Drug Testing

I should probably know the clearance time frame for all these drugs but I don't. What is the clearance time for BZO, OPI, and BAR? We are testing with urine drug screens using the i-cup. I know the clearance for THC is about 2 weeks if a patient smokes frequently and has numbers in the thousands on a lab result. But, what about the pt. that doesn't smoke that frequently, is it still about 2 weeks. Is there some sort of statistical chart or something of that nature used? We want to try to retest to hopefully get a neg result without waiting the full 2 weeks. This is easier when sending urine to lab for quantitative results to determine if a pt. quit smoking pot when they say they did and see the numbers drop. But, it's more difficult with the i-Cup giving a yes/no result. We are trying to avoid sending every positive result to lab. We will be putting the i-Cup results in the patient's charta. The plan is to somehow let the pt. know the i-Cup testing is on us but if results come back pos the 2nd time, they will have their insurance billed for the lab testing. This is an out-patient CD clinic. We were sending all urines to lab and absorbing the cost but are trying to cut costs by doing our own testing. I am being asked to write a policy for this i-Cup testing and a information sheet to go in the patient's info packets about it. The majority of staff doing these i-Cup tests are not nurses. If anyone may some advice on developing a policy can PM me. I would would really appreciate any input on this matter. Thank you in advance.