12.1 Mechanism of Action
STIOLTO RESPIMAT
STIOLTO RESPIMAT contains both tiotropium and olodaterol. The properties described below for the individual components apply to STIOLTO RESPIMAT. These drugs represent 2 different classes of medication (an anticholinergic and a beta-agonist) that have different effects on clinical and physiological indices.
Tiotropium
Tiotropium is a long-acting, muscarinic antagonist which is often referred to as an anticholinergic. It has similar affinity to the subtypes of muscarinic receptors, M1 to M5. In the airways, it exhibits pharmacological effects through inhibition of M3-receptors at the smooth muscle leading to bronchodilation. The competitive and reversible nature of antagonism was shown with human and animal origin receptors and isolated organ preparations. In preclinical in vitro as well as in vivo studies, prevention of methacholine-induced bronchoconstriction effects was dose-dependent and lasted longer than 24 hours. The bronchodilation following inhalation of tiotropium is predominantly a site-specific effect.
Olodaterol
Olodaterol is a long-acting beta2-adrenergic agonist (LABA). The compound exerts its pharmacological effects by binding and activation of beta2-adrenoceptors after topical administration by inhalation. Activation of these receptors in the airways results in a stimulation of intracellular adenyl cyclase, an enzyme that mediates the synthesis of cyclic-3’, 5’ adenosine monophosphate (cAMP). Elevated levels of cAMP induce bronchodilation by relaxation of airway smooth muscle cells. In vitro studies have shown that olodaterol has 241-fold greater agonist activity at beta2-adrenoceptors compared to beta1-adrenoceptors and 2299-fold greater agonist activity compared to beta3-adrenoceptors. The clinical significance of these findings is unknown.
Beta-adrenoceptors are divided into three subtypes: beta1-adrenoceptors predominantly expressed on cardiac muscle, beta2-adrenoceptors predominantly expressed on airway smooth muscle, and beta3-adrenoceptors predominantly expressed on adipose tissue. Beta2-agonists cause bronchodilation. Although the beta2-adrenoceptor is the predominant adrenergic receptor in the airway smooth muscle, it is also present on the surface of a variety of other cells, including lung epithelial and endothelial cells and in the heart. The precise function of beta2-receptors in the heart is not known, but their presence raises the possibility that even highly selective beta2-agonists may have cardiac effects.
12.2 Pharmacodynamics
Cardiac Electrophysiology
STIOLTO RESPIMAT
In two 52-week randomized, double-blind trials using STIOLTO RESPIMAT that enrolled 5162 patients with COPD, ECG assessments were performed post-dose on days 1, 85, 169, and 365. In a pooled analysis the number of subjects with changes from baseline-corrected QT interval of >30 msec using both the Bazett (QTcB) and Fredericia (QTcF), corrections of QT for heart rate were not different for the STIOLTO RESPIMAT group compared to olodaterol 5 mcg and tiotropium 5 mcg across the assessments conducted.
Tiotropium
The effect of tiotropium dry powder for inhalation on QT interval was also evaluated in a randomized, placebo- and positive-controlled crossover study in 53 healthy volunteers. Subjects received tiotropium inhalation powder 18 mcg, 54 mcg (3 times the recommended dose), or placebo for 12 days. ECG assessments were performed at baseline and throughout the dosing interval following the first and last dose of study medication. Relative to placebo, the maximum mean change from baseline in study-specific QTc interval was 3.2 msec and 0.8 msec for tiotropium inhalation powder 18 mcg and 54 mcg, respectively. No subject showed a new onset of QTc >500 msec or QTc changes from baseline of ≥60 msec.
In a multicenter, randomized, double-blind trial using tiotropium dry powder for inhalation that enrolled 198 patients with COPD, the number of subjects with changes from baseline-corrected QT interval of 30–60 msec was higher in the tiotropium group as compared with placebo. This difference was apparent using both the Bazett (QTcB) [20 (20%) patients vs. 12 (12%) patients] and Fredericia (QTcF) [16 (16%) patients vs. 1 (1%) patient] corrections of QT for heart rate. No patients in either group had either QTcB or QTcF of >500 msec. Other clinical trials with tiotropium did not detect an effect of the drug on QTc intervals.
Olodaterol
The effect of olodaterol on the QT/QTc interval of the ECG was investigated in 24 healthy male and female volunteers in a double-blind, randomized, placebo- and active (moxifloxacin)- controlled study at single doses of 10, 20, 30, and 50 mcg. Dose-dependent QtcI (individual subject corrected QT interval) prolongation was observed. The maximum mean (one-sided 95% upper confidence bound) difference in QTcI from placebo after baseline correction was 2.5 (5.6) ms, 6.1 (9.2) ms, 7.5 (10.7) ms, and 8.5 (11.6) ms following doses of 10, 20, 30, and 50 mcg, respectively.
