Brief Answer:
There is no definite way to do so

Detailed Answer:
Hello,
Thanks for using Healthcaremagic.

I read your query and understand your concerns.

First of all I like to inform you that there is no mechanism which can flush out the cocaine from your system in 12 hours. However I can delineate something which can help you in withdrawal.

I am writing down few of the strategies that will help you in management of Crack withdrawal

The first and foremost is adequate intake of water. Take at least four to five litres of water in 12 hour time. This will help you in flushing out the toxins of crack as soon as possible and will reduce oxidative stress on various organs of the body which are causing you the symptoms..

The second is deep breathing exercise. Try to hold your breath for 8-10 seconds and that exhale slowly. This will help in management of sleep and other stresses related to cocaine withdrawal. Aim to have one breath of 12-15 seconds.

The third is use of physical exercise. During this time it will be appropriate to engage for two hour exercise in 24 hour time. I understand it may sound as health advice but believe me that it helps by increasing the level of endorphins and combats with excessive fatigue and mood swings.

Ensure intake of adequate quantity of fiber with diet. This helps in eliminating toxins in the gastrointestinal tract and decreases the symptoms much early .

Close your eyes and rotate the eye balls for couple of minutes frequently.

Avoid starring for longer time at the computer screen or TV for longer time

Steam inhalation before going to sleep will be very refreshing

Have phenargan(promethazine) for sleep. It is over the counter medication and normally 25 mg is sedative for most of us.

There are many more which can be used but these are the first steps.

Wish you great health ahead.

Thanks and regards

---