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The Autacoid Functions of Adenosine in Asthma
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
R. Polosa, M. K. Church, S. T. Holgate
In a model of adenosine-induced bronchoconstriction in inbred rats, Pauwels and Van Der Straeten66 have confirmed an important role for histamine release. In this model, the observation that NEC A was appreciably more potent than adenosine and that theophylline, but not enprofylline, effectively suppressed the nucleoside response when compared to the functional protection afforded against 5-hydroxytryptamine supports the view of an A2 purinoceptor-mediated mechanism. In accordance with this view, sodium cromoglycate (a mast cell-stabilizing drug) and cyproheptadine (a 5-HT and histamine antagonist) are both effective in inhibiting the response.66 In addition, the same group has recently reported increased concentrations of histamine in bronchoalveolar lavage accompanying purine-provoked change in pulmonary mechanics.67
General Medical Emergencies
Published in Anthony FT Brown, Michael D Cadogan, Emergency Medicine, 2020
Anthony FT Brown, Michael D Cadogan
Give the patient a less sedating H1 histamine antagonist such as cetirizine 10 mg or fexofenadine 180 mg orally daily. These are minimally sedating, unlike promethazine. Refractory cases may respond to the addition of an H2 histamine antagonist such as ranitidine 150 mg orally b.d.
Adverse Reactions to Antibiotics in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Diane M. Parente, Cheston B. Cunha, Michael Lorenzo
“Red man” syndrome is a transient, non-allergic, reaction to vancomycin, characterized by flushing of the head and neck, typically beginning within an hour of the start of an infusion [31]. Severe cases have been associated with angioedema, hypotension, chest pain, and, rarely, severe cardiac toxicity and death [32–34]. Red man syndrome is more frequently associated with rapid administration (i.e., <30 minutes). Each gram of vancomycin should be infused over at least 60 minutes to avoid red man syndrome. Histamine antagonists may be helpful in preventing or limiting the reaction in patients who require vancomycin and who continue to have red man syndrome despite slow administration of the drug [31,35]. Patients who develop red man syndrome should not be classified as having a vancomycin allergy, as this can be managed by stopping the infusion, administering a histamine antagonist (e.g., diphenhydramine), and then eventually re-starting at a slower rate.
Emerging therapeutic targets for anorexia nervosa
Published in Expert Opinion on Therapeutic Targets, 2023
Since a common side effect of antihistamines, acting on H1, H2 and H3 receptors with the action on the H3 suspected to predominate the effect on body weight, is sedation and/or an increase in body weight, antihistamines have been suggested to be beneficial in the treatment of anorexia nervosa as well. Cyproheptadine, a serotonin and histamine antagonist, was tested in a four-arm randomized controlled trial with the following groups: cyproheptadine and behavioral therapy or cyproheptadine and control therapy, placebo and behavioral therapy or placebo and control therapy. While cyproheptadine had no effect on body weight gain, some effects were observed on body distortion and anorexia-related cognitions [74]. Another trial compared the effect of cyproheptadine against amitriptyline and placebo, and showed that cyproheptadine decreased the length of time to reach the weight gain objective similar to amitriptyline, while it reduced depressiveness significantly more than amitriptyline [75]. Interestingly, one small brain imaging study using positron emission tomography (PET) scan visualizing H1 binding showed increased H1 binding in female patients with anorexia compared to normal females predominantly in the left lenticular nucleus and the right amygdala [76]. Moreover, an inverse association was observed between H1 binding and anxiety and depressiveness [76] pointing toward a neuroanatomical correlate of the antidepressant effect of the antihistaminergic compound reported before. However, these data are not sufficient enough to justify a recommendation for antihistamines in the treatment of anorexia nervosa yet.
Biologics for dengue prevention: up-to-date
Published in Expert Opinion on Biological Therapy, 2023
Adam T Waickman, Krista Newell, Timothy P Endy, Stephen J Thomas
Ketotifen fumarate is a histamine antagonist and mast cell stabilizer and inhibits the release of mediators associated with hypersensitivity reactions. It is currently licensed as an ophthalmic solution for allergic conjunctivitis and as an oral pill to minimize the frequency and severity of asthma attacks [119]. Studies using ketotifen fumarate in DENV infection of cells in vitro demonstrated that ketotifen fumarate reduced the expression of β-hexosamidase, a marker for granule exocytosis during mast cell activation [120]. In a mouse model of DENV infection, ketotifen was demonstrated to reduce the metabolic dysregulation and inflammation associated with infection as compared to control mice [121]. Ketotifen is currently in clinical trials in Singapore as a treatment for vascular leakage associated with severe DENV infection, ClinicalTrials.gov Identifier: NCT02673840.
Understanding ocular comfort differences between 0.7% olopatadine and 0.3% pheniramine maleate/0.025% naphazoline hydrochloride eye drops
Published in Clinical and Experimental Optometry, 2023
Chris Lievens, Andrew D. Pucker, Gerald McGwin, Amy Logan, Quentin Franklin, Randy Brafford, Catherine Hogan, Laurel R Kelley, Mike Christensen
Fortunately, numerous topical options are available for allergic conjunctivitis relief. When prescribing therapy, considerations should include initial comfort upon instillation as poor topical drop comfort has the potential to negatively impact compliance as patients are unlikely to maintain consistent use of a drop that causes bothersome symptoms. Top current pharmacologic options indicated for allergic conjunctivitis include medications such as olopatadine (antihistamine with mast-cell stabiliser properties) and pheniramine maleate (antihistamine) paired with naphazoline hydrochloride (ocular decongestant). These topical medications provide more immediate relief than systemic medications, in part due to the drop flushing the ocular surface of allergens and by supplementing the tear film to minimise exposure.4 Naphazoline hydrochloride is an alpha adrenergic vasoconstrictor that results in decreased conjunctival hyperaemia.5 When combined with pheniramine maleate, a H1-histamine antagonist, a dual action antihistamine and redness-reliever is constructed.5 Olopatadine is a dual action anti-histamine and mast cell stabiliser with high H1 receptor affinity for improved anti-itch relief and effective reduction in mast cell degranulation.4,6 The prolonged duration of action is due to the subsequent decrease in release of other cellular mediators that upregulate the inflammatory response. While olopatadine may provide immediate relief, the optimal performance is when used consistently prior to allergen exposure.5,7 Although olopatadine at 0.1% and 0.2% concentrations have been in the market for a while, 0.7% olopatadine (Pataday Once Daily Relief Extra Strength; Alcon, Fort Worth, TX, USA) is a relatively new treatment that has been introduced in select markets.