The long-term use of benzodiazapines can cause physical dependence. The use of benzodiazepines should therefore commence only after medical consultation and benzodiazepines should be prescribed the smallest dosage possible to provide an acceptable level of symptom relief. Dependence varies with the benzodiazepine used and with the user.
The first benzodiazepine, chlordiazepoxide (Librium) was discovered serendipitously in 1954 by the Austrian scientist Leo Sternbach (1908–2005), working for the pharmaceutical company Hoffmann–La Roche. Chlordiazepoxide was synthesised from work on a chemical dye, quinazolone-3-oxides. Initially, he discontinued his work on the compound Ro-5-0690, but he "rediscovered" it in 1957 when an assistant was cleaning up the laboratory. Although initially discouraged by his employer, Sternbach conducted further research that revealed the compound was a very effective tranquilizer. Tests revealed that the compound had hypnotic, anxiolytic and muscle relaxant effects. Three years later chlordiazepoxide was marketed as a therapeutic benzodiazepine medication under the brand name Librium. Following chlordiazepoxide in 1963 diazepam hit the market under the brand name Valium, followed by many further benzodiazepine compounds which were introduced over the subsequent years and decades.
The original chemical name of chlordiazepoxide was methaminodiazepoxide but it was changed to chlordiazepoxide. It was marketed under the trade name Librium, derived from the final syllables of equilibrium. In 1959 it was used by over 2,000 physicians and more than 20,000 patients. It was described as "chemically and clinically different from any of the tranquilizers, psychic energizers or other psychotherapeutic drugs now available." During studies, chlordiazepoxide induced muscle relaxation and a quieting effect on laboratory animals like mice, rats, cats, and dogs. Fear and aggression were eliminated in much smaller doses than those necessary to produce hypnosis. Chlordiazepoxide is similar to phenobarbital in its anticonvulsant properties. However, it lacks the hypnotic effects of barbiturates. Animal tests were conducted in the Boston Zoo and the San Diego Zoo. Forty-two hospital patients admitted for acute and chronic alcoholism, and various psychoses and neuroses were treated with chlordiazepoxide. In a majority of the patients, anxiety, tension, and motor excitement were "effectively reduced." The most positive results were observed among alcoholic patients. It was reported that ulcers and dermatologic problems, both of which involve emotional factors, were reduced by chlordiazepoxide.
Chlordiazepoxide enabled the treatment of emotional disturbances without a loss of mental acuity or alertness. It assisted persons burdened by compulsive reactions like one that felt compelled to count the slats on venetian blinds upon entering a room.
Dr. Carl F. Essig of the Addiction Research Center of the National Institute of Mental Health spoke at a symposium on drug abuse at an annual meeting of the American Association for the Advancement of Science, in December 1963. He named meprobamate, glutethimide, ethinamate, ethchlorvynol, methyprylon, and chlordiazepoxide as drugs whose usefulness can hardly be questioned. However, Essig labeled these newer products as drugs of addiction, like barbiturates, whose habit-forming qualities were more widely-known. He mentioned a 90-day study of chlordiazepoxide, which concluded that the automobile accident rate among 68 users was ten times higher than normal. Participants' daily dosage ranged from 5 to 100 milligrams.
In 1963, approval for use was given to diazepam (Valium), a "simplified" version of chlordiazepoxide, primarily to counteract anxiety symptoms. Sleep-related problems were treated with nitrazepam (Mogadon), which was introduced in 1965, temazepam (Restoril), which was introduced in 1969, and flurazepam (Dalmane), which was introduced in 1973.
A related class of drugs that also work on the benzodiazepine receptors, the nonbenzodiazepines, has recently been introduced. Nonbenzodiazepines are molecularly distinct from benzodiazepines and have less addictive potential, while still offering benefits very similar to those of benzodiazepines.
Benzodiazepines bind at the interface of the α and γ subunits on the GABAA receptor. Benzodiazepine binding also requires that alpha subunits contain a histidine amino acid residue, (i.e., α1, α2, α3 and α5 containing GABAA receptors). For this reason, benzodiazepines show no affinity for GABAA receptors containing α4 and α6 subunits, which contain an arginine instead of a histidine residue. Other sites on the GABAA receptor also bind neurosteroids, barbiturates and certain anesthetics.
