Complex sentence: The methadone was found inside a container of a prescription drug called zolpidem which is commonly used for insomnia, while methadone is a powerful controlled substance used for pain and the treatment of heroin addiction.
Split into simpler sentences: The methadone was found inside a container of a prescription drug called zolpidem. Zolpidem is commonly used for insomnia, while methadone is a powerful controlled substance used for pain and the treatment of heroin addiction.