Substance Misuse - Benzodiazepine misuse

GPs can help substance misusers reduce their benzodiazepine use, explains Dr Meg Thomas.

Benzodiazepine misuse causes anxiety and reduces coping skills
Benzodiazepine misuse causes anxiety and reduces coping skills

Misuse of illicit benzodiazepine (BZ) is a common and serious problem in drug users.

BZs are not often used in isolation by drug users, but with other substances (polydrug use). A survey in England and Wales reported that 40 per cent of opiate users used BZs and nearly 25 per cent were dependent.1

Reasons given for the use of BZs are that they are a heroin substitute; for anxiety and insomnia; to come down from stimulants; and to control auditory hallucinations.

The risks misuse
The risks include memory impairment, emotional suppression and increased anxiety. About 15 per cent of patients are dependent after four months and 50 per cent at two years.

A withdrawal syndrome can occur with intense anxiety and the risk of convulsions or even fatalities. Polydrug use is linked with worse outcomes in terms of physical and mental health, as well as higher mortality rates.2

Interventions
There is little evidence for consistently effective interventions. Treatment for the primary drug of misuse can reduce BZ use.3

There is only weak evidence for gradual tapering off, psychological approaches such as cognitive behavioural therapy and contingency management.4

Substitute prescribing for opiate dependence has been shown to be beneficial in trials, but there is no evidence for any gain from substitute prescribing for BZ dependence.

The role of BZs cannot be ignored as they hamper recovery from other addictive drug abuse. Short-term prescribing for six months or less of doses less than 30mg may have some benefit. Higher doses are linked with cognitive impairment and should not be prescribed.4

Helping withdrawal
If a decision is made to help a patient discontinue BZs, certain criteria should be satisfied.5

Dependency should be confirmed from both their history and at least two urine tests, achievable and time-limited goals must be established and changes to drug use defined.

The BZ should then be dispensed daily on an FP10 (MDA) instalment prescribing form until they are stable, with a minimum fortnightly review.

The patient must understand the risks of long-term BZ use, be aware of the risks of using street BZ as well, and the risks of crushing then injecting prescribed BZ. If the patient is also receiving a methadone script this should be kept stable during the withdrawal period.5

A drug worker should be available to provide psychosocial support and for relapse prevention. Diazepam is the drug of choice. There is evidence that users will stabilise on doses that are about 40 per cent of the stated street dose. Patients using doses above 100mg will need specialist detoxification.

The daily dose should be split to facilitate sleep and avoid daytime drowsiness, starting with a maximum of 30mg per day.

Stepwise reduction of the dose is done gradually. Reduce by 5mg fortnightly to 20mg, then by 2mg fortnightly to 6mg and thereafter by 1mg fortnightly.

The process can be expedited if the patient is doing well, but slowed down if withdrawal symptoms are a problem.

Insomnia can be a problem. Antidepressants should only be used for underlying depression and not for sleep alone.

Amitriptyline and dosulepin should be avoided due to potential cardiotoxicity.

  • Dr Thomas is a GP in Swindon, Wiltshire

References
1. Williams H, Handyside D, Bashford K et al. Service response to benzodiazepine use in opiate addicts: results of a postal survey. Ir J Psychol Med 2005; 22: 15-8.

2. Gossop M, Marsden J, Stewart D et al. Methadone treatment practices and outcome for opiate addicts treated in drug clinics in general practice: results from the National Treatment Outcome Research Study. Br J Gen Pract 1999; 49: 31-4.

3. Lingford-Hughes AR, Welch S, Nutt DJ. Evidence based guidelines for the pharmacological management of substances misuse addiction and comorbidity: recommendations from the British Association of Psychopharmacology. J Psychopharmacol 2004; 18: 293-335.

4. DoH. Drug misuse and dependence: UK Guidelines on clinical management. London, DoH, 2007. Available from: www.nta.nhs.uk/publications/documents/clinical_guidelines_2007.pdf

5. Ford C, Roberts K, Barjolin J. Guidance on prescribing benzodiazepines to drug users in primary care. Substance Misuse Management in General Practice, updated October 2005. Available from www.smmgp.org.uk/download/guidance/guidance006.pdf

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