Formulation, pharmacokinetics and biodistribution of Ofloxacin-loaded albumin microparticles and nanoparticles

Effect of poly(ε-caprolactone) microspheres on population pharmacokinetic/pharmacodynamic model of a simple coumarin

This study aims to evaluated the impact of poly(ε-caprolactone) (PCL) microspheres on the pharmacokinetics and pharmacodynamics (PopPK/PD) of 6-methylcoumarin (6MC). For this, PCL microspheres loaded with 6MC were prepared using the emulsification-evaporation method. Particle size, zeta potential, drug loading, and entrapment efficiency were characterised by dynamic light scattering and UV spectrophotometry. In vitro release and pharmacokinetics in Wistar rats were assessed for free and encapsulated 6MC. Anti-inflammatory activity was evaluated using the carrageenan-induced paw edoema model, with PopPK and PopPK/PD models developed. Microspheres showed diameters between 2.9 and 7.1 µm, zeta potentials of -10 to -15 mV, and drug loading of 0.24 mg/mg. Encapsulation efficiency was 45.5% to 75.9%. PopPK models showed enhanced absorption and distribution, with increased anti-inflammatory potency of encapsulated 6MC. PCL microspheres significantly improved the pharmacokinetic and pharmacodynamic profiles of 6MC, enhancing its therapeutic potential for lipophilic drugs.

Modifications of quinolones and fluoroquinolones: hybrid compounds and dual-action molecules

ABSTRACT

This review is aimed to provide extensive survey of quinolones and fluoroquinolones for a variety of applications ranging from metal complexes and nanoparticle development to hybrid conjugates with therapeutic uses. The review covers the literature from the past 10 years with emphasis placed on new applications and mechanisms of pharmacological action of quinolone derivatives. The following are considered: metal complexes, nanoparticles and nanodrugs, polymers, proteins and peptides, NO donors and analogs, anionic compounds, siderophores, phosphonates, and prodrugs with enhanced lipophilicity, phototherapeutics, fluorescent compounds, triazoles, hybrid drugs, bis-quinolones, and other modifications. This review provides a comprehensive resource, summarizing a broad range of important quinolone applications with great utility as a resource concerning both chemical modifications and also novel hybrid bifunctional therapeutic agents.

GRAPHICAL ABSTRACT

A Three-Pulse Release Tablet for Amoxicillin: Preparation, Pharmacokinetic Study and Physiologically Based Pharmacokinetic Modeling

BACKGROUND

Amoxicillin is a commonly used antibiotic which has a short half-life in human. The frequent administration of amoxicillin is often required to keep the plasma drug level in an effective range. The short dosing interval of amoxicillin could also cause some side effects and drug resistance, and impair its therapeutic efficacy and patients' compliance. Therefore, a three-pulse release tablet of amoxicillin is desired to generate sustained release in vivo, and thus to avoid the above mentioned disadvantages.

METHODS

The pulsatile release tablet consists of three pulsatile components: one immediate-release granule and two delayed release pellets, all containing amoxicillin. The preparation of a pulsatile release tablet of amoxicillin mainly includes wet granulation craft, extrusion/spheronization craft, pellet coating craft, mixing craft, tablet compression craft and film coating craft. Box-Behnken design, Scanning Electron Microscope and in vitro drug release test were used to help the optimization of formulations. A crossover pharmacokinetic study was performed to compare the pharmacokinetic profile of our in-house pulsatile tablet with that of commercial immediate release tablet. The pharmacokinetic profile of this pulse formulation was simulated by physiologically based pharmacokinetic (PBPK) model with the help of Simcyp®.

RESULTS AND DISCUSSION

Single factor experiments identify four important factors of the formulation, namely, coating weight of Eudragit L30 D-55 (X1), coating weight of AQOAT AS-HF (X2), the extrusion screen aperture (X3) and compression forces (X4). The interrelations of the four factors were uncovered by a Box-Behnken design to help to determine the optimal formulation. The immediate-release granule, two delayed release pellets, together with other excipients, namely, Avicel PH 102, colloidal silicon dioxide, polyplasdone and magnesium stearate were mixed, and compressed into tablets, which was subsequently coated with Opadry® film to produce pulsatile tablet of amoxicillin. In vitro release study firstly indicated a three-pulse release profile of the tablet. Later the pulse tablet was found to generate the sustained release of amoxicillin in beagle dogs. Furthermore, the Simcyp® software was used to simulate the in vivo concentration time curve model of the three-pulse release tablet for amoxicillin in both human and beagle dog. The prediction by PBPK model nicely fitted the observation in human and beagle dog.

CONCLUSIONS

This study has demonstrated the interrelation of factors affecting the pulsatile formulation of amoxicillin using a Box-Behnken design. The three-pulse release tablets of amoxicillin were proven to generate pulsatile release in vitro and sustained release in vivo. This formulation was also found to extend the effective plasma concentration in human compared to the tablet of immediate release based on the simulation data by PBPK modeling. This study provides an example of using PBPK to guide the development of pulsatile dosage forms.

