Influence of different types of low substituted hydroxypropyl cellulose on tableting, disintegration, and floating behaviour of floating drug delivery systems

Reconstitutable spray dried ultra-fine dispersion as a robust platform for effective oral delivery of an antihyperlipidemic drug

The current article highlights the application of spray drying technique to produce an ultra-fine powder encapsulating the antihyperlipidemic drug, atorvastatin calcium (ATV). First, ATV was dissolved in an emulsion formulation, and different carriers (pectin, alginate, chitosan HCl and hydroxypropylmethyl cellulose) in two concentrations (1.5 and 3%) were added. Then, these carrier-containing formulations were subjected to spray drying, whereby ultra-fine ATV-loaded spray dried emulsions were produced (ATV-SDE). The optimum formulation; ATV-SDE7 containing 3% w/w pectin was selected showing an obviously enhanced dissolution profile compared to the other used polymers which could be attributed to its lower ability to swell in acidic medium, resulting in faster drug diffusion into release medium. Thus, ATV-SDE7 was subjected to further characterization including; DSC, XRPD, SEM and flowability properties. In-vivo studies were conducted using high-fat induced hyperlipidemic rats. The optimum formulation depicted normal lipid profile showing significant reduction in the measured parameters at the end of daily oral treatment, compared to ATV marketed tablets and control hyperlipidemic rats confirmed by normal liver sections upon histopathological examination. The superior lipid-lowering activity of ATV-SDE7 was not only due to the enhanced dissolution of ATV but also due to the presence of pectin which is capable of lowering both cholesterol and triglyceride serum levels. Hence, the present study suggests that the formulation strategy employing ultrafine redispersible spray dried emulsion with pectin as a carrier holds a promising approach for the development of a novel dosage form of enhanced antihyperlipidemic effect for ATV.

Understanding the compaction behaviour of low-substituted HPC: macro, micro, and nano-metric evaluations

The fast development in materials science has resulted in the emergence of new pharmaceutical materials with superior physical and mechanical properties. Low-substituted hydroxypropyl cellulose is an ether derivative of cellulose and is praised for its multi-functionality as a binder, disintegrant, film coating agent and as a suitable material for medical dressings. Nevertheless, very little is known about the compaction behaviour of this polymer. The aim of the current study was to evaluate the compaction and disintegration behaviour of four grades of L-HPC namely; LH32, LH21, LH11, and LHB1. The macrometric properties of the four powders were studied and the compaction behaviour was evaluated using the out-of-die method. LH11 and LH22 showed poor flow properties as the powders were dominated by fibrous particles with high aspect ratios, which reduced the powder flow. LH32 showed a weak compressibility profile and demonstrated a large elastic region, making it harder for this polymer to deform plastically. These findings are supported by AFM which revealed the high roughness of LH32 powder (100.09 ± 18.84 nm), resulting in small area of contact, but promoting mechanical interlocking. On the contrary, LH21 and LH11 powders had smooth surfaces which enabled larger contact area and higher adhesion forces of 21.01 ± 11.35 nN and 9.50 ± 5.78 nN, respectively. This promoted bond formation during compression as LH21 and LH11 powders had low strength yield.

Nasal drug absorption from powder formulations: The effect of three types of hydroxypropyl cellulose (HPC)

Despite the numerous advantages of powder formulations, few studies have described their nasal drug absorption. The first aim of this study was to compare the drug absorption from powder formulation with that from a liquid formulation in rats. Since pharmaceutical excipients are usually added to most powder formulations, the second aim of the study was to investigate the effect of hydroxypropyl cellulose (HPC) on nasal drug absorption from the powder. Three types of HPC with different polymerization degrees were used: HPC(SL), HPC(M), and HPC(H). The model drugs were warfarin (BCS Class I), piroxicam (BCS Class II), and sumatriptan (BCS Class III). The absorption of these model drugs in the powder form was higher than that from the solution. All HPCs failed to enhance warfarin absorption, while the piroxicam absorption was enhanced only by HPC(M). Sumatriptan absorption was not enhanced by HPC(SL), but by HPC(M) and HPC(H). The differences in nasal absorption of the three model drugs promoted by HPCs depend on the permeability and solubility of the drug. Moreover, the nasal retention of different formulations was increased by HPCs. Because HPCs showed no toxic effect on the nasal epithelium. These findings indicate that powder formulations supplemented with HPC are a valuable and promising approach to increase the nasal absorption of highly soluble and poorly permeable drugs.