The effect of 5 mcg and 10 mcg olodaterol on heart rate and rhythm was assessed using continuous 24-hour ECG recording (Holter monitoring) in a subset of 772 patients in the 48-week, placebo-controlled phase 3 trials. There were no dose- or time-related trends or patterns observed for the magnitudes of mean changes in heart rate or premature beats. Shifts from baseline to the end of treatment in premature beats did not indicate meaningful differences between olodaterol 5 mcg, 10 mcg, and placebo.
12.3 Pharmacokinetics
STIOLTO RESPIMAT
When STIOLTO RESPIMAT was administered by the inhalation route, the pharmacokinetic parameters for tiotropium and for olodaterol were similar to those observed when each active substance was administered separately.
Tiotropium
Tiotropium is administered as an inhalation spray. Some of the pharmacokinetic data described below were obtained with higher doses than recommended for therapy.
Olodaterol
Olodaterol showed linear pharmacokinetics. On repeated once-daily inhalation, steady-state of olodaterol plasma concentrations was achieved after 8 days, and the extent of exposure was increased up to 1.8-fold as compared to a single dose.
Absorption
Tiotropium
Following inhalation of the solution by young healthy volunteers, urinary excretion data suggests that approximately 33% of the inhaled dose reaches the systemic circulation. Oral solutions of tiotropium have an absolute bioavailability of 2% to 3%. Food is not expected to influence the absorption of tiotropium for the same reason. Maximum tiotropium plasma concentrations were observed 5 to 7 minutes after inhalation.
Olodaterol
Olodaterol reaches maximum plasma concentrations generally within 10 to 20 minutes following drug inhalation. In healthy volunteers the absolute bioavailability of olodaterol following inhalation was estimated to be approximately 30%, whereas the absolute bioavailability was below 1% when given as an oral solution. Thus, the systemic availability of olodaterol after inhalation is mainly determined by lung absorption, while any swallowed portion of the dose only negligibly contributes to systemic exposure.
Distribution
Tiotropium
The drug has a plasma protein binding of 72% and shows a volume of distribution of 32 L/kg. Local concentrations in the lung are not known, but the mode of administration suggests substantially higher concentrations in the lung. Studies in rats have shown that tiotropium does not penetrate the blood-brain barrier.
Olodaterol
Olodaterol exhibits multi-compartmental disposition kinetics after inhalation as well as after intravenous administration. The volume of distribution is high (1110 L), suggesting extensive distribution into tissue. In vitro binding of [14C] olodaterol to human plasma proteins is independent of concentration and is approximately 60%.
Elimination
Metabolism
Tiotropium
The extent of metabolism is small. This is evident from a urinary excretion of 74% of unchanged substance after an intravenous dose to young healthy volunteers. Tiotropium, an ester, is nonenzymatically cleaved to the alcohol N-methylscopine and dithienylglycolic acid, both not binding to muscarinic receptors.
In vitro experiments with human liver microsomes and human hepatocytes suggest that a fraction of the administered dose (74% of an intravenous dose is excreted unchanged in the urine, leaving 25% for metabolism) is metabolized by cytochrome P450-dependent oxidation and subsequent glutathione conjugation to a variety of Phase 2 metabolites. This enzymatic pathway can be inhibited by CYP450 2D6 and 3A4 inhibitors, such as quinidine, ketoconazole, and gestodene. Thus, CYP450 2D6 and 3A4 are involved in the metabolic pathway that is responsible for the elimination of a small part of the administered dose. In vitro studies using human liver microsomes showed that tiotropium in supra-therapeutic concentrations does not inhibit CYP450 1A1, 1A2, 2B6, 2C9, 2C19, 2D6, 2E1, or 3A4.
Olodaterol
Olodaterol is substantially metabolized by direct glucuronidation and by O-demethylation at the methoxy moiety followed by conjugation. Of the six metabolites identified, only the unconjugated demethylation product binds to beta2-receptors. This metabolite, however, is not detectable in plasma after chronic inhalation of the recommended therapeutic dose.
Cytochrome P450 isozymes CYP2C9 and CYP2C8, with negligible contribution of CYP3A4, are involved in the O-demethylation of olodaterol, while uridine diphosphate glycosyl transferase isoforms UGT2B7, UGT1A1, 1A7, and 1A9 were shown to be involved in the formation of olodaterol glucuronides.
Excretion
Tiotropium
The terminal half-life of tiotropium in COPD patients following once daily inhalation of 5 mcg tiotropium was approximately 25 hours. Total clearance was 880 mL/min after an intravenous dose in young healthy volunteers. Intravenously administered tiotropium bromide is mainly excreted unchanged in urine (74%). After inhalation of the solution by patients with COPD, urinary excretion is 18.6% (0.932 mcg) of the dose, the remainder being mainly non-absorbed drug in the gut that is eliminated via the feces. The renal clearance of tiotropium exceeds the creatinine clearance, indicating secretion into the urine. After chronic once-daily inhalation by COPD patients, pharmacokinetic steady state was reached by day 7 with no accumulation thereafter.
