Evaluation of systemic exposure of nanoparticle suspensions subcutaneously administered to mice regarding stabilization, volume, location, concentration and size.

Different routes of administration are likely to result in very different outcomes due to different availability or plasma profile. The objective of the present study was to evaluate the pharmacokinetic profile after different subcutaneous (s.c.) administration of nanoparticle suspensions of a lipophilic compound to mice. Pharmacokinetics of the selected test compound and the effect of drug concentration, particle size, location of administration, volume given and particle stabilizers were studied. Adding PEGylated lipids or pluronic F-127 to the negatively charged surface of the nanoparticles increased the stability of the particles and the bioavailability. The in vivo studies demonstrated linear absorption kinetics for the selected model compound up to at least 500 µmol/kg. Absorption from upper-neck resulted in different systemic exposure compared to administration in the hip. The former was preferred if a prolonged Cmax was desired while the latter ensured a flat profile for approximately 24 hours. Administering the double volume (but the same dose) had no effect on the pharmacokinetics, whereas smaller particle size significantly increased the exposure.