set string case to missing if a phrase is found

Hello,

I have a series of string variables (drug1 - drug25) that contain information on types of drugs. Below is an example of 2 of the variables and their contents:

Code:

* Example generated by -dataex-. For more info, type help dataex
clear
input str25 drug1 str27 drug2
"Fentanyl (0.91)"    "Norfentanyl (0)"         
"Fentanyl (2.25)"    "Norfentanyl (0.81)"      
"MDMA (0)"           "Methamphetamine (20.98)" 
"MDMA (0)"           "Methamphetamine (42.667)"
"THC (3.29)"         ""                        
"THC (48.51)"        ""                        
"THC (24.5)"         ""                        
"Hydrocodone (0)"    "Hydromorphone (0)"       
"Norhydrocodone (0)" "Noroxycodone (0)"        
"MDMA (0)"           "Methamphetamine (5.417)" 
end

What i want to do is whenever "(0)" appears, i want the contents of that cell set to missing or "". If it's anything other than "(0)" (e.g., 0.91) it's left alone.

Any help would be greatly appreciated!

Thanks