4 Hydroxytamoxifen Dilution without Etoh

This protocol is used for the dilution of 4-hydroxytamoxifen (Sigma H6278) without the use of ethanol, and was initially provided to me by Li Ye at the Scripps Research Institute. Below are protocols for dissolving 4-OHT from a single stock solution to either 2 or 4 mg/mL, for 20 or 40 mg/kg injections in mice, respectively. We add DMSO directly to vial from manufacturer to avoid weighing small quantities and subsequently store aliquots at -80.

Stock Solutions:

4-OHT Stock (40mg/mL): Add DMSO to 4-OHT to make 40 mg/mL solution. Aliquots of this can be stored in freezer. Store at -80 (samples stored at -20 can fall out of solution after some period of time. Maybe 6 months). 50ul aliquots are nice to make vials with a final volume of 1 mL (for 20 mg/kg), or 0.5 mL (for 40 mg/kg).

Tween80 Solution A, for 20 mg/kg injection (2.1% Tween80): To make 10 mL of 2.1% Tween-80 in saline. Add 210 uL to 9.79 mL saline. Vortex vigorously.

Tween80 Solution B, for 40 mg/kg injection (4.44% Tween80): To make 10 mL of 4.44% Tween-80 in saline. Add 444 uL to 9.556 mL saline. Vortex vigorously.

Working Solutions:

2 mg/mL, for 20 mg/kg injection

To make a 1mL of this solution, add 950uL of Solution A to 50 ul 4-OHT stock. It will drop out of solution. Vortex immediately until clear. May take about 10-30 seconds. Injecting at 10mL/kg will provide a dose of 20 mg/kg.

Final concentrations of DMSO and Tween-80 are 5% and 2%, respectively.

4 mg/mL, for 40 mg/kg injection

To make a 0.5mL of this solution, add 450uL of Solution B to 50 ul 4-OHT stock. It will drop out of solution. Vortex immediately until clear. May take about 10-30 seconds. Injecting at 10mL/kg will provide a dose of 40 mg/kg.

Final concentrations of DMSO and Tween-80 are 10% and 4%, respectively.

Important notes:
Make working solutions within a half hour of injecting
When you thaw 4OHT/DMSO solution, allow to warm and vortex prior to adding Solutions A/B