Absorption
Fluticasone Propionate: Healthy Subjects: Fluticasone propionate acts locally in the lung; therefore, plasma levels do not predict therapeutic effect. Trials using oral dosing of labeled and unlabeled drug have demonstrated that the oral systemic bioavailability of fluticasone propionate is negligible (<1%), primarily due to incomplete absorption and presystemic metabolism in the gut and liver. In contrast, the majority of the fluticasone propionate delivered to the lung is systemically absorbed.
Three (3) single-dose, placebo-controlled, crossover trials were conducted in healthy subjects: (1) a trial using 4 inhalations of fluticasone propionate and salmeterol HFA 230 mcg/21 mcg, salmeterol CFC inhalation aerosol 21 mcg, or fluticasone propionate CFC inhalation aerosol 220 mcg, (2) a trial using 8 inhalations of fluticasone propionate and salmeterol HFA 45 mcg/21 mcg, fluticasone propionate and salmeterol HFA 115 mcg/21 mcg, or fluticasone propionate and salmeterol HFA 230 mcg/21 mcg, and (3) a trial using 4 inhalations of fluticasone propionate and salmeterol HFA 230 mcg/21 mcg; 2 inhalations of ADVAIR DISKUS 500 mcg/50 mcg; 4 inhalations of fluticasone propionate CFC inhalation aerosol 220 mcg; or 1,010 mcg of fluticasone propionate given intravenously. Peak plasma concentrations of fluticasone propionate were achieved in 0.33 to 1.5 hours and those of salmeterol were achieved in 5 to 10 minutes.
Peak plasma concentrations of fluticasone propionate (N = 20 subjects) following 8 inhalations of fluticasone propionate and salmeterol HFA 45 mcg/21 mcg, fluticasone propionate and salmeterol HFA 115 mcg/21 mcg, and fluticasone propionate and salmeterol HFA 230 mcg/21 mcg averaged 41, 108, and 173 pg/mL, respectively.
Systemic exposure (N = 20 subjects) from 4 inhalations of fluticasone propionate and salmeterol HFA 230 mcg/21 mcg was 53% of the value from the individual inhaler for fluticasone propionate CFC inhalation aerosol and 42% of the value from the individual inhaler for salmeterol CFC inhalation aerosol. Peak plasma concentrations from fluticasone propionate and salmeterol HFA for fluticasone propionate (86 versus 120 pg/mL) and salmeterol (170 versus 510 pg/mL) were significantly lower compared with individual inhalers.
In 15 healthy subjects, systemic exposure to fluticasone propionate from 4 inhalations of fluticasone propionate and salmeterol HFA 230 mcg/21 mcg (920/84 mcg) and 2 inhalations of ADVAIR DISKUS 500 mcg/50 mcg (1,000/100 mcg) was similar between the 2 inhalers (i.e., 799 versus 832 pg•h/mL, respectively), but approximately half the systemic exposure from 4 inhalations of fluticasone propionate CFC inhalation aerosol 220 mcg (880 mcg, AUC = 1,543 pg•h/mL). Similar results were observed for peak fluticasone propionate plasma concentrations (186 and 182 pg/mL from fluticasone propionate and salmeterol HFA and ADVAIR DISKUS, respectively, and 307 pg/mL from the fluticasone propionate CFC inhalation aerosol). Absolute bioavailability of fluticasone propionate was 5.3% and 5.5% following administration of fluticasone propionate and salmeterol HFA and ADVAIR DISKUS, respectively.
Subjects with Asthma: A double-blind crossover trial was conducted in 13 adult subjects with asthma to evaluate the steady-state pharmacokinetics of fluticasone propionate and salmeterol following administration of 2 inhalations of fluticasone propionate and salmeterol HFA 115 mcg/21 mcg twice daily or 1 inhalation of ADVAIR DISKUS 250 mcg/50 mcg twice daily for 4 weeks. Systemic exposure (AUC) to fluticasone propionate was similar for fluticasone propionate and salmeterol HFA (274 pg•h/mL [95% CI: 150, 502]) and ADVAIR DISKUS (338 pg•h/mL [95% CI: 197, 581]).
