Comparative clinical efficacy, onset and duration of action of levocetirizine and desloratadine for symptoms of seasonal allergic rhinitis in subjects evaluated in the Environmental Exposure Unit (EEU).

The Environmental Exposure Unit, an indoor pollen challenge system to test anti-allergic medications, was used to compare the onset and duration of action and the efficacy of levocetirizine and desloratadine, two recently developed H1-antagonists. In this double-blind, placebo-controlled, parallel-group study, qualified subjects were randomised to once-daily levocetirizine 5 mg (n = 141), desloratadine 5 mg (n = 140) or placebo (n = 92) and exposed to ragweed pollen on two consecutive days (7 h and 6 h). Symptoms were self-rated every 30 min. On both days, levocetirizine produced a greater improvement in the major symptom complex score (primary efficacy variable) than desloratadine (p = 0.015); both were better than placebo (p < 0.001). Levocetirizine acted earlier (1 h vs. 3 h) and produced greater symptom relief at 24 h than desloratadine (p = 0.003). Levocetirizine also alleviated nasal obstruction better than desloratadine (p = 0.007) on day 1; and better than placebo (p = 0.014) after the second dose on day 2, which was not observed with desloratadine. Levocetirizine and desloratadine were safe and well tolerated.

Quality of life indices may be predictive of placebo and medication response to treatment for allergic rhinitis.

BACKGROUND: Quality of life (QOL) is known to be an important clinical endpoint in determining medication efficacy; however, the predictive value of QOL indices for response to medication or placebo has not been tested. OBJECTIVE: To determine whether a correlation between measures of QOL and response to medication/placebo exists in an evaluation of budesonide for allergic rhinitis. METHODS: Two hundred nine participants completed the 36-item short-form health QOL survey at screening for entry into a study examining the onset of action of budesonide in an allergen challenge system. During the treatment phase, symptom assessments were recorded hourly after dosing of double-blind medication. Participants were determined to be responders or nonresponders to study medication. A responder was defined as a participant who rated medication effectiveness as fair to excellent with regard to symptom relief, for three consecutive hourly assessments during the study day or one whose total symptom score decreased by > or =25% for three consecutive hourly assessments. Baseline QOL scores were compared between responders and nonresponders. RESULTS: Differences were noted among responders and nonresponders on the basis of whether budesonide or placebo was received. Ratings of general health perception, pain, physical function, and role limitation due to physical health were significantly lower among participants who responded to placebo, compared with placebo nonresponders. In addition, the overall physical health and 36-item short-form health survey averages were significantly lower. Differences between responders and nonresponders to budesonide did not reach statistical significance. CONCLUSIONS: Lower baseline QOL scores were associated with a clinically significant response to placebo in a trial of treatment for allergic rhinitis. QOL may be a factor in participant response to medication in clinical studies and, hence, a predictor of outcome.

Comparative onset of action and symptom relief with cetirizine, loratadine, or placebo in an environmental exposure unit in subjects with seasonal allergic rhinitis: confirmation of a test system.

BACKGROUND: The environmental exposure unit (EEU) is an instrument designed to determine onset of action of antiallergic treatment. Confirmation of test results would be useful in defining its role. OBJECTIVE: This study was intended to confirm a previous study comparing cetirizine, loratadine, and placebo in the EEU using an identical protocol design (randomized, double-blind, parallel-group comparison having the same symptom scoring system, endpoints, and statistical analyses), thus demonstrating reproducibility of studies conducted in the EEU. METHODS: Onset of action and symptom relief with once-daily cetirizine 10 mg, loratadine 10 mg, and placebo (n = 120 each group) were evaluated replicating a previous study design. Subjects meeting inclusion and exclusion criteria and qualifying symptom scores were randomized to 2 days' exposure (6 to 7 hours daily) with treatment. Changes in total and major symptom complex (TSC, MSC) scores based on 14 symptoms evaluated at 30-minute intervals served as primary efficacy variables. RESULTS: Onset of action again was earlier with cetirizine (at 1 hour, P < or = 0.001) versus loratadine (at 3 hours, P < or = 0.01). Cetirizine produced a 25.4% least-square mean reduction in TSC scores overall versus an 11.2% decrease with loratadine (P = 0.006) and a 4.8% increase with placebo (P < 0.001); loratadine and placebo were also significantly different (P = 0.002). Similar changes were also noted in MSC scores. Cetirizine consistently reduced TSC and MSC scores after the first dose versus placebo (P < or = 0.001) and at most time points versus loratadine (P < or = 0.05). Adverse events were reported in 1.7% of patients in each active-treatment group and in 2.5% on placebo. CONCLUSIONS: Cetirizine acted earlier and was more effective than loratadine or placebo in reducing symptoms of seasonal allergic rhinitis in subjects undergoing a controlled pollen challenge, replicating results from an earlier, identically designed study, demonstrating reproducibility of these assessments by the EEU.

Onset of action of intranasal budesonide (Rhinocort aqua) in seasonal allergic rhinitis studied in a controlled exposure model.

