Triamterene

Abstract: Context. —The choice of pharmacological treatment for the approximately 50 million people in the United States with hypertension has important therapeutic and financial implications. Objectives. —To describe national antihypertensive medication prescribing patterns for 1992 and 1995; to explore the influence of the Fifth Joint National Committee on the Detection, Evaluation, and Treatment of High Blood Pressure (JNC V), published in 1993, which recommended diuretics and β-blockers as firstline antihypertensive therapy unless contraindicated; and to estimate the impact of these prescribing patterns on the cost of antihypertensive treatment. Design. —All prescriptions for drugs approved for the treatment of hypertension dispensed by 35000 retail pharmacies were tabulated for 1992 and 1995 (62% of all US retail pharmacies were surveyed). Main Outcome Measures. —Number of prescriptions for each dosage form of medication and national cost estimates based on wholesale costs of medications dispensed. Results. —In 1992, of the 10 most frequently prescribed antihypertensive drugs, 3 were calcium antagonists, 3 were angiotensin-converting enzyme (ACE) inhibitors, 3 were β-blockers, and 1 was the combination of triamterene and hydrochlorothiazide. In 1995,4 were calcium antagonists, 3 were ACE inhibitors, 1 was a β-blocker, 1 was the combination of triamterene and hydrochlorothiazide, and 1 an a-blocker. In 1992, calcium antagonists accounted for 33% of antihypertensive prescriptions compared with 38% in 1995, ACE inhibitor use went from 25% to 33%, β-blocker use from 18% to 11% and diuretic use from 16% to 8%. The estimated wholesale costs for calcium antagonists in 1995 dollars increased from $2.67 billion in 1992 to $2.86 billion in 1995; ACE inhibitor costs increased from $1.37 billion to $1.67 billion; costs for diuretics declined from $353 million to $168 million; and costs for β-blockers declined from $763 million to $433 million. Conclusions. —From 1992 to 1995 use of calcium antagonists and ACE inhibitors for treatment of hypertension increased and diuretics and β-blockers declined, suggesting that the recommendations from JNC V had little effect on prescribing patterns. The cost implications of these practice patterns are enormous.

Abstract: Objective. —To investigate the patterns of electrolyte abnormalities resulting from thiazide administration and whether they cause ventricular arrhythmias, and to help resolve the controversy over whether clinicians should routinely prescribe potassium-conserving therapy to all patients treated with thiazides. Design. —Double-blind, randomized controlled trial. Participants. —A total of 233 hypertensive men aged 35 to 70 years. Interventions. —Participants were withdrawn from prior diuretic treatment and were replenished with oral potassium chloride and magnesium oxide. They were then randomized to 2 months of treatment with (1) hydrochlorothiazide; (2) hydrochlorothiazide with oral potassium; (3) hydrochlorothiazide with oral potassium and magnesium; (4) hydrochlorothiazide and triamterene; (5) chlorthalidone; or (6) placebo. Main Outcome Measures. —Ventricular arrhythmias on 24-hour Holter monitoring and serum and intracellular potassium and magnesium levels. Results. —Of the 233 participants, 212(91%) completed the study. Serum potassium levels were 0.4 mmol/L lower in the hydrochlorothiazide group than in the placebo group ( P P P =.02). Serum magnesium and intracellular potassium and magnesium levels were not reduced by hydrochlorothiazide, nor were they related to ventricular arrhythmias. Conclusions. —In the majority of hypertensive patients, treatment with 50 mg/d of hydrochlorothiazide does not cause marked hypokalemia or ventricular arrhythmias. However, because some individuals will develop hypokalemia after starting diuretic therapy, serum potassium levels should be monitored and potassiumsparing strategies should be used when indicated. ( JAMA . 1992;267:1083-1089)

Abstract: Sixteen patients with diuretic-induced hypokalemia underwent 24-hour ambulatory electrocardiographic monitoring during and after correction of hypokalemia. Plasma potassium averaged 2.83 +/- 0.08 mEq/liter before and 3.73 +/- 0.06 mEq/liter after correction with potassium chloride, triamterene or both. Premature atrial contractions decreased in 6 patients, increased in 6 and remained unchanged in 4. There was no improvement in ventricular ectopic activity after plasma potassium correction. Ventricular ectopic activity improved in 5 patients, worsened in 10 and remained unchanged in 1. Ventricular tachycardia was not observed in either phase. Plasma magnesium remained normal throughout. The investigators conclude that in patients with uncomplicated hypertension, correction of diuretic-induced hypokalemia does not significantly reduce the occurrence of spontaneous atrial or ventricular ectopic activity.