Mesoporous silica-based dosage forms improve bioavailability of poorly soluble drugs in pigs: case example fenofibrate.

OBJECTIVES: Mesoporous silicas (SLC) have demonstrated considerable potential to improve bioavailability of poorly soluble drugs by facilitating rapid dissolution and generating supersaturation. The addition of certain polymers can further enhance the dissolution of these formulations by preventing drug precipitation. This study uses fenofibrate as a model drug to investigate the performance of an SLC-based formulation, delivered with hydroxypropyl methylcellulose acetate succinate (HPMCAS) as a precipitation inhibitor, in pigs. The ability of biorelevant dissolution testing to predict the in vivo performance was also assessed. KEY FINDINGS: Fenofibrate-loaded mesoporous silica (FF-SLC), together with HPMCAS, displayed significant improvements in biorelevant dissolution tests relative to a reference formulation consisting of a physical mixture of crystalline fenofibrate with HPMCAS. In vivo assessment in fasted pigs demonstrated bioavailabilities of 86.69 ± 35.37% with combination of FF-SLC and HPMCAS in capsule form and 75.47 ± 14.58% as a suspension, compared to 19.92 ± 9.89% with the reference formulation. A positive correlation was identified between bioavailability and dissolution efficiency. CONCLUSIONS: The substantial improvements in bioavailability of fenofibrate from the SLC-based formulations confirm the ability of this formulation strategy to overcome the dissolution and solubility limitations, further raising the prospects of a future commercially available SLC-based formulation.

Mesoporous silica-based dosage forms improve release characteristics of poorly soluble drugs: case example fenofibrate.

OBJECTIVES: Mesoporous silica-based dosage forms offer the potential for improving the absorption of poorly soluble drugs after oral administration. In this investigation, fenofibrate was used as a model drug to study the ability of monomodal ('PSP A') and bimodal ('PSP B') porous silica to improve release by a 'spring' effect in in vitro biorelevant dissolution tests. Also investigated was the addition of various polymers to provide a 'parachute' effect, that is, to keep the drug in solution after its release. KEY FINDINGS: Loading fenofibrate onto PSP A or PSP B porous silica substantially improved the dissolution profile of fenofibrate under fasted state conditions compared with both pure drug and the marketed product, TriCor® 145 mg. Adding a polymer such as hydroxypropyl methylcellulose acetate succinate, polyvinylpyrrolidone or copovidon (HPMCAS, PVP or PVPVA) sustains the higher release of fenofibrate from the PSP A silica, resulting in a combination 'spring and parachute' effect - loading the drug onto the silica causes a 'spring' effect while the polymer enhances the spring effect (HPMCAS, PVP) and adds a sustaining 'parachute'. Interestingly, a silica to polymer ratio of 4:1 w/w appears to have an optimal effect for fenofibrate (HPMCAS, PVP). Dissolution results under conditions simulating the fasted state in the small intestine with the PSP A or the PSP B silica with HPMCAS added in a 4:1 w/w ratio show very substantial improvement over the marketed, nanosized product (TriCor® 145 mg). CONCLUSIONS: Further experiments to determine whether the highly positive effects on fenofibrate release observed with the silica prototypes investigated to date can be translated to further poorly soluble drugs and to what extent they translate into improved in-vivo performance are warranted.

Transferrin- and transferrin-receptor-antibody-modified nanoparticles enable drug delivery across the blood-brain barrier (BBB).

Human serum albumin (HSA) nanoparticles were manufactured by desolvation. Transferrin or transferrin receptor monoclonal antibodies (OX26 or R17217) were covalently coupled to the HSA nanoparticles using the NHS-PEG-MAL-5000 crosslinker. Loperamide was used as a model drug since it normally does not cross the blood-brain barrier (BBB) and was bound to the nanoparticles by adsorption. Loperamide-loaded HSA nanoparticles with covalently bound transferrin or the OX26 or R17217 antibodies induced significant anti-nociceptive effects in the tail-flick test in ICR (CD-1) mice after intravenous injection, demonstrating that transferrin or these antibodies covalently coupled to HSA nanoparticles are able to transport loperamide and possibly other drugs across the BBB. Control loperamide-loaded HSA nanoparticles with IgG2a antibodies yielded only marginal effects.