Nanomedicine

Nanomedicine uses the tools of nanotechnology (ie, biocompatible nanoparticles and nanorobots) to deliver drugs, diagnose disease, and do in vivo imaging. Nanotechnology has improved drug delivery by targeting specific organs to optimize the efficacy and safety profiles of individual drugs. The nanoparticle size (usually ranging from 1 to 100 nm), shape, and surface chemistry are important factors that contribute to its pharmacokinetics, including the degree of absorption Drug Absorption Drug absorption is determined by the drug’s physicochemical properties, formulation, and route of administration. Dosage forms (eg, tablets, capsules, solutions), consisting of the drug plus... read more , bioavailability Drug Bioavailability Bioavailability refers to the extent and rate at which the active moiety (drug or metabolite) enters systemic circulation, thereby accessing the site of action. Bioavailability of a drug is... read more , cellular uptake, biodistribution Drug Distribution to Tissues After a drug enters the systemic circulation, it is distributed to the body’s tissues. Distribution is generally uneven because of differences in blood perfusion, tissue binding (eg, because... read more , and clearance Drug Excretion The kidneys are the principal organs for excreting water-soluble substances. The biliary system contributes to excretion to the degree that drug is not reabsorbed from the gastrointestinal ... read more [ 1, 2, 3 General references Nanomedicine uses the tools of nanotechnology (ie, biocompatible nanoparticles and nanorobots) to deliver drugs, diagnose disease, and do in vivo imaging. Nanotechnology has improved drug delivery... read more ]).

Most nanomedicines are administered orally or intravenously and achieve their effects through passive targeting, which relies on nonspecific accumulation in tissues, including tumors (2 General references Nanomedicine uses the tools of nanotechnology (ie, biocompatible nanoparticles and nanorobots) to deliver drugs, diagnose disease, and do in vivo imaging. Nanotechnology has improved drug delivery... read more ). Liposomes were the first nanomedicines and remain one of the most successful nanoparticles conjugated to chemotherapeutic agents, such as doxorubicin and irinotecan, to improve their biodistribution (2, 4 General references Nanomedicine uses the tools of nanotechnology (ie, biocompatible nanoparticles and nanorobots) to deliver drugs, diagnose disease, and do in vivo imaging. Nanotechnology has improved drug delivery... read more ).

Polymeric nanoparticles (eg, peg-filgrastim) increase a drug’s half-life and bioavailability and have been used in controlled-release applications. Micelles are used to encapsulate poorly water-soluble drugs (eg, estradiol) to enhance their dissolution in aqueous solution and hence their absorption.

Nanocrystals are comprised of only the drug, at nanoscale dimension (eg, sirolimus), that leads to increased surface area for dissolution and solubility. With the burgeoning interest in nanomedicine-based drugs, the pharmacokinetics and pharmacodynamics Overview of Pharmacodynamics Pharmacodynamics (sometimes described as what a drug does to the body) is the study of the biochemical, physiologic, and molecular effects of drugs on the body and involves receptor binding... read more must be closely evaluated to optimize drug delivery to the target site while minimizing adverse effects since nanoparticles are designed to be long-lasting with minimal excretion within organs.

(See also Overview of Pharmacokinetics Overview of Pharmacokinetics Pharmacokinetics, sometimes described as what the body does to a drug, refers to the movement of drug into, through, and out of the body—the time course of its absorption, bioavailability, distribution... read more .)