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Despite the enormous success of second generation antihistamines, in the mid-1980s, about 10 years after their introduction in the market, several reports appeared in the literature indicating the rare occurrence of a form of polymorphic ventricular dysrhythmia, the 'torsade de pointes', after the administration of astemizole or terfenadine. This cardiac side-effect has been interpreted as a consequence of the interference of these drugs with cardiac K+ channels involved in action potential repolarization, and in particular with the IKr component of the cardiac repolarizing current. As the K+ channels encoded by the human ether-a-gogo-related gene (HERG) seem to represent the molecular basis of IKr, this cardiac K+ channel was soon recognized as a primary target for second generation antihistamine-induced proarrhythmic effects. In fact, both terfenadine and astemizole have been shown to block HERG K+ channels in a concentration range similar to that found in the plasma of subjects with cardiotoxic manifestations. However, no correlation can be found between the ability to prolong the cardiac action potential duration and the H1-antagonistic activity by several antihistamines, suggesting that HERG blockade and cardiotoxic potential are not class properties of second generation antihistamines. In fact, other molecules such as cetirizine, loratadine, acrivastine, and fexofenadine seem to lack both cardiotoxic potential and HERG-blocking ability at therapeutically relevant concentrations. The marked heterogeneity displayed by second generation antihistamines in their ability to prolong the cardiac action potential duration and to block HERG K+ channels might be of considerable therapeutical significance for those patients at risk of developing cardiac dysrhythmias and in need of therapy with H1-receptor blockers; it also emphasizes the importance of an evaluation of the possible blockade of HERG K+ channels during the early developmental phases of novel compounds belonging to this therapeutical class.
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Allergic rhinitis is a common chronic respiratory illness that affects quality of life, productivity, and other comorbid conditions, including asthma. Treatment should be based on the patient's age and severity of symptoms. Patients should be advised to avoid known allergens and be educated about their condition. Intranasal corticosteroids are the most effective treatment and should be first-line therapy for mild to moderate disease. Moderate to severe disease not responsive to intranasal corticosteroids should be treated with second-line therapies, including antihistamines, decongestants, cromolyn, leukotriene receptor antagonists, and nonpharmacologic therapies (e.g., nasal irrigation). With the exception of cetirizine, second-generation antihistamines are less likely to cause sedation and impair performance. Immunotherapy should be considered in patients with a less than adequate response to usual treatments. Evidence does not support the use of mite-proof impermeable covers, air filtration systems, or delayed exposure to solid foods in infancy.
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There is published evidence that cetirizine has a longer duration of effect than fexofenadine. This study compared duration of effect and other measures of efficacy of cetirizine, 10 mg; fexofenadine, 180 mg; and placebo in allergic subjects exposed to pollen in the Environmental Exposure Unit. Eligible subjects (n = 575) were exposed to ragweed pollen (day 1, 7 hours; day 2, 5 hours) and randomized in double-blind fashion to once-daily cetirizine, 10 mg; fexofenadine, 180 mg; or placebo. The total symptom severity complex (TSSC) score, the primary efficacy variable, was based on four rhinoconjunctivitis symptoms rated at 20-minute intervals. Treatment evaluation was divided into three periods: period 1 TSSC, average of 15 scores obtained 0-5 hours after the first dose; period 2 TSSC, average of 9 scores obtained 21-24 hours after the first dose; and period 3 TSSC, average of 6 scores obtained 0-2 hours after the second dose. The primary efficacy end point was the change from baseline TSSC at period 2. Baseline TSSC was the final pretreatment score on day 1 and was 9.7 for cetirizine, 9.8 for fexofenadine, and 9.7 for placebo. For the primary efficacy end point, the reduction in baseline TSSC at period 2 was greater for cetirizine (-3.6) compared with fexofenadine (-2.7; p < 0.001) and placebo (-2.0; p < 0.001), representing a 33% greater reduction for cetirizine versus fexofenadine. Cetirizine continued to reduce TSSC more than fexofenadine (-5.2 versus -4.6; p = 0.017) and placebo (-3.9; p < 0.001) (period 3). Similar efficacy was observed in period 1 for both active treatments. Treatment-related adverse events were similar in all groups with an incidence of somnolence of 1.3% for both active medications. In conclusion, cetirizine produced a 33% greater reduction in SAR symptoms over the 21- to 24-hour interval after the first dose and for 40 minutes after the second dose, indicating a superior and longer duration of effect, which is relevant because both are once-daily medications. Onset of action was comparable and both treatments were safe and well tolerated.
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Symptoms were evaluated by the investigator using a total symptom score (TS) and by the patient (first week). Responders (R) were patients with a TS decrease of at least 50%. Safety was assessed according to the spontaneous reporting of adverse events.
