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Biomedical subjects

E G Boyce

Publications and source records attributed to E G Boyce.

17 recordsLinked to original sources
PubMed2001

Sildenafil citrate: a therapeutic update.

BACKGROUND: Since its approval by the US Food and Drug Administration in March 1998, sildenafil citrate has been used by millions of men for the treatment of erectile dysfunction. Recent studies and consensus reports have expanded our understanding of its efficacy, safety, contraindications, and drug interactions. OBJECTIVE: This paper reviews recent studies of the efficacy of sildenafil, its adverse effects and drug interactions, and socioeconomic factors involved in its use, with a focus on specific patient populations (prostate cancer, diabetes mellitus, ischemic heart disease, spinal cord injuries, neurologic disorders). METHODS: Clinical studies, case reports, and commentaries and editorials concerning sildenafil published in the international literature between January 1999 and August 2000 were identified through searches of MEDLINE, PREMEDLINE, and International Pharmaceutical Abstracts, using the terms sildenafil, Viagra, and erectile dysfunction. RESULTS: Sildenafil has demonstrated effectiveness in men with erectile dysfunction associated with prostatectomy, radiation therapy, diabetes mellitus, certain neurologic disorders, and drug therapy (eg, selective serotonin reuptake inhibitors [SSRIs]). It has not been as effective in women with sexual dysfunction, with the exception of SSRI-associated sexual dysfunction. Some disorders unrelated to sexual dysfunction (eg, esophageal motility dysfunction) may also respond to sildenafil. In the general population, sildenafil is considered to have an acceptable tolerability profile; however, patients with moderate to severe cardiovascular disease or those taking nitrate therapy are at increased risk for potentially serious cardiovascular adverse effects with sildenafil therapy. In addition, patients taking drugs that inhibit the cytochrome P450 3A4 isozyme, which metabolizes sildenafil, may experience increased drug concentrations and possible toxicity from normal doses of sildenafil. CONCLUSIONS: Sildenafil is an effective first-line therapy for erectile dysfunction in men. The decision to prescribe this agent should include such considerations as the cost-risk-benefit balance, patient access, drug distribution pathways, and prescription drug coverage.

Drug Interactions↗
PubMed2001

Risedronate: a new oral bisphosphonate.

BACKGROUND: Bisphosphonates have been effective in the treatment of osteoporosis and Paget's disease of bone. Risedronate, the newest oral bisphosphonate, is approved by the US Food and Drug Administration for the prevention and treatment of postmenopausal osteoporosis and glucocorticoid-induced osteoporosis and the treatment of Paget's disease of bone. OBJECTIVE: This article reviews current studies of risedronate in osteoporosis and Paget's disease of bone and, to the extent possible, compares risedronate with other bisphosphonates and other therapies. Information on the pharmacokinetics and adverse effects of risedronate, and the drug's use in other disorders, is also reviewed. METHODS: Clinical studies and review articles concerning the use of risedronate published in the English-language literature from 1966 through October 2000 were identified through searches of MEDLINE, PREMEDLINE, and International Pharmaceutical Abstracts using the search terms risedronate and NE 58095. Recent clinical studies, review articles, and consensus statements regarding the use of other bisphosphonates were identified through searches of the same databases for this period using the search terms bisphosphonates, alendronate, osteoporosis, and Paget's disease of bone. RESULTS: The use of risedronate therapy in patients with postmenopausal osteoporosis has been shown to increase bone mineral density (BMD) and decrease the incidence of fractures compared with placebo. In glucocorticoid-induced osteoporosis, risedronate has been shown to increase BMD without having a consistently significant effect on the risk of fractures. Although there are no direct comparisons between bisphosphonates in glucocorticoid-induced osteoporosis, risedronate appears to be less effective than alendronate and more effective than etidronate in terms of effects on BMD and/or fracture risk. In Paget's disease of bone, risedronate has been reported to be more effective than etidronate in decreasing serum alkaline phosphatase levels and bone pain. Finally, risedronate has been associated with a lower incidence of gastric ulcers than alendronate. CONCLUSIONS: In terms of efficacy in the prevention and treatment of osteoporosis and the treatment of Paget's disease of bone, risedronate is comparable to alendronate, the other orally available bisphosphonate. It appears to have better gastrointestinal tolerability than alendronate and may be preferred for patients in whom this is a concern. However, direct comparative and pharmacoeconomic studies are necessary to determine risedronate's relative place in the therapy of osteoporosis and Paget's disease of bone.

