APTX 4869 (四八六九 Yon-Hachi-Roku-Kyuu), nicknamed "Prototype Detective" by members of the Black Organization, is a fictional toxin and derivative of an experimental formula of unknown purpose developed by Shiho Miyano, which is used by the Black Organization as an untraceable, lethal poison. Right now, there is a prototype antidote for it made by Shiho.
APTX is an abbreviation of "Apoptoxin," and, as the name implies, it involves the activation of apoptosis: the mechanism by which cells kill themselves. APTX contains ingredients which have other functions as well. It contains a component which activates telomerase: an enzyme which lengthens the caps at the end of DNA whose length limits the number of times a cell can divide.
In practice, most of the time APTX 4869 works as a lethal poison. Gin says it can't be detected when used, possibly indicating it leaves few traces that forensic examination could uncover. However, as said by Ai Haibara, a rare side effect can in fact de-age victims. She said in Episode 129, that everything besides organs, body hair, personality, and memories are reverted back to a state of ages 7-10 years old. Shinichi, the series' protagonist, was forced by Gin and Vodka to take the poison with the intention of killing him silently due to the police being around in Episode 1; later Shiho Miyano, was set to be executed for being a possible loose end after Gin and Vodka killed her sister Akemi. She was set to be executed, but to escape she took her own poison intending to commit suicide, however her body, like Shinichi's, was reverted back to childhood state.
 Name origin
APTX 4869 is a pun on "Sherlock Holmes". 4869 can also be pronounced "Shi-Ya-Ro-Ku", which translates into Sherlock. Adding to the pun, the password for the APTX data is "Shellingford", an unintentional misspelling of "Sherrinford", which was the name Arthur Conan Doyle called his detective character before deciding on "Sherlock". The password and the pun name seem to be related to why several members of the Black Organization call APTX 4869 the "incomplete detective", implying APTX 4869 is not finished yet.
- Main article: Prototype Antidote
Throughout the series there are several instances in which the APTX was temporarily neutralized and Shinichi and Shiho were returned to their actual age forms. The main ingredient for this reversal is a component found in baijiu, which Haibara has already incorporated in a prototype antidote for the APTX.
It is notable that in the instances where Shinichi or Shiho were successfully changed back, the recipient was suffering from a common cold while the component was ingested, indicating that the immune system somehow has to be taxed for the antidote to work. The only apparent canon exception was Shinichi's reversion in the London arc. While not canon, Crossroad in the Ancient Capital uses this idea as Conan is given a pill to give him the symptoms of a cold, while drinking baijiu.
Conan and Haibara briefly reverted to their true age while having rum cake (thought to contain among other things baijiu) in the live action drama Shinichi Kudo Returns! Confrontation with the Black Organization.
 Original intent
At first, it was revealed by Gin that the APTX 4869 was a poison to kill people who know too much about the Black Organization. He used Shinichi as a guinea pig. Shiho Miyano said that she didn't intend to create a poison, which suggests that APTX 4869 was originally developed with a different goal in mind. It probably was just a useful side effect that the current prototype kills while leaving no trace in the victim’s body, and was thus employed as a poison - a usage which Haibara detests. Additionally, APTX 4869 is nicknamed the "incomplete detective" by the Black Organization, which means its true purpose has not yet been achieved.
One possibility is that the goal of the APTX 4869 is to develop a therapy which will cause immortality, stall or reverse the effects of aging, or extend a human's lifespan. The de-aging effect that occurred when Shinichi and Haibara took APTX 4869 probably indicates the main intent of the drug's development. After Pisco saw Haibara shrink back to her child form, he commented that he was impressed she had developed the drug to that point, implying that deaging is in the right direction. Supporting this is Haibara’s line, "Kudo-kun? You would probably never even dream that you are already part of a project the Black Organization has been working on already for half a century." APTX 4869 is the only known intersection between Shinichi and the Black Organization; meaning that Shinichi's de-aging made him relevant to the Black Organization's project.
