Some drugs are conjugated to glucuronic acid to aid in their elimination from the body. For these drugs, very little of the parent drug will be detected in the urine, most of the drug will be in the conjugated form. Most laboratories do not have assays that measure the glucuronides. Instead, most labs process specimens to convert the conjugated drug back to the unconjugated free form of the drug. by performing an acid, alkaline, or enzyme hydrolysis on the urine specimen before extraction and analysis by GC/MS or LC/MS.
Drugs that are found as glucuronidated conjugates:
- THC-COOH
- Morphine
- Hydromorphone
- Oxymorphone
