From clinical guidelines to practice. Clinical experience in treatment of patients with allergic rhinitis

Introduction. Antihistamines are the most commonly prescribed class of medications for the treatment of allergic rhinitis (AR). However, they are also widely used in the treatment of inflammatory diseases of the ENT organs. One such drug is levocytirizine, (R) an enantiomer of cetirizine, which is a selective antagonist of peripheral histamine H1-receptors. This article analyzes the properties of levocytirizine in terms of safety and efficacy in allergic rhinitis.Aim of the study is to assess the efficacy of levocetirizine in patients with seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR) versus placebo, and safety for patients with allergic rhinitis.Materials and methods. In this, double-blind, placebo-controlled study, 52 patients with year-round allergic rhinitis and 28 patients with seasonal allergic rhinitis were randomized to receive levocetirizine 5 mg/day once or placebo. Mean overall measures of five symptoms (nasal congestion, nasal itching, itchy eyes, rhinorrhea, and sneezing) were compared between treatment groups at 1, 2, and 4 weeks. All individual symptom scores were also examined.Results. Levocetirizine showed a significant improvement in the condition of patients with CAR and SAR over the entire treatment period compared to placebo. Assessment of individual symptoms showed statistically significant differences in favor of levocetirizine. Conclusion. Levocetirizine is an effective, safe, and well-tolerated drug for the treatment of allergic rhinitis.

Microinjection of pruritogens in NGF-sensitized human skin

Single intradermal injections of nerve growth factor (NGF) evoke prolonged but temporally distinct sensitization patterns to somatosensory stimuli. Focal administration of the non-histaminergic pruritogen cowhage but not histamine resulted in elevated itch at day 21 after NGF administration. Here, we injected bovine adrenal medulla peptide 8–22 (BAM8–22), β-alanine (β-ALA) and endothelin-1 (ET-1) into NGF-treated skin of 11 healthy volunteers and investigated the corresponding itch/pain and flare reactions. β-ALA was the weakest pruritogen, while BAM8–22 and ET-1 were equally potent as histamine. NGF did not sensitize itch or flare reactions induced by any compound, but injection and evoked pain were increased at day 21 and 49. The involvement of histamine H1 receptors in itch was explored in eight subjects after oral cetirizine. ET-1-induced itch and flare were significantly reduced. BAM8–22 and β-ALA itch were not affected, but flare responses after BAM8–22 reduced by 50%. The results indicate that a single NGF injection does not sensitize for experimentally induced itch but increases pain upon pruritogen injection. In healthy humans, pruritic and algetic processing appear differentially regulated by NGF. However, in patients suffering chronic itch, prolonged elevation of NGF-levels under inflammatory conditions may contribute to elevated itch.

Molecular Determinants of the Kinetic Binding Properties of Antihistamines at the Histamine H1 Receptors

The binding affinity of ligands for their receptors is determined by their kinetic and thermodynamic binding properties. Kinetic analyses of the rate constants of association and dissociation (kon and koff, respectively) of antihistamines have suggested that second-generation antihistamines have a long duration of action owing to the long residence time (1/koff) at the H1 receptors. In this study, we examined the relationship between the kinetic and thermodynamic binding properties of antihistamines, followed by an evaluation of the structural determinants responsible for their kinetic binding properties using quantitative structure–activity relationship (QSAR) analyses. We found that whereas the binding enthalpy and entropy might contribute to the increase and decrease, respectively, in the koff values, there was no significant relationship with the kon values. QSAR analyses indicated that kon and koff values could be determined by the descriptors FASA_H (water-accessible surface area of all hydrophobic atoms divided by total water-accessible surface area) and vsurf_CW2 (a 3D molecular field descriptor weighted by capacity factor 2, the ratio of the hydrophilic surface to the total molecular surface), respectively. These findings provide further insight into the mechanisms by which the kinetic binding properties of antihistamines are regulated by their thermodynamic binding forces and physicochemical properties.

Pharmacological profile of antihistamines: focus on unwanted drug interactions

Differences between individual antihistamines are determined by such pharmacokinetic properties as the rate and completeness of absorption, half-life, the participation of hepatic and renal mechanisms of elimination from the body. Pharmacodynamic features of the antihistamine include selectivity and affinity for histamine H1-receptors and the presence of central effects. The mechanisms of the development of unwanted drug interactions with second-generation antihistamines are analyzed in detail. Three levels of interaction have been identified: 1) hepatic enzymes of the P450 system; 2) membrane carriers of organic anions (OATP) transport proteins on the sinusoidal membrane of hepatocytes and the luminal membrane of the epithelium of the proximal nephron tubule; 3) P-glycoprotein (Pgp, ABCB1-protein) of epithelial cells of the small intestine the area of absorption of oral forms of antihistamines, the epithelium of the proximal tubule and the BBB (blood-brain barrier). The emphasis is made on the description of the dependence of the pharmacological profile of antihistamines on its chemical structure. The elasticity of the bilastine molecule, the ability to induce a change in conformation underlies the high complementarity of bilastine to the recognition site of the H1-receptor which is a high affinity. Experimental evaluation confirms this conclusion: the dissociation constant (Dс) of the bilastin-receptor complex is in the nM concentration range. The bilastine molecule, as a representative of antihistamines with zwitterionic properties, carries both a positive and a negative charge at a physiological pH, making it difficult for its penetration into the brain. The peculiarities of the chemical nature of the bilastine molecule are reflected in the specific pharmacological profile of AGP. In vitro studies have shown a high specific affinity of bilastine for H1-receptors with a very low affinity for other histamine receptors (H2, H3, H4), serotonin, bradykinin, muscarinic and adrenergic receptors). According to this indicator, bilastine is 3 times higher than cetirizine and 5 times higher than fexofenadine. Bilastine is practically not metabolized in the body and is excreted mainly unchanged, and also does not have a cardiotoxic effect. Bilastine is well tolerated; as a therapeutic dose it has a less pronounced sedative potential compared to other second-generation antihistamines.