Olodaterol
Total clearance of olodaterol in healthy volunteers is 872 mL/min, and renal clearance is 173 mL/min. The terminal half-life following intravenous administration is 22 hours. The terminal half-life following inhalation in contrast is about 45 hours, indicating that the latter is determined by absorption rather than by elimination processes. However, the effective half-life at daily dose of 5 mcg calculated from Cmax from COPD patients is 7.5 hours.
Following intravenous administration of [14C]-labeled olodaterol, 38% of the radioactive dose was recovered in the urine and 53% was recovered in feces. The amount of unchanged olodaterol recovered in the urine after intravenous administration was 19%. Following oral administration, only 9% of olodaterol and/or its metabolites was recovered in urine, while the major portion was recovered in feces (84%). More than 90% of the dose was excreted within 6 and 5 days following intravenous and oral administration, respectively. Following inhalation, excretion of unchanged olodaterol in urine within the dosing interval in healthy volunteers at steady state accounted for 5% to 7% of the dose.
Drug Interactions
STIOLTO RESPIMAT
Pharmacokinetic drug interaction studies with STIOLTO RESPIMAT have not been performed; however, such studies have been conducted with individual components tiotropium and olodaterol.
When tiotropium and olodaterol were administered in combination by the inhaled route, the pharmacokinetic parameters for each component were similar to those observed when each active substance was administered separately.
Tiotropium
An interaction study with tiotropium (14.4 mcg intravenous infusion over 15 minutes) and cimetidine 400 mg three times daily or ranitidine 300 mg once-daily was conducted. Concomitant administration of cimetidine with tiotropium resulted in a 20% increase in the AUC0-4h, a 28% decrease in the renal clearance of tiotropium and no significant change in the Cmax and amount excreted in urine over 96 hours. Co-administration of tiotropium with ranitidine did not affect the pharmacokinetics of tiotropium.
Common concomitant medications (long-acting beta2-adrenergic agonists (LABA), inhaled corticosterioids (ICS)) used by patients with COPD were not found to alter the exposure to tiotropium.
Olodaterol
Drug-drug interaction studies were carried out using fluconazole as a model inhibitor of CYP 2C9 and ketoconazole as a potent P-gp (and CYP3A4, 2C8, 2C9) inhibitor.
Fluconazole: Co-administration of 400 mg fluconazole once a day for 14 days had no relevant effect on systemic exposure to olodaterol.
Ketoconazole: Co-administration of 400 mg ketoconazole once a day for 14 days increased olodaterol Cmax by 66% and AUC0-1 by 68%.
Tiotropium: Co-administration of tiotropium bromide, delivered as a fixed-dose combination with olodaterol, for 21 days had no relevant effect on systemic exposure to olodaterol, and vice versa.
Specific Populations
Olodaterol
A pharmacokinetic meta-analysis showed that no dose adjustment is necessary based on the effect of age, gender, and weight on systemic exposure in COPD patients after inhalation of olodaterol.
Geriatric Patients
Tiotropium
As expected for all predominantly renally excreted drugs, advancing age was associated with a decrease of tiotropium renal clearance (347 mL/min in COPD patients <65 years to 275 mL/min in COPD patients ≥65 years). This did not result in a corresponding increase in AUC0-6,ss and Cmax,ss values.
Renal Impairment
Tiotropium
Following inhaled administration of therapeutic doses of tiotropium to steady-state to patients with COPD, mild renal impairment (creatinine clearance 60 - <90 mL/min) resulted in 23% higher AUC0-6,ss and 17% higher Cmax,ss values. Moderate renal impairment (creatinine clearance 30 - <60 mL/min) resulted in 57% higher AUC0-6,ss and 31% higher Cmax,ss values compared to COPD patients with normal renal function (creatinine clearance >90 mL/min). In COPD patients with severe renal impairment (CLCR <30 mL/min), a single intravenous administration of tiotropium bromide resulted in 94% higher AUC0-4 and 52% higher Cmax compared to COPD patients with normal renal function.
Olodaterol
Olodaterol levels were increased by approximately 40% in subjects with severe renal impairment. A study in subjects with mild and moderate renal impairment was not performed.
Hepatic Impairment
Tiotropium
The effects of hepatic impairment on the pharmacokinetics of tiotropium were not studied.
Olodaterol
Subjects with mild and moderate hepatic impairment showed no changes in Cmax or AUC, nor did protein binding differ between mild and moderate hepatically impaired subjects and their healthy controls. A study in subjects with severe hepatic impairment was not performed.
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