Pharmacokinetics properties of surface-modified vesicles

Phospholipid vesicles, also called liposome, are potent carriers of various drugs and offer a drug targeting system into specific organs, tissues, or cells, to minimize the drug administration dose and improve the therapeutic safety. Recently, we have found that phospholipid vesicle containing an anionic amphiphile; 1,5-dihexadecyl-L-glutamate-N-succinic acid (Suc-2C ₁₆) and polyethylene glycol)-lipid (PEG-DSPE) are mainly up taken by rabbit bone marrow at a small injection dose (15 mg/kg b.w.). At 24 h after intravenous injection of 99m-technetimu ( ^99mTc)-labeled vesicles in rabbit, biodistribution data clearly indicated that the component of Suc-2C ₁₆ induced the significant affinity to bone marrow in comparison with control vesicles, which do not have Suc-2C ₁₆. Further incorporation of as little as 0.6 mol% of PEG-DSPE passively enhanced the distribution of Suc-Ve into bone marrow inhibiting the liver uptake, and this formulation was distributed in the bone marrow over the whole body, reaching to 70% of the injected dose by 6 h after injection.