research in last two decades suggested that resveratrol possesses anti-inflammatory, anti-cancer, anti-viral, anti-amyloid, anti-arthritic and antioxidant properties. Some clinical reports have proposed that resveratrol might be a potential candidate for the prevention and/or treatment of HIV/AIDS and synergistically enhances the anti-HIV-1 activity. Resveratrol is not toxic to cells, and by itself reduces viral replication by 20% to 30%. With almost 12% of the world population suffering from HIV/AIDS including its resurgence in the developed world, better management of this global threat is highly desired. Further, various studies demonstrated several issues associated with resveratrol which account for its poor systemic bioavailability (almost zero) due to rapid and extensive first pass metabolism and existence of enterohepatic recirculation. In order to improve bioavailability and cellular uptake of resveratrol, various strategies have been adopted to date which includes resveratrol prodrug and the development of nanostructured delivery systems. Besides, nanostructured delivery systems are also known to inhibit the P-glycoprotein (P-gp) efflux, reduced metabolism by gut cytochrome P-450 enzymes, and circumnavigate the hepatic first-pass effect, facilitating absorption of drugs via intestinal lymphatic pathways. This review paper provides an updated birds-eye view account on the publications and patents study on the recent novel approaches to deliver resveratrol in order to enhance oral bioavailability, overcome first pass metabolism and trounce enterohepatic recirculation to make resveratrol a therapeutically potent drug. Providing a relatively pithy overview, this paper thus presents recent advances of resveratrol for the treatment and prevention of HIV/AIDS.

Optimized PLGA nanoparticle platform for orally dosed trans-resveratrol with enhanced bioavailability potential

Background: Trans-resveratrol (t-RVT) is a potent antioxidant. The drug suffers enterohepatic recirculation and extensive first-pass metabolism by CYP3A4 in liver, resulting in very low bioavailability (almost zero). Objective: The current studies entail a novel formulation approach to develop systematically optimized (OPT) nanoparticles (NPs) to enhance the oral bioavailability potential using poly (dl-lactide-co-glycolide) (PLGA) of t-RVT and overcome enterohepatic recirculation. Methods: T-RVT-loaded PLGA NPs were prepared by nanoprecipitation method. Delineating the NP regions, the amounts of polymer and emulsifier were selected as the critical factors for systematically formulating the OPT NPs employing 32 central composite design. The pharmacokinetics, in vivo biodistribution and in situ single-pass intestinal perfusion (SPIP) studies of OPT formulation were investigated in male Wistar rats. Results: Augmentation in the values of Ka (7.17-fold) and AUC0 – ∞ (10.6-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT formulation compared to pure drug and marketed product. OPT formulation showed a 2.78-fold rise in the values of t-RVT concentrations in liver. In situ SPIP studies ascribed the significant enhancement in absorptivity and permeability parameters of OPT NPs to transport through the Peyers patches. Successful establishment of in vitro/in vivo correlation substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. Conclusion: The studies, therefore, could provide another useful tool for successful development of t-RVT NPs and an in vivo approach to designate nanoparticulate system of t-RVT with distinctly improved bioavailability and to overcome enterohepatic recirculation.

Trans-resveratrol self-nano-emulsifying drug delivery system (SNEDDS) with enhanced bioavailability potential: optimization, pharmacokinetics and in situ single pass intestinal perfusion (SPIP) studies

Abstract Trans-resveratrol (t-RVT) is a potent antioxidant. By virtue of extensive pre-systemic metabolism and existence of enterohepatic recirculation, t-RVT bioavailability is almost zero. The current study aimed to develop self-nanoemulsifying drug delivery systems (SNEDDS) using long-chain triglycerides (LCTs) of t-RVT in an attempt to circumvent such obstacles. Equilibrium solubility studies indicated the choice of Lauroglycol FCC as lipid, and of Labrasol and Transcutol P as surfactants, for formulating the SNEDDS. Ternary phase diagrams were constructed to select the areas of nanoemulsions, and the amounts of lipid (X1) and surfactant (X2) as the critical factor variables. The SNEDDS were optimized using 32 central composite design (CCD) and the optimized formulation (OPT) located using overlay plot. The nanometer size range and high negative values of zeta potential depicted non-coalescent nature of the SNEDDS. Optimized formulation indicated marked improvement in drug release profile vis-à-vis pure drug. Cloud point determination and accelerated stability studies ascertained the stability of OPT. Augmentation in the values of Ka (3.29-fold) and AUC (4.31-fold) indicated significant enhancement in the rate and extent of bioavailability by the OPT compared with pure drug. In situ perfusion (SPIP) studies in Wistar rats construed remarkable enhancement in the absorptivity and permeability parameters of SNEDDS vis-à-vis the pure drug. Successful establishment of level A of in vitro/in vivo correlation substantiated the judicious choice of the in vitro dissolution milieu for simulating the in vivo conditions. The present study, therefore, reports the successful development of SNEDDS with distinctly enhanced bioavailability of t-RVT.