Understanding the particokinetics of engineered nanomaterials for safe and effective therapeutic applications

Increasing numbers of engineered nanomaterials (ENMs) are being developed for therapeutic and diagnostic applications. However, the tunable and varied physicochemical properties of ENMs pose a new challenge for understanding their biological behavior, trafficking, and biodistribution. Herein the concept of "particokinetics" is introduced to address the dynamic biological behavior of ENMs at the molecular level (including gravitational sedimentation, dispersion, aggregation, and interaction with biomolecules in suspending media), cellular level (including cellular uptake, transport, biotransformation, and elimination), and whole-organism level (including absorption, distribution, metabolism, and excretion in vivo). Several mathematical modeling methods are introduced which guide a quantitative description of their biological behavior at different levels. Examples are also provided to delineate the impact of the physicochemical properties of ENMs on their particokinetics. A comprehensive understanding of the in vivo and in vitro particokinetics of ENMs will facilitate the design of tailor-made functional ENMs that act as highly effective and controllable drug-delivery systems with minimal side-effects.

Evaluation of 18F-labeled targeted perfluorocarbon-filled albumin microbubbles as a probe for microUS and microPET in tumor-bearing mice

OBJECTIVE

In this study, albumin-shelled, targeted MBs (tMBs) were first demonstrated with the expectation of visualization of biodistribution of albumin-shelled tMBs. The actual biodistribution of albumin-shelled tMBs is of vital importance either for molecular imaging or for drug delivery.

MOTIVATION

Recently, albumin microbubbles (MBs) have been studied for drug and gene delivery in vitro and in vivo through cavitation. Targeted lipid-shelled MBs have been applied for ultrasound molecular imaging and conjugated with radiolabeled antibodies for whole-body biodistribution evaluations. The novelty of the work is that, in addition to the lipid tMBs, the albumin tMBs was also applied in biodistribution detection.

METHODS

Multimodality albumin-shelled, (18)F-SFB-labeled VEGFR2 tMBs were synthesized, and their characteristics in mice bearing MDA-MB-231 human breast cancer were investigated with micro-positron-emission tomography (microPET) and high-frequency ultrasound (microUS).

RESULTS

Albumin-shelled MBs can be labeled with (18)F-SFB directly and conjugated with antibodies for dual molecular imaging. The albumin-shelled tMBs show a lifetime in 30min in the blood pool and a highly specific adherence to tumor vessels in mice bearing human breast cancer.

CONCLUSIONS

From the evaluations of whole-body biodistribution, the potential of the dual molecular imaging probe for drug or gene delivery in animal experiments with albumin shelled MBs has been investigated.

Estimating the delivery efficiency of drug-loaded microbubbles in cancer cells with ultrasound and bioluminescence imaging

The application of drug-loaded microbubbles (MBs) in combination with ultrasound (US), which results in an increase in capillary permeability at the site of US-sonication-induced MB destruction, may be an efficient method of localized drug delivery. This study investigated the mechanism underlying the US-mediated release of luciferin-loaded MBs through the blood vessels to targeted cells using an in vivo bioluminescence imaging (BLI) system. The luciferin-loaded MBs comprised an albumin shell with a diameter of 1234 ± 394 nm (mean ± SD) and contained 2.48 × 10⁹ bubbles/mL; within each MB, the concentration of encapsulated luciferin was 1.48 × 10⁻¹⁰ mg/bubble. The loading efficiency of luciferin in MBs was only about 19.8%, while maintaining both the bioluminescence and acoustic properties. In vitro and in vivo BLI experiments were performed to evaluate the US-mediated release of luciferin-loaded MBs. For in vitro results, the increase in light emission of luciferin-loaded albumin-shelled MBs after destruction via US sonication (6.24 ± 0.72 × 10⁷ photons/s) was significantly higher than that in the luciferin-loaded albumin-shelled MBs (3.11 ± 0.33 × 10⁷ photons/s) (p < 0.05). The efficiency of the US-mediated release of luciferin-loaded MBs in 4T1-luc2 tumor-bearing mice was also estimated. The signal intensity of the tumor with US destruction at 3 W/cm² for 30 s was significantly higher than without US destruction at 3 (p = 0.025), 5 (p = 0.013), 7 (p = 0.012) and 10 (p = 0.032) min after injecting luciferin-loaded albumin-shelled MBs. The delivery efficiency was, thus, improved with US-mediated release, allowing reduction of the total injection dose of luciferin.

Therapeutic strategies based on polymeric microparticles

The development of the field of materials science, the ability to perform multidisciplinary scientific work, and the need for novel administration technologies that maximize therapeutic effects and minimize adverse reactions to readily available drugs have led to the development of delivery systems based on microencapsulation, which has taken one step closer to the target of personalized medicine. Drug delivery systems based on polymeric microparticles are generating a strong impact on preclinical and clinical drug development and have reached a broad development in different fields supporting a critical role in the near future of medical practice. This paper presents the foundations of polymeric microparticles based on their formulation, mechanisms of drug release and some of their innovative therapeutic strategies to board multiple diseases.