BACKGROUND: Intranasal budesonide aqueous nasal spray (BANS) is recognized as an efficacious treatment for seasonal allergic rhinitis (SAR), but the time to onset of action is not known. OBJECTIVE: The primary objective was to evaluate the time at which the onset of action of BANS in the symptomatic relief of seasonal allergic rhinitis becomes evident within 12 hours after a single dose in a controlled ragweed pollen exposure setting. METHODS: The study was of a double-blind, randomized, parallel-group design, testing BANS (64 microgram and 256 microgram) and placebo on ragweed-sensitive subjects with symptoms for at least 1 year by using a controlled pollen challenge system (Environmental Exposure Unit). The efficacy variables were the combined nasal score (the sum of blocked nose, runny nose, and sneezing-itchy nose), individual nasal symptoms, overall evaluation of treatment efficacy reported by participants on diaries, and peak nasal inspiratory flow (PNIF). RESULTS: A total of 217 participants were treated with BANS or placebo. At 7 to 12 hours, BANS was better than placebo in reducing combined nasal and blocked nose symptoms. For PNIF, the time to onset of action was shortest for 256 microgram of BANS relative to placebo (3 hours, P =.003). BANS 64 microgram was better than placebo in reducing the individual scores of blocked nose, runny nose, and sneezing-itchy nose from 3 to 5 hours after administration. Treatment efficacy was higher for those receiving BANS compared with placebo starting at 5 hours. All treatments were well tolerated, and no specific adverse events occurred. CONCLUSIONS: The onset of action of intranasal BANS was 7 hours according to combined nasal and blocked nose symptom scores. Evidence of earlier response was observed at 3 hours for runny nose and PNIF.

Amiodarone-induced disruption of hamster lung and liver mitochondrial function: lack of association with thiobarbituric acid-reactive substance production.

Amiodarone (AM) is an efficacious antidysrhythmic agent that is limited clinically by numerous adverse effects. Of greatest concern is AM-induced pulmonary toxicity (AIPT) due to the potential for mortality. Mitochondrial alterations and free radicals have been implicated in the etiology of AM-induced toxicities, including AIPT. Isolated hamster lung and liver mitochondria were assessed for AM-induced effects on respiration, membrane potential, and lipid peroxidation. AM (50-400 microM) stimulated state 4 (resting) respiration at complexes I and II of tightly coupled lung mitochondria, with higher concentrations (200 and 400 microM) resulting in a subsequent inhibition. This biphasic effect of AM (200 microM) was also observed with isolated liver mitochondria. Only inhibition of respiration was observed with AM (50-400 microM) in less tightly coupled lung mitochondria. Based on safranine fluorescence, 200 microM AM decreased lung mitochondrial membrane potential (p < 0.05), while a concentration-dependent (50-200 microM) decrease of membrane potential was observed with liver mitochondria exposed to AM (p < 0.05). Formation of thiobarbituric acid-reactive substances (TBARS) was not altered by AM (50-400 microM) in incubations lasting up to 1 h. These results indicate that lipid peroxidation, as indicated by levels of TBARS, does not play a role in AM-induced alterations in mitochondrial respiration and membrane potential.

Bromobenzene and furosemide hepatotoxicity: alterations in glutathione, protein thiols, and calcium.

The nature of the events whereby the reactive intermediates resulting from the bioactivation of bromobenzene and furosemide induce hepatotoxicity is unknown. To examine a role for disturbances in intracellular calcium homeostasis, secondary to a depletion in cellular reduced glutathione (GSH) and reduced protein thiols (PSHs), isolated mouse hepatocytes were exposed to cytotoxic concentrations of bromobenzene or furosemide. Cytosolic calcium concentration, as well as thiol status, was determined. The incubation of hepatocytes with 3.0 mM bromobenzene, and subsequent additions (1.2 mM) of the agent every hour, resulted in significant GSH depletion. The loss of plasma membrane integrity at 1.5 h preceded both a rise in the cytosolic Ca2+ concentration and depletion of total PSH content. Furosemide (1.0 mM) produced a 70% depletion in cellular GSH content in isolated hepatocytes. The initiation of cell damage occurred concurrently with both a rise in the cytosolic Ca2+ concentration and a depletion of total PSH content 4 h following furosemide addition. Since the increase in cytosolic Ca2+ did not precede cytotoxicity, these results do not support an initiating role for Ca2+ deregulation in bromobenzene and furosemide hepatotoxicities. In addition, depletion of PSH content did not correlate with bromobenzene- or furosemide-induced cytotoxicity.

Evaluation of reactive oxygen species involvement in amiodarone pulmonary toxicity in vivo and in vitro.

