The exact processes that occur are not known even after 50 years since its discovery, but many studies present theories on the mechanisms of DIL.A predisposing factor to developing DIL is N-acetylation speed, or the rate at which the body can metabolize the drug. This is greatly decreased in patients with a genetic deficiency of the enzyme N-acetyltransferase. A study showed that 29 of 30 patients with DIL were slow acetylators. In addition, these patients had more hydralazine metabolites in their urine than fast acetylators. These metabolites (byproducts of the interactions between the drug and constituents in the body) of hydralazine are said to have been created when white blood cells have been activated, meaning they are stimulated to produce a respiratory burst. Respiratory burst in white blood cells induces an increased production of free radicals and oxidants such as hydrogen peroxide. These oxidants have been found to react with hydralazine to produce a reactive species that is able to bond to protein. Monocytes, one type of white blood cell, detect the antigen and relay the recognition to T helper cells, creating antinuclear antibodies leading to an immune response. Further studies on the interactions between oxidants and hydralazine are necessary to understand the processes involved in DIL.Of the drugs that cause DIL, hydralazine has been found to cause a higher incidence. Hydralazine is a medication used to treat high blood pressure. Approximately 5% of the patients who have taken hydralazine over long periods of time and in high doses have shown DIL-like symptoms.
Valrubicin (N-trifluoroacetyladriamycin-14-valerate, trade name Valstar) is a chemotherapy drug used to treat bladder cancer. Valrubicin is a semisynthetic analog of the anthracycline doxorubicin, and is administered by infusion directly into the bladder. It was originally launched as Valstar in the U.S. in 1999 for intravesical therapy of Bacille Calmette-Guérin (BCG)-refractory carcinoma in situ of the urinary bladder in patients in whom cystectomy would be associated with unacceptable morbidity or mortality; however, it was voluntarily withdrawn in 2002 due to manufacturing issues. Valstar was relaunched on September 3, 2009. Side effects
Blood in urine
Incontinence
painful or difficult urination
Unusually frequent urination


== References ==