Use Of Large Doses Research Articles

Sarin: guidelines on the management of victims of a nerve gas attack.

Sarin is now a weapon of the terrorist. Its acute effects are primarily due to unrestricted cholinergic activity at both muscarinic and nicotinic receptors. Treatment is based on the use of large doses of atropine and pralidoxime which may lead to practical problems of sufficient drug supplies for the average hospital. Ventilation may be necessary and present problems. Victim decontamination involves use of bleach, soap and water. Staff handling casualties need protection with respirators and butyl rubber boots and gloves.

The Effect of the Systemic Antimycotics, Itraconazole and Fluconazole, on the Pharmacokinetics and Pharmacodynamics of Intravenous and Oral Midazolam

We studied the interaction of azole antimycotics with intravenous (IV) and oral midazolam using a cross-over design in 12 volunteers, who ingested placebo, itraconazole, or fluconazole for 6 days. A 7.5-mg dose of midazolam was ingested on the first day, 0.05 mg/kg was administered IV on the fourth day, and 7.5 mg orally on the sixth day. Itraconazole reduced the clearance of IV midazolam by 69% and fluconazole reduced the clearance of IV midazolam by 51% (P < 0.001). A single dose of itraconazole and fluconazole increased the area under the oral midazolam concentration-time curve [AUC(0-infinity)] 3.5-fold (P < 0.001) and the peak concentration two-fold (P < 0.05) compared to placebo. On the sixth day the AUC(0- infinity) of oral midazolam was almost seven times greater with itraconazole (P < 0.001) and 3.6 times greater with fluconazole (P < 0.001) than without the antimycotics. The psychomotor effects of midazolam were also profoundly increased (P < 0.001). The psychomotor tests demonstrated only a weak interaction between the antimycotics and IV midazolam. When bolus doses of midazolam are given for shorttime sedation, the effect of midazolam is not increased to a clinically significant degree by itraconazole and fluconazole, and it can be used in normal doses. However, the use of large doses of IV midazolam increases the risk of clinically significant interactions also after IV midazolam. Use of oral midazolam with itraconazole and fluconazole should be avoided. (Anesth Analg 1996;82:511-6)

Magnesium carbonate as a phosphorus binder: A prospective, controlled, crossover study

The use of calcium carbonate (CaCO3) to bind phosphorus (P) in chronic hemodialysis patients has been a popular tactic in the past decade. Nonetheless, problems with hypercalcemia decrease its usefulness, particularly in patients treated with calcitriol. A P binder not containing calcium (Ca) would be of value in these circumstances. In short-term studies, we showed that magnesium carbonate (MgCO3) was well-tolerated and controlled P and Mg levels when given in conjunction with a dialysate Mg of 0.6 mg/dl. We, therefore, performed a prospective, randomized, crossover study to evaluate if the chronic use of MgCO3 would allow a reduction in the dose of CaCO3 and yet achieve acceptable levels of Ca, P, and Mg. We also assessed whether the lower dose of CaCO3 would facilitate the use of larger doses of calcitriol. The two phases were MgCO3 plus half the usual dose of CaCO3 and CaCO3 alone given in the usual dose. It was found that MgCO3 (dose, 465 +/- 52 mg/day elemental Mg) allowed a decrease in the amount of elemental Ca ingested from 2.9 +/- 0.4 to 1.2 +/- 0.2 g/day (P < 0.0001). The Ca, P, Mg levels were the same in the two phases. The maximum dose of i.v. calcitriol without causing hypercalcemia was 1.5 +/- 0.3 micrograms/treatment during the MgCO3 phase and 0.8 +/- micrograms/treatment during the Ca phase (P < 0.02). If these studies are confirmed, the use of MgCO3 and a dialysate Mg of 0.6 mg/dl may be considered in selected patients who develop hypercalcemia during treatment with i.v. calcitriol and CaCO3.

Optimization of in vivo tumor targeting in SCID mice with divalent forms of 741F8 anti-c-erbB-2 single-chain Fv: effects of dose escalation and repeated i.v. administration.

