S-fluoxetine in the prophylaxis of migraine: a phase II double-blind randomized placebo-controlled study

A tubular bioassay was used to measure analytically the local production and concentration of the antifungal Trichoderma secondary metabolite 6-n-pentyl-2H-pyran-2-one (6PAP) at the Trichoderma antagonist/pathogen interface. 6PAP levels significantly increased in the presence of the pathogen Botrytis cinerea, typically 300-700%, and were highest near the pathogen source. The level of response for a particular Trichoderma isolate was found to vary with the test organism used. Two products produced by biotransformation of 6PAP by B. cinerea in response to the interaction were also detected.     

Long-term clinical effect of nilvadipine in patients with chronic heart failure: a double-blind placebo-controlled study

The long-term effect of calcium channel blockers on chronic heart failure is disappointing, probably because of reflex sympathetic activation through arterial vasodilation. However, nilvadipine may be beneficial for treatment of chronic heart failure since this drug has minimal effects on sympathetic activation. In this study, the effects of 12-week administration of nilvadipine or placebo on symptoms of heart failure and cardiac function were investigated in 23 patients with mild-to-moderate chronic heart failure in a double-blind trial. The patients were randomly assigned to either a nilvadipine group (16 mg daily) or a placebo group. Intergroup comparisons did not show significant differences in any parameters. Serious adverse effects were not observed during the study. Thus, this study failed to show any beneficial effect of nilvadipine in the long-term treatment of patients with chronic heart failure. We conclude that the long-term administration of nilvadipine (16 mg daily) is neither effective nor harmful in the treatment of patients with chronic heart failure.     

A double-blind placebo-controlled trial evaluating the safety and efficacy of acarbose for the treatment of patients with insulin-requiring type II diabetes

OBJECTIVE: To determine whether a forced titration of acarbose (from 50 to 300 mg three times daily) administered over a 24-week period, in conjunction with diet and insulin therapy, improves glycemic control and reduces daily insulin requirements in insulin-requiring type II diabetes. RESEARCH DESIGN AND METHODS: This multicenter, randomized, double-blind, placebo-controlled trial was 36 weeks in duration. The trial consisted of a 6-week pretreatment period, a 24-week double-blind treatment period, and a 6-week post-treatment follow-up period. The primary efficacy variables were the mean change from baseline in HbA1c levels and the mean percentage change from baseline in total daily insulin dose. RESULTS: Treatment with acarbose was associated with significant reductions in HbA1c levels of 0.40% (P = 0.0001) and in total daily insulin dose of 8.3% (P = 0.0015). There were also significant reductions in all plasma glucose variables measured, including a 0.9 mmol/l reduction in fasting glucose (P = 0.0440), a 2.6 mmol/l reduction in glucose Cmax (P = 0.0001) and a 270 mmol.min-1.l-1 reduction in glucose area under the curve (P = 0.0002). Although acarbose treatment was associated with a greater incidence of adverse events than was placebo treatment, primarily flatulence and diarrhea, these events did not generally prevent patients from completing the study. CONCLUSIONS: The results of this study suggest that acarbose is a safe and effective adjunct to diet and insulin therapy for the management of insulin-requiring type II diabetes.     

Efficacy of metformin in type II diabetes: results of a double-blind, placebo-controlled, dose-response trial

PURPOSE: To study the efficacy and safety of various dosages of metformin as compared with placebo in patients with type II diabetes mellitus. PATIENTS AND METHODS: A 14-week, multicenter, double-blind, dose-response study was conducted. After a 3-week, single-blind, placebo-controlled washout, 451 patients with fasting plasma glucose levels of at least 180 mg/dL were randomized to receive an 11-week course of placebo or metformin given at 500, 1000, 1500, 2000, or 2500 mg daily. RESULTS: Metformin improved glucose variables as compared with placebo. The adjusted mean changes in fasting plasma glucose from baseline associated with each metformin group at week 7, 11, or at endpoint exceeded those associated with placebo by 19 to 84 mg/dL at dosages of 500 to 2000 mg daily, respectively. The corresponding between-group differences in glycated hemoglobin (HbA1c) ranged from 0.6% to 2.0% at dosages of 500 to 2000 mg daily, respectively. All between-group differences were significant (P < 0.05) for both fasting plasma glucose and HbA1c at week 7, week 11, and endpoint, except for the difference between placebo and metformin 500 mg in fasting plasma glucose at endpoint (P = 0.054). Treatment-related adverse events occurred in 15% of patients in the placebo group and in 28% in the metformin group (P = 0.02); these were primarily manifested as digestive disturbances, such as diarrhea. CONCLUSIONS: Metformin lowered fasting plasma glucose and HbA1c generally in a dose-related manner. Benefits were observed with as little as 500 mg of metformin; maximal benefits were observed at the upper limits of the recommended daily dosage. All dosages were well tolerated. Metformin appears to be a useful therapeutic option for physicians who wish to titrate drug therapy to achieve target glucose concentrations.     