Once bound to the BzR, the benzodiazepine ligand locks the BzR into a conformation in which it has a much higher affinity for the GABA neurotransmitter than otherwise. This increases the frequency of opening of the associated chloride ion channel and hyperpolarizing the membrane of the associated neuron. This potentiates the inhibitory effect of the available GABA, leading to sedatory and anxiolytic effects. As mentioned above, different benzodiazepines can have different affinities for BzRs made up of different collection of subunits. For instance, benzodiazepines with high activity at the α1 are associated with sedation, whereas those with higher affinity for GABAA receptors containing α2 and/or α3 subunits have good anti-anxiety activity. Benzodiazepines also bind to glial cell membranes.
Some benzodiazepines are full BzR agonists, producing anxiolytic and sedating properties. Compounds that, in the absence of agonist, have no apparent activity but that competitively inhibit the binding of agonists to the receptor are called BzR antagonists. Ligands that decrease GABA function are termed benzodiazepine receptor inverse agonists. Full inverse agonists have potent convulsant activities.
Some compounds lie somewhere between being full agonists and neutral antagonists, and are termed either partial agonists or partial antagonists. There has been interest in partial agonists for the BzR, with evidence that complete tolerance may not occur with chronic use, with partial agonists demonstrating continued anxiolytic properties with reduced sedation, dependence, and withdrawal problems.
However the anticonvulsant properties of benzodiazepines may be in part or entirely due to binding to voltage-dependent sodium channels rather than benzodiazepine receptors. Sustained repetitive firing seems to be limited by benzodiazepines effect of slowing recovery of sodium channels from inactivation.
Benzodiazepine receptors also appear in a number of non nervous-system tissues and are mainly of the peripheral benzodiazepine receptor (PBRs) type. These peripheral benzodiazepine receptors are not coupled (or "attached") to GABAA receptors. These are found in various tissues such as heart, liver, adrenal, and testis, as well as hemopoietic and lymphatic cells. In lymphatic tissues, they modulate apoptosis of thymocytes via reduction of mitochondrial transmembrane potential. PBRs have many other actions on immune cells including modulation of oxidative bursts by neutrophils and macrophages, and inhibition of macrophage secretion of cytokines inhibition of the proliferation of lymphoid cells and secretion of cytokines by macrophages.
Benzodiazepines are potent anticonvulsants and have life-saving properties in the acute management of status epilepticus. The most commonly-used benzodiazepines for seizure control are lorazepam and diazepam. A meta-analysis of 11 clinical trials concluded that lorazepam was superior to diazepam in treating persistent seizures. Although diazepam is much longer-acting than lorazepam, lorazepam has a more prolonged anticonvulsant effect. This is because diazepam is very lipid-soluble and highly protein-bound, and has a very large distribution of unbound drug, resulting in diazepam's having only a 20– to 30-minute duration of action against status epilepticus. Lorazepam, however, has a much smaller volume of distribution of unbound drug, which results in a more prolonged duration of action against status epilepticus. Lorazepam can therefore be considered superior to diazepam, at least in the initial stages of treatment of status epilepticus.
Benzodiazepines possess anti-anxiety properties and can be useful for the short-term treatment of severe anxiety. Benzodiazepines are usually administered orally for the treatment of anxiety; however, occasionally lorazepam or diazepam may be given intravenously for the treatment of panic attacks.
A panel of over 50 peer-nominated internationally recognized experts in the pharmacotherapy of anxiety and depression judged the benzodiazepines, especially combined with an antidepressant, as the mainstays of pharmacotherapy for anxiety disorders.
Despite increasing focus on the use of antidepressants and other agents for the treatment of anxiety, benzodiazepines have remained a mainstay of anxiolytic pharmacotherapy due to their robust efficacy, rapid onset of therapeutic effect, and generally favorable side effect profile. Treatment patterns for psychotropic drugs appear to have remained stable over the past decade, with benzodiazepines being the most commonly used medication for panic disorder.
Hypnotic benzodiazepines have strong sedative effects, and certain benzodiazepines therefore are often prescribed for the management of insomnia. Longer-acting benzodiazepines, such as nitrazepam, have side-effects that may persist into the next day, whereas the more intermediate-acting benzodiazepines (for example, temazepam) may have less "hangover" effects the next day. Benzodiazepine hypnotics should be reserved for short-term courses to treat acute conditions, as tolerance and dependence may occur if these benzodiazepines are taken regularly for more than a few weeks.