Single-chain Fv molecules in monovalent (sFv) and divalent [(sFv')2] forms exhibit highly specific tumor targeting in mice as a result of their small size and rapid systemic clearance. As a consequence, there is a rapid reversal of the sFv blood/tumor gradient, resulting in diminished retention of sFv species in tumors. In this report we investigate two distinct strategies, dose escalation and repetitive intravenous (i.v.) dosing, aiming to increase the absolute selective retention of radiolabeled anti-c-erbB-2 125I-741F8 (sFv')2 in c-erbB-2-overexpressing SK-OV-3 tumors in mice with severe combined immunodeficiency (SCID). A dose-escalation strategy was applied to single i.v. injections of 125I-741F8 (sFv')2. Doses from 50 micrograms to 1000 micrograms were administered without a significant decrease in tumor targeting or specificity. High doses resulted in large increases in the absolute retention of 125I-741F8 (sFv')2. For example, raising the administered dose from 50 micrograms to 1000 micrograms increased the tumor retention 24 h after injection from 0.46 microgram/g to 9.5 micrograms/g, and resulted in a net increase of greater than 9 micrograms/g. Over the same dose range, the liver retention rose from 0.06 microgram/g to 1 microgram/g, and resulted in a net increase of less than 1 microgram/g. The retention of 9.5 micrograms/g in tumor 24 h following the 1000-micrograms dose of (sFv')2 was comparable to that seen 24 h after a 50-micrograms dose of 125I-741F8 IgG, indicating that the use of large doses of (sFv')2 may partially offset their rapid clearance. When two doses were administered by i.v. injection 24 h apart, the specificity of delivery to tumor observed after the first dose was maintained following the second injection. Tumor retention of 125I-741F8 (sFv')2 was 0.32 microgram/g at 24 h and 0.22 micrograms/g at 48 h following a single injection of 20 micrograms, while 0.04 microgram/ml and 0.03 microgram/ml were retained in blood at the same assay times. After a second 20-micrograms injection at the 24-h assay time, tumor retention increased to 0.49 micrograms/g, and blood retention was 0.06 microgram/ml, at the 48-h point. These results suggest that multiple high-dose administrations of radiolabeled 741F8 (sFv')2 may lead to the selective tumor localization of therapeutic radiation doses.

Large Volumes of Dilute Lidocaine with Epinephrine Appear Safe for Liposuction Anesthesia

The use of large doses of dilute lidocaine with epinephrine in liposuction surgery has been questioned because it exceeds the manufacturer's

What is the evidence for once-daily aminoglycoside therapy?

Aminoglycosides are important antibacterial agents for the treatment of serious infection. Evidence suggests that high peak plasma concentrations must be achieved early in the course of treatment if these agents are to be effective, but prolonged high concentrations may cause ototoxicity and nephrotoxicity. Peak plasma concentrations of 6 to 10 mg/L and trough concentrations of less than 2 mg/L for gentamicin and tobramycin have been traditional goals of therapy. Extensive recent evidence from in vitro, animal and human studies suggests that these target concentrations need revision. Aminoglycosides display concentration-dependent bacterial killing, have a long postantibiotic effect, and induce adaptive resistance in Gram-negative bacteria. All of these factors support the use of larger doses of aminoglycosides that are given less frequently than conventional therapy. Studies in vitro support this approach, showing greater activity when aminoglycosides are given less frequently. Animal studies comparing different dosage intervals have shown varying results, with only a slight bias favouring the longer dosage interval. However, the short elimination half-lives for the drugs in animals limit the applicability of these models to humans. Importantly, there is convincing evidence in animal studies that nephrotoxicity and ototoxicity are both reduced when the same total daily dose is administered in less frequent doses. There have been at least 29 clinical trials comparing once-daily administration of aminoglycosides with conventional administration 2 to 4 times daily. In general, efficacy has not been shown to be different between regimens, although one trial showed an advantage for once-daily administration compared with administration 3 times daily. A small number of trials have shown less nephrotoxicity and ototoxicity with once-daily administration, leading several authors to suggest that there is sufficient evidence to warrant a change to once-daily administration of aminoglycosides. However, once-daily administration has not been well studied in the paediatric population, or in patients with renal failure or endocarditis, and cannot be recommended in these patients as yet. The choice of a 24-hour dosage interval is somewhat arbitrary, and the optimal interval may not necessarily be 24 hours. No studies have included dosage adjustment based on pharmacokinetic modelling methods, and the effect of this on treatment outcome needs to be assessed. The best method of administering aminoglycosides once daily is yet to be determined.

