Prazosin update. A review of its pharmacological properties and therapeutic use in hypertension and congestive heart failure.

Prazosin is an orally active post-synaptic selective alpha 1-adrenoreceptor antagonist that has been widely used in treating hypertension and congestive heart failure (CHF). Its role in the treatment of hypertension has previously been reviewed in this journal. Subsequent reports confirm its efficacy in treating mild to severe hypertension as a single agent or, more frequently, in combination with another antihypertensive agent and/or a diuretic. Recent studies of the metabolic effect of prazosin indicate that the drug may have a favourable effect on plasma lipids in hypertensive patients. Its recent use in treatment of congestive heart failure has shown prazosin to be comparable with nitroprusside in producing balanced arterial and venous dilation with generally sustained haemodynamic and clinical effects during long term therapy. Initial studies in Raynaud's phenomenon and in patients with aortic regurgitation or aortic stenosis or with mitral regurgitation are promising, but require confirmation from wider clinical experience. The drug has generally been well tolerated. The primary side effect of orthostatic hypotension can be largely avoided by beginning treatment with a low dose.

Total parenteral nutrition. A brief review.

The ideal solution for total parenteral nutrition (TPN) should contain nutrients equivalent to those of a well balanced, oral diet. With that goal in mind, available solutions usually provide adult patients with approximately 3,000 ml. solution daily, which supply about 12 gm. nitrogen and 2,400 kcal, with vitamins and minerals added as required. (Infants require relatively greater amounts of fluids and calories per kilogram.) The most critical concern in TPN is that of fluid and electrolyte balance, which varies with the patient. In this paper, the composition of four commercial TPN solutions is tabulated, as are recommendations for trace elements and vitamins which should be included.

Oxygen solubilization by lung surfactant.

To illustrate the concept of solubilization as a possible mode of gas transport in biological systems, dog lung surfactants in varying concentrations were tested for their ability to solubilize oxygen. The degree of gas solubilization was determined by GC, using a modified tonometer as an absorption chamber. The concentration of surfactant was found to be an essential factor for gas solubilization. Surfactant concentration above the CMC yielded anomalously high gas absorption. Solubilization of the gas is thought to occur by a partitioning effect into the interior of surfactant micelles.

Survey of potential drug interaction incidence in an outpatient clinic population.

A study was conducted at a large VA outpatient facility to determine the total number of potential drug interactions resulting from outpatient clinic prescribing. Interactions classified as of moderate or major clinical significance were tabulated. No attempt was made to ascertain whether patients taking digoxin and a thiazide diuretic without a potassium supplement were having their serum potassium levels monitored or if patients had been instructed to space their antacid dosages away from potential reacting drugs. Of the 3028 patients studied, 710 received drugs which had the potential to interact. A dramatic increase of potential interactions was seen as the number of prescriptions received per patient increased. Drug combinations which had potential for interaction and frequency of prescription are listed.

Dealing with DRGs: analysis of serum theophylline assays in Medicare patients.

To investigate the therapeutic and economic implications of serum theophylline assay (STA) use in Medicare patients classified in diagnosis-related group 88 as having chronic obstructive pulmonary disease, a retrospective audit was conducted of all serum theophylline assays ordered for these patients in a large teaching hospital during a 6-month period. Based on established pharmacokinetic principles of theophylline therapy, analysis was conducted on rational indication for assay use (n = 146), correct sampling procedure regarding steady-state and peak/trough concentrations (n = 99), and appropriateness of physician response (n = 100). Percentages of appropriate use found for these three parameters were 79.2%, 56.6%, and 85.0%, respectively. Overall compliance regarding all three considerations was 52.1%; this figure declined to 29.9% when admission level assays were excluded from consideration. A need is identified to improve STA sampling procedures in order to insure availability of accurate and valid results on which to make indicated changes in drug therapy.

Analysis of hydroxyzine hydrochloride, meperidine hydrochloride and atropine sulfate in glass and plastic syringes.

