Comment: dilution of vancomycin for intrathecal or intraventricular administration.
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Biomedical subjects
Publications and source records attributed to J F Connelly.
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Preliminary literature suggests that oral immunoglobulin therapy may be of value in severe GI infections, but the optimal antibody class, dosage, and duration of treatment still need to be defined in larger, controlled clinical trials. Most of the information currently available comes from case series and small, uncontrolled trials. Additionally, there is no clear indication on how to select the best candidates for this type of therapy, since the limited information in the literature comes from different patient populations. In all probability, the substantial cost of this approach to treatment will not be justifiable in most pediatric patients with gastroenteritis.
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The treatment of chronic hypertension in patients unable to take oral medications is challenging. Little information on the comparative safety and efficacy of i.v. alternatives is available. Hydralazine, methyldopate, enalaprilat, and nicardipine appear to be the best options for patients temporarily requiring i.v. medications for controlling chronic hypertension. Therapy should be selected on the basis of the individual patient's needs and diseases, the potential for adverse events, the monitoring required, drug costs, and the expected duration of therapy. The choices may be limited, but understanding the proper use of i.v. antihypertensives should enhance blood pressure control and patient care.
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OBJECTIVE: To introduce readers to the use of a new agent, interferon beta-1b (IFN beta ser), in the treatment of relapsing-remitting multiple sclerosis (RRMS). Therapeutic and economic issues surrounding IFN beta ser are discussed, as are its pharmacology, clinical efficacy, adverse effects, and dosage guidelines. DATA SOURCES: A MEDLINE search was used to identify pertinent literature, including clinical trials and reviews. STUDY SELECTIONS: All available trials were reviewed. DATA EXTRACTION: Since trials evaluating subcutaneously administered interferon beta are sparse, clinical trials evaluating intrathecal IFN beta ser were included, as was toxicology information from the oncology population. DATA SYNTHESIS: IFN beta ser has recently been approved by the Food and Drug Administration for the treatment of RRMS. Its exact mechanism of action is unknown, but it may downregulate interferon gamma (IFN gamma) production and the IFN gamma-stimulated major histocompatibility complex antigen expression, and/or augment T-suppressor cell function. Primary adverse effects include flu-like symptoms, fever, chills, myalgia, sweating, and injection-site reactions. Clinical efficacy has been investigated in 372 ambulatory patients with RRMS. IFN beta ser treatment resulted in a reduction in the annual exacerbation rate and a greater proportion of exacerbation-free patients. Burden of central nervous system disease was also significantly reduced in treated patients. However, no reductions were detected on the Scripps Neurologic Rating Scale or with confirmed endpoint scores on the Kurtzke Expanded Disability Status Scale. Although many questions remain concerning IFN beta ser's long-term efficacy, its benefits in patients with other types of multiple sclerosis (MS), and its effect on progression of disease and ultimate disability, IFN beta ser is the first treatment modality that has substantially altered the natural course of MS in a controlled clinical trial. CONCLUSIONS: IFN beta ser is not a cure for MS, but it is well tolerated and patients with RRMS have shown significant improvements in exacerbation rates and burden of central nervous system disease. IFN beta ser should be considered a definite improvement in RRMS treatment, although many therapeutic issues remain unanswered. Additional clinical trials are needed.
