Probably.
出来損ないの名探偵 (できそこないのめいたんてい) Dekisokonai no Meitantei or literally "Good for nothing/badly made detective." The password pun Sherrinford was the prototype name for Sherlock Holmes which informed the English translation.
What I am specifically claiming is that the current version of APTX is an incomplete, prototype version that has worked well as a poison. It is called a prototype because so far in development it hasn't done what Sherry intended it to do.Haibara has stated she didn't intend to make a poison. (V18-9 pg 9) She also detested her drug being used as a poison, which is the other reason besides Akemi that encouraged her to betray. (Same page as above) She also took APTX intending to commit suicide. Finally, someone in the Organization approved the use of APTX as a murder weapon which apparently is forensically undetectable (V1-1 pg 37), and it was used to kill many people. (A list of poisoned people marked dead was shown in the background behind Haibara in V18-9 pg 6 and Haibara mentions other people killed on the same page.) Taken together, this is pretty strong evidence that the current version of APTX works well as a poison and was used for this purpose. Presumably, APTX's effectiveness as a poison was discovered from its mostly lethal effects on the mice she tested it on. (Only one mouse shrank - and from Haibara's tone and conversation topic, it is easy to guess what happened to the rest of them). I would imagine that someone noticed the dead mice results, or Sherry reported her dead mice results, and someone got the idea to sidetrack part of the project from its intended purpose (which wasn't poison - discussed below) and develop the current version of APTX as a poison because it was convenient and useful to assassins.
Shiho however intended the APTX to do something else, not poison. The support for this is Haibara's not meaning to make poison and hating it being used as a poison mentioned above, the nickname incomplete/prototype detective, and Pisco's comment in response to watching Shiho deage into Haibara (He was impressed she had developed the drug to that point and that her parents would be proud - if poison was the goal, he wouldn't be impressed because she failed to die).
Generally, a prototype almost always refers to a product which is still in development and undergoing testing because it is being evaluated for performance and problems (and those problems need to be fixed) before it can be considered a final product. A "complete prototype" doesn't make much sense, because if it was complete, it wouldn't be considered a prototype any longer. Since Sherry needed to know if her latest APTX version was working closer to what she had intended (the real goal of the APTX 4869 project -- which isn't poison) she tested her drug on mice.