Antioxidant Vitamins and Coronary Heart Disease

This issue of the Journal contains two important reports of large-scale prospective studies, one in men1 and one in women,2 showing that the use of large doses of vitamin E supplements is associate...

Functional responses to extremely high plasma epinephrine concentrations in cardiac arrest.

To evaluate the action of high-dose epinephrine by measuring simultaneously its vasopressor and norepinephrine releasing effects in humans during cardiac arrest. A prospective study on consecutive patients admitted with cardiac arrest. Emergency Department in a large, urban hospital. Eighteen patients with out-of-hospital cardiac arrest undergoing cardiopulmonary resuscitation (CPR). Catheterization of both the aorta and right atrium for the recording of pressure and collection of blood samples. Throughout the study period (12.5 mins), 18 patients received epinephrine at both the standard dose (1 mg, approximately 0.015 mg/kg) and high dose (0.2 mg/kg). Blood samples were drawn five times, every 2.5 mins. Plasma epinephrine and norepinephrine concentrations; aorta, right atrial, and coronary perfusion pressures. Epinephrine concentrations (normal at rest = 160 +/- 10 [SEM] pmol/L) were increased at the time of the first sample (2.5 mins) by approximately 3,000-fold (to approximately 0.5 mumol/L), and, increased further to 12,000-fold (approximately 2.0 mumol/L) during the study. Aortic pressure increased from 20 +/- 3 to 28 +/- 3 mm Hg (p < .001), and coronary perfusion pressure increased from 4 +/- 3 to 10 +/- 3 mm Hg (p < .001). Simultaneous plasma norepinephrine concentrations were 30-fold higher than the normal resting value of 1.30 +/- 0.04 nmol/L, and increased by 90-fold during the study (p < .001). The spectral distributions of the individual correlations between plasma epinephrine and norepinephrine concentrations were segregated into high correlations (r > .83) in 12 of 18 patients and low r values (r = .29 to .79) in the remaining six patients. The distribution of the correlations was nonuniform by the Kolmogorov-Smirnov goodness-of-fit test with p < .001; this profile suggests that norepinephrine responsiveness to epinephrine can separate two populations, one of which (r > .83) would have preserved viability of the corresponding epinephrine receptors. The correlations between plasma epinephrine concentrations and coronary perfusion pressures were distributed more evenly, also in a nonuniform pattern (p < .02 by Kolmogorov-Smirnov goodness-of-fit test) and the relationship between the two sets of correlations was not significant. Despite the very high prevailing plasma epinephrine concentrations during cardiac arrest, further epinephrine increases still elicit biological responses. The present work provides physiologic support for the use of large doses of epinephrine during the course of CPR.

Prevention of endometrial hyperplasia by progesterone during long-term estradiol replacement: influence of bleeding pattern and secretory changes

To determine the relative influences of induction of withdrawal bleedings secretory transformation, and reduction of mitosis in glands on prevention of endometrial hyperplasia during long-term hormonal replacement therapy. Observational expanded clinical case report. Reproductive Endocrine Department of Hospital Necker, Paris, France, and Pathology Department of Women's Hospital, Los Angeles County and University of Southern California Medical Center, Los Angeles, California. Postmenopausal women seeking treatment for symptomatic menopause. Endometrial biopsy and/or ambulatory hysteroscopy. Endometrial histology including progestational maturation patterns and glandular epithelial mitosis rates. Macroscopic endometrial appearance. The use of larger doses of E2 and P induced more marked secretory changes and more frequent withdrawal bleeding than the lower doses. There was no evidence of endometrial hyperplasia after 5 years of E2/P replacement therapy independently of bleeding pattern or progestational maturation. Consistent reduction of mitosis rates in glandular epithelium was found after 9 or more days of P administration in each cycle. Control of endometrial growth is mainly related to control of mitosis in glands by a relatively low doses of P. Induction of withdrawal bleeding and endometrial secretory transformation, which require larger doses of Progesterone, do not provide additional benefit for prevention of hyperplasia. Induction of amenorrhea with a relatively low dose of P may be offered to women seeking hormone replacement therapy with similar levels of safety.

