Solid microparticles based on chitosan or methyl-β-cyclodextrin: a first formulative approach to increase the nose-to-brain transport of deferoxamine mesylate

Abstract

We propose the formulation and characterization of solid microparticles as nasal drug delivery systems able to increase the nose-to-brain transport of deferoxamine mesylate (DFO), a neuroprotector unable to cross the blood brain barrier and inducing negative peripheral impacts. Spherical chitosan chloride and methyl-β-cyclodextrin microparticles loaded with DFO (DCH and MCD, respectively) were obtained by spray drying. Their volume-surface diameters ranged from 1.77 ± 0.06 μm (DCH) to 3.47 ± 0.05 μm (MCD); the aerodynamic diameters were about 1.1 μm and their drug content was about 30%. In comparison with DCH, MCD enhanced the in vitro DFO permeation across lipophilic membranes, similarly as shown by ex vivo permeation studies across porcine nasal mucosa. Moreover, MCD were able to promote the DFO permeation across monolayers of PC 12 cells (neuron-like), but like DCH, it did not modify the DFO permeation pattern across Caco-2 monolayers (epithelial-like). Nasal administration to rats of 200 μg DFO encapsulated in the microparticles resulted in its uptake into the cerebrospinal fluid (CSF) with peak values ranging from 3.83 ± 0.68 μg/mL (DCH) to 14.37 ± 1.69 μg/mL (MCD) 30 min after insufflation of microparticles. No drug CSF uptake was detected after nasal administration of a DFO water solution. The DFO systemic absolute bioavailabilities obtained by DCH and MCD nasal administration were 6% and 15%, respectively. Chitosan chloride and methyl-β-cyclodextrins appear therefore suitable to formulate solid microparticles able to promote the nose to brain uptake of DFO and to limit its systemic exposure.

Keywords: Chitosan chloride; Deferoxamine mesylate; Methyl-β-cyclodextrin; Nasal formulations; Nose-to-brain transport; Pharmacokinetic studies.

Figure 1

Images obtained by SEM of DCH (left) (10.17 KX) and MCD (right) (20.00 KX)

Figure 2

The water uptake capacity (μl/mg) of the microspheres as well as freeze-dried formulation compared to the free drug as received. Data are reported as the mean value ± SD (n = 3).

Figure 3

XRD pattern of: DFO, MC, MCD, CH, DCH and DFOL.

Figure 4

The permeation profiles of DFO through hydrophilic (solid line) and lipophilic (dotted line) membranes from spray dried (filled symbol) and freeze-dried (empty symbol) formulations of the same concentration. Profiles are compared with those of drug as received and after freeze-drying. H and O letters have been used to indicate the permeation through hydrophilic and lipophilic membranes, respectively. Data are reported as the mean ±S.D of three independent experiments.

Figure 5

P_eff (bars) and TER values (line) of formulations compared with drug. Error bars indicate standard deviation of three independent measurements. H and O letters have been used to indicate the permeation through hydrophilic and lipophilic membranes, respectively. P < 0.05: *DCH H versus (vs.) MCD H, DCH H vs. DFO H; ^#DCHL H vs. MCDL H, DCHL H vs. DFOL H; ^§DCH O vs. MCD O, DCH O vs. DFO O; ^$MCD O vs. DFO O; ^‡DCHL O vs. MCDL O, DCHL O vs. DFOL O; ^†DFO H vs. DFO O, DFO H vs. DFOL H.

Figure 6

Ex vivo permeation profiles of DFO from microspheres. Profiles are compared with that of DFO as received. Data are reported as the mean ±S.D of three independent experiments.

Figure 7

Permeation profiles of DFO from microspheres through Caco-2 (filled symbol) and PC-12 cells (empty symbol). Profiles are compared with that of DFO as received. Data are reported as the mean ±S.D of two independent experiments.

Figure 8

Percentage of drug permeated in the acceptor medium, recovered in the donor compartment (no permeated) and calculated into the cells after 7.5 min and 60 min through Caco-2 (left) and PC-12 cell lines (right). Error bars indicate standard deviation of two independent measurements.

Figure 9

Elimination profile of DFO after 0.2 mg infusion to rats. Data are expressed as the mean ± SD of four independent experiments. The elimination followed an apparent first order kinetic, confirmed by the semilogarithmic plot reported in the inset (n = 6, r = 0.980, P < 0.01). The half-life was calculated to be 15.4 ± 1.8 min. The figure reports also the profile of plasma concentrations of DFO following nasal administration of the same dose of the drug encapsulated in DCH and MCD microparticles.

Figure 10

DFO concentrations (μg/mL) detected in the CSF after nasal administration of DCH and MCD microparticles. Each dose contained 200 μg of the drug. Data are expressed as the mean ± SD of four independent experiments.