Zotarolimus

Biological Activity

In vitro: Zotarolimus (ABT-578) is a semi-synthetic analogue of rapamycin, made by substituting a tetrazole ring for the native hydroxyl group at position 42 in rapamycin. Zotarolimus is highly effective in inhibiting both smooth muscle cell and endothelial cell proliferation, with IC50 values of 2.9 nM and 2.6 nM, respectively. Zotarolimus is mechanistically similar to sirolimus in having high-affinity binding to the immunophilin FKBP12 and comparable potency for inhibiting in vitro proliferation of both human and rat T cells. Zotarolimus inhibits Con A-induced human T cells and rat T cells proliferation with IC50 of 7.0 nM and 1337 nM respectively. In vivo: Zotarolimus-eluting stents effectively reduce neointima formation in a 28-day, well-characterized swine model of coronary artery restenosis. Zotarolimus appears effective in preventing neointimal thickening, reducing late loss from 1.03 to 0.62 mm with a 47% reduction in TVF compared with bare metal stents (15.4% with the Driver stent to 8.1% with the Endeavor stent). Zotarolimus is efficacious in suppressing adjuvant DTH, EAE, and cardiac allograft rejection with ED50 values of 1.72, 1.17, and 3.71 mg/kg/day, respectively.

Protocol (for reference only)

Cell Experiment
Cell lines	Human coronary artery cells
Preparation method	Cell proliferation is assayed by measuring tritiated thymidine incorporation in vitro. Human coronary artery cells (hCa) are seeded into tissue culture flasks for expansion and applied to 96-well plates at desired density in complete media (5000 hCaSMC; 10 000 hCaEC). After 2 days, complete media is replaced with incomplete media to synchronize cells and induce G0 state. Two days later, incomplete media are removed and replaced with complete media (serum/growth factors) to induce G0 to G1 transition. Complete media also contain drug at desired concentrations to determine its effects on cell proliferation. On day 7, 3H-thymidine is added to cells to monitor DNA synthesis, and cells are harvested after overnight incorporation of radioactivity. After an incubation period of 72 h, 25 μL (1 μCi/well) of 3H-thymidine are added to each well. The cells are incubated at 37°C for 16-18 h to allow for incorporation of 3H-thymidine into newly synthesized DNA and the cells harvested onto 96-well plates containing bonded glass fibre filters . The filter plates are air-dried overnight, MicroScint-20 (25 μL) added to each filter well and counted. Drug activity is determined by the inhibition of 3H-thymidine incorporation into newly synthesized DNA relative to cells grown in complete media.
Concentrations	~1 μM
Incubation time	5 days

Animal Experiment
Animal models	Male Sprague-Dawley rats
Formulation	ethanol: propylene glycol: cremophor EL: D5W vehicle (20: 30: 2: 48, by volume)
Dosages	2.5 mg/kg
Administration	intravenous or oral

Chemical Information

Molecular Weight	966.21
Formula	C52H79N5O12
CAS Number	221877-54-9
Solubility (25°C)	100 mg/mL in DMSO
Storage	Powder          -20°C   3 years ;  4°C   2 years In solvent       -80°C   6 months ;  -20°C   1 month

Conversion of different model animals based on BSA (PMID: 27057123)

Species	Mouse	Rat	Rabbit	Guinea pig	Hamster	Dog
Weight (kg)	0.02	0.15	1.8	0.4	0.08	10
Body Surface Area (m2)	0.007	0.025	0.15	0.05	0.02	0.5
Km factor	3	6	12	8	5	20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by	Animal B Km
	Animal A Km

For example, to modify the dose of Compound A used for a mouse (20 mg/kg) to a dose based on the BSA for a rat, multiply 20 mg/kg by the K_m factor for a mouse and then divide by the K_m factor for a rat. This calculation results in a rat equivalent dose for Compound A of 10 mg/kg.

References

[1] Iqbal J, et al. Circ Cardiovasc Interv. Comparison of zotarolimus- and everolimus-eluting coronary stents: final 5-year report of the RESOLUTE all-comers trial.

[2] Valgimigli M, et al. J Am Coll Cardiol. Zotarolimus-eluting versus bare-metal stents in uncertain drug-eluting stent candidates.