General practice

Prescribing injectable and oral methadone to opiate addicts: results from the 1995 national postal survey of community pharmacies in England and Wales

^a National Addiction Centre, Institute of Psychiatry and Maudsley Hospital, London SE5 8AF, ^b School of Pharmacy, London WC1N 1AX

Correspondence to: Professor Strang.

Abstract

Objective: To establish the extent of prescribing injectable and oral methadone to opiate addicts and the practice characteristics and dispensing arrangements attached to these prescriptions.
Design: National survey of 25% random sample of community (high street) pharmacies through postal questionnaire, with four mailings.
Setting: England and Wales.
Subjects: 1 in 4 sample of all 10 616 community pharmacies, stratified by family health services authority.
Main outcome measures: Data were collected on each prescription for controlled drugs currently being dispensed by pharmacies to misusers, describing the drug, form, dose, source (general practice or hospital; and NHS or private), and numbers of dispensing pick ups a week.
Results: Methadone was the opiate most commonly dispensed to misusers (96.0% of 3846 opiate prescriptions). 79.6% of methadone prescriptions were for the oral liquid form, 11.0% for tablet, and 9.3% for injectable ampoules. More than one third of all methadone prescriptions were for weekly or fortnightly pick up, with a further third being for daily pick up. Tablets and ampoules were even less likely to be dispensed on a daily basis. Private prescriptions were significantly more likely than NHS ones to be for tablets or ampoules, to be for substantially higher daily doses, and to be collected on a weekly or fortnightly basis.
Conclusions: The distinctively British practice of prescribing injectable methadone was found to be widespread and, contrary to guidance, to be as prevalent in non-specialist as specialist settings. In view of the frequent crushing and injecting of methadone tablets, clearer more authoritative guidance is needed on the contexts in which injectable methadone (tablets as well as ampoules) should be prescribed and on the responsibilities for monitoring and supervision which should be attached.

Introduction

Prescribing injectable methadone to opiate addicts is a practice almost exclusive to Britain¹ but is now being considered and piloted elsewhere.^{2 3 4} Despite longstanding international fascination with the prescribing of heroin in Britain, quantities of injectable methadone from doctors specialising in drug misuse overtook heroin in 1973⁵ and have remained larger ever since. Injectable methadone can also be prescribed by non-specialist doctors, who do not need a special prescribing licence (as they do for heroin).

No data have previously been presented on the extent of this practice.

Method

During 1995 we surveyed a 25% random sample of the 10 616 community (high street) pharmacies in England and Wales--overall response rate 74.8% (details described elsewhere).⁶ Of the responding pharmacies, 50.1% were currently dispensing prescribed supplies of controlled drugs to misusers. Of the 3846 prescriptions for opiates being dispensed to drug misusers, 3693 were for methadone, 64 for heroin, and 89 for other opiates. We analysed the different forms and doses of methadone prescribed and the dispensing intervals. the significance tests have been calculated on the basis of simple random sampling of the prescriptions.

Results

DIFFERENT FORMS OF METHADONE

Methadone was most commonly prescribed as oral liquid (for example, methadone mixture 1 mg/ml, British National Formulary) 79.6%, tablets (11.0%) and ampoules (9.3%) (see table 1). Oral liquid was the form most commonly prescribed by both hospital doctors and general practitioners, with little evidence of higher rates of prescribing the more unusual forms (tablets and ampoules) in secondary specialist services (table 1).

Table 1--Numbers (percentages) of doctors' prescriptions, to opiate addicts, of
methadone as oral liquid, tablet, or ampoule, by setting and practice
---------------------------------------------------------------------------------------------------------------------------------
                                           Setting                                               Practice
---------------------------------------------------------------------------------------------------------------------------------
                               General practice                Hospital                    NHS                    Private
Form                             (n = 1519)                   (n = 2135)                (n = 3556)               (n = 55)
---------------------------------------------------------------------------------------------------------------------------------
Oral liquid                      1199 (78.9)                  1713 (80.2)               2851 (80.1)               19 (35)
Tablet                            195 (12.8)                   205 (9.6)                 386 (10.9)               18 (33)
Ampoule                           125 (8.2)                    217 (10.2)                319 (9.0)                18 (33)
---------------------------------------------------------------------------------------------------------------------------------
General practice v hospital: 2 = 12.2; df = 2; P<0.005. NHS v private practice: 2 = 70.1; df = 2; P<0.0001.

Of NHS prescriptions for methadone, 80.1% were for oral liquid, with the rest being tablets (10.9%) or ampoules (9.0%). In private practice, tablets and ampoules were more commonly prescribed (33% in each case) than in the NHS, with only 35% of private prescriptions being for oral liquid (table 1). Private prescribing of methadone occurs predominantly in London, with 80% (44/55) of such prescriptions being from the Thames regions.