OBJECTIVE: To introduce the reader to the use of a new agent, vigabatrin, in the treatment of refractory complex partial seizures. Clinical trials and pharmacokinetic data are reviewed, as well as neuropathology, adverse effects, drug interactions, and dosage guidelines. DATA SOURCES: A MEDLINE search through March 1992 was used to identify pertinent English-language literature, including clinical trials, reviews, abstracts, and conference proceedings. Indexing terms included vigabatrin and anticonvulsants. STUDY SELECTIONS: All clinical trials (total of 21) were reviewed, as were all pharmacokinetic studies (total of 8). Selected studies highlighting chemistry, pharmacology, neuropathology, and adverse effects were also reviewed. DATA EXTRACTION: Performed subjectively by the author. Trials were assessed by design, sample size, types of seizures of the subjects, and clinical response. DATA SYNTHESIS: Vigabatrin represents the first of a new class of antiepileptic drugs (AEDs)--the gamma-aminobutyric acid transaminase (GABA-T) inhibitors. Vigabatrin works by selective, irreversible inhibition of GABA-T, thus preventing the breakdown of GABA. It has been shown to produce dose-dependent increases in cerebrospinal fluid GABA concentrations, and decreases in GABA-T activity. Vigabatrin may also cause a decrease in excitation-related amino acids. It is well absorbed, is not protein bound, and is eliminated by glomerular filtration. However, even with a short half-life (5-7 h), vigabatrin may be given once or twice daily because of its mechanism of action. Few drug interactions have been reported with this agent, although decreases in phenytoin concentration may reach clinical significance. Concern over neuropathologic findings (microvacuolization of white matter) in animals caused trials of vigabatrin to be halted in 1983, but trials have now resumed as there is no evidence of toxicity in humans. Clinical efficacy of vigabatrin has been evaluated in controlled trials and appears to be most effective in complex partial seizures, producing a 50 percent or greater reduction in seizure frequency in approximately 50 percent of the adult patients studied. Efficacy in children with partial seizures also appears promising, and one uncontrolled study suggests that further study of vigabatrin in infantile spasms may be warranted. CONCLUSIONS: Vigabatrin appears to be effective in treating refractory complex partial seizures in adults and refractory partial seizures in children. Its relatively benign adverse-effect profile and few known drug interactions may given this agent an advantage over existing anticonvulsants. However, definitive conclusions about the role of vigabatrin in epilepsy treatment should await the completion of ongoing Phase II and Phase III trials.
Two hundred and seventy-seven serum chloramphenicol concentrations in 90 patients with Haemophilus influenzae type b meningitis were analysed retrospectively. Most patients were given chloramphenicol 25 mg/kg 6 hourly initially. Chloramphenicol concentrations were categorized as pre-dose ('trough') or post-dose ('peak'). Twenty-six per cent of the results were in the potentially toxic range (above 30 mg/L), and 18% were below 10 mg/L. Analysis of 46 pre- and post-dose measurements showed that for the intravenous (i.v.) route of administration, 23% of the pre-dose concentrations were higher than the corresponding post-dose levels and, for the oral route, 42% of the pre-dose levels were higher. Multivariate analysis of covariance demonstrated that chloramphenicol concentrations decreased significantly with increasing number of days of treatment and that the decline was steeper with i.v. administration. The results of this study emphasize the need for therapeutic monitoring of chloramphenicol concentrations, and suggest that chloramphenicol should be given as a loading dose of 40 mg/kg, followed by 25 mg/kg per dose 8 hourly for 3-4 days and then 6 hourly.
Between 1977 and 1989, the Victorian Neonatal Thyroid Screening Programme detected five subjects with thyroid dyshormonogenesis and sensorineural deafness. These patients have been diagnosed as having Pendred syndrome. In two of the children, thyroid function tests which were initially abnormal at birth returned to normal spontaneously without treatment. However, hypothyroidism subsequently recurred and the children required thyroxine therapy. These two children could have been mistakenly diagnosed as having transient hypothyroidism. The detection of five patients with Pendred syndrome illustrates the importance of audiological assessment in all babies with thyroid dyshormonogenesis in whom there is increased uptake of isotope on thyroid scanning. In our experience, hearing loss in patients with Pendred syndrome may be progressive over time, so that repeated audiological assessments are necessary.
Serum sulphates of 5-androstene-3 beta,17 beta-diol (5-ADIOL-S), 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-DIOL-S) and dehydroepiandrosterone (DHEA-S), as well as 5 alpha-androstane-3 alpha,17 beta-diol glucuronide (3 alpha-DIOL-G) and unconjugated androstenedione (AD) and testosterone (T), sex hormone binding globulin (SHBG), free androgen index (FAI) and 17 alpha-hydroxyprogester-one (17OHP) were measured by specific radioimmunoassays (RIA) in 14 women with late-onset 21-hydroxylase deficiency (LOCAH), and in normal women (n = 73). The diagnosis of LOCAH was made on the finding of a (17OHP) response level greater than 30 nmol/l following ACTH stimulation, and/or an elevation of urinary metabolites of 17OHP. Mean values for serum concentrations of all steroids measured and the free androgen index (100 X T nmol/l divided by SHBG nmol/l) were significantly elevated, and SHBG levels depressed in patients with LOCAH. These studies show that in LOCAH, in addition to the unconjugated steroids AD and T, the sulphoconjugated steroids DHEA-S, 5-ADIOL-S and 3 alpha-DIOL-S are increased, as is the glucuronide conjugate 3 alpha-DIOL-G and the index of bioavailable testosterone (FAI), and that mean SHBG levels are depressed. These data suggest that as well as AD, 5-ADIOL-S and DHEA-S may act as pro-hormones for more potent steroids (T and 5 alpha-dihydrotestosterone) in peripheral tissues, while 3 alpha-DIOL-S and 3 alpha-DIOL-G may both reflect peripheral androgen metabolism in patients with LOCAH.
