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Biomedical subjects

N A Mason

Publications and source records attributed to N A Mason.

29 records · Page 2Linked to original sources
PubMed1992

Consumer vinegar test for determining calcium disintegration.

A consumer test and standardized methods were compared for measuring the disintegration of calcium tablets, and the disintegration results were compared with results of dissolution testing to determine the ability of the consumer test of disintegration to predict bioavailability of calcium. Disintegration of 17 calcium supplement products, in tablet form, was studied in Simulated Gastric Fluid Test Solution, USP, without pepsin (GF), in distilled water, and in white distilled vinegar. For disintegration testing with GF and with distilled water, six tablets of each product were placed in an apparatus and immersed in the solution at 37 degrees C for 60 minutes. Six tablets of each product were tested in 200 mL of vinegar at room temperature for 30 minutes. Disintegration was determined by visual observation. Seven products were tested for dissolution in GF or water. Three samples of each product were tested at intervals over 120 minutes for calcium content. Results of testing with an ion-selective electrode were converted to milligrams and compared with the calcium content of the tablets (as claimed on the package label). The mean disintegration times of various calcium products in vinegar ranged from 1.8 to greater than 30 minutes. The mean time in distilled water and GF ranged from 1.6 to greater than 60 minutes and from 1.0 to greater than 60 minutes, respectively. Results were in agreement in 87% to 93% of cases between the consumer vinegar test and the standardized disintegration test methods, a significant correlation. No correlation was found between disintegration time and the extent of dissolution. The disintegration and dissolution of commercially available calcium tablets was highly variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1992

Systemic absorption of intraperitoneal antimicrobials in continuous ambulatory peritoneal dialysis.

The factors that influence drug movement across the peritoneum are presented, and the feasibility of administering antimicrobials intraperitoneally to treat systemic infections in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) is explored. Antimicrobials are often administered intraperitoneally to treat peritonitis in patients undergoing CAPD. It would be advantageous to administer antimicrobials by the same route to treat systemic infections as well. Factors that determine the propensity of a drug to cross the peritoneal membrane include molecular weight, protein binding, volume of distribution, ionic charge, water or lipid solubility, the permeability and surface area of the peritoneum, blood flow rate, dialysate dwell time, and the concentration of dextrose in the dialysate. The bioavailability of i.p. drugs has been determined (1) by measuring the area under the plasma concentration-time curve (AUC) of an i.p. dose and comparing it with the AUC of the same dose given i.v. and (2) by estimating the residual drug content in the dialysate after a specified dwell period. Pharmacokinetic studies show that the bioavailabilities of antimicrobials given intraperitoneally in patients undergoing CAPD range from 50% to 92%. Vancomycin has been the agent most widely studied. Serum antimicrobial concentrations achieved by this route of administration are in many cases similar to those accomplished by the i.v. route and within the therapeutic range. Dosage regimens based on the pharmacokinetic data have been suggested; however, their efficacy has not been formally documented. The intraperitoneal route may have a role in the treatment of systemic infections in peritoneal dialysis patients, but specific recommendations cannot be made until clinical studies have been performed.

Absorption↗
PubMed1991

Alternative work schedules for female pharmacists.

The impact of the increased proportion of women in pharmacy is discussed, and two leadership positions for which part-time work schedules were implemented are described. Issues associated with the increased representation of women include pharmacist shortages, loss of future leaders, decreased staff productivity related to inadequate day-care services, and a reduced earning potential of pharmacists. Many of these problems can be addressed by altering benefit packages and work schedules to enable employees to raise children while continuing to work. Specific strategies include legislation, day-care programs, flex time and flex scheduling, telecommuting, and the creation of alternative work schedules or permanent part-time positions. At the University of Michigan, a part-time position that combines faculty and clinical responsibilities has been in place since 1988. At The Washington Hospital Center, one of the three assistant director of pharmacy positions is part-time. The women in both positions have met or exceeded job performance requirements while raising a family. Issues raised by the increasing number of female pharmacists must be addressed by the profession. Part-time work schedules are one strategy for enabling female pharmacists to meet both their family and career responsibilities.

District of Columbia↗
PubMed1990

Angiotensin-converting enzyme inhibitors and renal function.

The effects of angiotensin-converting enzyme (ACE) inhibitors on renal hemodynamics vary widely depending on the preexisting physiologic and pathologic state of the kidneys. Although some studies of ACE inhibitors in primary essential hypertension have demonstrated increases in glomerular filtration rate (GFR) and effective renal plasma flow in patients with renal impairment, other studies have not shown these same beneficial results. The difference may involve the choice of ACE inhibitor used in the investigations, but controlled comparison trials are needed to determine whether this is the case. The use of ACE inhibitors in renovascular hypertension remains controversial. ACE inhibition can interfere with the autoregulation of GFR mediated by angiotensin II and may lead to deterioration of renal function, especially in patients with bilateral renal artery stenosis or stenosis of a solitary kidney. Additionally, ACE inhibitors have been shown to cause a decline in GFR in the kidney affected by the stenosis, whether or not clinically apparent renal insufficiency occurs. Although the functional impairment associated with ACE inhibitors in renal artery stenosis has generally been reversible following removal of the drug, the consequences of a long-term reduction in GFR are unknown. Treatment of stable congestive heart failure (CHF) with ACE inhibitors can result in enhancement of GFR and reduction of sodium and fluid retention, thus improving the clinical state. However, in patients with decompensated cardiac failure, renal perfusion pressures may already be at or near the autoregulatory breakpoint and ACE inhibition may cause deterioration of renal function. In general, ACE inhibitors can be used safely in CHF if they are initiated cautiously, with adjustment of ACE inhibitor and diuretic dosages to avoid systemic hypotension and sodium and fluid depletion. In studies comparing the agents, enalapril and lisinopril have both been shown to cause higher incidences of renal function deterioration than has captopril. These findings suggest that the more complete or sustained ACE inhibition seen with the longer-acting agents may be detrimental to renal function in patients with CHF. The use of ACE inhibitors in the treatment of proteinuria is the newest area of research with these agents. At present it appears that ACE inhibitors reduce urinary protein excretion the most effectively in diabetic patients with mild proteinuria and in hypertensive patients with renal insufficiency and proteinuria due to glomerular disorders. More study is needed to determine whether these agents can reduce the rate of renal failure progression and to define the patient populations expected to benefit most.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