DOSE

Overall, significantly higher daily doses were prescribed by hospital and clinic doctors than by general practitioners (Mann-Whitney test, t = -7.2, df = 3533; P<0.0001) and by doctors working in private practice rather than in the NHS (t = -4.6, df = 53; P<0.0001). Examination of data for each form of methadone showed that daily doses of methadone for ampoules were nearly twice as high in private prescriptions as in NHS prescriptions (table 2).

Table 2--Dose of methadone (mg), as oral liquid, tablet,
or ampoule,* given on doctors' prescriptions to opiate
addicts, by practice
-------------------------------------------------------------
Form                  Overall      NHS           Private
-------------------------------------------------------------
Oral liquid:         (n = 2841) (n = 2759)      (n = 18)
 Mean                   44.3       44.3          55.2
 Median                  40        40.0           50
 Interquartile range    28-60      28-60         27-70
 Range                  2-200       2-200      12.5-200
 Mann-Whitney U test                U = 22010; P = 0.4
Tablet:              (n = 394)  (n = 374)       (n = 18)
 Mean                   53.3       51.9           82.5
 Median                  50         45             60
 Interquartile range    30-70      30-70        34-146
 Range                   5-300      5-300       10-200
 Mann-Whitney U test                U = 2616; P = 0.11
Ampoule:             (n = 327)  (n = 304)       (n = 18)
 Mean                   65.5       62.4          117.8
 Median                  50         50            100
 Interquartile range    40-90      40-80        100-150
 Range                  10-250     10-230        30-250
 Mann-Whitney U test                U = 1063; P<0.0001
-------------------------------------------------------------
*Patients might have received more than one form of methadone
and/or more than one opiate.

INTERVAL DISPENSING

Guidelines from the Department of Health and the Welsh Office advise doctors to instruct dispensing pharmacists to provide methadone in instalments--for example, daily dispensing.⁷ General practitioners prescribed with longer intervals between pick ups than hospital doctors, as did doctors working in private practice compared with NHS practice.

We then grouped dispensing arrangements as "daily," "several times a week," or "weekly or less frequently." Daily dispensing occurred in only a third of cases (36.6% of all prescriptions requiring pick up on six or seven days a week), while prescriptions of at least a week's supply occurred in a further third (37.2%) (fig 1). We then analysed whether doctors relied more on interval dispensing for forms of methadone with a greater potential for misuse and risk of diversion--that is, tablets and ampoules. Table 3 shows that doctors relied less on daily dispensing arrangements for tablets and ampoule and that more than half of all prescriptions for tablets and nearly a third of all those for ampoules were for collection weekly or less frequently.

View larger version (19K): [in this window] [in a new window]   Fig 1--Interval of dispensing for methadone prescriptions (n = 3585)

Table 3--Numbers (percentages) of doctors'
prescriptions of different forms of methadone to opiate
addicts, by interval of dispensing
---------------------------------------------------------------------
                           Oral liquid   Tablet   Ampoule
Interval                   (n = 2855)  (n = 393)  (n = 333)
---------------------------------------------------------------------
Daily*                     1172 (41.0)   83 (21.1) 119 (35.7)
Several times a week+       681 (23.8)   87 (22.1) 112 (33.6)
Weekly or less often++     1005 (35.2)  223 (56.7) 102 (30.6)
---------------------------------------------------------------------
2 = 95.6; df = 4; P<0.0001.
*Five, six, or seven times a week. +Two, three, or four times a week.
++Once a week, once a fortnight, or once a month.

Similar proportions of prescriptions from general practitioners and hospital doctors were for daily dispensing, but general practitioners were significantly more likely to arrange for a single pick up of a weekly or fortnightly supply (table 4). A significant lack of daily dispensing arrangements existed in private practice (table 4).

Table 4--Numbers (percentages) of doctors' prescriptions of methadone to opiate
addicts according to interval of dispensing, by setting and practice
----------------------------------------------------------------------------------------------------------------------------------
                                             Setting                                          Practice
----------------------------------------------------------------------------------------------------------------------------------
                                 General practice          Hospital                     NHS              Private
Interval                           (n = 1446)             (n = 2112)                 (n = 3461)          (n = 54)
----------------------------------------------------------------------------------------------------------------------------------
Daily*                             534 (36.9)              827 (392)                 1335 (38.6)          0 (0.0)
Several times a week+              259 (17.9)              618 (29.3)                 864 (25.0)          1 (1.9)
Weekly or less often++             653 (45.2)              667 (31.6)                1262 (36.5)         53 (98.1)
----------------------------------------------------------------------------------------------------------------------------------
General practice v hospital: 2 = 88.6; df = 2; P<0.0001. NHS v private practice: 2 = 86.4; df = 2; P<0.0001.
*Five, six, or seven times a week. +Two, three, or four times a week. ++Once a week, once a fortnight, or once
a month.