Antiretrovirals: Need for an effective drug delivery

Human Immunodeficiency Virus (HIV) is a retrovirus that causes irreversible destruction of the immune system, leading to the occurrence of opportunistic infections and malignancies. During the last decade, even though attempts were being made to eradicate HIV, it was found that eradication of HIV is highly unlikely, and effective antiretroviral therapy is required on a long-term basis to maintain viral suppression and reduce disease progression. During this decade, effective therapies aimed at continued suppression of HIV replication and targeted at resting HIV reservoirs such as brain, lymphatic systems will be critical to prolong survival and renewing hopes for a cure. Currently available antiHIV drugs can be classified into three categories: nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors and protease inhibitors. Most of these drugs bear some significant drawbacks such as relatively short half-life, low bioavailability, poor permeability and undesirable side effects. Efforts have been made to design drug delivery systems for antiHIV agents to: a) reduce the dosing frequency, b) increase the bioavailability and decrease the degradation/metabolism in the gastrointestinal tract, c) improve the CNS penetration and inhibit the CNS efflux, and d) deliver them to the target cells selectively with minimal side effects. This article is an attempt to compile all major research work towards drug delivery for AIDS therapy and channel future attempts in the area of more effective controlled delivery of antiHIV agents.

Response surface methodology and process optimization of sustained release pellets using Taguchi orthogonal array design and central composite design

Furosemide is a powerful diuretic and antihypertensive drug which has low bioavailability due to hepatic first pass metabolism and has a short half-life of 2 hours. To overcome the above drawback, the present study was carried out to formulate and evaluate sustained release (SR) pellets of furosemide for oral administration prepared by extrusion/spheronization. Drug Coat L-100 was used within the pellet core along with microcrystalline cellulose as the diluent and concentration of selected binder was optimized to be 1.2%. The formulation was prepared with drug to polymer ratio 1:3. It was optimized using Design of Experiments by employing a 32 central composite design that was used to systematically optimize the process parameters combined with response surface methodology. Dissolution studies were carried out with USP apparatus Type I (basket type) in both simulated gastric and intestinal pH. The statistical technique, i.e., the two-tailed paired t test and one-way ANOVA of in vitro data has proposed that there was very significant (P≤0.05) difference in dissolution profile of furosemide SR pellets when compared with pure drug and commercial product. Validation of the process optimization study indicated an extremely high degree of prognostic ability. The study effectively undertook the development of optimized process parameters of pelletization of furosemide pellets with tremendous SR characteristics.

Optimization of Pellets Containing Solid Dispersion Prepared by Extrusion/Spheronization Using Central Composite Design and Desirability Function

Furosemide is a class IV biopharmaceutical classification system drug having poor water solubility and low bioavailability due to the hepatic first-pass metabolism and has a short half-life of 2 h. To overcome the above drawback, this study was carried to prepare and evaluate the pellets containing furosemide solid dispersion (SD) for oral administration prepared by extrusion/spheronization. SD of furosemide was prepared with Eudragit L-100 at a drug-to-polymer ratio of 1:2 by employing a solvent evaporation method and characterized. Further, microcrystalline cellulose pellets containing SD were consequently prepared using a lab scale extrusion/ spheronizer and evaluated for in vitro drug release studies. The influence of process parameters used during extrusion/spheronization on the pellet properties was also studied using 2-factor, 3-level central composite design in order to improve the product quality. Additionally, the desirability function approach was applied to acquire the preeminent compromise between the multiple responses. Pellets containing solid dispersion (PSD) were prepared using optimal parameter settings demonstrated 88.52 ± 0.69% of the drug was released in a sustained release manner till 12 h. In vitro drug release data were fitted to various release kinetics models to study the mechanism of drug release. Drug release from the PSD was found to follow zero-order and Higuchi′s model. Both studied parameters had great influence on the responses. PSD showed augmentation in the drug release profile till 12 h. The final optimized formulation was obtained by encapsulating best SD formulation within the pellet core to release the drug in the most soluble form in stomach and a sustained fashion in intestine.

