Clinical Pharmacology for Pataday
Mechanism Of Action
Olopatadine, a structural analog of doxepin, is a non-steroidal, non-sedating, topically effective anti-allergic molecule that exerts its effects through multiple distinct mechanisms of action.
Olopatadine is a mast cell stabilizer and a potent, selective histamine H1 antagonist (10,12) that inhibits the in vivo type 1 immediate hypersensitivity reaction (13). Olopatadine inhibits the release of mast cell inflammatory mediators [i.e., histamine, tryptase, prostaglandin D2 and TNFα (4,10,12,13)] as demonstrated in in vitro studies and confirmed in patients (8). Olopatadine is also an inhibitor of pro-inflammatory cytokine secretion from human conjunctival epithelial cells (14).
Pharmacodynamics
Effects On Cardiac Repolarization (QTc)
In two placebo-controlled, two-way crossover cardiac repolarization studies, no signal of QT interval prolongation was observed relative to placebo following twice daily 5 mg oral doses for 2.5 days in 102 healthy volunteers, or following twice daily 20 mg oral doses for 13.5 days in 32 healthy volunteers. In addition, no evidence of QT interval prolongation was observed, relative to placebo, in 429 perennial allergic rhinitis patients given olopatadine hydrochloride nasal spray, 665 micrograms twice daily for up to 1 year.
Pharmacokinetics
Following topical ocular administration in man, olopatadine was shown to have low systemic exposure. Two studies in healthy volunteers (totalling 24 subjects) dosed bilaterally with Olopatadine 0.15% ophthalmic solution once every 12 hours for 2 weeks demonstrated plasma concentrations to be generally below the quantitation limit of the assay (<0.5 ng/mL).
In multiple oral dose studies, olopatadine plasma concentrations were shown to increase in proportion to the dose increment. The elimination half-life in plasma was 7-14 hours, and elimination was predominantly through renal excretion. Approximately 60-70% of the oral dose was recovered in the urine as parent drug. Peak plasma concentrations of the active metabolite, N-desmethyl olopatadine and inactive N-oxide metabolite were low, less than 1% and 3% of parent, respectively.
Special Populations And Conditions
Paediatrics
Effectiveness in paediatric patients has not been established. No overall difference in safety has been observed between paediatric and adult patients.
Geriatrics
No overall differences in safety and effectiveness have been observed between elderly and other adult patients.
Gender
In multiple oral dose studies, plasma concentrations of olopatadine are higher in female subjects, however, the differences are small and not clinically meaningful.
Race
No specific pharmacokinetic study examining the effect of race has been conducted.
Hepatic Insufficiency
No specific pharmacokinetic study examining the effect of hepatic impairment was conducted. Since metabolism of olopatadine is a minor route of elimination, no adjustment of the dosing regimen of PATADAY is warranted in patients with hepatic impairment.
Renal Insufficiency
The mean plasma Cmax values for olopatadine following single intranasal doses of olopatadine hydrochloride nasal spray 0.6% (665 μg/spray) were not markedly different between healthy subjects (18.1 ng/mL) and patients with mild, moderate and severe renal impairment (range 15.5 to 21.6 ng/mL). Plasma AUC was 2.5-fold higher in patients with severe impairment (creatinine clearance <30 mL/min/1.73m2). Predicted peak steady-state plasma concentrations of olopatadine in patients with renal impairment following administration of olopatadine hydrochloride ophthalmic solution, 0.1% are at least 10-fold lower than those observed following administration of olopatadine nasal spray 0.6%, and approximately 300-fold lower than those observed following the safe and well-tolerated administration of 20 mg oral doses for 13.5 days. These findings indicate that no adjustment of the dosing regimen of PATADAY is warranted in patients with renal impairment.
Clinical Studies
Study Demographics And Trial Design
A summary of the patient demographics for each of the 7 studies relevant to the evaluation of the efficacy of PATADAY is provided in Table 1. Overall, these demographics are representative of the population that would be expected to receive this medicinal product.
