In vitrocytotoxicity of mitoxantrone-incorporated albumin microspheres on acute promyelocytic leukaemia cells

Dexamethasone – PAMAM dendrimer conjugates for retinal delivery: preparation, characterization and in vivo evaluation

Objective

Ocular diseases affecting retina, such as diabetic retinopathy (DR), age-related macular degeneration (AMD) and glaucoma are the major causes of blindness, and their treatment is still a challenge due to the special structure of the eye. The purpose of this study was to prepare a sustained release DEX conjugate formulation with enhanced ocular permeation using poly(amidoamine) (PAMAM) dendrimers and to evaluate the effects of conjugation on DEX release and ocular residence time.

Methods

PAMAM G3.5 and PAMAM G4.5 dendrimers were used to prepare DEX conjugates, and conjugation was confirmed using 1H-NMR. Formulations were evaluated in terms of drug release in the presence of ocular enzymes and cytotoxicity on ARPE19 cell lines. Fluorotron analysis was performed and ocular pharmacokinetic properties of DEX–PAMAM conjugates were studied in Sprague Dawley rats following intravitreal and subconjunctival applications.

Key Findings

The results indicated that DEX–PAMAM conjugates were able to enhance ocular permeability and ocular tissue levels of DEX following subconjunctival injection, and results were encouraging when compared to the literature that has reported DEX getting cleared from vitreous in 3 h.

Conclusion

Current studies are focused on formulation improvement to enhance hydrolysis and clearance time.

Treatment of malignant gliomas with mitoxantrone-loaded poly (lactide-co-glycolide) microspheres

OBJECTIVE

Mitoxantrone (MTZ) has potent in vitro activity against malignant glioma cell lines, but it cannot be used effectively as a systemic agent for the treatment of brain tumors because of its poor central nervous system penetration. However, MTZ-loaded poly(lactide-co-glycolide) (PLGA) microspheres may be injected into the peritumoral area and into tumor tissue to provide effective and sustained local drug concentrations without causing systemic side effects.

METHODS

Fisher rats were randomized into three groups. The first group (n = 9) was concomitantly implanted with rat glioma (RG2) cells and blank PLGA microspheres. The second group (n = 6) was implanted with RG2 cells and MTZ-loaded PLGA microspheres. The third group (n = 9) was implanted with RG2 cells, and MTZ-loaded PLGA microspheres were injected into the same area after 7 days. Animals were sacrificed on Day 15 or 35. Tumor volumes were measured after hematoxylin and eosin staining. Distribution kinetics of MTZ in the brain was determined by high-performance liquid chromatography in nine rats injected with MTZ-loaded microspheres.

RESULTS

The tumor volumes were 76 +/- 11 and 107 +/- 11 mm (mean +/- standard error) on Days 15 (n = 6) and 35 (n = 3), respectively, in the control group. In rats treated with MTZ-loaded microspheres on Day 7, tumor volumes were significantly reduced to 17 +/- 4 and 23 +/- 2 mm on Days 15 (n = 6) and 35 (n = 3), respectively. No tumor formation was observed when glioma cells and MTZ-loaded PLGA microspheres were implanted concomitantly (n = 6). No systemic side effects or parenchymal inflammatory infiltration were observed in either group of rats. Brain MTZ concentration was highest at the injection site and declined with time and distance from the injection site and with time.

CONCLUSION

These data demonstrate that MTZ-loaded PLGA microspheres can deliver therapeutic concentrations of drug to the tumor and prevent glioma growth without causing side effects. This treatment method may increase the efficiency of antineoplastic therapy and positively impact survival.