The effect of nicotine and attention allocation on physiological and self-report measures of induced anxiety in PTSD: A double-blind placebo-controlled trial.

Rates of smoking among populations with psychiatric disorders are more than twice as high as among the general population, yet there are few controlled studies of the mechanisms of this relationship. This trial examined the effect of nicotine by way of cigarette smoking on both self-report and autonomic parameters of anxiety among individuals with PTSD who were also heavy smokers. Half of the participants were randomized to an anxiety-eliciting condition, whereas the other half were assigned to a condition of neutral emotional content. Within each of these conditions, participants were randomized into a nicotine condition (high-yield nicotine cigarette) or a placebo condition (denicotinized cigarette). The final layer of randomization involved assigning participants to either an attention-demanding task or a no task condition. We examined the interactive effects of nicotine and attentional demand on parameters of anxious responding. Nicotine exerted an anxiolytic effect relative to placebo on self-report measures; however, nicotine did not interact with attentional demand in producing this effect. In contrast to the findings on the self-report measures of distress, nicotine enhanced autonomic reactivity to trauma cues, thereby suggesting a decoupling of self-reported anxiety and autonomic arousal associated with responding to trauma-relevant cues. The implications for understanding smoking and psychiatric comorbidity are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Randomized, double-blind, placebo-controlled study of ascorbate on the preventive effect of nitrate tolerance in patients with congestive heart failure

Mitogen-activated protein kinase (MAPK) is a serine-threonine kinase that is activated by various extracellular stimuli. Extracellular signal-regulated kinases (ERK1 and ERK2), an MAPK subfamily, are activated by many oncogenes, such as ras and raf, and they induce cell proliferation. myc is also an oncogene and one of the targets of ERKs. Mutations of ras and overexpression of myc were found in various human cancers, and ERKs were also reported to play a role in carcinogenesis. In this study, we examined 39 biopsy specimens of oral squamous cell carcinoma (OSCC) and 5 of normal gingival mucosa for the expression of ERK protein and the proliferation marker, MIB-1 (Ki-67 antibody). Thirteen OSCC specimens and five normal gingival biopsies were also examined for the expression of ERKs mRNA by in situ hybridization. Double staining for ERKs and MIB-1 was also performed. Histologically, 18 patients (46%) were diagnosed with well-differentiated SCC, 17 (44%) with moderately differentiated SCC, and 4 (10%) with poorly differentiated SCC. The histologic grade correlated with the MIB-1 index. The localization of ERK1 was similar to that of ERK2. Positive signals for ERK proteins were localized in superficial keratinocytes in normal gingival mucosa, whereas these mRNAs were weakly positive in the basal and spinous layer. Basal and suprabasal cells were positive for MIB-1. In well-differentiated and moderately differentiated OSCC, positive signals for ERK mRNA and proteins were found at higher levels than in normal gingival mucosa in keratotic cells around cancer pearls. Some cells showed positive signals for ERKs and MIB-1. Furthermore, most cancer cells in poorly differentiated SCC were positive for both ERK and MIB-1. The histologic grade was statistically related to the percentage of cells positive for both ERK and MIB-1. This suggested that ERKs might be related to proliferation in OSCC.     

Albendazole in human loiasis: results of a double-blind, placebo-controlled trial

To assess the filaricidal activity and clinical safety of albendazole in human loiasis, a double-blind, placebo-controlled study was conducted in an endemic area in Benin, Africa. Twenty-three men with microfilaremia (100-30,000/mL) were randomly assigned to receive albendazole (200 mg; n = 11) or placebo (n = 12) twice daily for 21 days; 1 patient from each group withdrew from the study. There were no clinical adverse effects and no observed hepatotoxicity, renal toxicity, or hematologic abnormalities attributable to the drug. In the albendazole group, microfilarial levels began to decrease at day 14 after treatment and by 6 months had fallen to a geometric mean of 20% of pretreatment levels (vs. 84.8% in the placebo group). Blood eosinophil levels and anti-filarial IgG and IgG4 also fell significantly in response to albendazole. Taken together, these data suggest that albendazole has a primary (possibly embryotoxic) effect on the adult parasite, resulting in a slow decrease in microfilaremia.     