Administration, Oral↗
PubMed1999

The impact of estrogen replacement therapy and raloxifene on osteoporosis, cardiovascular disease, and gynecologic cancers.

OBJECTIVE: To compare the clinical utility of estrogen replacement therapy (ERT) and raloxifene in osteoporosis and cardiovascular disease in postmenopausal women and to evaluate the contrasting adverse effects of these therapies. DATA SOURCES: A MEDLINE search was performed for January 1980 through September 1998 using the key terms raloxifene, estrogen, CVD, lipoproteins, and osteoporosis. STUDY SELECTION AND DATA EXTRACTION: All clinical studies assessing ERT and raloxifene in cardiovascular disease or osteoporosis were evaluated. DATA SYNTHESIS: ERT remains the standard for prevention and treatment of osteoporosis in women. Its use increases total bone mineral density (BMD) up to 12.1% and reduces hip fracture risk by 66-73%. It reduces low-density lipoprotein (LDL) cholesterol by 15-19% and increases high-density lipoprotein (HDL) cholesterol by 6-18%. Raloxifene, an alternative to ERT in the prevention of osteoporosis, increases total BMD by 2.2%. It reduces LDL by 6.2-14.1% and increases HDL by 1.5-5.7%. Preliminary data suggest that raloxifene has contrasting effects on gynecologic cancers compared with the increased risk posed by ERT. CONCLUSIONS: Clinical trials have illustrated greater effects on BMD with ERT than with raloxifene. Studies of significant duration assessing raloxifene and its fracture risk effects are lacking. ERT appears to have greater beneficial cardiovascular risk factor effects than raloxifene. Prospective, primary prevention studies evaluating overall cardiovascular risk reduction do not exist for either intervention. Raloxifene, while more costly, is an alternative that may have a lower associated risk of breast cancer compared with ERT.

Aged↗
PubMed1999

Potential risk factors associated with thrombocytopenia in a surgical intensive care unit.

We conducted a retrospective chart review of 193 patients admitted during a 3-month period to determine the frequency of and potential risk factors associated with thrombocytopenia, and the association of acquired thrombocytopenia with length of stay in a surgical-trauma intensive care unit (SICU) and mortality. All records were reviewed beginning 24 hours after admission. Patients were followed for the duration of SICU stay or until death. Data collected and analyzed as potential risk factors for thrombocytopenia were age, gender, admitting diagnosis, classification (trauma, surgical, medical), APACHE II score, medical history, all scheduled drugs with start and stop dates, select laboratory values, arterial or central line placement, and complications. Thrombocytopenia occurred in 25 (13%) patients. These patients were more likely (p<0.05) than those without thrombocytopenia to have the following potential risk factors: presence of a central or arterial line (76% vs 46%, p<0.025), nonsurgical diagnosis (60% vs 37%, p<0.05), diagnosis of sepsis (p<0.001), and administration of phenytoin (p<0.01), piperacillin (p<0.005), imipenem-cilastatin (p<0.001), and vancomycin (p<0.005). A longer SICU stay (mean 21 vs 4.5 days, p<0.05) and increased mortality (16% vs 4%, p<0.05) were significantly associated with thrombocytopenia. Cefazolin administration was significantly associated with nonthrombocytopenia (p<0.05). Factors not associated with thrombocytopenia were age, gender, and administration of histamine2-receptor antagonists, heparin, enoxaparin, penicillins, ceftazidime, ceftriaxone, chloramphenicol, and amphotericin B. A central or arterial line was the only factor associated with the development of thrombocytopenia in a multiple linear regression analysis (p=0.0003, multiple r=0.2580). Thrombocytopenia is not a common occurrence in the SICU, but is associated with a longer SICU stay and increased mortality.

Adolescent↗
PubMed1998

Predictive performance of ten equations for estimating creatinine clearance in cardiac patients. Iohexol Cooperative Study Group.