The effect of 21 days of treatment with fluticasone propionate and salmeterol HFA 45 mcg/21 mcg (2 inhalations twice daily with or without a spacer) or ADVAIR DISKUS 100 mcg/50 mcg (1 inhalation twice daily) was evaluated in a trial of 31 children aged 4 to 11 years with mild asthma. Systemic exposure to fluticasone propionate was similar with ADVAIR DISKUS and fluticasone propionate and salmeterol HFA with a spacer (138 pg•h/mL [95% CI: 69, 273] and 107 pg•h/mL [95% CI: 46, 252], respectively) and lower with fluticasone propionate and salmeterol HFA without a spacer (24 pg•h/mL [95% CI: 10, 60]).
Salmeterol Xinafoate: Healthy Subjects: Salmeterol xinafoate, an ionic salt, dissociates in solution so that the salmeterol and 1-hydroxy-2-naphthoic acid (xinafoate) moieties are absorbed, distributed, metabolized, and eliminated independently. Salmeterol acts locally in the lung; therefore, plasma levels do not predict therapeutic effect.
Peak plasma concentrations of salmeterol (N = 20 subjects) following 8 inhalations of fluticasone propionate and salmeterol HFA 45 mcg/21 mcg, fluticasone propionate and salmeterol HFA 115 mcg/21 mcg, and fluticasone propionate and salmeterol HFA 230 mcg/21 mcg ranged from 220 to 470 pg/mL.
In 15 healthy subjects receiving fluticasone propionate and salmeterol HFA 230 mcg/21 mcg (920/84 mcg) and ADVAIR DISKUS 500 mcg/50 mcg (1,000/100 mcg), systemic exposure to salmeterol was higher (317 versus 169 pg•h/mL) and peak salmeterol concentrations were lower (196 versus 223 pg/mL) following fluticasone propionate and salmeterol HFA compared with ADVAIR DISKUS, although pharmacodynamic results were comparable.
Subjects with Asthma: Because of the small therapeutic dose, systemic levels of salmeterol are low or undetectable after inhalation of recommended dosages (42 mcg of salmeterol inhalation aerosol twice daily). Following chronic administration of an inhaled dose of 42 mcg of salmeterol inhalation aerosol twice daily, salmeterol was detected in plasma within 5 to 10 minutes in 6 subjects with asthma; plasma concentrations were very low, with mean peak concentrations of 150 pg/mL at 20 minutes and no accumulation with repeated doses.
A double-blind crossover trial was conducted in 13 adult subjects with asthma to evaluate the steady-state pharmacokinetics of fluticasone propionate and salmeterol following administration of 2 inhalations of fluticasone propionate and salmeterol HFA 115 mcg/21 mcg twice daily or 1 inhalation of ADVAIR DISKUS 250 mcg/50 mcg twice daily for 4 weeks. Systemic exposure to salmeterol was similar for fluticasone propionate and salmeterol HFA (53 pg•h/mL [95% CI: 17, 164]) and ADVAIR DISKUS (70 pg•h/mL [95% CI: 19, 254]).
The effect of 21 days of treatment with fluticasone propionate and salmeterol HFA 45 mcg/21 mcg (2 inhalations twice daily with or without a spacer) or ADVAIR DISKUS 100 mcg/50 mcg (1 inhalation twice daily) was evaluated in 31 children aged 4 to 11 years with mild asthma. Systemic exposure to salmeterol was similar for fluticasone propionate and salmeterol HFA, fluticasone propionate and salmeterol HFA with spacer, and ADVAIR DISKUS (126 pg•h/mL [95% CI: 70, 225], 103 pg•h/mL [95% CI: 54, 200], and 110 pg•h/mL [95% CI: 55, 219], respectively).
Distribution
Fluticasone Propionate: Following intravenous administration, the initial disposition phase for fluticasone propionate was rapid and consistent with its high lipid solubility and tissue binding. The volume of distribution averaged 4.2 L/kg.