Table 1: Summary of trial design and patient demographics for clinical trials
| Study # | Trial design | Dosage, route of administration and duration | Study subjects (n=number) | Mean age (Range) | Gender |
C-00-36 CAC | randomized, double-masked, placebo-controlled | PATADAY or placebo, 1 drop each eye at each visit, dosed contra-laterally; visits on 3 non-consecutive days | n = 45 | 42.3 yrs (19 – 70) | 18 M 27 F |
C-01-18 CAC | randomized, double-masked, placebo-controlled | PATADAY, placebo, or PATADAY and placebo dosed contra-laterally, 1 drop each eye at each visit, visits on 2 non-consecutive days | n = 36 | 38.1 yrs (20-58) | 16 M 20 F |
C-01-100 CAC | randomized, double-masked, placebo-controlled | PATADAY (OU), placebo (OU), PATADAY (OS) and placebo (OD), or PATADAY (OD) and placebo (OS), 1 drop each eye at each visit, visits on 2 non-consecutive days | n = 92 | 39.2 yrs (20-67) | 38 M 54 F |
C-02-67 Environmental (grass) | randomized, double-masked, placebo-controlled parallel group | PATADAY or placebo, 1 drop each eye once daily, 10 weeks | n = 260 | 36.4 yrs (11-75) | 123 M 137 F |
C-04-60 Environmental (grass) | randomized, double-masked, placebo-controlled parallel group | PATADAY or placebo, 1 drop each eye once daily, 6 weeks | n = 287 | 36.4 yrs (10-81) | 127 M 160 F |
C-01-10 Environmental (ragweed) | randomized, double-masked, placebo-controlled, parallel group | PATADAY or placebo, 1 drop each eye once daily, 12 weeks | n = 240 | 37.3 (10-66) | 94 M 146 F |
C-01-90 Environmental (grass) | randomized, double-masked, placebo-controlled, parallel group | PATADAY or placebo, 1 drop each eye once daily, 12 weeks | n = 239 | 37.4 (10-73) | 94 M 145 F |
| OU= both eyes, OD=right eye, OS=left eye |
Study Results
Conjunctival Allergen Challenge (CAC) Studies
Three studies were conducted to assess the safety and efficacy of PATADAY versus placebo in the treatment of allergen-mediated conjunctivitis using the CAC model at 27 minutes (onset-of-action), and either 16 hours or 24 hours or both (duration-of-action), after instillation. All three studies demonstrated that PATADAY dosed once daily was statistically superior to placebo in the treatment of ocular itching, has a rapid onset-of-action and a prolonged duration-of-action.
Table 2: CAC Itching Results from Contralateral Eye Analyses in Studies with PATADAY
| Onset-of-Action | 24Hr Duration-of-Action | 16Hr Duration-of-Action |
| time post-challenge | time post-challenge | time post-challenge |
| 3 min | 5 min | 7 min | 10 min | 20 min | 3 min | 5 min | 7 min | 10 min | 20 min | 3 min | 5 min | 7 min | 10 min | 20 min |
C-00-36 PATADAY -Placebo | Mean Diff | -1.31 | | | -1.60 | -1.13 | -0.93 | | | -0.99 | -0.65 | -0.93 | | | -0.88 | -0.39 |
| pvalue | <0.001 | | | <0.001 | <0.001 | <0.001 | | | <0.001 | <0.001 | <0.001 | | | <0.001 | 0.014 |
C-01-18 PATADAY -Placebo | Mean Diff | -1.50 | | | -1.67 | -0.79 | | | | | | -1.25 | | | -1.04 | -0.50 |
| pvalue | 0.0002 | | | 0.0003 | 0.0180 | | | | | | 0.0011 | | | 0.0044 | 0.0456 |
C-01-100 PATADAY -Placebo | Mean Diff | -1.56 | -1.66 | -1.53 | | | | | | | | -0.98 | -1.07 | -1.07 | | |
| pvalue | <0.0001 | <0.0001 | <0.0001 | | | | | | | | <0.0001 | <0.0001 | <0.0001 | | |
| Shaded areas indicate that ocular itching was not evaluated at these time-points; bold numbers indicate statistical significance. |
Environmental Studies
Four environmental studies were designed to assess the safety and efficacy of PATADAY in comparison with placebo in the treatment of the signs and symptoms of seasonal allergic conjunctivitis. All studies were randomized, double-masked, placebo-controlled, multi-centre, parallel group studies. Three studies (C-02-67, C-04-60, and C-01-90) enrolled patients with a history of seasonal allergic conjunctivitis, a positive diagnostic skin prick test for grass antigen within the past 2 years, and a positive response to grass in the Conjunctival Allergen Challenge model of the required magnitude. One study (C-01-10) enrolled patients with a positive skin prick test for ragweed antigen. Daily pollen counts were recorded for each study site.
Clinical Study C-02-67
Two hundred and sixty (260) patients were enrolled in this 10-week environmental study. The primary efficacy analysis was based on the subject self-evaluation of the frequency of ocular itching during the three days prior to each weekly assessment visit. The results showed that PATADAY statistically significantly reduced the effects of pollen on ocular itching relative to vehicle when dosed once a day (Figure 1).
Figure 1: Mean Scores for Itching Frequency by Visit Day (Intent-to-Treat) (C-02-67)
An analysis of the slopes of the lines measuring the effects of pollen on ocular itching also showed a statistically significant difference between PATADAY and placebo when pollen counts were taken into consideration.
The secondary analysis showed that PATADAY, dosed once a day, statistically significantly reduced the effects of pollen on daily itching severity when compared to vehicle (Table 3).
