OBJECT DRUGS

• Zidovudine (Retrovir)

PRECIPITANT DRUGS

Glucuronidation Inhibitors:

• Probenecid (Benemid)
• Trimethoprim (Bactrim)
• Valproic acid (Depakene, etc.)

Comment:

Drugs that can inhibit glucuronidation such as probenecid, trimethoprim, and valproic acid may increase zidovudine serum concentrations, probably by inhibition of hepatic metabolism (reduced renal excretion may also be involved). Zidovudine toxicity (e.g., anemia) has been reported.

Class 3: Assess Risk & Take Action if Necessary

• Consider Alternative: If possible use an alternative to the glucuronidation inhibitor. Some have recommended use of an alternative to the zidovudine that is not metabolized by glucuronidation. In one case substitution of stavudine (Zerit) for zidovudine was successful.
• Monitor: Zidovudine dose may need to be adjusted if these drugs are initiated, discontinued or changed in dosage. Watch for anemia in patients receiving zidovudine and valproic acid.