Therapeutics

Drug Particle Size Plays a Key Role in Cancer Treatment

Reducing the size of drug particles enhances their uptake into cells leading to more effective tumor treatment.

One of the greatest challenges of our time is the early detection and effective treatment of cancer. Nanomedicine, which is a branch of nanotechnology, has been implemented in various ways to tackle this problem.

Endocytosis is the active transport of material, for example, nanomedicine, into a cell. In work recently reported by Chao Qin, Lifang Yin and their team at the School of Pharmacy, China Pharmaceutical University in Nanjing, China caveolae-mediated endocytosis is focused on as this mechanism bypasses the acidic endosomes and lysosomes that would degrade the nanomedicine. This results in the delivery of a greater amount of active drugs with more efficient and immediate access to intracellular targets.

Qin, Yin and team worked with paclitaxel nanosuspensions (PTX-Ns) and specifically investigated the importance of the size of these rod-shaped particles. PTX is one of the most widely used drugs for cancer treatment. They discovered that the delivery of PTX-Ns to cancer cells within solid tumors is strongly size-dependent. A decrease in the size of the PTX-Ns from 500 to 160 nm significantly enhanced cellular internalization and thus promoted cancer cell apoptosis due to the participation of caveolae-mediated endocytosis. In addition their work demonstrated that 1) the size reduction of PTX-Ns did not alter the tumor accumulation, but resulted in prolonged retention in the tumor site; 2) smaller PTX-Ns could dramatically increase the systemic exposure and significantly prolong the circulation time; and 3) PTX-Ns with a size not greater than 200 nm could significantly inhibit tumor growth. These new insights will assist in the design and optimization of nanosuspension formulations for disease therapy.

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