What factors affect medication-storage practice among patients on methadone maintenance treatment?

Medication storage in patients' homes is an important safety issue. Safe storage of methadone oral solution is of particular concern. Previous studies have suggested that only about half of patients store methadone appropriately. The aims of this study were to describe medication-storage practice in a sample of patients receiving methadone maintenance treatment (MMT), and to identify factors associated with safe storage.

The setting was a primary health care centre in Edinburgh, Scotland. One hundred and four consecutive patients on MMT completed a self-administered questionnaire covering medication-storage practice, together with clinical and demographic variables. Storage of medication was classified as 'acceptable' if medication was out of sight and out of reach of children, and 'optimal' if it was also kept in a secure container.

Percentages (95% confidence intervals) for acceptable and optimal storage were as follows: methadone 80% (71-86%) and 33% (24-42%); other prescribed medication 69% (59-78%) and 27% (19-37%); purchased medication 64% (50-76%) and 28% (17-42%). Safe storage of methadone was more common in patients taking higher doses of methadone (P = 0.004 for acceptable storage, and P = 0.012 for optimal storage), and in those with children in the house (P = 0.007 and 0.061). Safe storage of prescribed and purchased medication was strongly associated with safe storage of methadone (P < 0.01 in both cases).

Medication-storage practice was better than in previous surveys of patients on MMT. This may reflect the high profile given to safety issues for children of drug-using parents in Scotland, as well as local initiatives. Some aspects of prescribing and dispensing practice could be improved further.