Impact of polymeric nanoparticles on oral pharmacokinetics: a dose-dependent case study with estradiol

Milk protein-shelled gold nanoparticles with gastrointestinally active absorption for aurotherapy to brain tumor

Orally absorbable gold nanoparticles (AuNP) having cancer ablation therapy is strongly demanded to treat glioblastoma multiforme (GBM) for patients with its highest incidence rate. Here, we develop a milk protein lactoferrin-conjugated AuNP for its oral absorption and targeting to the GBM through the interaction between lactoferrin (Lf) and lactoferrin receptor (LfR) that is highly expressed in the intestine, blood-brain barrier and GBM. For stability and long circulation of AuNP, glutathione and polyethylene glycol (PEG) is introduced, which is called to Lf-PEG-AuNP. When Lf-PEG-AuNP are orally administered to orthotopic GBM-bearing mice, 11-fold and 8-fold higher concentrations of AuNP are measured in bloodstreams and GBM in the brain, respectively, compared with unconjugated-AuNP. Therefore, orally administered Lf-PEG-AuNP exhibit an outstanding temperature rise in GBM by irradiating laser and significantly reduce tumor volume. Collectively, we suggest that the Lf-PEG-AuNP can fundamentally target GBM in the brain through oral absorption, and that its efficient photothermal therapy is possible.

Recent nanotechnological interventions targeting PI3K/Akt/mTOR pathway: A focus on breast cancer

Breast cancer is the major cause of deaths in women worldwide. Detection and treatment of breast cancer at earlier stages of the disease has shown encouraging results. Modern genomic technologies facilitated several therapeutic options however the diagnosis of the disease at an advanced stage claim more deaths. Therefore more research directed towards genomics and proteomics into this area may lead to novel biomarkers thereby enhancing the survival rates in breast cancer patients. Phosphoinositide-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway was shown to be hyperactivated in most of the breast carcinomas resulting in excessive growth, proliferation, and tumor development. Development of nanotechnology has provided many interesting avenues to target the PI3K/Akt/mTOR pathway both at the pre-clinical and clinical stages. Therefore, the current review summarizes the underlying mechanism and the importance of targeting PI3K/Akt/mTOR pathway, novel biomarkers and use of nanotechnological interventions in breast cancer.

Polyester Nanoparticle Encapsulation Mitigates Paclitaxel-Induced Peripheral Neuropathy

Chemotherapy utilizing cytotoxic drugs, such as paclitaxel (PTX), is still a commonly used therapeutic approach to treat both localized and metastasized cancers. Unlike traditional regimens in which PTX is administered at the maximum tolerated dose, alternative regimens like metronomic dosing are beneficial by administering PTX more frequently and in much lower doses exploiting antiangiogenic and immunomodulatory effects. However, PTX-induced peripheral neuropathy and lack of patient compliant dosage forms of PTX are major roadblocks for the successful implementation of metronomic regimens. Because of the success of polyester nanoparticle drug delivery, we explored the potential of nanoparticle-encapsulated paclitaxel (nPTX) in alleviating peripheral neuropathy using a rat model. Rats were injected intraperitoneally with 2 mg/kg body weight of PTX or nPTX on four alternate days, and neuropathic pain and neuronal damage were characterized using behavioral assessments, histology, and immunohistochemistry. The reduction in tactile and nociceptive pressure thresholds was significantly less in nPTX-treated rats than in PTX-treated rats over a 16-day study period. Histological analysis showed that the degree of dorsal root ganglion (DRG) degeneration and reduction in motor neurons in the spinal cord was significantly lower in the nPTX group than the PTX group. Further, immunofluorescence data reveals that nPTX-treated rats had an increased density of a neuronal marker, β-tubulin-III, reduced TUNEL positive cells, and increased high molecular weight neurofilament in the spinal cord, DRG, and sciatic nerves compared with PTX-treated rats. Therefore, this work has important implications in improving risk-benefit profile of PTX, paving the way for metronomic regimens.

Engineering poly(lactic-co-glycolic acid) (PLGA) micro- and nano-carriers for Controlled Delivery of 17β-Estradiol

With menopause, circulating levels of 17β-estradiol (E2) markedly decrease. E2-based hormone therapy is prescribed to alleviate symptoms associated with menopause. E2 is also recognized for its beneficial effects in the central nervous system (CNS), such as enhanced cognitive function following abrupt hormonal loss associated with ovariectomy. For women with an intact uterus, an opposing progestogen component is required to decrease the risk of developing endometrial hyperplasia. While adding an opposing progestogen attenuates these detrimental effects on the uterus, it can attenuate the beneficial effects of E2 in the CNS. Poly(lactic-co-glycolic acid) (PLGA) micro- and nano- carriers (MNCs) have been heavily investigated for their ability to enhance the therapeutic activity of hydrophobic agents following exogenous administration, including E2. Multiple PLGA MNC formulation parameters, such as composition, molecular weight, and type of solvent used, can be altered to systematically manipulate the pharmacokinetic and pharmacodynamic profiles of encapsulated agents. Thus, there is an opportunity to enhance the therapeutic activity of E2 in the CNS through controlled delivery from PLGA MNCs. The aim of this review is to consider the fate of exogenously administered E2 and discuss how PLGA MNCs and route of administration can be used as strategies for controlled E2 delivery.