The following are some of the criteria for Intensive care unit monitoring
Midazolam or diazepam can also be used as a sedative anxiolytic to quell anxiety and agitation experienced by animals in veterinary practice, for example, during transport. Diazepam has also been found to have tranquillising effects on various animals tested with the following properties; myorelaxation, stress reduction and aggression inhibition.
Benzodiazepines are also commonly used for the control of muscular conditions in animals. Diazepam has been prescribed for the effective treatment and control of tremors by veterinarians in animals. Corticosteroids and or Diazepam have been found to be effective for the control of tremors in veterinarian practice. Diazepam has also been used in to control muscle spasms that were the result of tetanus in cats.
Benzodiazepines, such as diazepam, are used in the treatment of various forms of epilepsy in dogs. Benzodiazepines have potent anticonvulsant properties and are very effective in the short term in managing seizure disorders in animals. However, with prolonged usage, benzodiazepines tend to lose their anticonvulsant properties. Partial benzodiazepine receptor agonists have shown some promise, with continued efficacy being demonstrated with benzodiazepine receptor partial agonists and also displaying mild withdrawal symptoms upon discontinuation, which may make them superior to benzodiazepines in the long-term management of epilepsy in animals. Phenobarbital is the drug of choice and potassium bromide is the drug of second choice in the treatment of epilepsy in dogs and diazepam is recommended for the treatment at home of cluster seizures.
Midazolam can also be used along with other drugs in the sedation and capture of wild animals.
When benzodiazepines are used as an adjunct in the treatment of seizures, an increase in dosage of the primary agent may be required. The concomitant administration of benzodiazepines and anti-convulsants may precipitate an increase in certain seizure activity, specifically tonic-clonic seizures.
In a letter to the British Medical Journal, it was reported that a high proportion of parents referred for actual or threatened child abuse were taking drugs at the time, often a combination of benzodiazepines and tricyclic antidepressants. Many mothers described that instead of feeling less anxious or depressed, they became more hostile and openly aggressive towards the child as well as to other family members while consuming tranquilizers. The author warned that environmental or social stresses such as difficulty coping with a crying baby combined with the effects of tranquilizers may precipitate a child abuse event.
Paradoxical rage reactions from benzodiazepines are thought to be due to partial deterioration from consciousness, generating automatic behaviors, fixation amnesia, and aggressiveness from disinhibition with a possible serotonergic mechanism playing a role.
Benzodiazepine withdrawal is best managed by transferring the physically-dependent patient to an equivalent dose of diazepam because it has the longest half-life of all of the benzodiazepines and is available in low-potency, 2-mg tablets, which can be quartered for small dose reductions. The speed of benzodiazepine reduction regimes varies from person to person, but is usually 10% every 2–4 weeks. A slow withdrawal, preferably under medical supervision by a physician that is knowledgeable about the benzodiazepine withdrawal syndrome, with the patient in control of dosage reductions coupled with reassurance that withdrawal symptoms are temporary, have been found to produce the highest success rates. The withdrawal syndrome can usually be avoided or minimized by use of a long half-life benzodiazepine such as diazepam (Valium) or chlordiazepoxide (Librium) and a very gradually tapering off the drug over a period of months, or even up to a year or more, depending on the dosage and degree of dependency of the individual. A slower withdrawal rate significantly reduces the symptoms. In fact, some people feel better and more clear-headed as the dose gradually gets lower, so withdrawal from benzodiazepines is not necessarily an unpleasant event. People that report severe experiences from benzodiazepine withdrawal have almost invariably withdrawn or been withdrawn too quickly.
Benzodiazepine use is widespread among amphetamine users, and those that have used amphetamines and benzodiazepines have greater levels of mental health problems, social deterioration, and poorer general health. Benzodiazepine injectors are almost four times more likely to inject using a shared needle than non-benzodiazepine-using injectors. It has been concluded in various studies that benzodiazepine use causes greater levels of risk and psycho-social dysfunction among drug users. Those who use stimulants and depressant drugs are more likely to report adverse reactions from stimulant use, more likely to be injecting stimulants, and more likely to have been treated for a drug problem than those using stimulants but not depressant drugs.
Once benzodiazepine dependence has been established a clinician should first establish the average daily consumption of benzodiazepines and then convert the patient to an equivalent dose of diazepam before beginning a gradual reduction program, starting initially with 2mg-size reductions. Additional drugs, such as antidepressants like buspirone, β blockers, and carbamazepine, should not be added into the withdrawal program unless there is a specific indication for their use.