According to Haibara’s description about APTX 4869, APTX 4869 activates telomerase, an enzyme which can increase the number of times a cell can divide, and therefore affect a cell's lifespan and “reproductive potential”. The goal of this might be to revert all non-neural cells to a "youthful", high reproductive potential state. Vermouth's unnatural youth is another indicator that the Black Organization may be involved in research towards extending lifespan, halting aging, or rejuvenating the body.
 Raising the dead
The original purpose of APTX 4869 might be to raise the dead. Once when Conan asked Haibara directly what APTX 4869 was meant to do she replied, "It's a nostrum to raise the dead. I wonder if that answer is satisfactory?" The context of the comment, however, makes it unclear if she was merely bluffing to provoke Conan into revealing that he had been looking into the Black Organization behind her back, rather than making a serious statement of the purpose of the drug.
 "Silver Bullet" and "APTX 4869" are two names for the same project
- See also: Silver Bullet (drug)
In a flashback, Shiho recalls the end of the recorded message left by her mother which revealed Elena had been working on "a truly terrifying drug" the Miyano parents called the Silver Bullet. It is unclear whether Silver Bullet is the Miyano parents' personal nickname for what is currently called APTX 4869, or if it was a closely related project they developed in parallel. Whatever the case, Silver Bullet and APTX 4869 are probably closely linked if not the same in-development drug. Haibara took over her parents' research after they died, with the APTX project named specifically. After watching Haibara shrink, Pisco, who knew about the project the Miyanos worked on, commented that Shiho's parents would be proud of the progress Shiho had made on the drug. In addition, Haibara had earlier referred to APTX 4869 as a dream-like drug, the same expression Elena's labmates used to describe Silver Bullet. During her recollection of the tapes, Haibara was holding and considering the antidote to APTX 4869. She then regrets that she didn't understand the drug was something that should have never been made, strongly implying she worked on the same drug as well. Lastly, Vermouth, who was in the Organization long enough to have heard the Miyanos use the name "Silver Bullet", may have given Conan the same nickname in reference to his deaged state caused by the drug. On the other hand, Shuichi Akai also has the nickname Silver Bullet, but no apparent connection to the drug other than dating Akemi Miyano, the sister/daughter of the drug's creators.
- ^ Manga Volume 24, File 10
- ^ Manga Volume 24, File 10 (241), page 11: " The Bullet from the Past". This has been confirmed to be spelled as "Shellingford" in the original Japanese.
- ^ "The name comes from Arthur Conan Doyle's earliest notes for A Study in Scarlet, which gave the great detective's name as "Sherrinford Holmes" and that of his medical companion as "Ormond Sacker"." "Sherlockian.Net: William S. Baring-Gould". Chris Redmond. 2010. http://www.sherlockian.net/societies/baringgould.html. Retrieved on 2012-01-28.
- ^ a b Manga Volume 24, File 8 (239), pg 4: "The Black Burial Ranks ". Gin is conversing with Pisco and tells him, "Of course, it's up to you if you use the 'Incomplete Detective' or not...". Earlier on the phone, Gin had mentioned it was fine if Pisco used the drug which both Haibara and Conan took to mean APTX 4869.
- ^ a b Manga Volume 24, File 10 (241), page 11: "A Bullet from the Past". Haibara tells Conan that "the members of the Organization sometimes gave this uncompleted drug a nickname... 'the Incomplete Detective'."
- ^ a b Manga Volume 10, Files 4-5 (092-095): "The Great Detective of the West"
- ^ a b Manga Volume 24, File 10 (241): "The Bullet from the Past"
- ^ Manga Volume 26, Files 2-4 (255-257): "School Play Case"
- ^ a b Manga Volume 18, File 9 (179), page 9: "The Girl Made Of Lies"
- ^ a b Manga Volume 24, File 11, page 9: "The White World"
- ^ Manga Volume 19, File 9 (189): "The Endangered Ball "; Episodes 130-131
- ^ a b Manga Volume 38, File 2, page 8: "The Old Picture"
- ^ a b c Manga Volume 78, File 4 (821), pg 7: "Mystery Train 「Junction」"
- ^ Vermouth has been in the Organization at least 20 years dated by when she assassinated Jodie's father which is more time than the theoretical maximum 18 years the tapes could be recorded -- dated to Shiho's conception.