The heyday of cell population kinetics: Insights from the 1960s and 1970s

Thirty years of intensive research into the cell population kinetics of cancer therapy has produced a wealth of knowledge but so far has failed to provide a rational basis for improved treatments. The main reason for this failure is one that is characteristic of the cancer problem: the needle in a haystack. There are roughly 109 cells in every gram of tumor, and if only a handful are left intact at the end of treatment they may regrow the tumor. Heterogeneity of tumor-cell populations and the survival of the fittest lead to an inevitable tendency for regrowth to come from a small minority of cells that will often be atypical of the tumor cell population before treatment. Once treatment has begun, even a quite ineffective therapy may kill 99 cells in every 100, so the search for and the study of the survivor is a tricky task. A similar problem afflicts studies of the cell kinetics of carcinogenesis: spontaneous tumors tend to be monoclonal and the search for a rare developing malignant focus that may contain only, say, 103 cells (say, 0.001 rag) is fraught with difficulty. The use of large doses of carcinogen to increase the frequency of neoplastic foci often produces widespread tissue damage and creates a complex histolog

Potential Complications of High-Dose Epinephrine-Reply

In Reply. — Fleg suggests an interesting possibility. None of the animal studies that support the use of larger doses of epinephrine for the treatment of cardiac arrest has considered age. 1 We would also guess that most of the animals studied were not senescent. Our study compared the pressor response after standard- and high-dose epinephrine and found that in patients in prolonged cardiac arrest there was a significant difference in the change in coronary perfusion pressure after standard and high doses of epinephrine, with high-dose epinephrine causing a greater increase. To answer Fleg's question, we analyzed the difference in pressor response with respect to age. This showed no significant relationship ( r =.23; P =.46). Although this does not indicate a relationship between age and response to high-dose epinephrine, the small sample size could easily hide a slight effect. Because the serum levels of epinephrine after administration of high-dose epinephrine

Symptoms and correlates of anabolic‐androgenic steroid dependence

Forty-nine male weight lifters, all users of anabolic-androgenic steroids (AASs), completed an anonymous, self-administered questionnaire to investigate addictive patterns of use. At least one DSM-III-R symptom of dependence was reported by 94% of the sample. Three or more symptoms, consistent with a diagnosis of dependence, were reported by 57%. Dependent users (n = 28) could be distinguished from non-dependent users (n = 21) by their use of larger doses, more cycles of use, more dissatisfaction with body size, and more aggressive symptoms. Multiple regression analysis revealed that dosage and dissatisfaction with body size were the best predictors of dependent use. Patterns of other substances used, although not predictive of AAS dependence, revealed very low cigarette use and at the same time high alcohol consumption. These data support the notion that AASs are addicting, and suggest that dissatisfaction with body size may lead to dependent patterns of use. The implications for both prevention and treatment are discussed.

Rationale for high‐dose H2‐receptor blockade in the treatment of gastro‐oesophageal reflux disease

Chronic gastro-oesophageal reflux disease is a common clinical problem. The underlying pathophysiology is considered to be acid injury to the oesophageal mucosa secondary to reflux of gastric contents across an incompetent lower oesophageal sphincter. Evidence suggests that gastro-oesophageal reflux disease is primarily a motility disorder, possibly the combined effect of decreased lower oesophageal sphincter pressure, abnormal oesophageal peristalsis, and, perhaps, delayed gastric emptying. The rationale for the use of acid-suppressing drugs in chronic gastro-oesophageal reflux disease is based on control of the known destructive role of acid and pepsin. Recent evidence indicates, however, that standard doses of H2-receptor blockers are often inadequate to control gastric acid-induced injury in many patients with chronic reflux. Long-term maintenance therapy with standard doses of these drugs has proved unsuccessful in approximately 50% of patients. More recent studies show that greater symptom relief and improved healing can be achieved with the use of larger doses of H2-receptor antagonists. This has been shown particularly with ranitidine at a dosage of 300 mg four times daily.