Amiodarone (AM) is an effective antidysrhythmic agent, restricted in use by the development of adverse effects, including potentially fatal AM-induced pulmonary toxicity (AIPT). Although the pathogenesis of AIPT is unknown, an oxidant mechanism has been proposed. The present study evaluated the role of reactive oxygen species (ROS) in AM-induced toxicity. The effect of inhibiting lung antioxidant defense on in vivo development of AIPT was evaluated in hamsters. Lung glutathione reductase activity was inhibited by 66%, 6 hours following administration of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) (20 mg/kg i.p.). When AM (1.83 mumol) was administered intratracheally 6 hours after BCNU, toxicity was enhanced, as indicated by lung hydroxyproline content and histological evaluation 21 days later. However, BCNU treatment did not affect AM-induced alterations in lung glutathione, suggesting that the increased toxicity was not due to decreased antioxidant capacity following BCNU. The effect of BCNU on AM cytotoxicity in vitro was evaluated using rabbit lung alveolar macrophages. Incubation with 5 microM BCNU for 2 hours caused greater than 95% inhibition of glutathione reductase activity. However, BCNU treatment had no effect on 146 microM AM-induced cytotoxicity, as assessed by lactate dehydrogenase latency following 12 hours of incubation. Rabbit macrophages loaded with 2',7'-dichlorofluorescein, which is oxidized by ROS to fluorescent 2',7'-dichlorofluorescein (DCF), were used to evaluate ROS generation by AM. Incubation of macrophages with AM (73 or 146 microM) for 1 hour, with or without the catalase inhibitor sodium azide (1 mM), did not result in DCF formation. Overall, these results do not support the hypothesis that AIPT is due to ROS action.

Mechanisms in the pathogenesis of amiodarone-induced pulmonary toxicity.

Although amiodarone is a highly efficacious antidysrhythmic agent, the drug produces numerous adverse effects. The most critical of these is pulmonary toxicity because of the potential for mortality. This review examines the experimental model systems used to study amiodarone toxicity, summarizes the current state of knowledge regarding the processes involved in amiodarone-induced pulmonary toxicity (AIPT), and includes a discussion of potential future directions. Possible contributing processes to initiation of AIPT include phospholipidosis, altered calcium ion regulation, generation of reactive oxygen species, formation of an amiodarone aryl radical, and perturbation of cellular energy production. In addition, an immune response to the parent compound or to a metabolite could play a role. It is expected that elucidation of the mechanism(s) of AIPT will lead to safer antidysrhythmic agents and (or) to effective treatments for the prevention or amelioration of AIPT.

Effects of N-acetylcysteine and dithiothreitol on glutathione and protein thiol replenishment during acetaminophen-induced toxicity in isolated mouse hepatocytes.

Isolated mouse hepatocytes were incubated with 1.0 mM acetaminophen (AA) for 1.5 h to initiate glutathione (GSH) and protein thiol (PSH) depletion and cell injury. Cells were subsequently washed to remove non-covalently bound AA and resuspended in medium containing N-acetylcysteine (NAC, 2.0 mM) or dithiothreitol (DTT, 1.5 mM). The effects of these agents on the replenishment of GSH and total PSH content were related to the development of cytotoxicity. When cells exposed to AA were resuspended in medium containing NAC or DTT, both agents replenished GSH and total PSH content to levels observed in untreated cells but only DTT was able to attenuate cytotoxicity. Addition of the GSH synthesis inhibitor, buthionine sulfoximine (BSO, 1.0 mM, 1.5 h), to cells in incubation medium containing AA, enhanced GSH and total PSH depletion and potentiated cytotoxicity. Resuspension of these cells in medium containing NAC did not alter the potentiating effects of BSO; GSH and PSH levels were not replenished and no cytoprotective effects were observed. However, when cells exposed to AA and BSO were resuspended in medium containing DTT, PSH content was replenished but GSH levels were not restored. In addition, DTT was able to delay the development of cytotoxicity. It appears that DTT, unlike NAC, has a GSH-independent mechanism of PSH replenishment. These observations suggest that while replenishment of GSH and total PSH content does not result in cytoprotection, the regeneration of critical PSH by DTT may play an important role in the maintenance of proper cell structure and/or function.

Comparison of the in vivo pulmonary toxicity of amiodarone and des-oxo-amiodarone in the hamster.

Amiodarone (AM) is an effective antidysrhythmic agent, the use of which is limited because of the drug's potential for causing life-threatening pulmonary fibrosis. Oxidative stress involving keto oxygen-derived free radical formation has been postulated to be responsible for initiating AM-induced pulmonary toxicity (AIPT). We have investigated whether des-oxo-amiodarone (DOAM), which has a methylene group in place of the keto oxygen group of AM, causes pulmonary fibrosis in an experimental animal. Hamsters were given a single intratracheal instillation of AM HCl or DOAM HCl (1.83 mumol). At 21 days postdosing, animals treated with either AM or DOAM had increased lung wet weight, hydroxyproline content, and histological disease index compared to control. Both AM and DOAM treatments caused marked septal thickening and fibrosis, and an influx of inflammatory cells into alveolar and interstitial spaces. AM caused a greater degree of alveolar macrophage infiltration than did DOAM, which contributed to the higher lung disease index for AM treatment. Interestingly, a greater quantity of DOAM than AM remained in the lungs and bronchoalveolar lavage fluid 1 and 5 hr after treatment. Thus, DOAM possess fibrogenic properties similar to AM but based on the greater quantity of DOAM in the lung, it appears to be a less potent inducer of pulmonary toxicity. If oxidative stress has a role to play in AIPT, the results indicate that the keto oxygen is not the major determinant of AM-induced pulmonary fibrosis.