Effects of doxycycline in actively purging cholera patients: a double-blind clinical trial

In 51 actively purging cholera patients the efficacy of doxycycline, a long-acting tetracycline, was compared with a placebo and tetracycline hydrochloride. Seventeen patients who were given doxycycline at the recommended dose of 2 mg/kg at the beginning of the study, at 12 h, and at the repeated dose once daily purged a mean volume of 5.1 liters of stool and received an average of 5.7 liters of intravenous fluid. Nineteen patients receiving the placebo purged 10.1 liters of stool and received 9.7 liters of fluid. Fifteen patients given tetracycline hydrochloride at 6-h intervals passed 4.8 liters of stool and received 5.5 liters of fluid. The durations of diarrhea calculated in 8-h periods were 3.5, 8.0, and 4.1 h in the respective groups receiving doxycycline, placebo, and tetracycline. The differences between the doxycycline and placebo treatments and the tetracycline and placebo treatments were statistically significant. Those receiving doxycycline became vibrio-free in about 3 days as compared with 2 days for those receiving tetracycline; the group given the placebo were vibrio positive for the duration of their hospitalization. The results show that in the treatment of cholera the administration of doxycycline once daily has effects equal to those when tetracycline is administered at 6-h intervals. This is a distinct advantage because it decreases the demand on nursing personnel in epidemics. Also, doxycycline may be safely administered in cases of suspected renal failure from prolonged shock in cholera.     

Randomized, double-blind placebo-controlled trial of coenzyme Q10 in patients with acute myocardial infarction

Adherence with inhaled beta-agonists and corticosteroids in 24 asthmatic children was tracked over 3 months utilizing the metered-dose inhaler chronolog (MDIC). Patients seldom took all of their medications as prescribed, and failed to take any inhaled corticosteroid doses on a median of 41.8% of days or inhaled beta-agonists on 28.1% of days despite prescribed daily use. Medication nonadherence was correlated with lower levels of asthma knowledge (Asthma Knowledge Questionnaire) and family dysfunction (Family Assessment Device), but not child behavior disorder (Child Behavior Checklist). Patients tended to dramatically over-report medication use. Improved identification of the markers of nonadherence can directly facilitate more efficient targeting of behavioral interventions, resulting in improved adherence, better illness control, and less requirement of urgent medication intervention.     

Effects of influenza vaccination in HIV-infected adults: a double-blind, placebo-controlled trial

Annual influenza vaccine is recommended for persons with HIV infection. Recent reports indicate that immunizations may increase HIV replication in infected individuals. Forty-seven HIV-infected patients were randomized to influenza vaccine or saline placebo using a double blind study design. One month after vaccination, plasma HIV-1 RNA increased in the vaccinated but not placebo group (p = 0.029). At 3 months, CD4% dropped an average of 1.6 points in the vaccinated group compared to an increase of 0.1 points in the placebo group (p = 0.039). Patients on stable antiretroviral regimens had CD4% drop an average of 2.3 points in the vaccinated group at 3 months versus 0.1 points in the placebo group (p = 0.015). It is concluded that HIV-infected patients are at risk for increased HIV replication and decreases in CD4% following influenza vaccination. Since influenza has not been associated with significant morbidity in this population, further study of routine influenza vaccination for HIV-infected patients is warranted.     

A randomized, double-blind, placebo-controlled trial of buspirone in combination with an SSRI in patients with treatment-refractory depression

BACKGROUND: Case reports and open studies have reported beneficial therapeutic effects of adding buspirone to a selective serotonin reuptake inhibitor (SSRI) in the management of treatment-refractory depression. This is the first placebo-controlled study to evaluate the efficacy and safety of this combination. METHOD: One hundred nineteen patients (82 women, 37 men) who fulfilled criteria for a major depressive episode according to DSM-IV and who had failed to respond to a minimum of 4 weeks (mean = 211 days) of treatment with citalopram or paroxetine were randomly assigned to 4 weeks of treatment with an SSRI plus buspirone (N = 58) or an SSRI plus placebo (N = 61). In addition, 97 patients participated in an optional open-label poststudy treatment phase with the SSRI plus buspirone for 2 weeks. The primary outcome measure was the score on the Clinical Global Impressions-Improvement (CGI-I) scale. RESULTS: A total of 50.9% of patients in the buspirone group and 46.7% in the placebo group responded after 4 weeks of treatment. The difference in response rate was not statistically significant. No statistically significant differences were found in the frequency of adverse events. At the follow-up of the open SSRI plus buspirone treatment, 69.4% of patients had responded. CONCLUSION: Adding buspirone to an SSRI is a safe and well-tolerated drug regimen. This study failed to demonstrate any difference in efficacy between buspirone or placebo augmentation of an SSRI. It could be argued, however, that the study was inconclusive due to the unusually high placebo response.     

