Clinical experience with a new combination formulation of triamterene and hydrochlorothiazide (Maxzide) in patients with mild to moderate hypertension

Echocardiographic guidance for diagnostic and therapeutic percutaneous procedures

Echocardiographic guidance has an important role in percutaneous cardiovascular procedures and vascular access. The advantages include real time imaging, portability, and availability, which make it an effective imaging modality. This article will review the role of echocardiographic guidance for diagnostic and therapeutic percutaneous procedures, specifically, transvenous and transarterial access, pericardiocentesis, endomyocardial biopsy, transcatheter pulmonary valve replacement, pulmonary valve repair, transcatheter aortic valve implantation, and percutaneous mitral valve repair. We will address the ways in which echocardiographic guidance provides these procedures with detailed information on anatomy, adjacent structures, and intraprocedural instrument position, thus resulting in improvement in procedural efficacy, safety and patient outcomes.

Ceftriaxone in treatment of serious infections. Skin and soft tissue infections

Ceftriaxone is generally recognized to be safe and effective when administered either intravenously or intramuscularly to both adults and children as a single drug for skin and skin structure infections. An advantage of ceftriaxone over the other third-generation cephalosporins is its long serum half-life, which allows it to be given every 12 hours in children and every 24 hours in most adults. There is no question that ceftriaxone is effective for skin and soft tissue infections, particularly those caused by staphylococci and streptococci. The drug's sales to home infusion companies around the country attest to its widespread use for such infections. The fact remains, however, that the data required to substantiate efficacy and safety for ceftriaxone or for any of the other third-generation cephalosporins are just not available in large numbers.

A comparison of the anti-hypertensive effectiveness of two triameterene/hydrochlorothiazide combinations: Maxzide versus Dyazide

The hydrochlorothiazide component of Maxzide (Lederle Laboratories, Pearl River, NY) has been shown to be more bioavailable than the hydrochlorothiazide component of Dyazide (Smith, Kline and French Laboratories, Philadelphia, PA). The authors compared the antihypertensive effectiveness of a half-tablet of Maxzide (25 mg of hydrochlorothiazide and 37.5 mg of triamterene) to one capsule of Dyazide (25 mg of hydrochlorothiazide and 50 mg of triamterene) to determine if the difference in bioavailability would be reflected in differences in blood pressure control and metabolic changes. Thirty patients were studied in a randomized open-label crossover design study. There was a significant reduction in systolic blood pressure for both treatments although there was no difference in blood pressures at any time during the study between the two agents. There were no statistically significant differences between Maxzide and Dyazide in terms of metabolic changes for potassium, magnesium, glucose, cholesterol, triglycerides, uric acid, or calcium. Although the hydrochlorothiazide component of Maxzide is more bioavailable than that of Dyazide this did not translate into enhanced hypotensive efficacy.

Absorption and disposition of a new low-dose combination formulation of hydrochlorothiazide and triamterene

Two studies are reported that assess the bioequivalence of a new half-strength drug combination containing 25 mg hydrochlorothiazide and 37.5 mg triamterene compared to a full-strength formulation containing 50 mg hydrochlorothiazide and 75 mg triamterene. The first study (I) compared the absorption and disposition of the two drugs after administration of two tablets of the half-strength product as a single dose compared to a single dose of the full-strength product. The second study (II) assessed the bioavailability of the new product given as a single tablet on two occasions separated by an interval of 12 h compared to the full-strength product given as a single dose. Urine parameters in the first study indicated bioequivalence of the half-strength to the full product for both rate and extent of absorption. When given in divided doses, the half-strength product demonstrated bioequivalence to the full-strength product for extent of absorption. Additional data from the second study suggest that absorption of triamterene is greater when given in smaller divided doses and when given at night.

Magnesium depletion, diuretics, and arrhythmias

Increasing information on the potentially serious risks of potassium and magnesium depletion associated with diuretic therapy demands a clinical focus on understanding the factors involved and on methods for preventing these electrolyte deficiencies. Data suggest that serum potassium and magnesium levels may be normal in the presence of tissue depletion, but decreases in serum levels are almost always associated with tissue and whole-body depletion of these electrolytes in patients in whom such depletion cannot be risked. Ventricular ectopy has also been associated with depletion of potassium and magnesium, which may explain the increased risk of sudden unexpected death in hypertensive patients. Any clinician who treats hypertension or congestive heart failure must consider whether to replete potassium and magnesium in patients already receiving diuretic therapy, or, better still, consider how to prevent depletion of these electrolytes in patients in whom such depletion cannot be risked. If prevention is selected, the clinician must then evaluate the data on available diuretic combinations for efficacy in electrolyte conservation, bioavailability, and dosage convenience. The combination of triamterene and hydrochlorothiazide (Maxzide, 75 mg triamterene/50 mg hydrochlorothiazide) has demonstrated electrolyte conservation, with bioavailability and dosage convenience.