OBJECTIVE: The predictive performance of 10 equations used to estimate creatinine clearance (Clcr) was assessed retrospectively from data collected on 420 patients. DESIGN: This study is a retrospective data analysis of information collected on hemodynamically stable patients awaiting coronary angiography during the Iohexol Cooperative Study. SETTING: The Iohexol Cooperative Study was a multicenter study that compared nephrotoxicity of high- and low-osmolar contrast media in patients undergoing coronary angiography. Data used for this analysis were preangiography 24-hour urine collections that were primarily collected in hospitalized patients. PATIENTS: Patients selected from the Iohexol Cooperative Study database for analysis were participants categorized into one or more of six subgroups: elderly (n = 222), hypoalbuminemic (n = 25), chronic renal insufficiency (n = 128), low serum creatinine (n = 115), obese (n = 208), and diabetic (n = 191) who had baseline urine collections of at least 24 hours. OUTCOME MEASURES: Predictive performance was assessed using bias, precision, slopes, and y-intercepts. RESULTS: The Salazar-Corcoran equation was unbiased in the entire group as well as in five of the subgroups. The Cockcroft-Gault equation was unbiased in three of the subgroups. All other equations were biased in predicting Clcr in the entire group as well as in at least four of the subgroups. Precision was generally poor. All slopes were significantly different than one and all y-intercepts were significantly different than zero (p < 0.01). Correlation coefficients were between 0.63 and 0.79 with the exceptions of the low serum creatinine subgroup (r values 0.35-0.64) and the Davis-Chandler equation (r values 0.35-0.71 across groups). CONCLUSIONS: Of the equations studied, Salazar-Corcoran and Cockcroft-Gault appear to be the best for predicting Clcr.

Aged↗
PubMed1994

Treatment of rheumatoid arthritis with blackcurrant seed oil.

The objective of this study was to assess the clinical efficacy and side effects of blackcurrant seed oil (BCSO), in a randomized, double-blind, placebo controlled, 24-week trial in patients with RA and active synovitis. BCSO is rich in gammalinolenic acid (GLA) and alphalinolenic acid (ALA). Both GLA and eicosapentaenoic acid which derives from ALA suppress inflammation and joint tissue injury in animal models. Treatment with BCSO resulted in reduction in signs and symptoms of disease activity in patients with RA (P < 0.05). In contrast, patients given a placebo showed no change in disease. Overall clinical responses (significant change in four measures) were no better in the treatment group than in the placebo group. No patients withdrew from BCSO treatment because of adverse reactions. However, many patients withdrew because BCSO and its placebo had to be administered in 15 large capsules daily. Nonetheless, the study indicates that BCSO is a potentially effective treatment for active RA. However, means must be found to reduce the size and number of capsules taken, so that larger studies of longer duration in RA patients can be done.

Adult↗
PubMed1993

Treatment of rheumatoid arthritis with gammalinolenic acid.

OBJECTIVE: To assess the clinical efficacy and side effects of gammalinolenic acid, a plant-seed-derived essential fatty acid that suppresses inflammation and joint tissue injury in animal models. DESIGN: A randomized, double-blind, placebo-controlled, 24-week trial. SETTING: Rheumatology clinic of a university hospital. PATIENTS: Thirty-seven patients with rheumatoid arthritis and active synovitis. INTERVENTION: Treatment with 1.4 g/d gammalinolenic acid in borage seed oil or cotton seed oil (placebo). MEASUREMENTS: Physicians' and patients' global assessment of disease activity; joint tenderness, joint swelling, morning stiffness, grip strength, and ability to do daily activities. RESULTS: Treatment with gammalinolenic acid resulted in clinically important reduction in the signs and symptoms of disease activity in patients with rheumatoid arthritis (P < 0.05). In contrast, patients given a placebo showed no change or showed worsening of disease. Gammalinolenic acid reduced the number of tender joints by 36%, the tender joint score by 45%, swollen joint count by 28%, and the swollen joint score by 41%, whereas the placebo group did not show significant improvement in any measure. Overall clinical responses (significant change in four measures) were also better in the treatment group (P < 0.05). No patients withdrew from gammalinolenic acid treatment because of adverse reactions. CONCLUSION: Gammalinolenic acid in doses used in this study is a well-tolerated and effective treatment for active rheumatoid arthritis. Gammalinolenic acid is available worldwide as a component of evening primrose and borage seed oils. It is usually taken in far lower doses than used in this trial. It is not approved in the United States for the treatment of any condition and should not be viewed as therapy for any disease. Further controlled studies of its use in rheumatoid arthritis are warranted.

Adult↗
PubMed1990

Persistent metronidazole-induced peripheral neuropathy.

We report the case of a young woman with Crohn's disease who developed a debilitating peripheral neuropathy when treated with metronidazole 2000 mg/d for 50 days. The patient's neuropathy improved considerably after the discontinuation of metronidazole, but still persists two years later. The current literature on this topic is reviewed. Reports such as this one underscore the need to closely monitor the neurologic status of patients undergoing chronic treatment with metronidazole.

Adult↗
PubMed1989

Comparison of gentamicin immunoassays using univariate and multivariate analyses.

