Introduction: Although drug-related problems (DRPs) are known to be prevalent in elderly patients, there are not many studies that have been performed in geriatric outpatients at public health facilities in South Africa. Thus, the prevalence of DRPs in elderly outpatients attending Addington Hospital was investigated and suitable preventive intervention strategies to overcome or minimise these DRPs were developed. Research Methodology: The study was conducted in two phases. Phase 1 was conducted in March and April 1998, during which 281 elderly patients on chronic medical treatment were chosen for the study by systematic random sampling, according to specific inclusion criteria. Data collection was via a retrospective review of the elderly patient's medical notes and by personally interviewing the patient. Two research instruments were used in this phase. The customised Patient Profile (PF) form helped to delineate DRPs in the elderly patients. A Prescription Intervention Form (PIF) was used to inform the prescriber of the DRP and to make recommendations to change the drug therapy in order to overcome the DRP. In phase 2 of the study, intervention strategies were devised to address some of the major DRPs identified in phase 1 of the study. A patient counselling leaflet, prescribing guidelines for geriatric patients and a protocol for counselling of in-patients were developed. In addition, two DRP reporting systems were developed for surveillance of adverse drug reactions and medication errors during dispensing. Results and Discussions: Most geriatric subjects suffered from multiple, chronic conditions, these being hypertension (64.8%) followed by ischaemic heart disease (43.8%), musculoskeletal disorders (arthritis or gout) (42.7%), diabetes (29.2%), chronic obstructive airways disease (13.2%), hypercholesteremia (11.7%) and arrythmias (atrial fibrillation) (11.0%). The 281 patients were taking 1730 prescribed drugs, with a mean of 6.2 (range 3 to 15) prescribed drugs per patient. An astounding 45.6% of the total geriatric patients were taking or using between 7 to 9 medicines and 10.3% were taking or using between 10 to 15 medicines. The antihypertensives (15.9%) were the most widely prescribed drugs followed by medicines acting on CNS (10.9%), coronary vasodilators (9.1%), diuretics (9.1%) and medicines acting on the musculoskeletal system (8.7%). A total of 856 actual DRPs experienced by 262 geriatric patients (93.2%) ranged from 1 to 11 DRPs. The greater the number of prescribed drugs the greater the actual DRPs experienced by geriatric patients (p = 0.000). The most common DRPs were those involved in drug safety (56.6%); effectiveness of the drug therapy (20.8%); compliance (7.8%) and indication of drug therapy (7.6%). 159 elderly patients (56.6%) experienced 223 adverse effects either with their current or past prescribed medicines. The most common ADRs were as follows: gastro-intestinal ulceration (11.0%), cough (9.3%), diuretic side effects (dehydration, fatigue, hypotension, etc) (7.1%), constipation (6.8%), equilibrium problems (6.4%) and headaches (6.4%). For those DRPs warranting interventions, the mean number of prescription interventions in the entire sample population of 281 elderly patients was 0.65 ± 1.16. 87 elderly patients (30.1 %) had from 1 to 4 interventions on their current prescription. The most common prescription interventions were on problems involving drug therapy monitoring (26.9%), safety of drug therapy (26.5%), indication of drug therapy (17.5%), prescribing errors (15.3%) and prescription information omission (11.1 %). The three intervention strategies and DRPs surveillance reporting systems were successfully devised and developed. Conclusions: A profile related to the elderly patient's medical history and pharmacotherapy was completed for each of the 281 patients. General trends of prescribing pattern prevalence of DRPs and the prescribed inappropriate medication was established. The interventions of problem prescriptions were based on a newly developed PIF. The development and implementation of suitable intervention strategies to minimise DRPs were as follows: a compliance information leaflet, prescribing guidelines and the protocol for counselling in-patients. A medication error form as well as an adverse drug reaction reporting forms was developed for surveillance of DRPs. The recommendations for clinical practice and directions for future research that are presented should help to make drug therapy in the elderly safer and more effective. / Thesis (M.Pharm.)-University of Durban-Westville, 2000.