The Relaxant Effect of Plantago Major on Rat Tracheal Smooth Muscles and Its Possible Mechanisms

This study was conducted to evaluate the possible mechanisms of the relaxant effects of hydroalcoholic extract of Plantago major (P. major) on tracheal smooth muscle (TSM) in rats. The effects of cumulative concentrations of P. major (5, 10, 20 and 40 mg/mL) and theophylline (0.2, 0.4, 0.6 and 0.8 mM) were evaluated on pre-contracted TSM with 10 µΜ methacholine or 60 mM KCl. To determine the possible mechanisms, the relaxant effect of the plant was also examined on incubated TSM with atropine, indomethacin, chlorpheniramine, glibenclamide, diltiazem, papaverine, and propranolol. The results indicated concentration-dependent relaxant effects for P. major in nonincubated TSM contracted by methacholine or KCl. There was no statistically significant difference in the relaxant effects of P. major between non-incubated and incubated tissues with indomethacin, papaverine, and propranolol. However, the relaxant effects of P. major in incubated tissue with atropine (p<0.01 to p<0.001), chlorpheniramine (p<0.05 to p<0.001), glibenclamide (p<0.05), and diltiazem (p<0.01) were significantly lower than non-incubated TSM. P. major indicated relatively potent relaxant effects which were lower than those of theophylline. Muscarinic and histamine (H1) receptors inhibition, as well as calcium channel blocking and potassium channel opening effects are suggested to contribute to the TSM relaxant effect of the plant.

Aripiprazole: An FDA Approved Bioactive Compound to Treat Schizophrenia- A Mini Review

Objective: Aripiprazole, a synthetic compound, obtained by chemical modification of the structure of quinolinone is considered as an atypical antipsychotic drug. The present review is an attempt to summarize the updated information related to reported chemistry and pharmacology of Aripiprazole. Development: Aripiprazole, under development by Otsuka Pharmaceutical, was approved by the U.S. Food and Drug Administration (USFDA) by the end of 2002 with an aim to treat patients with schizophrenia. This drug got approved by European Commission in February 2013 to treat the patients having severe manic episodes in bipolar I disorder Additionally, it got approval in Japan in January 2006 and in Canada in 2014. Pharmacology: Aripiprazole shows high specificity for dopamine receptor especially D2 and D3, serotonin 5-HT1A and serotonin 5-HT2A receptors, reasonable specificity for dopamine D4, serotonin 5- HT2C and 5-HT7, alpha1-adrenergic and histamine H1 receptors. It also shows moderate specificity for the serotonin reuptake. The major side effects include headache, agitation, akithesia, anxiety, tachycardia, insomnia, postural hypotension, constipation, vomiting, dizziness, nervousness and somnolence. Conclusion: The present article embarks the available information on Aripiprazole with emphasis on its clinical pharmacology, mechanism of action, pharmacokinetics, pharmacodynamics, metabolism and clinical trials.

The use of histafen in the complex treat-ment of patients with senile itching

The purpose of the work is to evaluate the efficacy and tolerability of the drug Histafen (sechifenadine) in com­parison with the drug Loratodin in patients with senile itching. Materials and research methods. Under our supervision there were 60 patients over the age of 50 years. Clinical and laboratory examination and dynamic observation consisted of conducting a general clinical ex­amination and treatment of thematic patients with a sub­sequent analysis of the results. 30 patients of the main group who were prescribed with Histafen (sechifenadine) and 30 patients of the comparison group treated with Lor- atodine have been included in the complex treatment with the use as a blocker of histamine H1-receptors and sero­tonin 5-HT1-receptors. Histafen was prescribed 1 tablet twice a day, Loratadine - 1 tablet once a day. The ob­served patients took both drugs for 14 days. Results and its discussion. When assessing the therapeutic effect in patients of the main group as a result of the therapy with the Histafen drug, “excellent improvement” was regis­tered in 10 (33.33 %) cases, “good improvement” - in 18 (60.0 %), and “moderate improvement” - in 2 (6.67 %); “no improvement” and “deterioration” were not marked. Conclusions. The use of the drug Histafen in the treat­ment of patients with senile itching made it possible to achieve pronounced positive dynamics with rapid relief of subjective symptoms.

Pruritus associated with abrupt mirtazapine discontinuation: Single case report

It is well known that antidepressants have the potential to cause withdrawal symptoms upon abrupt discontinuation. At the time of this case report, no literature has identified intense, body-wide pruritus as a result of abrupt mirtazapine discontinuation. However, there is literature to suggest that mirtazapine may be used as a treatment for pruritus at doses as low as 15 mg/d due to its high affinity for central and peripheral histamine H1 receptors. Considering this information, it is suspected that the abrupt discontinuation of mirtazapine in the following patient case resulted in pruritus due to the reversal of antagonism at histamine receptors.