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Monographs of Topical Drugs that Have Caused Contact Allergy/Allergic Contact Dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Orphenadrine (2-methyldiphenhydramine) is a tertiary amino compound which is the phenyl-o-tolylmethyl ether of 2-(dimethylamino)ethanol. It has a role as a NMDA receptor antagonist, a H1-receptor antagonist, an antiparkinson drug, a parasympatholytic, a muscle relaxant, a muscarinic antagonist and an antidyskinesia agent. Orphenadrine is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions. In pharmaceutical products, orphenadrine is employed as orphenadrine citrate (CAS number 4682-36-4, EC number 225-137-5, molecular formula C24H31NO8) or as orphenadrine hydrochlo- ride (CAS number 341-69-5, EC number 206-435-4, molecular formula C18H24ClNO) (1).
Overview of Clinical Trials
Published in Ding-Geng (Din) Chen, Karl E. Peace, Pinggao Zhang, Clinical Trial Data Analysis Using R and SAS, 2017
Ding-Geng (Din) Chen, Karl E. Peace, Pinggao Zhang
Mechanism of action trials attempt to identify how the drug induces its effects. An example is the class of H2-receptor antagonists, such as cimetidine, ranitidine, famotidine and zanatidine, which by blocking the H2-receptor reduce the secretion of gastrin which in turn leads to a reduction of gastric acid production. Another example is the H1-receptor antagonist, seldane, which by blocking the H1-receptor reduces histamine release. Other examples are the ACE (angiotensin-converting-enzyme) inhibitors (e.g., captopril, enalapril, quinapril) which are competitive inhibitors of ACE. ACE inhibitors block the formation of the chemical: angiotensin II (AT-II) which causes muscles surrounding blood vessels to contract. Blocking the formation of AT-II leads to reduced vasoconstriction, increased vasodilation, and reduced blood pressure.
Third Histamine Receptor: From Discovery to Clinics, Long-Lasting Love Story at INSERM and Bioprojet
Published in Divya Vohora, The Third Histamine Receptor, 2008
Finally, our studies in healthy volunteers support the notion that association of tiprolisant with antipsychotic drugs might compensate the pro-obesity potential of those in which it clearly appears now to be related with blockade of H1 receptors in brain. In agreement, olanzapine, an extremely potent H1-receptor antagonist, elicited a clear-cut antisatiety effect in a group of healthy volunteers, evidenced with an adequate self-rating scale, which was completely abolished when it was associated with tiprolisant: presumably, the histamine release elicited by the latter in brain had competitively displaced olanzapine from the H1 receptor. It should be underlined that these antisatiation effects of a large number of antipsychotics are likely at the origin of the development of the metabolic syndrome, a major side effect, as well as a major obstacle to compliance.
Comparative safety review of current pharmacological treatments for interstitial cystitis/ bladder pain syndrome
Published in Expert Opinion on Drug Safety, 2021
Po-Yen Chen, Wei-Chia Lee, Yao-Chi Chuang
Hydroxyzine and cimetidine are the commonly used antihistamines for IC/BPS and suggested as second line therapy in AUA and significant value treatment in EAU guideline. Hydroxyzine bases on the mechanism of histamine H1-receptor antagonist and cimetidine acts as H2-receptor antagonist, inhibiting mast cells activation and stabilizing hypersensitive bladder. The typical dose of hydroxyzine is 25 to 75 mg. Although the clinical efficacy was described in the case series which showed improvement in symptom scores, the RCT in 121 patients compared hydroxyzine to oral PPS showed nonsignificant efficacy and low response rate as low as 31%. [38,39] The typical dose of cimetidine is 300–400 mg twice daily. Of the 36 patients recruited RCT, cimetidine decreased symptom scores and nocturia without histological change of bladder wall [40].
Efficiency and safety of desloratadine in combination with compound glycyrrhizin in the treatment of chronic urticaria: a meta-analysis and systematic review of randomised controlled trials
Published in Pharmaceutical Biology, 2021
Yulong Wen, Yidan Tang, Miaoyue Li, Yu Lai
According to most of the current hypotheses, CU is caused by the action of histamines and the H receptor involving the pathogenesis of autoimmunity (Su et al. 2020). Therefore, antihistamine drugs are widely applied in clinical treatment. Desloratadine, a second-generation H1 receptor antagonist, is highly selective for peripheral H1 receptors (Liang et al. 2014). In a related study, it was suggested that the efficacy and safety of desloratadine in the treatment of CU is obviously superior to that of other antihistamines, such as cetirizine, mizolastine, or loratadine. As a result, it is considered to have good efficacy and reliable safety in the treatment of urticaria (Lang et al. 2019). Nevertheless, the efficacy of desloratadine alone is limited, and the CU recurrence rate is relatively high (Maurer et al. 2013; Sui et al. 2018).
Pharmacotherapeutic management of atopic keratoconjunctivitis
Published in Expert Opinion on Pharmacotherapy, 2020
Ibtesham T Hossain, Priyanka Sanghi, Bita Manzouri
Oral antihistamines relieve pruritus and may reduce nocturnal eye rubbing. First-generation H1 receptor antagonists exhibit sedating side effects due to the lipophilic nature of the molecule resulting in penetration of the blood-brain barrier. Furthermore, these antagonists are nonselective and exert cross-reactivity on H2 receptors resulting in cardiac arrhythmias [32]. Other anticholinergic effects include dry mouth, blurred vision, urinary retention, and dry eyes. Second-generation H1 receptor antagonists (astemizole, fexofenadine, terfenadine, cetirizine, loratadine, ebastine, mizolastin, bepotastin, rupatadine, and bilastine) are more commonly used in allergic eye disease; they are non-sedating with less anticholinergic activity, although dry eyes may still occur. Bilastine was introduced in 2014 and is a potent selective second-generation H1 receptor antagonist. It is excreted largely unaltered in urine as well as feces and has fractional penetration of the blood-brain barrier. The efficacy of bilastine in improving nasal and ocular symptoms in patients with allergic rhinitis has been demonstrated in a large number of clinical trials [33]. However, there is no clear evidence of efficacy in atopic keratoconjunctivitis.