The government should just accept the fact that the drugs can't be eliminated. As long as the demand exists, the people will find a way to secure them. The only viable option is to legalize and regulate them.
Making it legalize and regulate them would really cause to much more trouble on this world and its not really right to exclude it and I would rather choose to stick on prohibiting it rather than on legalizing it because i cant imagine a society on which drugs are legal.