The apparent stability of combinations of hydroxyzine hydrochloride and meperidine hydrochloride (50 mg/2 ml each) and of these two drugs (50 mg/2.5 ml each) and atropine sulfate (0.4 mg/2.5 ml) in prefilled glass and plastic syringes was studied. Syringes (3 ml) containing the combinations were stored at 25 C and 3 C for 10 days and analyzed at specific time intervals. Absorption spectra, chromatographic characteristics and pH were determined in addition to visual inspection. Results of these qualitative tests indicated that the mixtures apparently were stable for 10 days at room temperature or when refrigerated. No differences were found between solutions stored in glass and those stored in plastic syringes. Degradation of the syringe contents or appearance of additional constituents was not detected in any of the admixtures, and they were considered to be chemically compatible within the limitations of the study. The study suggests that storage of these combinations in syringes is feasible but the results cannot be extrapolated to drug solutions or syringes other than those studied.

Self-care habits and disease-state understanding of diabetic patients.

Diabetic patients who had never participated in a formal diabetes education program were surveyed to assess their self-care patterns and knowledge of diabetes. A sample of 142 men was selected from the diabetes clinic of a VA hospital. Patients were interviewed, a questionnaire was given to the insulin-dependent patients, and medical records were reviewed to determine concurrent use of antidiabetic medications and other drugs. The majority of patients (91%) were aware of the effects of alcohol, glucose rich foods, and lack of medication on diabetic control. However, 42% of the patients were aware of the effects of excessive exercise, and only 52% were aware of the effects of omitting meals. The most frequently cited problems involved factors of dietary control such as the use of food measurements, exchange lists, and caloric allotments. Patient knowledge of urine testing techniques was greater than knowledge of other areas. Only 24% of the patients knew the symptoms of hyperglycemia. The importance of foot care was understood by 44% of the patients, but only 13% knew how to remove corns and calluses correctly. The results of the supplemental questionnaire showed that the lowest levels of knowledge concerned insulin measurement and conversions. The appropriate aseptic procedures were known by the majority of the patients, and the time of insulin administration was understood by 97%. Medical records revealed that 23 patients were taking thiazides concurrently with their antidiabetic medication. An inverse relationship was found between age and knowledge scores, and a direct relationship was found between educational level and knowledge scores. These results should be useful in developing educational programs for diabetic patients.

Current approaches to management of potassium deficiency.

Current issues related to oral potassium supplementation are reviewed, with emphasis on recommendations for the appropriate use of potassium supplementation for both replacement and preventive therapy. Dietary potassium intake, potassium-sparing diuretics, and the various forms of oral potassium supplements are reviewed in terms of indications for use, advantages, and limitations. Attention is given to controversial areas, i.e., gastrointestinal tolerance of controlled-release potassium oral dosage preparations and the need for potassium supplementation in hypertensive patients treated with diuretics.

Detection of particles in intravenous fluids using scanning electron microscopy.

A study was conducted to compare the particles in intravenous solutions found in glass and plastic containers, and to investigate the use of scanning electron microscopy in detecting and identifying such particulate contamination. The method used was to filter one liter of each fluid from glass and plastic containers through a membrane filter, attach the membrane to aluminum studs and coat the specimens with a thin layer of gold-palladium in a vacuum evaporator. Scanning electron microscopy was then used to examine the specimens, and photomicrographs were prepared. The results showed that the particles found in glass and in plastic containers have distinctive differences and that scanning electron microscopy is useful in detecting and characterizing these particles.

Physicochemical stability of a preanesthetic mixture of hydroxyzine hydrochloride and atropine sulfate.

The stability of a combination of hydroxyzine hydrochloride and atropine sulfate stored in syringes was studied. Syringes containing the two drugs were stored at 25 C and 3 C for ten days and analyzed at specific time intervals. Absorption spectra, chromatographic characteristics and pH were determined. Results showed the admixture to be stable for ten days at room temperature or under refrigeration. The technique used would probably not detect any significant degradation of atropine sulfate unless the reaction occurred with the hydroxyzine hydrochloride.