Serum sulphates of 5-androstene-3 beta,17 beta-diol (5-ADIOL-S), 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-DIOL-S) and dehydroepiandrosterone (DHEA-S), unconjugated androstene-dione (AD) and testosterone (T), sex hormone binding globulin (SHBG), free androgen index (FAI), 17 alpha-hydroxyprogesterone (17OHP), luteinising hormone (LH) and follicle stimulating hormone (FSH) were measured by specific radioimmunoassay in 28 hirsute women with polycystic ovarian disease (PCO) and in normal women (n = 73). Mean levels of steroids measured were significantly elevated, and SHBG significantly depressed, in the women with PCO with values (mean +/- SE) for 5-ADIOL-S (516 +/- 51 vs 267 +/- 10 nmol/l), 3 alpha-DIOL-S (130 +/- 9 vs 52 +/- 2 nmol/l), DHEA-S (7.3 +/- 0.5 vs 4.4 +/- 0.2 mumol/l), AD (11.3 +/- 1.1 vs 3.4 +/- 0.2 nmol/l), T (3.3 +/- 0.2 vs 1.5 +/- 0.1 nmol/l) and 17OHP (5.1 +/- 0.8 vs 2.8 +/- 0.2 nmol/l). SHBG levels were 31 +/- 2.9 vs 65 +/- 2.5 nmol/l, and the free androgen index [100 x T (nmol/l) divided by (SHBG nmol/l)] was 12.5 +/- 1.4 vs 2.4 +/- 0.1. The mean LH to FSH ratio was also elevated at 2.8 +/- 0.3. These studies suggest that the measurement of 5-ADIOL-S and DHEA-S may indicate adrenal gland involvement in PCO while 3 alpha-DIOL-S appears to be a reflection of peripheral androgen metabolism. A comprehensive biochemical profile of PCO should thus include the analysis of these sulphoconjugates as well as unconjugated steroids.
The diagnosis of non-classical 3 beta-hydroxysteroid dehydrogenase deficiency (NC-3BHSD) is made either on the basis of significantly elevated serum levels of basal and post-ACTH 5-ene-steroids or by the presence of elevated urinary 5-ene-steroid metabolites. There has been only one report to date describing a single patient where the diagnosis was based on both serum and urinary 5-ene-steroid levels. We, therefore, measured both serum 5-ene-steroid responses to ACTH 1-24 (by RIA) and urinary 5-ene-steroid metabolites (GC-MS) in 42 hirsute premenopausal women. While the serum 5-ene-steroid profile was consistent with NC-3BHSD in 5 women, only 2 of them had increased excretion of 5-ene-steroid metabolites. Elevated 5-ene-steroid excretion was also observed in several patients with normal serum 5-ene-steroids. Detection of NC-3BHSD by either elevated serum 5-ene-steroids or increased urinary excretion of their metabolites in isolation may not therefore be reliable.
