The application of intraocular drug delivery is usually limited due to special anatomical and physiological barriers, and the elimination mechanisms in the eye. Organic nano-drug delivery carriers exhibit excellent adhesion, permeability, targeted modification and controlled release abilities to overcome the obstacles and improve the efficiency of drug delivery and bioavailability. Solid lipid nanoparticles can entrap the active components in the lipid structure to improve the stability of drugs and reduce the production cost. Liposomes can transport hydrophobic or hydrophilic molecules, including small molecules, proteins and nucleic acids. Compared with linear macromolecules, dendrimers have a regular structure and well-defined molecular mass and size, which can precisely control the molecular shape and functional groups. Degradable polymer materials endow nano-delivery systems a variety of size, potential, morphology and other characteristics, which enable controlled release of drugs and are easy to modify with a variety of ligands and functional molecules. Organic biomimetic nanocarriers are highly optimized through evolution of natural particles, showing better biocompatibility and lower toxicity. In this article, we summarize the advantages of organic nanocarriers in overcoming multiple barriers and improving the bioavailability of drugs, and highlight the latest research progresses on the application of organic nanocarriers for treatment of ocular diseases.
Drug Carriers ; Delayed-Action Preparations ; Drug Delivery Systems ; Nanoparticles/chemistry*

Polymeric drug delivery system for insulin controlled-release is one of the most active fields of research and development in the world. Up to date, several kinds of intelligent drug carriers for glucose-responsive insulin delivery have been reported. On the basis of a large quantity of references on this topic, a review has been made on the developments of the intelligent polymeric systems for glucose-responsive insulin delivery.
Delayed-Action Preparations ; Drug Carriers ; Drug Delivery Systems ; instrumentation ; Hypoglycemic Agents ; administration & dosage ; Insulin ; administration & dosage

The intelligent controlled drug delivery systems are a series of the preparations including microcapsules or nanocapsules composed of intelligent polymers and medication. The properties of preparations can change with the external stimuli such as pH value, temperature, chemical substance, light, electricity and magnetism. According to this properties, the drug delivery can be intelligently controlled. This paper has reviewed research on syntheses and applications of intelligent controlled drug delivery systems with polymers.
Delayed-Action Preparations ; Drug Carriers ; chemistry ; Drug Delivery Systems ; Polymers ; chemistry ; Technology, Pharmaceutical

OBJECTIVETo evaluate the effect of different preparation methods on the encapsulation efficiency (EE) and drug loading (DL) of paclitaxel-loaded polybutylcyanoacrylate nanoparticles (PTX-PBCA-NPs) and optimize the preparation of PTX-PBCA-NPs.

METHODSWith DL and EE as the major indexes, the qualities of PTX-PBCA-NPs produced by the interfacial polymerization and emulsion polymerization method were compared. The optimized prescription was obtained by orthogonal design.

RESULTSThe ranges of EE of PTX-PBCA-NPs with the two methods were both 94.39%-99.23%. The highest DL with interfacial polymerization was (1.07-/+0.03)%, as compared to (0.86-/+0.01)% with emulsion polymerization. The optimized preparation conditions resulted in the mean size of PTX-PBCA-NPs of 235.6 nm, DL of 0.80%, and EE of 95.71%.

CONCLUSIONThe EE of PTX-PBCA-NPs prepared by the above two methods is consistent with the requirement of the Pharmacopoeia of China, and PTX-PBCA-NPs containing higher DL can be obtained via interfacial polymerization.

Delayed-Action Preparations ; chemical synthesis ; Drug Carriers ; chemistry ; Drug Delivery Systems ; Enbucrilate ; chemistry ; Nanoparticles ; chemistry ; Paclitaxel ; administration & dosage ; Polymerization

Delayed-Action Preparations ; Drug Carriers ; Drug Delivery Systems ; Lactic Acid ; Microspheres ; Nanotechnology ; Polyesters ; Polymers ; Technology, Pharmaceutical ; methods

As a drug additive, polyvinyl alcohol(PVA) has merits of solubility, easy forming, strong conglutination, high thermal stability, low toxicity and no irritation. In these years, PVA has been applied wider and wider in medicine industry. In the study of modem preparations of TCM PVA, as film material of membrane and pellicles, is very promising owing to its easy forming and excellent toughness. PVA is good polymer matrix for suppositories and gel, because it can not only carry drug but also improve the properties of preparations on application and technology. It can be said that PVA is an excellent carrier. At the present, PVA is mainly applied in vitro preparations of TCM, but its applications will be spread with further research. The prospective applications of PVA in osmotic pump controlled release preparations, drug carried microspheres and swelling controlled release system are foreseen.
Delayed-Action Preparations ; Drug Carriers ; Drug Delivery Systems ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; Plants, Medicinal ; chemistry ; Polyvinyl Alcohol

