Thiazides in the 1990s

Diuretic-related hypokalaemia: the role of diuretics, potassium supplements, glucocorticoids and beta 2-adrenoceptor agonists. Results from the comprehensive hospital drug monitoring programme, berne (CHDM)

All 5,047 consecutive inpatients admitted to the Internal Medicine Division of a teaching hospital (Zieglerspital, Berne) between 1982 and 1985 were registered in accordance with the CHDM (Comprehensive Hospital Drug Monitoring) questionnaire of adverse drug reactions (ADRs). Of them, 2,439 were treated with at least one potassium losing diuretic. The hospital records of the patients were reviewed with particular regard to serum potassium levels, and on the basis of this evaluation, the patients were assigned to four different diuretic treatment groups, and the incidence of hypokalaemia related to diuretic treatment was estimated. The overall rate of occurrence of hypokalaemia was 21.1% at a serum potassium level < 3.5 mmol.l-1, and 3.8% < 3.0 mmol.l-1. Hypokalaemia of less than 3.5 mml.l-1 developed 24.9% (217/870) of patients treated with potassium losing diuretics alone; in 19.7% (101/513) treated with potassium losing diuretics in conjunction with potassium substitution, in 15.1% (66/438) treated with a combination of diuretics (potassium losing with potassium sparing), and in 20.0% (12/60) treated with combined diuretics and potassium substitution. Only the differences between the first and the two subsequent groups were statistically significant. The overall incidence of hypokalaemia below 3.0 + mmol.l-1 was significantly lower in the patients on combined diuretics without potassium substitution than in the patients on potassium losing diuretics with potassium substitution. Oral or parenteral administration of glucocorticoids (prednisone 5 to 2,000 mg/d) was a significant risk factor for hypokalaemic events. beta 2-Adrenoceptor agonists had not effect. The patient's age, sex, renal function and numbers of drugs received were evaluated in a multivariate analysis, in order to take into account their influence on the risk of developing hypokalaemia. The number of drugs above 12 (and, less importantly, female sex) was the main risk factor for this ADR. The comparison between hypokalaemia and hyperkalaemia in this group of inpatients showed the significance of reduced renal function in the occurrence of hyperkalaemia.

Effects of hydrochlorothiazide, amiloride, and lisinopril on the metabolic response to adrenaline infusions in normal subjects

Twelve healthy male volunteers were given adrenaline infusions, 0.05 microgram/kg body weight/min over 120 minutes in order to achieve serum adrenaline concentrations comparable with those seen in acute myocardial infarction. The infusions were given on four occasions, at intervals of at least 4 weeks. Before the infusions the subjects were given, in random order, 14 days of pretreatment with placebo, hydrochlorothiazide 50 mg once daily, amiloride 10 mg once daily, or lisinopril 20 mg once daily. The adrenaline infusion induced a drop in serum potassium of the same magnitude in all four groups, with the lowest absolute value after hydrochlorothiazide because of the lowest pre-adrenaline level. The infusion-induced decreases in serum calcium and magnesium were of the same magnitude in all groups, with the absolute calcium being least low in the hydrochlorothiazide group because of the highest preinfusion value. Preinfusion serum urate was highest after hydrochlorothiazide and fell during the adrenaline infusion in all groups, although not significantly. Blood glucose increased during the adrenaline infusion in all groups, but significantly more after hydrochlorothiazide and amiloride than after lisinopril. Heart rate increased during the adrenaline infusion in all groups but least after lisinopril. QTc preinfusion was longer after hydrochlorothiazide than after amiloride and placebo, but the infusion-induced prolongation of QTc was of the same magnitude in all pretreatment groups. Since our results were obtained in short-term experiments in normal subjects, their clinical relevance is questionable, but they support the view that ACE inhibitors may have certain metabolic advantages over diuretics.

New developments in antihypertensive drugs

New developments in antihypertensive drug treatment include optimizing the use of established drugs, the introduction of novel compounds, and a renewed appreciation that hypertension is but one of various cardiovascular risk factors that must be addressed in managing the patient with raised blood pressure. Thus, the approach used must be tailored to the individual patient both in terms of drug choice and dose as well as preventive measures. New drug development depends very much on improving our understanding of the pathophysiologic mechanisms involved in hypertension and seems likely to be applied at the level of the renin angiotensin system and other local factors governing vascular smooth muscle function.