A double-blind, randomized, placebo-controlled trial of prostaglandin E1 in liver transplantation

A double-blind placebo-controlled trial of intravenous prostaglandin PGE1 (40 micrograms/h) was conducted in adult orthotopic liver transplant recipients. Infusion was started intraoperatively and continued for up to 21 days. Patients were followed up for 180 days postoperatively. Among 172 patients eligible for treatment in the study, 160 could be evaluated (78 PGE1; 82 placebo). Patient and graft survival were similar (PGE1: 16 deaths, 9 retransplantations [7 survivors]; controls: 15 deaths, 6 retransplantations [3 survivors]). In patients with surviving grafts, however, PGE1 administration resulted in a 23% shorter mean duration of hospitalization following transplantation (PGE1: 24.4 days; controls: 31.8 days; P = .02) and a 40% shorter length of time postoperatively in the intensive care unit (PGE1: 8.2 days; controls 13.7 days; P = .05). Reduced needs for renal support (P = .03) or surgical intervention other than retransplantation (P = .02) were also noted with PGE1 use. Further, PGE1 administration resulted in a trend toward improved survival rates in patients with mild renal impairment (preoperative serum creatinine 1.5 mg percent or greater; P = .08). Neither the incidence of acute cellular rejection nor of primary nonfunction was significantly different in the two groups. Phlebitis was the only complication that was more common during PGE1 administration, (PGE1: 9; controls: 4). These results suggest that PGE1 use in hepatic allograft recipients reduces morbidity and may result in sizable cost reductions.     

A double-blind, randomized, placebo-controlled trial of fluoxetine in children and adolescents with depression

BACKGROUND: Depression is a major cause of morbidity and mortality in children and adolescents. To date, randomized, controlled, double-blind trials of antidepressants (largely tricyclic agents) have yet to reveal that any antidepressant is more effective than placebo. This article is of a randomized, double-blind, placebo-controlled trial of fluoxetine in children and adolescents with depression. METHODS: Ninety-six child and adolescent outpatients (aged 7-17 years) with nonpsychotic major depressive disorder were randomized (stratified for age and sex) to 20 mg of fluoxetine or placebo and seen weekly for 8 consecutive weeks. Randomization was preceded by 3 evaluation visits that included structured diagnostic interviews during 2 weeks, followed 1 week later by a 1-week, single-blind placebo run-in. Primary outcome measurements were the global improvement of the Clinical Global Impressions scale and the Children's Depression Rating Scale--Revised, a measure of the severity depressive symptoms. RESULTS: Of the 96 patients, 48 were randomized to fluoxetine treatment and 48 to placebo. Using the intent to treat sample, 27 (56%) of those receiving fluoxetine and 16 (33%) receiving placebo were rated "much" or "very much" improved on the Clinical Global Impressions scale at study exit (chi 2 = 5.1, df = 1, P = .02). Significant differences were also noted in weekly ratings of the Children's Depression Rating Scale--Revised after 5 weeks of treatment (using last observation carried forward). Equivalent response rates were found for patients aged 12 years and younger (n = 48) and those aged 13 years and older (n = 48). However, complete symptom remission (Children's Depression Rating Scale--Revised < or = 28) occurred in only 31% of the fluoxetine-treated patients and 23% of the placebo patients. CONCLUSION: Fluoxetine was superior to placebo in the acute phase treatment of major depressive disorder in child and adolescent outpatients with severe, persistent depression. Complete remission of symptoms was rare.     