Preparation and Characterization of Pioglitazone Cyclodextrin Inclusion Complexes

Pioglitazone, a class II Biopharmaceutical Classification System drug having poor water solubility and slow dissolution rate may have a negative impact on its subtherapeutic plasma drug levels leading to therapeutic failure. In order to improve its water solubility and thus dissolution, cyclodextrin complexation technique was followed. The phase solubility studies were carried using three different types of cyclodextrins viz., β, methyl-β and γ-cyclodextrins. The Gibbs free energy was calculated in order to determine ease of the complexation. Binary systems of pioglitazone with cyclodextrins were prepared by kneading method and spray drying method. The phase solubility profiles with all the three cyclodextrins were classified as A L -type, indicating the formation of 1:1 stoichiometric inclusion complexes. The complexation capability of cyclodextrins with pioglitazone increased in the order of methyl-β > β > γ-cyclodextrin. The Gibbs free energy was found to be in the order γ > methyl-β > β cyclodextrin. Characterization of inclusion complexes was done by solubility studies, in vitro dissolution studies, Fourier transformation-infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and X-ray powder diffractometry studies. Inclusion complexes exhibited higher rates of dissolution than the corresponding physical mixtures and pure drug. Greater solubility was observed with spray-dried methyl-β cyclodextrin complexes (2.29 ± 0.001 mg/ml) in comparison to the kneaded methyl-β cyclodextrin complexes (1.584 ± 0.053 mg/ml) and pure drug (0.0714 ± 0.0018 mg/ml).

In-vitro/in-vivo characterization of trans-resveratrol-loaded nanoparticulate drug delivery system for oral administration

The current studies entail successful formulation of systematically optimized (OPT) nanoparticulate drug delivery system to increase the oral bioavailability using Eudragit RL 100 of trans‐resveratrol (t‐RVT), and evaluate their in‐vitro/in‐vivo performance.

In vitro and in vivo performance of supersaturable self-nanoemulsifying system of trans-resveratrol

To develop an optimized supersaturable self-nanoemulsifying drug delivery system (S-SNEDDS) in order to improve the oral bioavailability of trans-resveratrol (t-RVT), together with surmounting poor aqueous solubility, enterohepatic recirculation and controlling drug precipitation, by employing a precipitation inhibitor (PPI) that is, hydroxypropyl methylcellulose (HPMC). The long-term stability of a previously reported formulation optimized long chain triglycerides (OPT LCT-SNEDDS), consisting of Lauroglycol FCC and Transcutol P, indicated rapid precipitation of trans-resveratrol. Following incorporation of the selected PPI, the precipitates were differentiated using the X-ray diffraction (XRD) technique. An in vitro supersaturation test was carried out for the S-SNEDDS formulation. The S-SNEDDS formulation was appraised for pharmacokinetic and in situ perfusion studies. In vitro dilution of the S-SNEDDS formulation resulted in the formation of a nanoemulsion, followed by a slow precipitation of t-RVT in the S-SNEDDS formulation vis-à-vis SNEDDS formulated with OPT-LCT, where it undergoes rapid precipitation, yielding a low t-RVT concentration. The pharmacokinetic study indicated that the AUC0-8h of the S-SNEDDS formulation increased by nearly 1.33-fold in the presence of HPMC vis-à-vis the OPT LCT-SNEDDS, at a drug dose of 20 mg/kg. The in situ perfusion parameters, viz., fraction absorbed and effective permeability, demonstrated significant improvement in the rate and extent of absorption from the S-SNEDDS formulation. This case demonstrates that the supersaturatable approach is effective in delivering and in improving the oral bioavailability of t-RVT.

Development and validation of a HPLC method for the determination of trans-resveratrol in spiked human plasma

A simple, accurate, precise, sensitive, and reproducible high-performance liquid chromatography method was developed for the determination of Resveratrol (trans-3, 4’,5-trihydroxystilbene) in human plasma using liquid-liquid extraction. Caffeine was employed as an internal standard (IS). However, little information is known about its distribution in the organism generally because of the lack of accurate and precise detection methods. The chromatographic separation was achieved on a Phenomenex C18 column (250 mm × 4.6 mm, 5 μm) at room temperature in isocratic mode, and the column effluent was monitored by UV detector at 306 nm. The mobile phase used was methanol: phosphate buffer (pH 6.8 adjusted with 0.5% (v/v) orthophosphoric acid solution in Milli-Q water) (63:37%, v/v) at a flow rate of 1.0 ml/min. Nominal retention times of trans-resveratrol and IS were 3.94 and 7.86 minutes, respectively. Limits of detection and Limits of quantification of trans-resveratrol were 0.006 μg/ml and 0.008 μg/ml, respectively. This method was linear over the range of 0.010 to 6.4 μg/ml with regression coefficient greater than 0.9998. The inter- and intra-day precisions in the samples, 0.010, 3.2 and 6.4 μg/ml of trans-resveratrol was in the range 0.63 to 2.12% relative standard deviation (RSD) and 0.46 to 1.02% RSD, respectively. Resveratrol was found to be stable for a period of 15 days on storage at -20°C. The method was found to be precise, accurate, and specific during the study.