Next Generation Precision-Polyesters Enabling Optimization of Ligand-Receptor Stoichiometry for Modular Drug Delivery

The success of receptor-mediated drug delivery primarily depends on the ability to optimize ligand-receptor stoichiometry. Conventional polyesters such as polylactide (PLA) or its copolymer, polylactide-co-glycolide (PLGA), do not allow such optimization due to their terminal functionality. We herein report the synthesis of 12 variations of the PLA-poly(ethylene glycol) (PEG) based precision-polyester (P2s) platform, permitting 5-12 periodically spaced carboxyl functional groups on the polymer backbone. These carboxyl groups were utilized to achieve variable degrees of gambogic acid (GA) conjugation to facilitate ligand-receptor stoichiometry optimization. These P2s-GA combined with fluorescent P2s upon emulsification form nanosystems (P2Ns) of size <150 nm with GA expressed on the surface. The P2Ns outclass conventional PLGA-GA nanosystems in cellular uptake using caco-2 intestinal model cultures. The P2Ns showed a proportional increase in cellular uptake with an increase in relative surface GA density from 0 to 75%; the slight decline for 100% GA density was indicative of receptor saturation. The intracellular trafficking of P2Ns in live caco-2 cells demonstrated the involvement of endocytic pathways in cellular uptake. The P2Ns manifest transferrin receptor (TfR) colocalization in ex vivo intestinal tissue sections, despite blocking of the receptor with transferrin (Tf) noncompetitively, i.e., independently of receptor occupation by native ligand. The in vivo application of P2Ns was demonstrated using cyclosporine (CsA) as a model peptide. The P2Ns exhibited modular release in vivo, as a function of surface GA density. This approach may contribute to the development of personalized dose regimen.

Drug-Loaded Polymeric Nanoparticles for Cancer Stem Cell Targeting

Cancer stem cells (CSCs) have been reported to play critical roles in tumor initiation, propagation, and regeneration of cancer. Nano-size vehicles are employed to deliver drugs to target the CSCs for cancer therapy. Polymeric nanoparticles have been considered as the most efficient vehicles for drug delivery due to their excellent pharmacokinetic properties. The CSCs specific antibodies or ligands can be conjugated onto the surface or interior of nanoparticles to successfully target and finally eliminate CSCs. In this review, we focus on the approaches of polymeric nanoparticles design for loading drug, and their potential application for CSCs targeting in cancer therapy.

In vivo in silico pharmacokinetic simulation studies of carvedilol-loaded nanocapsules using GastroPlus

BACKGROUND

The study aimed at in vivo pharmacokinetic evaluation of carvedilol loaded nanocapsules (CLN) followed by in silico predictions and establishment of IVIVC.

METHOD

LC/MS-MS method was developed and validated to estimate the pharmacokinetic profile of CLN. The in silico and IVIVC were established using GastroPlus.

RESULTS

The CLN demonstrated 221.09% increase in bioavailability of carvedilol over aqueous suspension. The simulation of plasma concentration profile of CLN exhibited a sensible level of superimposition. The regional absorption of the CLN showed maximum absorption from duodenum and jejunum. The Wagner-Nelson method was found to be most suitable deconvolution method for establishing the IVIVC of CLN.

CONCLUSION

The study demonstrated CLN as efficient delivery system to ferry carvedilol with improved bioavailability.

Flip-flop pharmacokinetics--delivering a reversal of disposition: challenges and opportunities during drug development

Flip-flop pharmacokinetics is a phenomenon often encountered with extravascularly administered drugs. Occurrence of flip-flop spans preclinical to human studies. The purpose of this article is to analyze both the pharmacokinetic interpretation errors and opportunities underlying the presence of flip-flop pharmacokinetics during drug development. Flip-flop occurs when the rate of absorption is slower than the rate of elimination. If it is not recognized, it can create difficulties in the acquisition and interpretation of pharmacokinetic parameters. When flip-flop is expected or discovered, a longer duration of sampling may be necessary in order to avoid overestimation of fraction of dose absorbed. Common culprits of flip-flop disposition are modified dosage formulations; however, formulation characteristics such as the drug chemical entities themselves or the incorporated excipients can also cause the phenomenon. Yet another contributing factor is the physiological makeup of the extravascular site of administration. In this article, these causes of flip-flop pharmacokinetics are discussed with incorporation of relevant examples and the implications for drug development outlined.

Polymeric particulate technologies for oral drug delivery and targeting: a pathophysiological perspective

The oral route for delivery of pharmaceuticals is the most widely used and accepted. Nanoparticles and microparticles are increasingly being applied within this arena to optimize drug targeting and bioavailability. Frequently the carrier systems used are either constructed from or contain polymeric materials. Examples of these nanocarriers include polymeric nanoparticles, solid lipid nanocarriers, self-nanoemulsifying drug delivery systems and nanocrystals. It is the purpose of this review to describe these cutting edge technologies and specifically focus on the interaction and fate of these polymers within the gastrointestinal system.

Nano-advantage in enhanced drug delivery with biodegradable nanoparticles: contribution of reduced clearance

The aim of this study was to investigate the contribution of reduced apparent clearance to the enhanced exposure reported for biodegradable nanoparticles after extravascular and intravascular routes of administration. Plasma concentration profiles for drug and nanoparticle formulations after administration by intravenous, intraduodenal, and oral routes were extracted from the literature. Data were fit to pharmacokinetic models using BOOMER. The compartmental pharmacokinetic analysis of literature data for six drugs (camptothecin, 9-nitrocamptothecin, epirubicin, vinpocetine, clozapine, and cyclosporine) showed that the encapsulation of drug molecules in nanoparticles significantly reduced the apparent clearance and prolonged the apparent circulation half-life compared with those for the plain drug. Positively charged nanoparticles assessed in this study had lower apparent clearance, lower elimination rate constant values, and longer apparent circulation half-life than neutral and negatively charged nanoparticles. After oral administration, a reduction in apparent clearance contributed substantially to elevations in plasma drug exposure with nanoparticles. For the drugs and delivery systems examined, the nano-advantage in drug delivery enhancement can be explained, in part, by reduced clearance.