Effects of docosahexaenoic acid on serum lipoproteins in patients with combined hyperlipidemia: a randomized, double-blind, placebo-controlled trial

OBJECTIVE: The objective of this study was to evaluate the effects of daily dietary supplementation with 1.25 g or 2.5 g of docosahexaenoic (DHA), in the absence of eicosapentaenoic acid (EPA), on serum lipids and lipoproteins in persons with combined hyperlipidemia (CHL) [serum low-density lipoprotein cholesterol (LDL-C) 130 to 220 mg/dL and triglycerides 150 to 400 mg/dL]. METHODS: After a 6-week dietary stabilization period, subjects entered a 4-week single-blind placebo (vegetable oil) run-in phase. Those with adequate compliance during the the run-in were randomized into one of three parallel groups (placebo, 1.25, or 2.5 g/day DHA) for 6 weeks of treatment. Supplements were administered in a triglyceride form contained in gelatin capsules. Primary outcome measurements were plasma phospholipid DHA content, serum triglycerides, high-density lipoprotein cholesterol (HDL-C). LDL-C and non-HDL-C. RESULTS: The DHA content of plasma phospholipids increased dramatically (2 to 3 fold) in a dose-dependent manner. Significant (p < 0.05) changes were observed in serum triglycerides (17 to 21% reduction) and HDL-C (6% increase) which were of similar magnitude in both DHA groups. Non-HDL-C [+1.6 (NS) and +5.7% (p < 0.04)] and LDL-C [+9.3% (NS) and +13.6% (p < 0.001)] increased in the DHA treatment groups. All lipid effects reached an apparent steady state within the first 3 weeks of treatment. CONCLUSION: Dietary DHA, in the absence of EPA, can affect lipoprotein cholesterol and triglyceride levels in patients with combined hyperlipidemia. The desirable triglyceride and HDL-C changes were present at a dose which did not significantly increased non-HDL-C or LDL-C. These preliminary findings suggest that dietary supplementation with 1.25 g DHA/day, provided in a triglyceride form, may be an effective tool to aid in the management of hypertriglyceridemia.     

The effect of flumazenil on subclinical psychometric or neurophysiological alterations in cirrhotic patients: a double-blind placebo-controlled study

Posttransplant lymphoproliferative disorder (PTLD) is associated with Epstein-Barr virus (EBV), and may clinically resemble acute allograft rejection. Three methods to show EBV in tissue were evaluated in 15 liver allograft biopsies from 12 patients including four with PTLD: (1) semiquantitative polymerase chain reaction (PCR) for EBV DNA; (2) in situ hybridization for EBV RNA (EBER); and (3) immunoperoxidase for EBV latent membrane protein (LMP). Index cases had a PCR dot blot result of "positive" or "weak positive." Findings were correlated with histology, clinical data, therapy, and outcome. All four PTLD patients had a clinical diagnosis of acute rejection. All four showed EBV: PCR 4, EBER 4, LMP 3, Liver function tests were elevated in three, but EBV viral capsid antigen (VCA) IgM was not increased in three, but EBV viral capsid antigen (VCA) IgM was not increased in three. Immunosuppression was withdrawn and all four patients underwent a second transplantation. One died 4 days posttransplant with disseminated PTLD, two died of sepsis at 1.5 and 14 months, and one is well at 3 years without PTLD. Eleven biopsies without PTLD showed: acute rejection 7, acute rejection and hepatitis 1, hepatitis B 1, and non-inflammatory changes 2. In this group, EBV results included: PCR weak positive in 10 and 1+ in one, EBER negative in ten and rare positive cells in one, LMP negative in 11. Liver function tests were elevated in 10, whereas VCA IgM was not increased in three and increased in one. Patients with acute rejection were treated with increased immunosuppression: none developed PTLD, with follow-up of at least 6 months in nine cases. Two patients died within 4 months of biopsy. One patient with PTLD in tonsils had a liver biopsy showing both acute rejection and EBV (PCR 1+, rare EBER + small cells). Histological studies combined with special EBV detection methods, can be useful to evaluate atypical lymphoid infiltrates in liver allograft biopsies and confirmation of a diagnosis of PTLD. All three methods are useful; EBER and PCR are the most sensitive. EBER and LMP can use paraffin sections.     