Improvement of amphotericin B activity during experimental cryptococcosis by incorporation into specific immunoliposomes

Cryptococcosis is an opportunistic infection that is responsible for increased morbidity and mortality in patients with the acquired immunodeficiency syndrome. The high toxicity of the antifungal agent that is mainly used against cryptococcosis, amphotericin B (AMB), accounts for the need for new treatments, especially in patients with the acquired immunodeficiency syndrome because of the high relapse rate of cryptococcosis. Drug targeting may be one of these alternate treatments. Since we have demonstrated that an immunoglobulin G1 (IgG1) anti-Cryptococcus neoformans serotype A monoclonal antibody (E1) was protective during experimental cryptococcosis in mice, we investigated whether specific targeting of AMB with liposomes that bear E1 would improve the therapeutic index of the drug. For that purpose, in vitro and in vivo experiments were designed to compare the specificities and activities of these liposomes with those of control immunoliposomes bearing a nonrelated IgG1 monoclonal antibody (CY34). The immunoliposomes were prepared by covalently linking E1 or CY34 and small unilamellar vesicles. When immunoliposomes were incubated with yeast cells, only E1-bearing liposomes recognized C. neoformans. In vivo, mice that were treated 24 h after infection with one injection of AMB (0.12 mg/kg of body weight) intercalated into E1-bearing liposomes survived significantly longer than did those given the same dose of AMB alone or AMB intercalated into nontargeted liposomes or control immunoliposomes. None of the mice that were given control treatments did statistically better than those that were given AMB. Keeping in mind that this kind of therapy requires knowledge of the antigenic type of the infecting organism, the results suggest that specific targeting of small doses of AMB improve the efficacy of AMB and might be an alternative to the use of larger doses of AMB.

Fluconazole: A New Triazole Antifungal Agent

Fluconazole is a fluorine-substituted, bis-triazole antifungal agent. Its mechanism of action, like that of other azoles, involves interruption of the conversion of lanosterol to ergosterol via binding to fungal cytochrome P-450 and subsequent disruption of fungal membranes. Activity against Aspergillus spp., Blastomyces dermatitidis, Candida spp., Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, and Paracoccidioides brasiliensis has been demonstrated in several animal models. Fluconazole can be administered both orally and intravenously. Mean peak serum concentrations achieved in human volunteers after 50 and 100 mg (oral) are 3.1 and 7.0 mumols/L respectively. Protein binding is low (11 percent) and cerebrospinal fluid to serum ratio is 0.58 to 0.89. Serum half-life is long (22-32 hours) and elimination is via renal clearance of unchanged drug. Clinical trials and reports support the use of fluconazole in treatment of candidiasis, particularly oropharyngeal and esophageal infections in immunocompromised hosts. Fluconazole is also approved for initial and suppressive therapy of cryptococcal meningitis. Its role in management of systemic fungal infections will be further defined once results of other comparative trials become available. Fluconazole is well tolerated and its effects on steroidogenesis are markedly less than those of ketoconazole. Antipyrine clearance is not altered at low doses (50 mg) of fluconazole; however, drug interactions with the use of larger doses can be anticipated with agents such as cyclosporin, phenytoin, oral hypoglycemics, and warfarin. Rifampin appears to decrease metabolic clearance of fluconazole. Fluconazole is available as oral and parenteral formulations. Once-daily doses of 100-400 mg are recommended. Dosage reduction is advised for patients with impaired renal function.

Failure of Fixed-Dose, Fixed Muscle Injection of Botulinum Toxin in Torticollis

We studied the effect of botulinum toxin injection in 30 patients with torticollis in a double-blind, placebo-controlled, crossover study. A fixed dose of toxin was injected into the contralateral sternocleidomastoid and both trapezius muscles. Clinical improvement was assessed by a rating scale and by patient self-evaluation. Subjective rating noted improvement in some patients, but there was no change in objective measures. The use of larger doses and injection of additional muscles may be necessary to achieve increased efficacy of botulinum toxin in the treatment of torticollis.

Growth Hormone for the Elderly?