The percentage of fluticasone propionate bound to human plasma proteins averages 99%. Fluticasone propionate is weakly and reversibly bound to erythrocytes and is not significantly bound to human transcortin.
Salmeterol: The percentage of salmeterol bound to human plasma proteins averages 96% in vitro over the concentration range of 8 to 7,722 ng of salmeterol base per milliliter, much higher concentrations than those achieved following therapeutic doses of salmeterol.
Elimination
Fluticasone Propionate: Following intravenous dosing, fluticasone propionate showed polyexponential kinetics and had a terminal elimination half-life of approximately 7.8 hours. The total clearance of fluticasone propionate is high (average, 1,093 mL/min), with renal clearance accounting for <0.02% of the total. Less than 5% of a radiolabeled oral dose was excreted in the urine as metabolites, with the remainder excreted in the feces as parent drug and metabolites. Terminal half-life estimates of fluticasone propionate for fluticasone propionate and salmeterol HFA, ADVAIR DISKUS, and fluticasone propionate CFC inhalation aerosol were similar and averaged 5.6 hours.
Salmeterol: In 2 healthy adult subjects who received 1 mg of radiolabeled salmeterol (as salmeterol xinafoate) orally, approximately 25% and 60% of the radiolabeled salmeterol was eliminated in urine and feces, respectively, over a period of 7 days. The terminal elimination half-life was about 5.5 hours (1 volunteer only).
The xinafoate moiety has no apparent pharmacologic activity. The xinafoate moiety is highly protein bound (>99%) and has a long elimination half-life of 11 days. No terminal half-life estimates were calculated for salmeterol following administration of fluticasone propionate and salmeterol HFA.
Metabolism: Fluticasone Propionate: The only circulating metabolite detected in man is the 17β-carboxylic acid derivative of fluticasone propionate, which is formed through the CYP3A4 pathway. This metabolite had less affinity (approximately 1/2,000) than the parent drug for the glucocorticoid receptor of human lung cytosol in vitro and negligible pharmacological activity in animal studies. Other metabolites detected in vitro using cultured human hepatoma cells have not been detected in man.
Salmeterol: Salmeterol base is extensively metabolized by hydroxylation, with subsequent elimination predominantly in the feces. No significant amount of unchanged salmeterol base was detected in either urine or feces.
An in vitro study using human liver microsomes showed that salmeterol is extensively metabolized to α-hydroxysalmeterol (aliphatic oxidation) by CYP3A4. Ketoconazole, a strong inhibitor of CYP3A4, essentially completely inhibited the formation of α-hydroxysalmeterol in vitro.
Specific Populations
A population pharmacokinetic analysis was performed for fluticasone propionate and salmeterol utilizing data from 9 controlled clinical trials that included 350 subjects with asthma aged 4 to 77 years who received treatment with ADVAIR DISKUS, fluticasone propionate and salmeterol HFA, fluticasone propionate inhalation powder (FLOVENT DISKUS), HFA-propelled fluticasone propionate inhalation aerosol (FLOVENT HFA), or CFC-propelled fluticasone propionate inhalation aerosol. The population pharmacokinetic analyses for fluticasone propionate and salmeterol showed no clinically relevant effects of age, gender, race, body weight, body mass index, or percent of predicted FEV1 on apparent clearance and apparent volume of distribution.
Patients with Hepatic and Renal Impairment: Formal pharmacokinetic studies using fluticasone propionate and salmeterol HFA have not been conducted in patients with hepatic or renal impairment. However, since both fluticasone propionate and salmeterol are predominantly cleared by hepatic metabolism, impairment of liver function may lead to accumulation of fluticasone propionate and salmeterol in plasma. Therefore, patients with hepatic disease should be closely monitored.