Environmental stimuli-responsive microcapsules are getting more and more interests because of their potential applications in site-specific and time- and rate-programmed controlled-release. In this study, thermo-responsive microcapsules with linear grafted poly(N-isopropylacrylamide) (PNIPAM) gates on the inner pore surface were prepared, and the thermo-responsive controlled-release experiments were carried out. Interfacial polymerization was introduced to prepare polyamide porous microcapsules, and plasma-graft pore-filling polymerization was used to graft PNIPAM into the pore of the microcapsule membranes. The experimental results showed that PNIPAM-grafted microcapsules were featured with thermo-responsiveness due to the thermoresponsive swollen-shrunken property of PNIPAM chains grafted on the inner pore surface of the microcapsule membrane. At temperatures below the lower critical solution temperature (LCST), the linear grafted PNIPAM chains on the inner pore surface were in the swollen state, and the pores in the membrane were closed and the solute molecules were restrained to pass, as a result the release rate was low. In contrast, the grafted PNIPAM chains were in the shrunken state at temperatures above the LCST, and therefore the pores in the membrane were open, and a high release rate was the result.
Acrylic Resins ; chemistry ; Biocompatible Materials ; Capsules ; Delayed-Action Preparations ; Drug Carriers ; Drug Delivery Systems ; Humans ; Polymers ; Porosity ; Temperature

Dendrimers are highly branched macromolecules that have attractive nano-sized architectures. It seems that they can enter various cells easily because of their unique nanostructures and chemical properties, which make them to be one of important candidates of non-virus carriers for drug delivery or gene therapy. However, the understanding of cytotoxicity and related mechanisms of dendrimers are still limited. In recent years there has been rapid increases of researches regarding the biological effects of dendrimers, including the interactions of dendrimers to cells, transport mechanisms, intracellular distribution and biodistribution in vivo, as well as improvement of biocompatibility of dendrimers by surface engineering. In this paper, recent advances in the investigations of biological effect and surface modification for the dendrimers as drug or gene delivery systems were reviewed.
Animals ; Dendrimers ; chemistry ; pharmacology ; Drug Carriers ; chemistry ; Drug Delivery Systems ; methods ; Humans ; Macromolecular Substances ; chemistry ; Nanostructures

AIMTo study the erosion behaviour during dissolution of matrices using different molecular weight polyethylene oxide (PEO) as hydrophilic polymer.

METHODSPEO hydrophilic matrix tablets with no added drug and excipients were prepared by direct compression method. The erosion rates of matrices comprised of pure or blending PEO polymers were evaluated in distilled water at (37 +/- 0.5) degrees C with rotating rate of 50 r x min(-1). The relationship between PEO molecular weight and erosion rate of matrices was investigated by experimental and mathematical model methods.

RESULTSThe gravimetric erosion experimental results indicated that the power-law relationship which relates the polymer erosion rate and weight average molecular weight: k infinity (M(w)) -1.30 4 was proved to have great potential utility in predicting the degree of polymer erosion of matrices comprised of either intermediate molecular weight (97. 98 x 10(4) - 553. 36 x 10(4)) or blends of lower and higher molecular weight polymers. Based on the semiempirical equation for mass transfer rate: Jp = (fp < Dp > (2/3) v (-1/6) omega (1/2)) C(p,dis), a theoretical mathematic model was developed for describing the relationship between PEO erosion rate and PEO weight average molecular weight: Jp infinity M(-1.241), where the exponent of -1. 241 was very close to the exponent of - 1. 130 4 obtained from practical determination.

CONCLUSIONPEO was proved to be a good candidate of hydrophilic polymer and appeared to have great potential for controlled release applications. The mathematic model presented together with the utilization of the erosion behaviour discussed in our study could provide a guide line to predict the degree of polymer erosion for other intermediate polymer grades and / or mixture of the polymers utilized in this study, which could play an active role in designing PEO hydrophilic sustained delivery systems.

Delayed-Action Preparations ; chemistry ; Drug Carriers ; chemistry ; Drug Delivery Systems ; Drug Stability ; Excipients ; chemistry ; Molecular Weight ; Polyethylene Glycols ; administration & dosage ; chemistry ; Polymers ; Solubility ; Tablets ; Water

To prepare verapamil hydrochloride (VH) core-in-cup tablets with tri-layered tablet and four-layered tablet as core tablets, separately, which can provide biphasic release with double-pulsatile and multi-phasic release, core tablets were prepared by direct compression method, and core-in-cup tablets by dry-compression coated technology. The parameter, time-lag (T(lag)), was used to evaluate the influence of factors, such as the weight of the top cover layer, the amount of hydroxypropylmethylcellulose (HPMC), and the compression load on VH release. With the increase of the weight and HPMC amount of the top cover layer, the first lag time T(lag1) was prolonged. The second lag time T(lag2) of core-in-cup tablet with four-layered tablet as core tablet increased with the increasing amount of HPMC K100M. With the increase of compression load among the range (6 - 10 kg x cm(-2)), the two lag times were prolonged. Core-in-cup tablets with double-pulsatile and multi-phasic release released VH after the first lag time (4 -5 h), then kept sustained release for 12 h or 13 h, finally released rapidly. The drug in the core-in-cup tablet only released from the top cover layer. T(lag) is determined by the erosion rate of the inhibitor layers (the top cover layer and the sustained-release layer of the multi-layer core tablet).
Delayed-Action Preparations ; Drug Carriers ; Drug Compounding ; methods ; Drug Delivery Systems ; Excipients ; chemistry ; Hypromellose Derivatives ; Methylcellulose ; analogs & derivatives ; chemistry ; Tablets ; Verapamil ; administration & dosage