ABSTRACT
As a novel targeting drug delivery system, acid-sensitive micelles have many advantages, such as increasing solubility of lipophilic drugs, acid-sensitive release, high drug loading, etc. They can load drugs though non-covalent encapsulation and covalent conjugation methods. In tumor tissues, drugs are released quickly from the depolymerized micelles with lipophilic copolymer protonation or lypohydrophilic copolymer hydrolysis and covalent conjugated drugs are released when the acid-sensitive covalent linkage breaks. This review mainly advances acid-sensitive micelles for the tumor targeting drug delivery systems from drug-loaded methods and release mechanisms.
Subject(s)
Animals , Humans , Antibiotics, Antineoplastic , Pharmacology , Antineoplastic Agents, Phytogenic , Pharmacology , Cell Line, Tumor , Doxorubicin , Pharmacology , Drug Carriers , Chemistry , Drug Delivery Systems , Hydrogen-Ion Concentration , Lactates , Chemistry , Micelles , Paclitaxel , Pharmacology , Polyethylene Glycols , Chemistry , PolymersABSTRACT
Generation 4 polyamidoamine (PAMAM) dendrimer was PEGylated with polyethylene glycol (PEG) at an average molecular weight 5 000 via amide bond. PAMAM and PEGylated PAMAM (PAMAM-PEG) dendrimer were used as drug nanocarriers. Methotrexate (MTX), an antineoplastic agent, was selected as a model drug. PAMAM/MTX and PAMAM-PEG/MTX complexes were prepared. The pharmacokinetic characters and anti-tumor activity of the PAMAM-PEG/MTX complex were studied as compared with MTX injection and PAMAM/MTX complex by intravenous injection in rats and S180 tumor bearing mice, separately. The plasma samples from normal rats were analyzed by HPLC method, and concentration-time data were analyzed using a non-compartmental analysis. Their anti-tumor effects in vivo were evaluated against S180 solid tumors in mice by measuring average tumor weight and calculating the inhibitory rate of tumor on day 17 after successive injections. The results showed that both plasma half-life and mean retention time (MRT) of the complexes were longer than that of MTX injection (P<0.01), while the area under the plasma concentration vs time curve (AUC) of PAMAM-PEG/MTX was the largest as compared with that of free drug and PAMAM/MTX complex (P<0.01). The inhibitory rate of tumor of PAMAM-PEG/MTX complex enhanced 2.1 and 1.8 times over that of free drug and PAMAM/MTX complex, respectively, indicating that PAMAM-PEG/MTX exhibited the highest antitumor activity. In summary, PEGylated PAMAM could be useful as a potential drug delivery carrier.