Use of indapamide in hospital and community clinics and its effect on plasma potassium in Chinese patients

Objectives: To investigate the usage pattern of indapamide and other antihy pertensive drugs in patients attending a community-based government outpati ent clinic (GOPC) or a hospital-based specialist clinic (SC). The plasma po tassium concentrations of patients receiving indapamide and other diuretics were also examined. Method: Prescriptions from the SC and the GOPC were reviewed and collected during January 1998. Patients' plasma potassium concentrations and the date of initiation of each medication were retrieved from the hospital computer databases at SC. An age- and sex-matched control group of patients on non- diuretic antihypertensive drugs was identified. Results: A total of 1648 and 773 prescriptions were collected from the SC d uring a 1-week period and GOPC during a I-month period, respectively. Appro ximately half (45%) of the patients received antihypertensive treatment. In dapamide was five times more frequently prescribed in GOPC than SC (84.7 vs . 17.7%, P<0.001). Calcium channel blocking agents were the commonest antih ypertensive drugs used in both clinics. The mean plasma potassium concentra tion of patients taking indapamide was lower than that of the control group (P=0.037). Multiple linear regression analysis showed that consumption of indapamide (P=0.002) and duration of diuretic therapy (P=0.023) were signif icantly related to changes in plasma potassium concentrations [multiple reg ression equation for potassium level= 4.09-0.145 (thiazide=1)-0.377 (indapa mide=1) - 0.00468 (duration of diuretic therapy in months)]. Conclusion: Indapamide was used extensively in the community clinic and les s in the hospital-based outpatient clinic. Patients receiving indapamide ha d a significantly lower plasma potassium concentration as compared to other diuretics or antihypertensive groups and this was predicted by a multiple linear regression model. Monitoring plasma electrolytes before initiation o f indapamide treatment and at regular intervals thereafter is essential for detecting the hypokalaemia that may occur in Chinese patients.