Table 3: Mean Itching Severity during 14 Consecutive Days of Peak Pollen (Intent-to-Treat) (C-02-67)
| ITCHING |
| PATADAY | Mean | 1.10 |
| Std | 0.92 |
| N | 127 |
| PLACEBO | Mean | 1.48 |
| Std | 1.04 |
| N | 129 |
| Difference from Vehicle | | -0.38 |
| p-value (t-test) | | 0.0023 |
Clinical Study C-04-60
Two hundred and eighty-seven (287) patients were enrolled in this 6-week environmental study. Severity scores for daily ocular itching, as recorded by patients three times per day in their diaries, were statistically significantly lower compared to placebo in the morning, mid-day, and evening when averaged over the 14 consecutive days of the peak pollen period. Additionally, the average diary itching scores are statistically significantly reduced in patients treated with PATADAY compared with placebo (Table 4).
Table 4: Average Diary Itching Over the Peak Pollen Period by Time (Intent-to-Treat) (C-04-60)
| Average Diary Itching |
| Mean | Std | N | P-value |
| Morning | PATADAY | 0.55 | 0.60 | 144 | 0.0204 |
| Vehicle | 0.72 | 0.64 | 143 | |
| Mid-Day | PATADAY | 0.50 | 0.61 | 144 | 0.0130 |
| Vehicle | 0.69 | 0.63 | 143 | |
| Evening | PATADAY | 0.54 | 0.65 | 144 | 0.0084 |
| Vehicle | 0.74 | 0.67 | 143 | |
Clinical Study C-01-10
A total of 240 patients were enrolled in this 12-week environmental study during ragweed season. The primary efficacy endpoint was subject self-evaluation of the frequency scores of ocular itching over a 12-week study period. The primary efficacy endpoint did not show any statistically significant difference between PATADAY and placebo in this study.
Clinical Study C-01-90
A total of 239 patients were enrolled in a 12-week environmental study during grass season. The primary efficacy endpoint was subject self-evaluation of the worst daily ocular itching averaged over a two-week, peak pollen period. The primary efficacy endpoint did not show any statistically significant difference between PATADAY and placebo in this study. The planned secondary efficacy analysis showed that PATADAY statistically significantly reduced the effects of pollen on ocular itching.
Detailed Pharmacology
Olopatadine is an anti-allergic agent that exerts its effects through multiple distinct mechanisms of action. Olopatadine is a mast cell stabilizer and a potent, selective histamine H1 antagonist (11) that inhibits the in vivo type 1 immediate hypersensitivity reaction. In vitro studies have demonstrated the ability of olopatadine to stabilize rodent basophils and human conjunctival mast cells and inhibit immunologically-stimulated release of histamine. In addition, olopatadine inhibits the release of other mast cell inflammatory mediators [i.e., histamine, tryptase, prostaglandin D2 and TNFα (4,10,12,13)] as demonstrated in in vitro studies. Olopatadine is a selective histamine H1 receptor antagonist in vitro and in vivo as demonstrated by its ability to inhibit histamine binding and histamine-stimulated vascular permeability in the conjunctiva following topical ocular administration (12). Olopatadine is also an inhibitor of pro-inflammatory cytokine secretion from human conjunctival epithelial cells (14). Decreased chemotaxis and inhibition of eosinophil activation has also been reported (6,9). Olopatadine is devoid of effects on alpha-adrenergic, dopamine, muscarinic type 1 and 2, and serotonin receptors.
Human Pharmacodynamics
Olopatadine had no observed effect on heart rate, cardiac conduction (PR and QRS interval duration), cardiac repolarization (QT duration) or wave form morphology relative to placebo in 2 double-masked, placebo controlled, 2-way crossover studies of 102 subjects given 5-mg oral doses of olopatadine every 12 hours for 2.5 days and 32 subjects given 20-mg oral doses twice-daily for 13.5 days. No clinically relevant or statistically significant changes in mean QTcF (determined to be the most appropriate heart correction formula for both study populations) at steady-state from baseline were observed in either study. A categorical analysis of QTc (< 30 ms, 30 ms-60 ms, or > 60 ms) showed no statistically significant differences between olopatadine and placebo in both studies. An analysis of the maximal change from baseline in QTcF showed the difference was higher for placebo than for olopatadine.
Human Pharmacokinetics
Systemic bioavailability data upon topical ocular administration of PATADAY are not available. Following topical ocular administration in man, olopatadine was shown to have low systemic exposure. Two studies in normal volunteers (totalling 24 subjects) dosed bilaterally with Olopatadine 0.15% ophthalmic solution once every 12 hours for 2 weeks demonstrated plasma concentrations to be generally below the quantitation limit of the assay (< 0.5 ng/mL). Samples in which olopatadine was quantifiable were typically found within 2 hours of dosing and ranged from 0.5 to 1.3 ng/mL. These plasma concentrations were greater than 300 fold below those observed with a well-tolerated 20 mg oral multiple-dose regimen. In oral studies, olopatadine was found to be well absorbed. The half-life in plasma was 7-14 hours, and elimination was predominantly through renal excretion. Approximately 60-70% of the dose was recovered in the urine as parent drug. Two metabolites, the mono-desmethyl and the N-oxide, were detected at low concentrations in the urine.
REFERENCES
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