Angiotensin-II regulates dosing time-dependent intratumoral accumulation of macromolecular drug formulations via 24-h blood pressure rhythm in tumor-bearing mice.

One approach to increasing pharmacotherapy effects is administering drugs at times of day when they are most effective and/or best tolerated. Circadian variation in expression of pharmacokinetics- and pharmacodynamics-related genes was shown to contribute to dosing time-dependent differences in therapeutic effects of small molecule drugs. However, influence of dosing time of day on effects of high molecular weight formulations, such as drugs encapsulated in liposomes, has not been studied in detail. This study demonstrates that blood pressure rhythm affects dosing time-dependent variation in effects of high molecular weight formulations. Systolic blood pressure in sarcoma 180-bearing mice showed significant 24-h oscillation. Intratumoral accumulation of fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA), an indicator of tumor vascular permeability, varied with dosing time of day, matching phases of blood pressure circadian rhythm. Furthermore, intratumoral accumulation of liposome-encapsulated oxaliplatin (Lipo-L-OHP) increased with increases in systolic blood pressure. Our findings suggest that circadian blood pressure oscillations may be an important factor to consider in dosing strategies for macromolecular drugs and liposomes in cancer therapy.