Pharmacokinetics and pharmacodynamics of olopatadine following administration via nasogastric tube to healthy horses.

OBJECTIVE: To investigate the pharmacokinetics and antihistaminic effects (pharmacodynamics) of olopatadine in a small population of healthy horses after administration via nasogastric tube. ANIMALS: 4 healthy adult Thoroughbreds. PROCEDURES: Olopatadine (0.1 mg/kg, once) was administered via nasogastric tube. Blood samples were collected at predetermined time points for pharmacokinetic analyses of the drug in plasma. Olopatadine effects were investigated by measurement of cutaneous wheals induced by ID histamine injection (0.1 mL [10 µg]/injection) at predetermined time points. Inhibition effect ratios were calculated on the basis of measured wheal size (area) after versus before olopatadine administration. RESULTS: Mean ± SD maximum plasma olopatadine concentration was 48.8 ± 11.0 ng/mL approximately 1.5 hours after administration. Median terminal half-life was 6.11 hours. Mean ± SD maximal effect was 88.2 ± 4.9% inhibition approximately 3.5 hours after drug delivery, and the inhibition effect remained > 80% for 12.5 hours after treatment. No signs of adverse clinical effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested olopatadine may have a strong, long-term inhibitory effect against histamine-induced wheals in the skin of horses. Clinical research with a larger number of horses is warranted.

Probe dependency in the determination of ligand binding kinetics at a prototypical G protein-coupled receptor.

Drug-target binding kinetics are suggested to be important parameters for the prediction of in vivo drug-efficacy. For G protein-coupled receptors (GPCRs), the binding kinetics of ligands are typically determined using association binding experiments in competition with radiolabelled probes, followed by analysis with the widely used competitive binding kinetics theory developed by Motulsky and Mahan. Despite this, the influence of the radioligand binding kinetics on the kinetic parameters derived for the ligands tested is often overlooked. To address this, binding rate constants for a series of histamine H1 receptor (H1R) antagonists were determined using radioligands with either slow (low koff) or fast (high koff) dissociation characteristics. A correlation was observed between the probe-specific datasets for the kinetic binding affinities, association rate constants and dissociation rate constants. However, the magnitude and accuracy of the binding rate constant-values was highly dependent on the used radioligand probe. Further analysis using recently developed fluorescent binding methods corroborates the finding that the Motulsky-Mahan methodology is limited by the employed assay conditions. The presented data suggest that kinetic parameters of GPCR ligands depend largely on the characteristics of the probe used and results should therefore be viewed within the experimental context and limitations of the applied methodology.

Pharmacokinetics of intranasal olopatadine in the fixed-dose combination GSP301 versus two monotherapy intranasal olopatadine formulations.

BACKGROUND: GSP301 is a fixed-dose combination of the antihistamine olopatadine hydrochloride and the corticosteroid mometasone furoate developed as a single nasal spray. OBJECTIVE: To assess the relative bioavailability of olopatadine administered as GSP301 versus two olopatadine monotherapy nasal spray formulations. METHODS: In this single-dose, open-label, crossover study, healthy adults (18-65 years old) were equally randomized to one of six treatment sequences for three 48-hour treatment periods with GSP301 (olopatadine 665 µg-mometasone 50 µg), the olopatadine monotherapy component of GSP301 (OLO-sponsor; 665 µg) and U.S. Food and Drug Administration approved olopatadine (OLO; 665 µg); each treatment was administered as a single dose (two sprays in each nostril). To assess the relative bioavailability of olopatadine in the fixed-dose nasal spray versus two monotherapies, pharmacokinetic (PK) estimates, maximum plasma concentration (Cmax), area under the plasma concentration time curve (AUC) from time 0 to the last time point with measurable concentration (AUC0-t), and AUC from time 0 to time infinity (AUC0-∞) were compared by analysis of variance. Safety and tolerability were also evaluated. RESULTS: A total of 30 healthy adults (mean age, 43.1 years) were randomized. The majority of the subjects were white men. The geometric mean ratios for natural log transformed Cmax, AUC0-t, and AUC0-∞ of olopatadine in GSP301 and OLO-sponsor were 86.63, 86.92, and 92.83, respectively. For GSP301 and OLO, geometric mean ratios for Cmax, AUC0-t, and AUC0-∞ were 84.68, 87.87, and 93.80, respectively. The percentage of subjects who reported treatment-emergent adverse events (AE) for GSP301, OLO-sponsor, and OLO were 13.8, 10.3, and 10.0%, respectively, with mild AEs reported. One subject withdrew from the study due to an AE (minor oropharyngeal pain) during OLO treatment, before receiving GSP301. CONCLUSION: Olopatadine bioavailability with GSP301 was comparable with OLO-sponsor and OLO. The presence of mometasone in GSP301 did not considerably affect the PK of olopatadine. GSP301 was well tolerated, with only mild AEs reported.

Olopatadine hydrochloride ophthalmic solution for the treatment of allergic conjunctivitis.

INTRODUCTION: Olopatadine hydrochloride is an antihistamine and mast cell stabilizer available as oral, intranasal and ocular preparations. Most of the practical applications of olopatadine therapy focus on the treatment of allergic rhinoconjunctivitis via intranasal and ocular routes. Areas covered: This article was created from a comprehensive literature search with information taken from meta-analyses, systematic reviews, and clinical trials of children and adults. The articles that have been selected, evaluate the use of intranasal and ocular antihistamines and their role in allergic rhinoconjunctivitis. Expert opinion: Olopatadine is significantly more effective than placebos in relieving the symptoms of allergic rhinoconjunctivitis. It can function both as a viable alternative or addition to first line therapies such as intranasal steroids and oral antihistamines.

Ocular pharmacokinetics comparison between 0.2% olopatadine and 0.77% olopatadine hydrochloride ophthalmic solutions administered to male New Zealand white rabbits.

PURPOSE: The primary objective of this study was to compare uptake and distribution of the commercially available formulation of 0.2% olopatadine and the newly developed 0.77% olopatadine hydrochloride ophthalmic solution formulation with improved solubility following a single (30 µL), bilateral topical ocular dose in male New Zealand white rabbits. METHODS: Each animal received a single 30-µL topical ocular dose (0.2% olopatadine or 0.77% olopatadine hydrochloride ophthalmic solution) to the right (OD) eye followed by the left (OS) eye for a total dose of 60 µL. Olopatadine concentrations were measured in ocular tissues (cornea, bulbar, conjunctiva, choroid, iris-ciliary body, whole lens, retina), aqueous humor, and plasma at prespecified time points over 24 h using a qualified liquid chromatography coupled with mass spectrometry (LC-MS/MS) analytical method. RESULTS: Olopatadine was absorbed into the eye and reached maximal levels (Cmax) within 30 min (0.5 h) to 2 h (Tmax) in ocular tissues and plasma for both treatment groups, except for the lens in which the Tmax was 4 h in the 0.2% olopatadine group and 8 h in the 0.77% olopatadine hydrochloride group, respectively. Tissues associated with the site of dosing, that is, the conjunctiva and cornea, had the highest concentrations of olopatadine in both the 0.2% olopatadine (609 and 720 ng/g) and 0.77% olopatadine hydrochloride (3,000 and 2,230 ng/g) dose groups. The greatest differences between 0.2% olopatadine and 0.77% olopatadine hydrochloride were associated with the overall duration and level of ocular exposures. CONCLUSIONS: The newly developed 0.77% olopatadine hydrochloride ophthalmic solution formulation resulted in a higher and more prolonged olopatadine concentration in the target tissue, that is, conjunctiva compared to the commercial formulation of 0.2% olopatadine ophthalmic solution.