Female pattern androgenic alopecia (AA) is a relatively common endocrine abnormality in premenopausal women. However, unlike hirsutism, little is known about the androgen metabolism and plasma C19 steroid sulphate profiles in this disorder. We have therefore measured the plasma levels of dehydroepiandrosterone sulphate (DHEA-S), 5-androstene-3 beta,17 beta-diol sulphate (5-ADIOL-S), 5 alpha-androstane-3 alpha, 17 beta-diol sulphate (3 alpha-DIOL-S), androstenedione (AD), total testosterone (T), free testosterone (FT), sex hormone binding globulin (SHBG), non-SHBG bound T, luteinizing hormone (LH) and follicle stimulating hormone (FSH), and have calculated the free androgen index (FAI): 100 x T (nmol/l) divided by SHBG (nmol/l), in premenopausal women with AA (n = 25-45) and in normal premenopausal women (n = 17-73). While mean plasma concentrations of DHEA-S and T were not significantly different from controls, mean SHBG concentrations were significantly lower (47 +/- 3 vs 64 +/- 3 nmol/l) and the mean free androgen index (4.4 +/- 0.4 vs 2.4 +/- 0.2), and mean concentrations of free testosterone (45 +/- 5 vs 26 +/- 1.4 pmol/l), non-SHBG bound T (0.9 +/- 0.2 vs 0.6 +/- 0.1 nmol/l) and androstenedione (4.3 +/- 0.3 vs 3.4 +/- 0.2 nmol/l) were significantly elevated in women with AA. Furthermore, mean plasma concentrations of 5-ADIOL-S (512 +/- 42 nmol/l) and 3 alpha-DIOL-S (76 +/- 7 nmol/l) were significantly higher than levels found in normal women (272 +/- 12 nmol/l and 52 +/- 2 nmol/l respectively). The nature of the hyperandrogenism associated with AA may thus only be revealed by a comprehensive plasma androgen and androgen sulphate profile, which may explain apparently aberrant data for a given patient. In addition, 5-ADIOL-S and 3 alpha-DIOL-S may serve as excellent plasma markers of both the existence of the disorder and the efficacy of its treatment.
Serum sulphates of 5-androstene-3 beta, 17 beta-diol (5-ADIOL-S), 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-DIOL-S) and dehydroepiandrosterone (DHEA-S), as well as unconjugated androstenedione (AD), testosterone (T) and 17 alpha-hydroxyprogesterone (17OHP), sex hormone binding globulin (SHBG) and the free androgen index (FAI) were measured by specific radioimmunoassay in girls with premature adrenarche (n = 9-16), and in hirsute women with (1) late onset 21 hydroxylase deficiency (n = 14), (2) polycystic ovarian disease (n = 28) and (3) idiopathic hirsutism (n = 74). Levels were also determined in females with androgenic alopecia (n = 35-45), in normal prepubertal girls (n = 9-14) and in normal adult women (n = 50-73). Mean serum concentrations of 5-ADIOL-S, 3 alpha-DIOL-S, DHEA-S, AD, T, and FAI were elevated and SHBG depressed, in all patient groups compared with controls, except for DHEA-S and T in patients with alopecia. We conclude that in addition to DHEA-S, 5-ADIOL-S may have a role as a pro-hormone in the synthesis of more potent androgens (T, DHT) in peripheral tissues such as skin; in addition, 3 alpha-DIOL-S may be a marker of peripheral androgen metabolism.
Serum sex hormone binding globulin (SHBG), testosterone (T), DHEA sulphate (DHEA-S), androstenedione (AD) and delta 5-androstene-3 beta,17 beta-diol sulphate (5-ADIOL-S) levels were measured by specific radioimmunoassay in 16 girls presenting with premature adrenarche (PA) and in 14 normal girls. Mean levels of steroids measured were elevated, and SHBG significantly depressed, in the girls with PA, with values (mean +/- SE) for DHEA-S (1.73 +/- 0.17 vs 0.25 +/- 0.06 mumol/l), 5-ADIOL-S (104 +/- 8 vs 31 +/- 4 nmol/l), AD (0.89 +/- 0.06 vs 0.62 +/- 0.04 nmol/l), and T (0.49 +/- 0.03 vs 0.23 +/- 0.06 nmol/l). SHBG levels were 68 +/- 6 vs 108 +/- 5 nmol/l, and the free androgen index [100 x T (nmol/l) divided by SHBG (nmol/l)] was 0.89 +/- 0.17 vs 0.22 +/- 0.01. These studies show that SHBG is depressed in girls with premature adrenarche; with the increased testosterone levels, this results in a markedly elevated free androgen index, a measure of testosterone which is bioavailable to target tissue. This may be compounded by the elevated levels of 5-ADIOL-S in girls with PA since its role may be as a prohormone for more potent androgens (testosterone, 5 alpha-dihydrotestosterone) in target tissues such as pubic skin.