Scottish guidelines for clinical pharmacy practice in primary care were published in February 1999 to promote the strategy of targeting pharmaceutical care towards 'high risk' patient groups¹. Patients on chronic medication with a low therapeutic index drug (LTI) appear to have a greater potential to experience drug-related problems² and can easily be identified from repeat prescribing/dispensing databases. This study examined a model which engaged community pharmacists (CPhs) on a sessional basis to structure pharmaceutical care needs in a TDM support role to the GP practice and within a multidisciplinary network linked to a specialist laboratory.

Methods
After an initial training programme from the Clinical Pharmacokinetics Laboratory (CPL), five CPhs were attached to five GP practices on a sessional basis from April 1997 to May 1998. A total of 324 prescribing records were identified, from which 132 (41%) records (126 patients' records) were studied. This sample represented 37-44% of all patients prescribed each of the following drugs; digoxin, phenytoin, carbamazepine, lithium or theophylline. Pharmaceutical care issues were defined as potential problems requiring discussion with the prescriber. Care issues were categorised and followed up at a second interview with the prescriber after a period of at least 2 months.

Results
In 126 patients 418 care issues (mean per patient 3.3, SD 1.5) were initially identified of which 128 (31%) were TDM-related, identified in 101 (80%) patients and followed up after a mean of 5.6 (SD 2.1) months. A total of 299 care issues (72%) were found to be resolved (table 1). Patient monitoring (laboratory and clinical) care issues were more likely to remain outstanding when compared to other types (prescribing, therapeutic effectiveness and patient counselling; chi-squared, p<0.01).

The five pharmacists reported the need for even greater contact with the GP and the CPL if they were to carry out the role more effectively. The CPL reported contact with the CPhs was less than expected for them to fully function in a TDM support role.

Discussion
Patients on chronic medication with an LTI drug deserve to be targeted by pharmacists acting in a TDM support role and in the overall delivery of pharmaceutical care to a primary care population. If the TDM support role is to be formalised, improvements in two-way communication with the CPL must occur. The length of time between initial discussion and follow-up varied considerably between patients due to difficulties encountered in arranging visits to the surgery. Future considerations should address whether CPhs operate from within their own pharmacy or within the surgery.

Acknowledgement: Funded by the Primary Care Development Fund, Greater Glasgow Health Board.

References

1. Clinical Resource and Audit Group (1999). 'Clinical pharmacy practice in primary care', A Working Party Report (Chairman, Professor JA Cromarty). The Scottish Office, National Health Service in Scotland, Edinburgh.
2. Koecheler JA, Abramowitz PW, Daniels CE. Indicators for the selection of ambulatory patients who warrant pharmacist monitoring. Am J Hosp Pharm 1989; 46: 729-732.