The levamisole test kits should be made available to the smugglers. If the smugglers knew they were shipping (detectably) impure cocaine, there would be pressure on the producers to stop cutting the product.
(... and a little voice in my head tells me that we'd be better off if drugs were regulated rather than illegal.)
Decriminalisation, and to some extent regulation (addicts can take pure drugs in certain clinics as part of a process to stop taking drugs), is currently providing some improvement in user and crime rates in Portugal: http://www.time.com/time/health/article/0,8599,1893946,00.ht...
Technically cocaine is already regulated and legal. It's just that the regulations are such that it's very difficult to get unless you're an ophthalmologist or ENT doctor.
(... and a little voice in my head tells me that we'd be better off if drugs were regulated rather than illegal.)