A six-year study on 51 Vietnam veterans who were drug abusers of either mainly stimulants (11 people), mainly opiates (26 people), or mainly benzodiazepines (14 people) was carried out to assess psychiatric symptoms related to the specific drugs of abuse. After six years, opiate abusers had little change in psychiatric symptomatology; 5 of the stimulant users had developed psychosis, and 8 of the benzodiazepine users had developed depression. Therefore, long-term benzodiazepine abuse and dependence seems to carry a negative effect on mental health, with a significant risk of causing depression.
Increased mortality was found in drug misusers that also used benzodiazepines against those that did not. Heavy alcohol misuse was also found to increase mortality among multiple-drug users.
Benzodiazepines have also been used as a tool of murder by serial killers, murderers, and as a murder weapon by those with the condition Munchausen syndrome by proxy. Benzodiazepines have also been used to facilitate rape or robbery crimes, and benzodiazepine dependence has been linked to shoplifting due to the fugue state induced by the chronic use of the drug. When benzodiazepines are used for criminal purposes against a victim they are often mixed with food or drink. Flunitrazepam, temazepam, and midazolam are the most common benzodiazepines used to facilitate date rape. Alprazolam has been abused for the purpose of carrying out acts of incest and for the corruption of adolescent girls. However, alcohol remains the most common drug involved in cases of drug rape. Although benzodiazepines and ethanol are the most frequent drugs used in sexual assaults, GHB is another potential date rape drug which has received increased media focus. Some benzodiazepines are more associated with crime than others especially when abused or taken in combination with alcohol. The potent benzodiazepine flunitrazepam (Rohypnol), which has strong amnesia producing effects can cause abusers to become cold blooded and ruthless and also cause feelings of being invincible. This has led to some acts of extreme violence to others, often leaving abusers with no recollection of what they have done in their drug-induced state. It has been proposed that criminal and violent acts brought on by benzodiazepine abuse may be related to lowered serotonin levels via enhanced GABAergic effects. Flunitrazepam has been implicated as the cause of one serial killers violent rampage, triggering off extreme aggression with anterograde amnesia. A study on forensic psychiatric patients who had abused flunitrazepam at the time of their crimes found that the patients displayed extreme violence, lacked the ability to think clearly and experienced a loss of empathy for their victims while under the influence of flunitrazepam, and it was found that the abuse of alcohol or other drugs in combination with Flunitrazepam compounded the problem. Their behaviour under the influence of flunitrazepam was in contrast to their normal psychological state.
Patients reporting to two emergency rooms in Canada with violence-related injuries were most often found to be intoxicated with alcohol and were significantly more likely to test positive for benzodiazepines (most commonly temazepam) than other groups of individuals, whereas other drugs were found to be insignificant in relation to violent injuries.
The antidote for all benzodiazepines is flumazenil (Anexate), a benzodiazepine antagonist, which is occasionally used empirically in patients presenting with unexplained loss of consciousness in an emergency room setting. As with all overdose situations, the care provider must be aware of the possibility that multiple substances were utilized by the patient. Supportive measures should be put in place prior to administration of any benzodiazepine antagonist in order to protect the patient from both the withdrawal effects and possible complications arising from simultaneous utilization of chemically-unrelated pharmaceutical compounds. A determination of possible deliberate overdose should be considered with appropriate scrutiny, and precautions taken to prevent any attempt by patient to commit further bodily harm.
Flumazenil should be administered only by physicians that are familiar and suitably trained in the use of flumazenil in benzodiazepine overdose. Treating benzodiazepine overdose with flumazenil may reduce the chance of the patient being admitted to intensive care; however, caution should be exercised in the administration of flumazenil. The treating physician should bear in mind the possibility of mixed overdoses, especially mixed overdoses of other drugs or substances, as cocktails of drugs are often taken in overdose situations with their own overdose risks.
Elderly people are more sensitive to benzodiazepines and are at an increased risk of dependence. Up to 10% of hospital admissions of the elderly are because of benzodiazepines. The elderly are more sensitive to the intellectual and cognitive impairing effects of benzodiazepines including amnesia, diminished short-term recall, and increased forgetfulness. Chronic use of benzodiazepines and benzodiazepine dependence in the elderly can resemble dementia, depression or anxiety syndromes, which worsens with longer-term use of benzodiazepines. The success of gradual-tapering benzodiazepines is as great in the elderly as in younger people. Benzodiazepines should be prescribed to the elderly only with caution and only for a short period at low doses.
