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W G Byerly

Publications and source records attributed to W G Byerly.

16 recordsLinked to original sources
PubMed1991

Verapamil in the treatment of maternal paroxysmal supraventricular tachycardia.

Paroxysmal supraventricular tachycardia (PSVT) is seen somewhat frequently in the emergency department but less frequently during pregnancy. Although verapamil is widely used as the drug of choice for PSVT with a narrow QRS complex in a hemodynamically stable patient, the acute IV use of verapamil during pregnancy has not been well studied. Only a limited number of case reports document its safety and efficacy in the treatment of maternal or fetal PSVT. In general, the use of medication during pregnancy requires careful assessment of both the maternal and fetal risks versus benefits and documentation of patient consent. Because it crosses the placenta, one of the major concerns with the acute use of IV verapamil centers around the drug's potential effect on fetal heart rate. The case we present describes the occurrence of PSVT on two separate occasions in a woman in the third trimester of pregnancy. In both episodes, as much as 10 mg IV verapamil was given with resulting successful conversion to normal sinus rhythm. Fetal heart monitoring during drug administration failed to show significant change in fetal heart rate.

Adult↗
PubMed1990

Angiotensin-converting enzyme inhibitors: a comparative review.

The chemistry, pharmacology, pharmacokinetics, adverse effects, and dosages of the three currently available angiotensin-converting enzyme (ACE) inhibitors are reviewed. This class of agents effectively inhibits the conversion of angiotensin I to the active vasoconstrictor angiotensin II, a hormone that also promotes, via aldosterone stimulation, increased sodium and water retention. The ACE inhibitors, therefore, are capable of lowering blood pressure primarily by promoting vasodilatation and reducing intravascular fluid volume. Captopril, the first orally active, commercially available ACE inhibitor, is a sulfhydryl-containing compound. Captopril was followed by the introduction of enalapril and lisinopril, two non-sulfhydryl ACE inhibitors. The pharmacokinetic profiles of these three ACE inhibitors differ. Captopril has rapid onset with relatively short duration of action, whereas enalapril and lisinopril have slower onset and relatively long duration of action. Captopril is an active ACE inhibitor in its orally absorbable parent form. In contrast, enalapril must be deesterified in the liver to the metabolite enalaprilat in order to inhibit the converting enzyme; this accounts for its delayed onset of action. Lisinopril does not require metabolic activation to be effective; however, a slow and incomplete absorption pattern explains the delay in onset of activity. Captopril and its disulfide metabolites are primarily excreted in the urine with minor elimination in the feces. Approximately two-thirds of an administered enalapril dose is excreted in the urine as both the parent drug and the metabolite enalaprilat; the remainder of these two substances are excreted in the feces. Lisinopril does not undergo measurable metabolism and approximately one-third is excreted unchanged in the urine with the remaining parent drug being excreted in the feces. The ACE inhibitors lower systemic vascular resistance with a resultant decrease in blood pressure. Their efficacy is comparable to diuretics and beta-blockers in treating patients with mild, moderate, or severe essential and renovascular hypertension. In those patients with severe congestive heart failure (CHF) the ACE inhibitors produce a reduction in systemic vascular resistance, blood pressure, pulmonary capillary wedge pressure, and pulmonary artery pressure. These drugs may produce improvement in cardiac output and stroke volume and, with chronic administration, may promote regression of left ventricular hypertrophy. The antihypertensive effects of the ACE inhibitors are enhanced when these agents are combined with a diuretic. Captopril and enalapril have been shown to be of particular benefits as adjunctive therapy in patients with congestive heart failure, both in terms of subjective improvement of patient symptoms, and in improving overall hemodynamic status.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

To be an Army Doc.

Explore the source record for details and available documents.

Career Choice↗
PubMed1988

Comparative dissolution performance of internationally available piroxicam products.

Piroxicam is a widely used nonsteroidal antiinflammatory drug available worldwide under various trade names by several manufacturers. Only one brand of piroxicam (Feldene) is currently marketed in the U.S., and the United States Pharmacopeial Convention established an official dissolution requirement for piroxicam in 1985. The purpose of this study was to evaluate and compare the dissolution performance of several internationally available piroxicam products using the United States Pharmacopeia (USP) dissolution test for piroxicam capsules. Of 25 brands of piroxicam capsules evaluated, 72 percent of the brands failed to meet the USP requirement, several by a wide margin. Although there is no specific USP dissolution test for tablets, the test for capsules was applied to five different brands of piroxicam tablets, and 80 percent of the tablet brands tested failed to meet the USP requirement. Although comparative bioavailability studies would be required to establish any definitive relationship between dissolution test performance and bioavailability, the failure of most of these products to meet the USP requirement for dissolution indicates formulation differences that could result in altered bioavailability. The substantial differences in dissolution performance observed among the piroxicam oral dosage forms tested have implications concerning the equivalency and standards of multisource products available on the international market, and should be taken into account by health care providers worldwide.

Biological Availability↗
PubMed1986

Determination of bioequivalence of psychotropic drugs and concerns involving product interchange.

There is a growing debate among researchers and practitioners concerning the validity of the Food and Drug Administration (FDA) standards for establishing generic interchange through assignment of "therapeutically equivalent" designations for noninnovator or generic drugs. This debate has particular significance for psychotropic drugs which are used in the management of patients with severely debilitating mental diseases. Thus, the controversy primarily focuses on the appropriateness of using the FDA's therapeutic equivalence designation as a criterion for interchange. This is particularly important in light of the lack of well-defined standards for bioequivalence studies and in view of the effect of mandatory substitution laws and financial incentives that encourage generic dispensing that can lead to frequent and indiscriminate interchange among multiple generic brands. Specific concerns include the validity of assay techniques for drug in biologic fluids, statistical power analysis, the appropriateness of the "70/70 rule," and the relevance of studies carried out in healthy normal volunteers in the determination of bioequivalence.

Antipsychotic Agents↗