Drug carrier

About: Drug carrier is a research topic. Over the lifetime, 18276 publications have been published within this topic receiving 997718 citations. The topic is also known as: drug carriers & drug vehicle.

Molecular design and in vitro studies of novel pH-sensitive hydrogels for the oral delivery of calcitonin

Abstract: pH-sensitive hydrogels are suitable candidates for oral drug delivery of peptides due to their ability to respond to their environment. We have developed new hydrogels composed of poly(methacrylic acid) (PMAA) grafted with poly(ethylene glycol) (PEG) (P(MAA-g-EG)) which can be used as drug delivery carriers for salmon calcitonin. P(MAA-g-EG) hydrogels were prepared by free radical solution polymerization. The monomer mixture was diluted using a 50% w/w solution of ethanol and water. The percentage of monomer in solution was varied from 84% to 45% v/v. Swelling studies were conducted to investigate the effects of solvent content used during polymer preparation in the swelling behavior. The effects of dilution on the swelling behavior were not observed until the monomer mixture was diluted to approximately 50%. Salmon calcitonin was successfully incorporated and released in vitro from the system. Solutions of approximately 0.1 mg/mL of salmon calcitonin were used to load the protein into the gels at pH = 7 ...

Lipase-sensitive polymeric triple-layered nanogel for "on-demand" drug delivery.

Abstract: We report a new strategy for differential delivery of antimicrobials to bacterial infection sites with a lipase-sensitive polymeric triple-layered nanogel (TLN) as the drug carrier. The TLN was synthesized by a convenient arm-first procedure using an amphiphilic diblock copolymer, namely, monomethoxy poly(ethylene glycol)-b-poly(e-caprolactone), to initiate the ring-opening polymerization of the difunctional monomer 3-oxapentane-1,5-diyl bis(ethylene phosphate). The hydrophobic poly(e-caprolactone) (PCL) segments collapsed and surrounded the polyphosphoester core, forming a hydrophobic and compact molecular fence in aqueous solution which prevented antibiotic release from the polyphosphoester core prior to reaching bacterial infection sites. However, once the TLN sensed the lipase-secreting bacteria, the PCL fence of the TLN degraded to release the antibiotic. Using Staphylococcus aureus (S. aureus) as the model bacterium and vancomycin as the model antimicrobial, we demonstrated that the TLN released alm...

Carrier effects on biological activity of amphotericin B.

Abstract: Amphotericin B (AmB), the drug of choice for the treatment of most systemic fungal infections, is marketed under the trademark Fungizone, as an AmB-deoxycholate complex suitable for intravenous administration. The association between AmB and deoxycholate is relatively weak; therefore, dissociation occurs in the blood. The drug itself interacts with both mammalian and fungal cell membranes to damage cells, but the greater susceptibility of fungal cells to its effects forms the basis for its clinical usefulness. The ability of the drug to form stable complexes with lipids has allowed the development of new formulations of AmB based on this property. Several lipid-based formulations of the drug which are more selective in damaging fungal or parasitic cells than mammalian cells and some of which also have a better therapeutic index than Fungizone have been developed. In vitro investigations have led to the conclusion that the increase in selectivity observed is due to the selective transfer of AmB from lipid complexes to fungal cells or to the higher thermodynamic stability of lipid formulations. Association with lipids modulates AmB binding to lipoproteins in vivo, thus influencing tissue distribution and toxicity. For example, lipid complexes of AmB can be internalized by macrophages, and the macrophages then serve as a reservoir for the drug. Furthermore, stable AmB-lipid complexes are much less toxic to the host than Fungizone and can therefore be administered in higher doses. Experimentally, the efficacy of AmB-lipid formulations compared with Fungizone depends on the animal model used. Improved therapeutic indices for AmB-lipid formations have been demonstrated in clinical trials, but the definitive trials leading to the selection of an optimal formulation and therapeutic regimen have not been done.