Elsewhere in the world, however, benzodiazepines which are often subject to heavy abuse and addiction are often more strictly regulated or controlled. Temazepam, nimetazepam, and flunitrazepam are the worlds most heavily regulated benzodiazepines.
Flunitrazepam (Rohypnol), Nimetazepam (Erimin), and Temazepam (Restoril; Normison) are treated more severely under International law than other benzodiazepines. For example, in the United States, despite being Schedule IV like any other benzodiazepine, flunitrazepam is not commercially available. It also carries tougher Federal penalties for trafficking and possession than other Schedule IV drugs. With the exception of cases involving 5 grams or more of cocaine or morphine, flunitrazepam is the only controlled substance whose first-offense simple possession is a federal felony. Temazepam is the only benzodiazepine which may require specially-coded prescriptions in some states.
Throughout Europe, including the United Kingdom, temazepam and flunitrazepam also carry tougher penalties for trafficking and possession. In Ireland, temazepam and flunitrazepam are both Schedule 3 drugs under the Misuse of Drugs (Amendment) Regulations, (1993), while all other benzodiazepines are Schedule 4. As a result of continued abuse, illegal diversion, distrubtion, and clandestine manufacture in the Netherlands and Eastern Europe, Germany is currently in the process of possibly taking temazepam off of Anlage 3 (equivalent to Schedule 3 or Class C) of the BtMG (or Betäubungsmittelgesetz, which means Narcotics Act) and placing it under Anlage 2 (equivalent to Schedule 2 or Class B).
In Australia, both temazepam and flunitrazepam, in all forms are restricted as Schedule 8 controlled drugs. As Schedule 8 controlled substances, it is illegal to possess either drug without an authority prescription from a registered doctor. In New Zealand, temazepam and flunitrazepam are completely illegal to possess and/or traffic. All other benzodiazepines are not illegal to possess for personal use, but distribution/traffic of any benzodiazepine is punishable by law.
In East Asia and Southeast Asia, temazepam and nimetazepam are often heavily controlled and restricted. In certain countries, triazolam, flunitrazepam, flutoprazepam, and midazolam are also restricted or controlled to certain degrees. In Hong Kong for example, temazepam and nimetazepam are regulated under Schedule 1 of Hong Kong's Chapter 134 Dangerous Drugs Ordinance. Triazolam, flunitrazepam, flutoprazepam, and midazolam are regulated under Schedule 2 of Hong Kong's Chapter 134 Dangerous Drugs Ordinance. Other benzodiazepines are not scheduled or controlled substances.
In Singapore, the Misuse of Drugs Act lists both temazepam and nimetazepam as Class A/Schedule I controlled drugs. Flutoprazepam, flunitrazepam, and triazolam are listed as Class C/Schedule II controlled drugs. Furthermore, a number of other benzodiazepines are regulated. Regulation of certain benzodiazepines under Schedule III was based on the relative ease by which they may be used to manufacture controlled benzodiazepines. They are as follows: camazepam, clonazepam, diazepam, estazolam, lorazepam, lormetazepam, nitrazepam, oxazepam, and prazepam. These benzodiazepines are regulated under Schedule III as controlled equipment, materials or substances useful for manufacturing controlled drugs. Restriction of these benzodiazepines is a measure against any clandestine manufacture of anyone of the controlled benzodiazepines, as seen with the growing illicit manufacture and distribution of temazepam in other regions of the world. Other benzodiazepines are not controlled drugs, but are available only by prescription and if used to manufacture any of the controlled benzodiazepines, automatically become Schedule III substances or material.
Internationally, temazepam, nimetazepam, and flunitrazepam are Schedule IV drugs under the Convention on Psychotropic Substances. Though they are classed as a Schedule IV internationally, penalties for their possession and/or trafficking are more severe than other Schedule IV drugs, including all other benzodiazepines. Temazepam and nimetazepam continue to be the most widely abused benzodiazepines worldwide. Seizures of the two drugs by authorities are far higher in number than seizures of all the other benzodiazepines combined, including flunitrazepam. Worldwide, seizures of temazepam and nimetazepam may be comparable in number to seizures of the hypnotic, methaqualone.
Various other countries limit the availability of benzodiazepines legally. Even though it is a commonly-prescribed class of drugs, the Medicare Prescription Drug, Improvement, and Modernization Act specifically states that insurance companies that provide Medicare Part D plans are not allowed to cover benzodiazepines.