An unknown number of rape incidents — many of which go undocumented due to memory loss — are done with the aid of so-called "date rape" drugs, according to law enforcement and victims' advocates.

Many drugs can be used for a date-rape purposes, such as alcohol, cocaine and ecstasy. But authorities lump date-rape drugs into their own category because few people generally consider them to be recreational. The following is a breakdown of three specific drugs:

Rophynol (search) is the most common of the three. It is an intensely powerful sedative, although it is 10 times more powerful than Valium. The pill looks similar to aspirin and has the word "roche" on one side.

It can be quickly dissolved into drinks since it is colorless, odorless and tasteless; however, when dissolved into alcoholic beverages, a slight bitter taste is noticeable. The effects range from a mild sedation and lowered inhibitions to complete blackouts. Street names for Rophynol are 'roofies,' 'rope' and 'R2.'

Gamma Hydroxy Butrate (search) is an illegally manufactured drug, which means it is even more dangerous than Royphnol because it isn't approved or checked by the FDA. It is usually found in liquid form and is also usually placed in the victim's drink. It goes by the street names of 'Grievous Bodily Harm,' 'Liquid X' and 'Liquid E.' The effects include dizziness, memory loss, unconsciousness or even coma.

Ketamine Hydrochloride (search) is a legal drug, commonly used as a hospital-grade anesthetic or veterinary sedative. It is a disassociative, meaning that users of the drug will find themselves disconnected from their surroundings or even their usual consciousness.

It is often snorted by recreational users or can be put into liquid form for date-rape purposes. The effects include losing a sense of time and identity, vivid hallucinations or loss of motor control.

Source: Date Rape Drugs: Information for Teens, North Carolina Coalition Against Sexual Assault.