IN addition to promoting linear growth in prepubertal children, growth hormone is often described as having anabolic, lipolytic, and diabetogenic properties. These descriptions are based on the results of diverse short-term studies of humans, animals, and isolated tissues, many of which involved the use of large doses of growth hormone. Until the production of growth hormone by recombinant-DNA methods began, the small supply of pituitary-derived human growth hormone limited its use to the treatment of children with growth hormone deficiency. The wide availability of synthetic human growth hormone has made possible long-term studies of other potentially beneficial uses of growth . . .

Reversal of profound paralysis: use of large doses of edrophonium to antagonize vecuronium and pancuronium induced neuromuscular blockade

The ability to evoke reversal of dense vecuronium- and pancuronium-induced paralysis (T1 10% of control) with edrophonium 1.0 mg.kg-1 was studied using train-of-four nerve stimulation and electromyographic monitoring. Two different end-points, train-of-four ratios of 0.5 and 0.7, were used to define "adequate reversal", and the results for both relaxants were compared. Reversal was reliable and rapid for vecuronium if either ratio was used with times of 2.8 (1.5) and 9 (3) min required to achieve ratios of 0.5 and 0.7, respectively. However, if the block was due to pancuronium, reversal was unreliable with 2 of 9 and 4 of 9 patients not achieving ratios of 0.5 and 0.7, respectively. Reversal was also markedly prolonged in this group with a mean time of 37 (23) min to achieve a ratio of 0.7, and in almost half these patients a supplementary dose of edrophonium was required.

Intensive care for children after orthotopic liver transplantation.

We report our experience in the management of children after orthotopic liver transplantation (OLT). From 03/84 to 04/87 50 patients (pts) were transplanted. Mean age was 4 3/12 years (8/12 to 13 2/12) and mean body weight 14.7 kg (5.8 to 40). Hospital mortality was 14%. Problems related to the surgery included: Abdominal complications: bleeding (8 pts), infection (18 pts), ascites and fistula (1 pt), need for secondary abdominal surgery (10 patients). Respiratory problems: lobar atelectasis (11 pts), right diaphragmatic paralysis (2 pts) and right pleural effusion (11 pts). Problems related to immunosuppression included: Bacterial infection (29 pts) fungal infection (5 pts), one patient died of disseminated cytomegalovirus infection. Side effect of cyclosporin A (CsA) were systemic blood hypertension (S.B.H.) (47 pts), sinusal bradycardia (37 pts), associated to SBH (24 pts), hypertensive encephalopathy (2 pts). Generalized seizures (2 pts in the absence of SBH). Renal side effects of CsA were hypercreatininemia, decreased sodium bicarbonate and hyperkaliemia. The nephrotoxicity of CsA was favoured by the use of other nephrotoxic drugs such as aminoglycosides, amphotericin B. Edematous pancreatitis was observed in 3 patients and related to the use of large doses of steroids. Problems related to the functioning of the graft included: Primary non-function of the graft (4 pts), hepatic artery thrombosis (8 pts) and severe acute rejection unresponsive to therapy (1 pt); these situations needed to be recognised early in order to organize a second OLT. Other causes of hepatic dysfunction were: portal vein thrombosis (1 pt), biliary tract obstruction (2 pts), angiocholitis (3 pts), right hepatic lobe necrosis (2 pts). Acute hepatic insufficiency in 7 children.(ABSTRACT TRUNCATED AT 250 WORDS)

High-dose contrast-enhanced computed tomography (CECT) with iopamidol in the detection of cerebral metastases. Tolerance of the contrast agent.

Intravenously administered iodinated contrast media have been demonstrated, since early experience with computed tomography of the brain, to improve clinical value of the procedure for detecting intracranial lesions. There is no universal agreement about the amount and the method of administration of the contrast medium. Many authors maintain that the use of large doses gives better results for the diagnosis of tumors and metastases. The purpose of this paper is to evaluate the tolerance of iopamidol administered by rapid intravenous infusion in a large number of patients undergoing contrast enhanced computed tomography to detect brain metastases. The authors examined 969 consecutive adult patients suffering from lung cancer, brain metastases have been detected in 17% of cases. Adverse reactions to contrast media occurred in 3 patients. Non ionic contrast media are recommended in this diagnostic procedure.