Benzodiazepines and drugs for dementia

Benzodiazepines and drugs for dementia




Benzodiazepines


The benzodiazepines are known as ‘minor tranquillisers’. During the 1960s and 1970s they were enormously popular, but as the risk of dependence has been better understood they have been much less frequently prescribed. They are generally subdivided into two groups – the short acting hypnotics (e.g. temazepam), and the longer acting anxiolytics (e.g. diazepam).



How do benzodiazepines work?


Benzodiazepines are gamma-amino butyric acid (GABA) receptor agonists. GABA receptors occur throughout the cortex and limbic system in the brain, and act to inhibit neuronal activity.



Indications


Currently there are five main psychiatric indications for prescription of benzodiazepines:


1 Severe acute emotional distress, for example following a bereavement or assault, where short-term sedation can provide relief. The prescription should be for as short a period and as low a dose as possible.

2 Medical management of withdrawal from alcohol. Chlordiazepoxide is most commonly used, starting with a dose that is high enough to control all withdrawal symptoms, and reducing over 7–10 days.

3 As an adjunct to antipsychotic medication in patients with marked agitation due to severe mental illness, such as mania. Again the prescription should be short-term, although when used in these circumstances is unlikely to lead to dependency. Benzodiazepines are used in combination with antipsychotic drugs in rapid tranquillisation.

4 For patients who are dependent upon benzodiazepines prescribed to them over many years. These patients should be given opportunities to stop the drugs completely, by prescribing a slowly reducing course. Some, however, are unable to manage complete withdrawal.

5 For people with generalised anxiety disorder who continue to experience high levels of distress and disability despite having tried all other treatments and who understand and accept the risks of tolerance and dependence.


Side effects


The main side effects of benzodiazepines are sedation and psychomotor impairment which may affect driving ability. They can also cause headaches, confusion, ataxia, and dysarthria. Some patients have a paradoxical reaction to benzodiazepines, and become disinhibited, excited or aggressive. This appears to be a particular risk in patients who have poor impulse control associated with brain injury, learning disability or personality disorder, and in younger and older patients. Respiratory depression is rare with oral formulations but can occur if benzodiazepines are used intravenously. In this event, the benzodiazepine antagonist, flumazenil, may be used.


Tolerance and dependency can develop rapidly, although are more likely after long-term treatment.



Management of benzodiazepine withdrawal


It is thought that about half of all benzodiazepine users experience withdrawal symptoms. This is more likely if benzodiazepines with short half-lives are used (particularly lorazepam); they are used for a long time, at high dose; the patient has alcohol or other drug dependency, or a personality disorder; or they are used without medical supervision. Withdrawal symptoms vary widely. Some patients are able to withdraw without difficulty, even after many years of treatment, others suffer severe symptoms with insomnia, anxiety, agitation, depressed mood and perceptual changes. Withdrawal should be managed by first of all switching to an equivalent dose of diazepam, as withdrawal symptoms tend to be less severe with this longer-acting drug. The dose is then slowly reduced, titrating the speed of reduction against the patient’s symptoms. The aim is to allow withdrawal symptoms to settle fully before attempting the next reduction in dose. The reductions in dose become smaller as the withdrawal proceeds.



Hypnotic drugs


Hypnotic drugs induce sleep and are used to treat insomnia. Insomnia is a change to the normal sleep pattern, due to difficulty in either getting to sleep or maintaining sleep. What is regarded as a ‘normal’ sleep pattern varies enormously from one individual to another, although most healthy adults sleep between 7 and 9 hours each night. The causes of insomnia are shown in Table 1.


Table 1 Causes of insomnia






Life events
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Jul 12, 2016 | Posted by in PSYCHIATRY | Comments Off on Benzodiazepines and drugs for dementia

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