Discussion

These data show the feasibility of addictions research into the prescribing behaviour of doctors through the keyhole of community pharmacies. This new information on the extent and nature of prescribing of injectable methadone is an important addition to the debate on the prescribing of injectable opiates. Such a study should be repeated to monitor this feature of Britain's policy on drugs that attracts such international interest.^{8 9}

Daily dispensing and supervised consumption of methadone are the norm internationally. British guidelines recommending such practice^{7 10 11} carry no statutory authority. No data have previously been presented on doctors' compliance with these guidelines. We find the option of daily dispensing to be widely disregarded, thus increasing known dangers of misuse and diversion to the black market.¹² Particularly disturbing is the widespread disregard of the facility of daily dispensing with prescriptions--especially of tablets and ampoules.

A high prevalence of prescribing injectable methadone--both overtly injectable (ampoules) and covertly injectable (tablets)--has been identified. The extensive prescribing of methadone tablets is disturbing and contrary to recommendations.^{7 11} Doses of injectable methadone are sufficiently high to warrant special scrutiny, especially alongside the infrequent use of daily dispensing.

Every British doctor has the authority to prescribe any form of methadone to treat opiate addiction. Recent United Kingdom recommendations from the Drug Treatment TaskForce^{13 14} presume the existence of a system for triage, with specialist services having responsibility for the more difficult forms of treatment (such as injectable methadone). We found little evidence, however, of differentiation of prescribing between primary and secondary healthcare services.

Major differences were found between the prescribing habits of doctors working in the NHS and those of doctors in private practice. Methadone prescriptions from doctors in private practice were higher dose, more frequently in the form of ampoule or tablet, and more frequently with bulk provision in weekly, fortnightly, or even monthly pick ups. Doctors issuing private prescriptions should exercise the same precautions against misuse and diversion as their NHS colleagues, and the current stark differences between NHS and private prescriptions should be examined critically.

Overall, these findings indicate a system that is operating inefficiently--perhaps even a system in trouble. The lack of evidence of differentiation of primary and secondary healthcare prescribing is disturbing, as are the profound differences between NHS and private practice. The widespread disregard of the opportunities for interval dispensing (especially for tablets and ampoules, which have a greater potential for misuse) indicates a failure to appreciate the abuse potential and the substantial value on the black market of injectable forms of methadone. With the prescribing of methadone increasing so rapidly¹⁵ and with the above evidence of the instability of this feature of Britain's drug policy, policymakers and planners must find improved methods of harnessing the benefits of methadone prescribing.^{16 17 18}

Funding: This study was supported by a grant from the Drug Treatment Effectiveness TaskForce at the Department of Health and by the Welsh Office. The views expressed are those of the authors and do not necessarily represent those of the Department of Health or the Welsh Office.

Conflict of interest: None.