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Ovalbumin sensitization and challenge caused rhinitis pathology including inflammatory cell infiltration, IL-4, and protein leakage in the nasal lavage fluid (NLF) and presence of inflammatory cells in nasal epithelium. A 5-day treatment of antihistamines reduced these markers of inflammation. SUN-1334H, cetirizine and hydroxyzine caused comparable inhibition of NLF leukocytes, IL-4 and total protein concentrations. Fexofenadine and desloratadine showed moderate inhibition of NLF leukocytes and had no significant effect on IL-4 concentration. While fexofenadine had no effect on total protein concentration, the effect of desloratadine was comparable with the other antihistamines. In neurogenic nasal inflammation induced by capsaicin, SUN-1334H and fexofenadine caused better inhibition at lower and middle dose levels than the other antihistamines. In skin allergy models, SUN-1334H showed potent reduction of passive and active cutaneous anaphylactic reactions. In central nervous system side effects models, SUN-1334H, desloratadine and fexofenadine were devoid of any significant effects.
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More than 89% of new LM starts had no history of an ICS in the claims database. Overall, 61% of all (new and existing) LM patients did not have a claim for an ICS in their drug claims profile during the study period. An estimated 25% of LM utilization was not for asthma. No differences in ER utilization were found between ICS users and LM users; however, the ER utilization rate (0.090 ER visits per patient per year) was lower with combination therapy compared with monotherapy with ICS (0.110 ER visits per patient per year, P = 0.001) or LM (0.119 emergency room visits per patient per year, P<0.001).
The crude aqueous extracts showed the possibilities to present caffeine and cetirizine or its derivatives like molecules. On the other hand, the crude methanolic extract may contain Loratadine or its derivatives like molecules. Both type of extracts showed hemagglutination inhibition activities in all types of human blood samples tested. However, they showed stronger binding with AB+ blood group than those of A+ and B+ blood.
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Concentration-time profiles for cetirizine in serum and tear fluid were similar, although the mean maximum concentration in tear fluid was reached later than in serum (90 and 30 min, respectively). However, at 60 and 120 min the cetirizine concentration in tear fluid was 98 and 92% of the mean maximum concentration, respectively, showing a plateau region and indicating that the disposition rate for the tear fluid compartment was very similar to that for the blood compartment.
The failure of the second-generation antihistamines cetirizine and fexofenadine to prevent motion sickness suggests that the therapeutic actions of this class of antihistamines against motion sickness may be mediated through central versus peripheral receptors. The sedative effect of other antihistamines, such as hydroxyzine, may play a more significant role in alleviating motion sickness than previously thought.
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Our randomised study in parallel groups, double-blind double placebo, has compared the efficacy, onset of action and safety of terfenadine and cetirizine in chronic idiopathic urticaria. Over a fourteen day period, patients of the first group received a tablet containing 120 mg of terfenadine, those of the second group a tablet containing 10 mg of cetirizine. Symptoms were assessed every two hour period for the ten first hours on the first day (D1), and before and at the end of the study by the investigators. 193 patients were included by 48 dermatologists between May 1989 and July 1990. Both groups were well matched for all general characteristics and baseline symptoms scores. The onset and the intensity of regression of symptoms (pruritus, erythema and discomfort during sleeping time) were similar in both treatment groups public physicians: improvement of pruritus in over 90% of the patients. Meanwhile the tolerability was good or excellent for dermatologists and allergologists for 92% of the patients under terfenadine against 81% of the patients under cetirizine (p < 0.05). Adverse events (fatigue and drowsiness) were significantly reported less frequently (p < 0.05) in patients on terfenadine (19%) than on cetirizine (33%). This study confirms the efficacy of terfenadine compared with cetirizine in the treatment of chronic idiopathic urticaria. Adverse events were less significant for terfenadine (n = 18) than for cetirizine (n = 29) (p < 0.05).
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HMVEC-d or HMVEC-l were grown to confluence on micropore filters in transwells inserted into a 24-well tissue culture dish. Eosinophils were isolated by density gradient centrifugation and negative immunomagnetic selection. Untreated eosinophils or eosinophils pre-incubated (30 min at 37 degrees C) with a concentration range of cetirizine or levocetirizine (10-5 to 10-9 m) were added to the upper chamber of the transwell which was incubated for 60 min at 37 degrees C. Both spontaneous eosinophil TEM and TEM to 100 ng/mL of human eotaxin in the lower chamber were assessed.
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Modified three-step empirical therapy was as efficacious as primary three-step therapy for chronic cough, but was preferable because it had fewer side-effects.