Disulfiram-induced hepatitis: case report and review of the literature.

A case of hepatitis is reported in a 38-year-old alcoholic woman taking disulfiram to aid in maintaining sobriety. She presented with anorexia, vomiting, fatigue, right upper-quadrant pain, pruritus, darkened urine, and jaundice after about two weeks of disulfiram 500 mg/d. The patient also had been taking enalapril 10 mg/d for one year. Hepatocellular enzymes, total bilirubin, and eosinophils were significantly elevated. Hepatitis B core antibody, hepatitis A antibody, hepatitis B surface antibody, and antinuclear antibody were negative. After discontinuation of disulfiram, the clinical and biochemical manifestations of hepatitis began to resolve and the patient was discharged in a much improved condition. Seventeen previous cases of disulfiram-induced hepatitis are reviewed. It has been suggested that the mechanism of hepatotoxicity is an allergic or hypersensitivity reaction. The findings in this case are consistent with the earlier descriptions of hypersensitivity hepatitis, and lend further support to the possibility that disulfiram may cause hepatitis.

Adult↗
PubMed1984

Justifying additional pharmacist staff in an era of cost reductions.

A proposal is described that justified adding one full-time equivalent (FTE) pharmacist in a 125-bed community hospital that already employed in its pharmacy department 2.5 FTE pharmacists and 5.2 FTE other personnel. The administrative steps taken included identifying the need for an additional staff member and documenting the cost effectiveness of various clinical activities. Literature references were used to justify the proposed ratio of pharmacists to technicians; to show the results of deficiencies in supervision, motivation, and scheduling; and to demonstrate the cost effectiveness of serum concentration monitoring, formulary review, and patient discharge-medication consultations. Results of formulary review, drug-use audits, dosing guidelines, and serum concentration monitoring performed by the pharmacy department were included in the proposal. Prospective drug-use reviews, computerized pharmacokinetic dose determinations, additional educational programs, and tighter purchasing policies were identified as other cost-saving activities that could be performed with an additional pharmacist. A 12-page proposal was submitted in July 1983 to the hospital administrator and the budget review committee, and the additional staff position was approved. The key to maintaining the new pharmacist position will be the continual documentation of cost-saving activities within the department.

Budgets↗
PubMed1981

Factors affecting diazepam infusion: solubility, administration-set composition, and flow rate.

The sorption of diazepam in large-volume i.v. admixtures to administration-set components and in i.v. containers was analyzed quantitatively. Solubility of diazepam in phosphate buffer at various pH levels and in i.v. fluids was measured. Partition coefficients of diazepam into components of i.v. administration sets and i.v. containers were studied by shaking a solution of diazepam in 0.9% sodium chloride, with finely cut components and measuring the change in diazepam in the aqueous phase. Flow studies through an administration set of a 0.04-mg/ml diazepam solution in 5% dextrose injection were done, varying both the flow rate and the length of tubing. The maximum free-base solubility of diazepam in phosphate buffer was 0.048 mg/ml; its solubility was 0.058, 0.050, and 0.064 mg/ml in lactated Ringer's, 0.9% sodium chloride, and 5% dextrose injections, respectively. Equilibrium partition coefficients were highest for polyvinyl chloride tubing and flexible bags. Volume-control sets made of cellulose propionate had lower but sufficiently large partition coefficients to cause diazepam loss. Polyolefin semi-rigid and glass containers had low partition coefficients. In the flow studies, the amount of solution-contact time correlated with the extent of absorption. As flow rate decreased or tubing length increased, the amount of diazepam absorbed increased proportionately. A nomogram and a predictive dosing chart are presented for calculation of actual diazepam doses delivered at various flow rates and tubing lengths. Diazepam can be administered safely and effectively by i.v. infusion. The use of volume-control sets and flexible polyvinyl chloride bags should be avoided with diazepam solutions. Polyolefin semi-rigid containers are acceptable alternatives to glass. The concentration of diazepam infusions should not exceed 0.04 mg/ml.

Absorption↗
PubMedDate not supplied

Calcitriol in the management of secondary hyperparathyroidism of renal failure.

Secondary hyperparathyroidism (HPT) is characterized by persistent hypersecretion of parathyroid hormone (PTH), and produces characteristics of hyperparathyroid bone disease and a variety of biochemical and hormonal derangements. Management of uremic secondary HPT involves both prevention and treatment. Among preventive measures are attempts to control serum phosphate and serum calcium concentrations through dietary restriction, administration of phosphate binders, and calcium supplementation. Treatment with a vitamin D analog such as calcitriol returns plasma calcium concentrations toward normal and suppresses PTH secretion. The availability of a parenteral formulation of calcitriol, and new information regarding alternative routes of administration and regimens employing oral pulse dosing have renewed interest in calcitriol for the management of uremic secondary HPT.

Administration, Oral↗