Gentamicin concentrations, pharmacokinetic parameters, and calculated doses from enzyme multiplied immunoassay (EMI) and fluorescence polarization immunoassay (FPIA) were compared in 79 samples from 39 patients. Associations between patient factors and the differences between assay results were also assessed. Concentrations were lower when measured by EMI than by FPIA in 71 of the 79 samples (p less than 0.001). Mean EMI values for elimination rate constant, volume of distribution, clearance, dose, and daily dose were 10-20% higher than mean FPIA values (p less than or equal to 0.01). Dosing intervals calculated from EMI and FPIA data were different in 20 pairs of intervals and varied depending on the length of calculated interval. Univariate and multivariate analyses revealed that renal function and the presence or absence of cardiovascular disease, cimetidine, or ranitidine, and heparin were related to differences between the assay results. EMI and FPIA yielded different results for gentamicin concentrations, pharmacokinetic parameters, and calculated daily doses in the clinical setting. Such differences could result in toxic or subtherapeutic doses being administered and may be related, in part, to various patient factors.

Adult↗
PubMed1988

Simulated effect of gentamicin assay errors on calculated pharmacokinetic values.

The effects of errors in gentamicin concentrations were assessed using computer simulation. Steady-state concentrations at the end of a one-hour infusion (Cmax) and at the end of the dosing interval (Cmin) were calculated for four simulated patients with three dosing schemes each. Errors from -80% to +80% were systematically induced in Cmax or Cmin, or both. Pharmacokinetic values were calculated from the error concentrations and then used to determine new dosing regimens given specific desired concentrations. True Cmax and Cmin values were calculated using the new dosing regimens and original pharmacokinetic values. As the absolute value of the induced error increased, increases were generally seen in the absolute value of the resultant error and in the deviation of the true Cmax and Cmin from desired values. Resultant error was more evident with induced error less than zero, when error was induced into Cmax, and with shorter dosing intervals. Resultant error in pharmacokinetic variables was greater than induced error at induced errors as low as +/- 5%. Toxic and suboptimal values for the true Cmax and Cmin rarely occurred with induced errors of -20% to +20%. Errors in serum gentamicin concentration measurements are more likely to cause larger resultant errors as the errors in concentration values (1) increase in magnitude, (2) result in underreporting of the concentration values, or (3) affect peak concentration values. Shorter dosing intervals may also increase the influence of assay errors.

Biological Assay↗
PubMedDate not supplied

The effect of rifampin on theophylline kinetics.

The effect of rifampin on the pharmacokinetics of theophylline was studied in ten healthy nonsmoking men (age, 23-42 years). Each subject received 5.9-6.8 mg/kg of aminophylline intravenously over 20 minutes before and at the end of two weeks of oral rifampin therapy (600 mg/d). Theophylline serum concentrations were measured serially over the 24 hours following each aminophylline infusion. In every subject, rifampin caused an increase in total clearance (from 0.88 +/- 0.21 to 1.21 +/- 0.29 mL/min/kg) and terminal elimination rate constant (from 0.104 +/- 0.023 to 0.148 +/- 0.030 hr-1) and a decrease in the area under the theophylline concentration-time curve (from 104 +/- 29 to 76 +/- 19 hr-mg/L) and half-life of theophylline (from 7.0 +/- 1.7 to 4.8 +/- 0.9 hr). All of these changes were significant (P less than .02, Wilcoxon matched-pair, signed-rank, two-tailed test). The apparent volume of distribution of theophylline did not consistently change following rifampin administration (mean change, -4%; range, -18(-)+20%, P greater than .20). Patients should be monitored for signs of decreased theophylline efficacy when rifampin is added, or of increased theophylline toxicity when rifampin is discontinued from maintainance therapy.

Adult↗
PubMedDate not supplied

Cross-sectional study of the ethics of pharmacy students.

The importance of ethics in pharmacy education and practice has recently received increased attention. Previous studies have addressed occupational orientation and personality traits as well as the nature of attitudes and values. Many unanswered questions remain. This cross-sectional study was designed to compare the attitudes and value priorities of pharmacy students in preprofessional and professional years of study and to evaluate a modified questionnaire. The 495 students who completed the questionnaire were representative of the 835 pharmacy students enrolled in this "0/5" undergraduate pharmacy program. The survey results indicated that honesty and full disclosure are preferences held by preprofessional students, whereas what may be described as professional judgment predominates in students during their final two professional years. Most students felt they had an idealistic or humanistic orientation. The differences among the classes may be due to any of a number of factors including curricula, normal maturation, or chance differences in the students within each class.

Cross-Sectional Studies↗