Her death was ultimately ruled an accidental drug overdose of the sedative chloral hydrate that became increasingly lethal when combined with other prescription drugs in her system, specifically four benzodiazepines: Klonopin (Clonazepam), Ativan (Lorazepam), Serax (Oxazepam), and Valium (Diazepam). Furthermore, she had taken Benadryl (Diphenhydramine) and Topamax (Topiramate), an anticonvulsant AMPA/Kainate antagonist, which likely contributed to the sedative effect of chloral hydrate and the benzodiazepines. Although the individual levels of any of the benzodiazepines in her system would not have been sufficient to cause death, their combination with a high dose of chloral hydrate led to her overdose. The autopsy report indicates that chloral hydrate was the "toxic/lethal" drug, but it is difficult to know whether chloral hydrate ingestion alone would have killed her, since Dr. Perper indicated (in the March 26 press conference) that she had built up a tolerance to the drug and took more than the average person. He indicated that she took about three tablespoons, whereas the normal dosage is between one and two teaspoons. Chloral hydrate, first synthesized in 1832, was the first depressant developed for the specific purpose of inducing sleep. The infamous "Mickey Finn" or "knockout drops" was a solution of alcohol and chloral hydrate that was popular in Victorian England and in that era's literature. When used properly, and without the introduction of alcohol or other depressants, chloral hydrate is effective in easing sleeplessness due to pain or insomnia. But according to Avis (1990), the effective dose and lethal dose of chloral hydrate are so close that the sedative should be considered dangerous. Today, the use of chloral hydrate has declined as other agents, including barbiturates and benzodiazepines, have largely replaced them. Despite rumors of methadone use due to its involvement in Smith's son's death, Dr. Perper only found methadone in her bile, indicating it could only have been ingested 2–3 days prior to her death and therefore was not a contributing factor. The autopsy report indicates that abscesses on her buttocks (presumably from prior injections of vitamin B12 in the form of cyanocobalamin, as well as human growth hormone), and viral enteritis were contributory causes of death. Tests for influenza A and B were negative.