Acetylator status - urine or plasma

Last updated: Friday, 12, March, 2004

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Item Process
Specimen

Laboratories differ in the drugs used to assess acetylator status - consult pathologist before commencing test.

If the protocol specifies caffeine or a drug which the patient is already taking, a random specimen of urine is satisfactory. Otherwise, the patient is given a specified dose of a drug that undergoes acetylation (usually a sulphonamide) and urine is collected between five and six hours after the dose. For most drugs, the test can also be performed on plasma.

This functional test is increasingly being replaced by pharmacogenetic tests.

Method

Spectrophotometry, HPLC, GC.

Reference Interval

Depends on the drug. Slow acetylators usually excrete less than 60-80% of the drug in its acetylated form, whereas fast acetylators excrete more than 60-80% of the drug in its acetylated form.

Application

Assessment of the ability to perform acetylation of a potentially toxic drug which is detoxified by acetylation. Such drugs include sulphonamides (especially salicylazosulphapyridine), hydralazine, procainamide, isoniazid.

Interpretation

Slow acetylators are more likely to develop toxicity when given the drug.

Reference

Pillans PI. Intern Med J 2001; 31: 476-8.