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The aim of the present study was to establish antihistamines drug prescribing pattern in order to improve the rational prescribing of antihistamines by physicians at Panjab University Health Centre. The study was performed in between the months of November 2005 to April 2006. Five hundred out patients were monitored and data was collected on WHO-based prescription-auditing performa. Demographic analysis of this prospective study revealed that out of the 500 patients, 293 (58.6 %) were male and 207 (41.4 %) were female and maximum patients were in the age group of 21-40 (34.8 %). Chlorpheniramine maleate (235 prescriptions) was the highest prescribed among antihistamine prescriptions (36.89 %) followed by diphenhydramine hydrochloride (186 prescriptions, 29.19%), cetirizine (175 prescriptions, 27.47 %) and promethazine (41 prescriptions, 6.4%). In comparison to generic drugs (169 prescriptions, 26.54%), branded were more prescribed at PUHC. Majority of antihistamines were in form of tablets (414 prescriptions, 64.99%) followed by liquid formulations (195 prescriptions, 30.61%) and injections (28 prescriptions, 4.40%). The average cost of different antihistamine drugs prescribed was as follows: diphenhydramine hydrochloride Rs. 34.74 followed by promethzine Rs. 22.46, chlorpheniramine maleate Rs. 15.30, and cetirizine Rs. 13.50. Average numbers of drugs prescribed per prescription were 1.27. The average consulting and dispensing time was 4.82 and 3.56 min, respectively. Out of the 500 university patients, 258 (51.6%) had the knowledge regarding the medication prescribed and 242 (48.4%) were unaware of the medication prescribed.
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A multicenter, double-blind, parallel-group, placebo-controlled trial compared the efficacy and safety of fexofenadine HCl (120 and 180 mg administered once daily) and cetirizine (10 mg once daily) in the treatment of seasonal allergic rhinitis.
Pharmacists can play an important role in the management of allergic rhinitis and CIU by considering the relative advantages of newer-generation agents when reviewing treatment options.
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The tuberomammillary nucleus (TMN) of the posterior hypothalamus has a high density of histaminergic neurons, the projection fibers of which are present in many areas of the brain, including the nucleus tractus solitarius (NTS), which controls arterial pressure (AP). In this study, we investigated whether the TMN-NTS pathway is involved in central cardiovascular regulation. Bicuculline, a gamma-aminobutyric acid type A (GABAA) receptor antagonist, was microinjected into the ventral TMN of anesthetized rats and its effects on AP and heart rate (HR) were observed. We also evaluated the effect of cetirizine, an H1 receptor antagonist, microinjected into the NTS on cardiovascular responses induced by electrical stimulation of the TMN Both AP and HR increased following bicuculline microinjection into the ventral TMN Similar pressor and tachycardic responses were observed after electrical stimulation of the ventral TMN Microinjection of cetirizine into the NTS partially inhibited the pressor response but had no effect on HR Finally, the treadmill test was associated with a high level of c-Fos expression in both ventral TMN and NTS neurons. These results suggest that the TMN-NTS pathway is involved in regulation of AP, presumably under a high-arousal phase, such as that during exercise.
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Levocetirizine is the pharmacologically active enantiomer of cetirizine. It is a potent histamine H-1 receptor antagonist with anti-inflammatory and antiallergic properties. The review analyses the levocetirizine's properties in terms of safety and efficacy both in allergic rhinitis and urticarioid syndromes.
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The skin vascular responses (weal, flare, blood flow measurements) elicited by intradermal administration by pricking of histamine (HS) and substance P (SP) were evaluated 6 h after a single intake of anti-H1 agents displaying different activity profile on skin tests at currently recommended dosages (loratadine 10 mg, cetirizine 10 mg) as compared to placebo (P). The weal and flare response and the increases of blood flow occurring in the usual flare area after HS and SP were almost completely abolished by cetirizine. Inhibition of HS- and SP-induced weal and flare reactions was less marked after loratadine and blood flow in the expanding flare after HS and SP showed significant fluctuations over time. In view of the present results and of data obtained in previous experiments with intradermal injection of agonists, we hypothesize that mode of administration of agonists significantly influences the size of the residual weal after anti-H1 agents. We demonstrate that SP weals induced by pricking are largely inhibited by a potent H1 blockade which supports the view that this phenomenon, as well as the SP-flare, is due to SP-induced histamine liberation. We also, for the first time, report on fluctuations recorded at the edge of the developing flare with laser Doppler flowmetry early after prick testing with a weak H1 blockade. This opens up new avenues in dynamically testing H1-receptor occupancy in vivo and in situ in human skin.
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Chronic idiopathic urticaria (CIU) is a common dermatological condition. Its pathogenesis involves mainly histamine and also other mediators, including platelet-activating factor (PAF) and tumor necrosis factor-α (TNF-α). In the absence of an exact etiology, H1 -antihistaminics are the mainstay of treatment. Levocetirizine is widely prescribed for CIU. Rupatadine, a newer antihistaminic, has PAF receptor antagonist activity and has shown anti-TNF-α activity in vitro. These additional anti-inflammatory effects may improve its efficacy.
Mequitazine is a so-called 'non-sedative' second-generation antihistamine even though it has never been firmly established that this drug's sedative potential actually differs from that of the 'sedative' first-generation antihistamines.
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Histamine induces acute electrochemical changes in human pleura mainly via interaction with the H(1) and partially with the H(2) histamine receptors. It also interferes with trans-cellular permeability and therefore may participate in pleural fluid recycling.