1. Strang J, Ruben S, Farrell M, Gossop M. Prescribing heroin and other injectable drugs. In: Strang J, Gossop M, eds. Heroin addiction and drug policy: the British system. Oxford: Oxford University Press, 1994:192-206.
2. Bammer G. Should the controlled provision of heroin be a treatment option? Australian feasibility consideration. Addiction 1993;88:467-75. [Medline]
3. Derks J. The efficacy of the Amsterdam morphine-dispensing programme. In: Ghodse AH, Kaplan C, Mann R, eds. Drug misuse and dependence. Carneforth: Parthanon, 1990:85-108.
4. Uchtenhagen A, Dobler-Miklos A, Gutzwiller F. Medically-controlled prescription of narcotics: fundamentals, research plan and first experiences. In: Medical prescription of narcotics. Fribourg: Huber (in press).
5. Mitcheson M. Drug clinics in the 1970s. In: Strang J, Gossop M, eds. Heroin addiction and drug policy: the British system. Oxford: Oxford University Press, 1994:178-91.
6. Sheridan J, Strang J, Barber N, Glanz A. Role of community pharmacies in relation to HIV prevention and drug misuse: findings from the 1995 national survey in England and Wales. BMJ 1996;313:272-4. [Abstract/Free Full Text]
7. Department of Health, Scottish Home and Health Department, Welsh Office. Drug misuse and dependence: guidelines on clinical management. London: HMSO, 1991.
8. Strang J, Gossop M, eds. Heroin addiction and drug policy: the British system. Oxford: Oxford University Press, 1994.
9. Strang J. "The British system": past, present and future. International Review of Psychiatry 1989;1:109-20.
10. Department of Health and Social Security. Guidelines for good clinical practice in the treatment of drug misuse. London: DHSS, 1984.
11. Advisory Council on the Misuse of Drugs. AIDS and drug misuse: update report. London: HMSO, 1993.
12. Lauzon P, Vincelette J, Bruneau J, Lamothe F, Lachance N, Brabant M, et al. Illicit use of methadone among IV drug users in Montreal. J Subst Abuse Treat 1994;11:457-61. [Medline]
13. Polkinghorne J. Task force to review services for drug misusers: progress report (supplement). Drug Link 1995;Jan:1-4.
14. Drug Treatment Effectiveness Task Force. Report to Department of Health. London: Department of Health, 1996.
15. Home Office. Statistics on the misuse of drugs: addicts notified to the Home Office, United Kingdom, 1994. London: HMSO, 1995.
16. Ball JC, Ross A. The effectiveness of methadone maintenance treatment: patients, programs, services and outcomes. New York: Springer, 1991.
17. Ward J, Mattick R, Hall W. Key issues in methadone maintenance treatment. Sydney: New South Wales University Press, 1992.
18. Farrell M, Ward J, Des Jarlais DC, Gossop M, Stimson G, Hall W, et al. Methadone maintenance programmes: review of new data with special reference to impact on HIV transmission. BMJ 1994;309:997-1001. [Free Full Text]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    StumbleUpon    Technorati    What's this?

Relevant Articles

Treatment in general practice can be successful

Chris Ford and Brian Whitehead
BMJ 1996 313: 1481-1482. [Extract] [Full Text]

Clinical judgment is important

Colin Brewer and Catherine Neill
BMJ 1996 313: 1482. [Extract] [Full Text]

This article has been cited by other articles:

• White, R., Shearman, L. (2008). Injectable opiate prescribing in Cornwall. Psychiatr. Bull. 32: 387-390 [Abstract] [Full text]  
• Morgan, O., Griffiths, C., Hickman, M. (2006). Association between availability of heroin and methadone and fatal poisoning in England and Wales 1993-2004. Int J Epidemiol 35: 1579-1585 [Abstract] [Full text]  
• Strang, J., Sheridan, J. (2003). Effect of national guidelines on prescription of methadone: analysis of NHS prescription data, England 1990-2001. BMJ 327: 321-322 [Full text]  
• Dunn, J. (2003). A survey of methadone prescribing at an inner-city drug service and a comparison with national data. Psychiatr. Bull. 27: 167-170 [Abstract] [Full text]  
• Myton, T., Fletcher, K. (2003). Descriptive study of the effects of altering formulation of prescribed methadone from injectable to oral. Psychiatr. Bull. 27: 3-6 [Abstract] [Full text]  
• Fiellin, D. A., O'Connor, P. G. (2002). Office-Based Treatment of Opioid-Dependent Patients. NEJM 347: 817-823 [Full text]  
• Milroy, C M, Forrest, A R W (2000). Methadone deaths: a toxicological analysis. J. Clin. Pathol. 53: 277-281 [Abstract] [Full text]  
• Matheson, C., Bond, C. M, Hickey, F. (1999). Prescribing and dispensing for drug misusers in primary care: current practice in Scotland. Fam Pract 16: 375-379 [Abstract] [Full text]  
• Day, E, Kahn, A, Georgiou, G (1999). Misusers may receive methadone from drug centres and GPs simultaneously. BMJ 318: 395a-395 [Full text]  
• Strang, J., Sheridan, J. (1998). Effect of government recommendations on methadone prescribing in south east England: comparison of 1995 and 1997 surveys. BMJ 317: 1489-1490 [Full text]  
• (1997). Helping patients who misuse drugs. DTB 35: 18-22 [Abstract] [Full text]  
• Calman, L., Finch, E., Powis, B., Strang, J. (1996). Only half of patients store methadone in safe place. BMJ 313: 1481-1481 [Full text]  
• Brewer, C., Neill, C. (1996). Clinical judgment is important. BMJ 313: 1482-1482 [Full text]  
• Robertson, J R, Macleod, J (1996). Methadone treatment. BMJ 313: 1480c-1481 [Full text]  
• Ford, C., Whitehead, B. (1996). Treatment in general practice can be successful. BMJ 313: 1481b-1482 [Full text]  
• Sorensen, J. L (1996). Methadone treatment for opiate addicts. BMJ 313: 245-246 [Full text]