This timeline is taken from the publication New benzodiazepines in Europe – a review.
The first benzodiazepine used as a medicine, chlordiazepoxide(1), was the accidental result of a research programme to develop new tranquillisers by the pharmaceutical company F. Hoffmann-La Roche AG in the 1950s. In the course of the research and development process, the chemist in charge, Leon Sternbach, and his team realised that, instead of the benzheptoxdiazines they had intended to synthesise, they had made quinazoline 3-oxides (Sternbach et al., 1979). The structure was subsequently determined as a 1,4-benzodiazepine.
In most countries, benzodiazepines authorised as medicines are controlled under drug control laws and are available by prescription only. This is in agreement with the 1971 United Nations Convention on Psychotropic Substances, which currently controls 38 benzodiazepines(3). These are alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, clorazepate, clotiazepam, cloxazolam, delorazepam, diazepam, estazolam, ethyl loflazepate, etizolam (since 2020), flualprazolam (since 2020), fludiazepam, flurazepam, flunitrazepam, halazepam, haloxazolam, ketazolam, loprazolam, lorazepam, lormetazepam, medazepam, midazolam, nimetazepam, nitrazepam, nordazepam, oxazepam, oxazolam, phenazepam (since 2016), pinazepam, prazepam, temazepam, tetrazepam and triazolam.