Bromazepam

Indications

Side-effects

Bromazepam is similar in side effects to other benzodiazepines. The most common side effects reported are drowsiness, sedation, ataxia, memory impairment, and dizziness. Impairments to memory functions are common with bromazepam and include a reduced working memory and reduced ability to process environmental information. A 1975 experiment on healthy, male college students exploring the effects of four different drugs on learning capacity observed that taking bromazepam alone at 6 mg 3 times daily for 2 weeks impaired learning capacities significantly. In combination with alcohol, impairments in learning capacity became even more pronounced. Various studies report impaired memory, visual information processing and sensory data and impaired psychomotor performance; deterioration of cognition including attention capacity and impaired co-ordinative skills; impaired reactive and attention performance, which can impair driving skills; drowsiness and decrease in libido. Unsteadiness after taking bromazepam is, however, less pronounced than other benzodiazepines such as lorazepam.

On occasion, benzodiazepines can induce extreme alterations in memory such as anterograde amnesia and amnesic automatism, which may have medico-legal consequences. Such reactions occur usually only at the higher dose end of the prescribing spectrum.

Very rarely, dystonia can develop.

Up to 30% treated on a long-term basis develop a form of dependence, i.e. these patients cannot stop the medication without experiencing physical and/or psychological benzodiazepine withdrawal symptoms.

Leukopenia and liver-damage of the cholostatic type with or without jaundice (icterus) have additionally been seen; the original manufacturer Roche recommends regular laboratory examinations to be performed routinely.

Ambulatory patients should be warned that bromazepam may impair the ability to drive vehicles and to operate machinery. The impairment is worsened by consumption of alcohol, because both act as central nervous system depressants. During the course of therapy, tolerance to the sedative effect usually develops.

Tolerance, dependence and withdrawal

Bromazepam shares with other benzodiazepines the risk of abuse, misuse, psychological dependence or physical dependence. A withdrawal study demonstrated both psychological dependence and physical dependence on bromazepam including marked rebound anxiety after 4 weeks chronic use. Those whose dose was gradually reduced experienced no withdrawal.

Patients treated with bromazepam for generalised anxiety disorder were found to experience withdrawal symptoms such as a worsening of anxiety, as well as the development of physical withdrawal symptoms when abruptly withdrawn bromazepam. Abrupt or over rapid withdrawal from bromazepam after chronic use even at therapeutic prescribed doses can lead to a severe withdrawal syndrome including status epilepticus and a condition resembling delerium tremens.

Animal studies have shown that chronic administration of diazepam or bromazepam causes a decrease in spontaneous locomotor activity, decreased turnover of noradrenaline and dopamine and serotonin, increased activity of tyrosine hydroxylase and increased levels of the catecholamines. During withdrawal of bromazepam or diazepam a fall in tryptophan, serotonin levels occurs as part of the benzodiazepine withdrawal syndrome. Changes in the levels of these chemicals in the brain can cause headaches, anxiety, tension, depression, insomnia, restlessness, confusion, irritability, sweating, dysphoria, dizziness, derealization, depersonalization, numbness/tingling of extremities, hypersensitivity to light, sound, and smell, perceptual distortions, nausea, vomiting, diarrhea, appetite loss, hallucinations, delirium, seizures, tremor, stomach cramps, myalgia, agitation, palpitations, tachycardia, panic attacks, short-term memory loss, and hyperthermia.

Contraindications and special precautions

Benzodiazepines require special precaution if used in elderly, pregnant, child, alcohol- or drug-dependent individuals and individuals with comorbid psychiatric disorders.

Special populations

Interactions

Cimetidine, fluvoxamine and propranolol causes a marked increase in the elimination half-life of bromazepam leading to increased accumulation of bromazepam.

Pharmacology

Bromazepam is a "classical" benzodiazepine; other classical benzodiazepines include; diazepam, clonazepam, oxazepam, lorazepam, nitrazepam, flurazepam, and clorazepate. Its molecular structure is composed of a diazepine connected to a benzene ring and a pyridine ring, the benzene ring having a single nitrogen atom that replaces one of the carbon atoms in the ring structure. It is a 1,4-benzodiazepine, which means that the nitrogens on the seven-sided diazepine ring are in the 1 and 4 positions.

Bromazepam binds to the GABA receptor GABA_A, causing a conformational change and increasing the inhibitory effects of GABA. Bromazepam is a long-acting benzodiazepine and is lipophilic and metabolised hepatically via oxidative pathways. It does not possess any antidepressant or antipsychotic qualities.

After night time administration of bromazepam a highly significant reduction of gastric acid secretion occurs during sleep followed by a highly significant rebound in gastric acid production the following day.

Bromazepam alters the electrical status of the brain causing an increase in beta activity and a decrease in alpha activity in EEG recordings.

Pharmacokinetics

Bromazepam is reported to be metabolized by a hepatic enzyme belonging to the Cytochrome P450 family of enzymes. In 2003, a team led by Dr. Oda Manami at Oita Medical University reported that CYP3A4, a member of the Cytochrome P450 family, was not the responsible enzyme since itraconazole, a known inhibitor of CYP3A4, did not affect its metabolism. In 1995, J. van Harten at Solvay Duphar B.V.'s Department of Clinical Pharmacology in Weesp reported that fluvoxamine, which is a potent inhibitor of CYP1A2, a less potent CYP3A4 inhibitor, and a negligible inhibitor of CYP2D6, does inhibit its metabolism.

The active metabolite of bromazepam is hydroxybromazepam, which has a half-life approximately equal to that of bromazepam.

Overdose

Bromazepam is commonly involved in drug overdoses. A severe bromazepam benzodiazepine overdose may result in an alpha pattern coma type. The toxicity of bromazepam in overdosage increases when combined with other CNS depressant drugs such as alcohol or sedative hypnotic drugs. Bromazepam is the most common benzodiazepine involved in intentional overdoses in France. Bromazepam has also been responsible for accidental poisonings in companion animals. A review of benzodiazepine poisonings in cats and dogs from 1991-1994 found bromazepam to be responsible for significantly more poisonings than any other benzodiazepine.

Drug misuse

Bromazepam has a similar misuse risk as other benzodiazepines such as diazepam. In France car accidents involving psychotropic drugs in combination with alcohol (itself a major contributor) found benzodiazepines, mainly diazepam, nordiazepam, and bromazepam, to be the most common drug present in the blood stream, almost twice that of the next-most-common drug cannabis. Bromazepam has also been used in serious criminal offences including robbery, homicide, and sexual assault.

Legal status

Bromazepam is a Schedule IV drug under the Convention on Psychotropic Substances.

Synthesis

anthranilamide + P4O10 Phosphorus pentoxide → anthranilonitrile + 2-pyridyllithium → 2-(2-Aminobenzoyl)pyridine.