Outpatient conversion of treatment to potassium-sparing diuretics

Thiazide diuretics frequently cause a decrease in serum potassium levels. In this study, 34 percent of patients taking hydrochlorothiazide had serum potassium levels below 3.5 meq/liter. The response of the serum potassium level was studied after treatment in 56 patients was switched from 50 mg of hydrochlorothiazide daily to either two capsules of hydrochlorothiazide/triampterene (Dyazide), or one tablet of hydrochlorothiazide/amiloride (Moduretic) daily, over nine to 15 months. The 24 patients whose treatment was changed to Dyazide had a rise in serum potassium levels from a mean of 3.56 meq/liter to 4.17 meq/liter in two to three weeks. The 32 patients whose treatment was changed to Moduretic had a rise in serum potassium levels from a mean of 3.76 meq/liter to 4.14 meq/liter in two to three weeks. The resultant rise in potassium levels was stable throughout the follow-up period in both groups. Patient acceptance of this change was excellent.

A new antihypertensive agent: Maxzide (75 mg triamterene/50 mg hydrochlorothiazide)

The combination of potassium-sparing diuretics with hydrochlorothiazide is extensively used by hypertensive patients. In the United States, a capsule formulation containing 50 mg triamterene and 25 mg hydrochlorothiazide (Dyazide) is the most popular fixed-combination product. However, several investigators have confirmed that absorption of both the triamterene and hydrochlorothiazide components of Dyazide is markedly reduced. This reduced bioavailability may reduce its effectiveness in hypertensive patients who change from optimally bioavailable hydrochlorothiazide tablets to Dyazide capsules in an effort to correct hypokalemia. Scored tablets containing 75 mg triamterene/50 mg hydrochlorothiazide (Maxzide) have been developed using a patented parallel granulation manufacturing process and evaluated in a series of bioavailability-bioequivalence studies. The triamterene and hydrochlorothiazide components of Maxzide tablets were found to be as bioavailable as liquid preparations of the active ingredients given singly or in combination. Unlike Dyazide capsules, the hydrochlorothiazide component of Maxzide tablets was found to be absorbed to the same extent as single-entity hydrochlorothiazide tablets. These studies demonstrated that two Dyazide capsules (total of 100 mg triamterene/50 mg hydrochlorothiazide) deliver to the bloodstream approximately one-half the quantity of hydrochlorothiazide as one Maxzide (75 mg triamterene/50 mg hydrochlorothiazide) tablet or one 50 mg hydrochlorothiazide tablet. Similarly, two Dyazide capsules deliver approximately one-half the quantity of triamterene as one Maxzide tablet. The safety of Maxzide tablets (dose of one tablet a day) was then evaluated in three groups of hypertensive patients: those who previously had been given two Dyazide capsules a day, those who had received four Dyazide capsules a day, and newly diagnosed patients who had received no medication. The clinical condition of the patients who changed from two or four Dyazide capsules to one Maxzide tablet was not compromised. Indeed, significant reductions in blood pressures were observed, especially in some patients who had remained hypertensive while receiving Dyazide. As expected, the blood pressures of the previously untreated group also decreased significantly with Maxzide tablets. Clinically significant hyperkalemia or hypokalemia did not develop. There were no clinically significant changes in blood urea nitrogen, creatinine, or uric acid levels. In addition to enhanced bioavailability, Maxzide tablets offer the advantages of once-a-day dosing.

Bioequivalence study of a new tablet formulation of triamterene and hydrochlorothiazide

A three-treatment, single-dose, crossover bioequivalence study was conducted in healthy volunteers to compare urinary drug recovery following administration of hydrochlorothiazide tablets, the currently marketed capsule formulation of triamterene and hydrochlorothiazide (Dyazide), and a new tablet preparation of these active ingredients (Maxzide). No significant differences were observed in the urinary recovery of hydrochlorothiazide after the administration of hydrochlorothiazide tablets and Maxzide tablets. However, only about one-half as much hydrochlorothiazide was recovered following the administration of Dyazide capsules. Similarly, the urinary recovery of triamterene and the sulfate ester of hydroxy-triamterene after administration of Dyazide capsules was approximately one-half the levels observed after giving the new tablet formulation. The clinical consequences of the limited bioavailability of the active ingredients of Dyazide are discussed.