Long-term evaluation of tamsulosin in benign prostatic hyperplasia: placebo-controlled, double-blind extension of phase III trial. Tamsulosin Investigator Group

The blood residence half-life and organ distribution of recombinant human tumor necrosis factor-alpha (TNF-alpha) encapsulated in sterically stabilized liposomes, were investigated in rats bearing a soft tissue sarcoma in the hind leg. We studied the decay in blood concentration of "empty" liposomes using the aqueous marker 67gallium-desferal, as well as the blood concentration of soluble TNF-alpha and liposome encapsulated TNF-alpha using l25I. Encapsulation efficacy of TNF-alpha was 24%. The pharmacokinetics of TNF-alpha were markedly altered after encapsulation in liposomes, with a 33-fold increase in mean residence time of TNF-alpha in the blood, and a concomitant 14-fold increase in the area under the plasma concentration vs. time curve for liposomal TNF-alpha. Although the liposomes exhibit Stealth characteristics, uptake by mononuclear phagocyte-rich organs (e.g., liver and spleen) was noticeable, especially at later time points. Encapsulation of TNF-alpha in sterically stabilized liposomes resulted in a marked increase in localization of the cytokine in tumor measured as total uptake over time. However, peak TNF-alpha concentration levels in tumor were not significantly enhanced compared with free TNF-alpha. Besides the augmented localization of TNF-alpha after encapsulation in sterically stabilized liposomes, a diminished toxicity was observed.     

Fluvoxamine in the treatment of binge-eating disorder: a multicenter placebo-controlled, double-blind trial

OBJECTIVE: The purpose of this study was to assess the efficacy of fluvoxamine in the treatment of binge-eating disorder. Binge-eating disorder is a newly described eating disorder characterized by recurrent episodes of binge eating but without purging behaviors. Uncontrolled reports have suggested that serotonin selective reuptake inhibitors (SSRIs) may be effective in treating this disorder. METHOD: Eighty-five outpatients with a DSM-IV diagnosis of binge-eating disorder were randomly assigned to receive either fluvoxamine (N=42) or placebo (N=43) in a 9-week, parallel-group, double-blind, flexible dose (50-300 mg) study at three centers. The primary outcome measures were frequency of binge eating, expressed as log ([binges/week]+1), and Clinical Global Impression (CGI) scale ratings. Secondary measures included the level of response (based on the percentage change in frequency of binges), body mass index, and Hamilton Rating Scale for Depression score. Except for the level of response, the outcome measures were analyzed by random regression methods; the treatment-by-time interaction was the measure of treatment effect. RESULTS: Compared with placebo, fluvoxamine was associated with a significantly greater rate of reduction in the frequency of binges, rate of reduction in CGI severity scores, rate of increase in CGI improvement scores, level of response for patients who completed the 9-week study, and rate of reduction in body mass index. There was no significant difference between placebo and fluvoxamine groups in the rate of decrease in Hamilton depression scale scores. A significantly greater proportion of patients receiving fluvoxamine than those receiving placebo discontinued treatment because of an adverse medical event. CONCLUSIONS: In this placebo-controlled trial, fluvoxamine was found to be effective according to most outcome measures in the acute treatment of binge-eating disorder.     

Randomized, double-blind, placebo-controlled study of carvedilol on the prevention of nitrate tolerance in patients with chronic heart failure

OBJECTIVES: This study was designed to evaluate the effect of carvedilol on nitrate tolerance in patients with chronic heart failure. BACKGROUND: The attenuation of cyclic guanosine 5'-monophosphate (cGMP) production due to inactivation of guanylate cyclase by increased superoxide has been reported as a mechanism of nitrate tolerance. Carvedilol has been known to combine alpha/beta-blockade with antioxidant properties. METHODS: To evaluate the effect of carvedilol on nitrate tolerance, 40 patients with chronic heart failure were randomized to four groups that received either carvedilol (2.5 mg once a day [carvedilol group, n=10]), metoprolol (30 mg once a day [metoprolol group, n=10]), doxazosin (0.5 mg once a day [doxazosin group, n=10]) or placebo (placebo group, n=10). Vasodilatory response to nitroglycerin (NTG) was assessed with forearm plethysmography by measuring the change in forearm blood flow (FBF) before and 5 min after sublingual administration of 0.3 mg NTG, and at the same time blood samples were taken from veins on the opposite side to measure platelet cGMP. Plethysmography and blood sampling were obtained serially at baseline (day 0); 3 days after carvedilol, metoprolol, doxazosin or placebo administration (day 3); and 3 days after application of a 10-mg/24-h NTG tape concomitantly with carvedilol, metoprolol, doxazosin or placebo (day 6). RESULTS: There was no significant difference in the response of FBF (%FBF) and cGMP (%cGMP) to sublingual NTG on day 0 and day 3 among the four groups. On day 6, %FBF and %cGMP were significantly lower in the metoprolol, doxazosin and placebo groups than on day 0 and day 3, but these parameters in the carvedilol group were maintained. CONCLUSIONS: These results indicated that carvedilol may prevent nitrate tolerance in patients with chronic heart failure during continuous therapy with NTG.