Loratadine. A review of recent findings in pharmacology, pharmacokinetics, efficacy, and safety, with a look at its use in combination with pseudoephedrine

Loratadine-associated cystoid macular edema: A case report

Purpose

To report the first known case of bilateral cystoid macular edema in a patient undergoing long-term loratadine treatment.

Observations

A 49-year-old Chinese woman who had been undergoing treatment with loratadine for the past 6 years presented with decreased visual acuity and bilateral cystoid macular edema (CME). Upon cessation of loratadine, macular edema partially resolved, and visual acuity markedly improved. Fundus autofluorescence (FAF), optical coherence tomography (OCT), and fluorescence fundus angiography (FFA) were used to document the severity of CME and its subsequent resolution after cessation of loratadine therapy.

Conclusions and Importance

Long-term use of loratadine might cause CME that partially resolves with discontinuation of the drug. The pathophysiology of drug-induced CME without leakage remains unclear. Dysfunction of histamine receptor1-expressed retinal neurons and the associated signal transduction, toxicity to Müller cells or RPE cells with subsequent intracellular fluid accumulation, and subclinical damage to the blood-retina barrier leading to leakage of extracellular fluid, have been proposed.

Novel polar AhR-active chemicals detected in sediments of an industrial area using effect-directed analysis based on in vitro bioassays with full-scan high resolution mass spectrometric screening

Studies investigating aryl hydrocarbon receptor (AhR)-active compounds in the environment typically focus on non- and mid-polar substances, such as PAHs; while, information on polar AhR agonists remains limited. Here, we identified polar AhR agonists in sediments collected from the inland creeks of an industrialized area (Lake Sihwa, Korea) using effect-directed analysis combined with full-scan screening analysis (FSA; using LC-QTOFMS). Strong AhR-mediated potencies were observed for the polar and latter fractions of RP-HPLC (F3.5-F3.8) from sediment organic extracts in the H4IIE-luc in vitro bioassays. FSA was performed on the corresponding fractions. Twenty-eight tentative AhR agonists were chosen using a five-step process. Toxicological confirmation using bioassay revealed that canrenone, rutaecarpine, ciprofloxacin, mepanipyrim, genistein, protopine, hydrocortisone, and medroxyprogesterone were significantly active. The relative potencies of these AhR-active compounds compared to that of benzo[a]pyrene ranged from 0.00002 to 2.0. Potency balance analysis showed that polar AhR agonists explained, on average, ~6% of total AhR-mediated potencies in samples. Some novel polar AhR agonists also exhibited endocrine-disrupting potentials capable of binding to estrogen and glucocorticoid receptors, as identified by QSAR modeling. In conclusion, the focused studies on distributions, sources, fate, and ecotoxicological effects of novel polar AhR agonists in the environment are necessary.

Structural and clinical impact of anti-allergy agents: An overview

Allergic disorders are markedly rising in industrialized countries. The identification of compounds that trigger the immunoglobulin E (IgE)-dependent allergic reaction remain the means to improve the quality of life by limiting patient's exposure to critical allergens. Information concerning the treatment and onset of allergic disorders including atopic dermatitis, allergic rhinitis, and bronchial asthma has been provided by the research over the past decade. Recent studies also indicated that allergic inflammation is associated closely with their exacerbation and progression and indeed is the basic pathophysiology of allergic diseases. As a result of immunological and molecular biological studies our understanding of the mechanism of allergic inflammation with regard to therapeutic agents has improved. While much effort has been paid to developing a new anti-allergic agent, the allergic disease has yet to be completely conquered. The more extensive research will allow the development of new therapeutics to combat allergic diseases. Currently, with respect to mechanism of action anti-allergy drugs are classified into five types including histamine H₁ antagonists, leukotriene antagonists, Th₂ cytokine inhibitors, thromboxane A₂ inhibitors and mediator-release inhibitors. The use of two or more anti-allergy agents together is not acknowledged at present, but this will be the subject of research in the future because with different mechanisms of action anti-allergy agents used at the same time will theoretically increase their effects. This review article focuses on anti-allergy agents highlighting their applications, clinical trials and recent advancement on drugs.

Effects of methysergide and loratadine on food intake, mood, and performance of humans living in a residential laboratory

The effects of loratadine, a peripherally acting histamine (H1) antagonist, and methysergide, a serotonin (5-HT) antagonist, were evaluated in seven normal-weight, male research volunteers, participating in a placebo-controlled, double-blind, 17-day residential study. Participants received oral loratadine (10 or 20 mg), methysergide (4 or 8 mg), or placebo at 1000 and 1700 hours daily. Active drug was administered on Days 4, 5, 7, 8, 11, 12, 15, and 16; placebo was administered on all other days. Drug and dose order were counterbalanced across participants. Food intake, performance, and subjective ratings were measured repeatedly throughout the day. Loratadine had no effect on food intake, performance, or subjective ratings. In contrast, total caloric intake significantly decreased from approximately 3500 kcal during placebo administration to 3065 kcal on the first but not the second day of methysergide administration. Consumption of carbohydrate (p < 0.055), protein, and fat decreased on the first day of methysergide administration. This decrease in food intake was due to a decrease in meal size; the number of meals consumed was not affected. The proportion of calories derived from carbohydrates significantly increased on the first day of methysergide administration. Methysergide also significantly impaired performance of a psychomotor task on the first day of high-dose administration and increased ratings of several subjective measures, including "Vomiting," "Stomach Pain," and "Miserable." These results suggest that the anorectic effect occurred as a result of the somatic and mood changes produced by methysergide. In addition, the inability of loratadine to affect food intake indicates that antagonism of central histamine receptors may be responsible for the increases in food intake produced by other antihistamines (e.g., diphenhydramine).

Effect of loratadine, an H1 antihistamine, on induced cough in non-asthmatic patients with chronic cough

BACKGROUND

H1 antihistamines have been shown to have an antitussive effect in patients with asthma, postnasal drip, and allergic rhinitis. No study has been performed to determine whether orally administered H1 antihistamines can reduce the number of coughs induced by stimulation of cough receptors in non-asthmatic patients with chronic dry cough.

METHODS

The effect of loratadine (10 mg) on the number of coughs induced by ultrasonically nebulised distilled water (UNDW) was examined in 10 patients with nasal disease and in seven patients with unexplained chronic cough using a randomised, double blind crossover method. Eleven normal volunteers were also studied. Each subject inhaled UNDW for one minute, and the numbers of coughs during the one minute inhalation and the 30 seconds following it were counted.

RESULTS

There was no difference in the results of pulmonary function tests performed before and one minute after UNDW inhalation for either patients or normal subjects. There was also no significant difference between the results of pulmonary function tests before or after oral administration of loratadine. Loratadine significantly reduced the number of coughs in patients with nasal disease and in those with unexplained chronic cough, but not in normal subjects.

CONCLUSIONS

The H1 antihistamine loratadine reduces cough induced by UNDW. The release of histamine may contribute to the chronic cough in patients with unexplained chronic cough or nasal disease.