Drug Interaction Studies
In the repeat- and single-dose trials, there was no evidence of significant drug interaction in systemic exposure between fluticasone propionate and salmeterol when given alone or in combination via the DISKUS. Similar definitive studies have not been performed with fluticasone propionate and salmeterol HFA. The population pharmacokinetic analysis from 9 controlled clinical trials in 350 subjects with asthma showed no significant effects on fluticasone propionate or salmeterol pharmacokinetics following co-administration with beta2-agonists, corticosteroids, antihistamines, or theophyllines.
Inhibitors of Cytochrome P450 3A4: Ritonavir: Fluticasone Propionate: Fluticasone propionate is a substrate of CYP3A4. Coadministration of fluticasone propionate and the strong CYP3A4 inhibitor ritonavir is not recommended based upon a multiple-dose, crossover drug interaction trial in 18 healthy subjects. Fluticasone propionate aqueous nasal spray (200 mcg once daily) was coadministered for 7 days with ritonavir (100 mg twice daily). Plasma fluticasone propionate concentrations following fluticasone propionate aqueous nasal spray alone were undetectable (<10 pg/mL) in most subjects, and when concentrations were detectable peak levels (Cmax) averaged 11.9 pg/mL (range: 10.8 to 14.1 pg/mL) and AUC(0-τ) averaged 8.43 pg•h/mL (range: 4.2 to 18.8 pg•h/mL). Fluticasone propionate Cmax and AUC(0-τ) increased to 318 pg/mL (range: 110 to 648 pg/mL) and 3,102.6 pg•h/mL (range: 1,207.1 to 5,662.0 pg•h/mL), respectively, after coadministration of ritonavir with fluticasone propionate aqueous nasal spray. This significant increase in plasma fluticasone propionate exposure resulted in a significant decrease (86%) in serum cortisol AUC.
Ketoconazole: Fluticasone Propionate: In a placebo-controlled crossover trial in 8 healthy adult volunteers, coadministration of a single dose of orally inhaled fluticasone propionate (1,000 mcg) with multiple doses of ketoconazole (200 mg) to steady state resulted in increased plasma fluticasone propionate exposure, a reduction in plasma cortisol AUC, and no effect on urinary excretion of cortisol.
Salmeterol: In a placebo-controlled, crossover drug interaction trial in 20 healthy male and female subjects, coadministration of salmeterol (50 mcg twice daily) and the strong CYP3A4 inhibitor ketoconazole (400 mg once daily) for 7 days resulted in a significant increase in plasma salmeterol exposure as determined by a 16-fold increase in AUC (ratio with and without ketoconazole 15.76 [90% CI: 10.66, 23.31]) mainly due to increased bioavailability of the swallowed portion of the dose. Peak plasma salmeterol concentrations were increased by 1.4-fold (90% CI: 1.23, 1.68). Three (3) out of 20 subjects (15%) were withdrawn from salmeterol and ketoconazole coadministration due to beta-agonist–mediated systemic effects (2 with QTc prolongation and 1 with palpitations and sinus tachycardia). Coadministration of salmeterol and ketoconazole did not result in a clinically significant effect on mean heart rate, mean blood potassium, or mean blood glucose. Although there was no statistical effect on the mean QTc, coadministration of salmeterol and ketoconazole was associated with more frequent increases in QTc duration compared with salmeterol and placebo administration.
Erythromycin: Fluticasone Propionate: In a multiple-dose drug interaction trial, coadministration of orally inhaled fluticasone propionate (500 mcg twice daily) and erythromycin (333 mg 3 times daily) did not affect fluticasone propionate pharmacokinetics.
Salmeterol: In a repeat-dose trial in 13 healthy subjects, concomitant administration of erythromycin (a moderate CYP3A4 inhibitor) and salmeterol inhalation aerosol resulted in a 40% increase in salmeterol Cmax at steady state (ratio with and without erythromycin 1.4 [90% CI: 0.96, 2.03], P = 0.12), a 3.6-beat/min increase in heart rate ([95% CI: 0.19, 7.03], P<0.04), a 5.8-msec increase in QTc interval ([95% CI: -6.14, 17.77], P = 0.34), and no change in plasma potassium.