Flunitrazepam, sold under the brand name Rohypnol among others,[3] is a benzodiazepine used to treat severe insomnia and assist with anesthesia.

Rohypnol lowers the side effects of the anesthetic (ketamine), resulting in less confusion in awakening states, less negative influence on pulse rate, and fewer fluctuations in blood pressure.

[13] Flunitrazepam may cause a paradoxical reaction in some individuals, including anxiety, aggressiveness, agitation, confusion, disinhibition, loss of impulse control, talkativeness, violent behavior, and even convulsions.

Use of benzodiazepines including flunitrazepam in late pregnancy, especially high doses, may result in hypotonia, also known as floppy baby syndrome.

[16] It also impairs psychomotor functions similar to other benzodiazepines and nonbenzodiazepine hypnotic drugs; falls and hip fractures were frequently reported.

[18] Impairment of driving skills with a resultant increased risk of road traffic accidents is probably the most important adverse effect.

As of 2016, blood tests can identify flunitrazepam at concentrations of as low as 4 nanograms per millilitre; the elimination half life of the drug is 4–12 hours.

[24] Flunitrazepam can be measured in blood or plasma to confirm a diagnosis of poisoning in hospitalized patients, provide evidence in an impaired driving arrest, or assist in a medicolegal death investigation.

Blood or plasma flunitrazepam concentrations are usually in a range of 5–20 μg/L in persons receiving the drug therapeutically as a nighttime hypnotic, 10–50 μg/L in those arrested for impaired driving and 100–1000 μg/L in victims of acute fatal overdosage.

Flunitrazepam shows high affinity for the α-5 subunit of the GABA-A receptor, which causes some of its unique side effects, such as amnesia.

[33] Flunitrazepam was discovered at Roche as part of the benzodiazepine work led by Leo Sternbach; the patent application was filed in 1960 and it was first marketed in 1972.

[34] [35] Due to use of the drug for date rape and recreation, in 1998 Roche modified the formulation to give lower doses, make it less soluble, and add a blue dye for easier detection in drinks.

When calculated in relation to utilization, the narcotic analgesics codeine, pentazocine, and ketobemidone were at the top of the list for the highest number of overall prescription forgeries, suggesting a higher abuse potential of these drugs.

Other benzodiazepines and nonbenzodiazepines (anxiolytic or hypnotic) such as zolpidem and zopiclone (as well as cyclopyrrolones, imidazopyridines, and pyrazolopyrimidines) are also found in high numbers of suspected drugged drivers.

Many drivers have blood levels far exceeding the therapeutic dose range, suggesting a high degree of potential for addiction for benzodiazepines and similar drugs.

[40][41] Flunitrazepam is known to induce anterograde amnesia in sufficient doses; individuals are unable to remember certain events that they experienced while under the influence of the drug, which complicates investigations.

[12] It is also known as Circles, Forget Me Pill, La Rocha, Lunch Money Drug, Mexican Valium, Pingus, R2, and Roach 2.