Absorption
Fluticasone Propionate:
Fluticasone Propionate/Salmeterol MDPI acts locally in the lung; therefore, plasma levels may not predict therapeutic effect. Trials using oral dosing of labeled and unlabeled drug have demonstrated that the oral systemic bioavailability of fluticasone propionate was 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 was systemically absorbed.
After administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI to patients aged 12 years and older with persistent asthma in a clinical trial, the mean Cmax value of fluticasone propionate was 66 pg/mL with a median tmax value of approximately 2 hours.
Salmeterol:
After administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI to patients aged 12 years and older with persistent asthma, the mean Cmax values of salmeterol was 60 pg/mL. The median tmax was 5 minutes.
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:
Volume of distribution data are not available for 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. Terminal half-life estimates of fluticasone propionate following oral inhalation administration of Fluticasone Propionate/Salmeterol MDPI were approximately 10.8 hours.
Metabolism
The total clearance of fluticasone propionate is high (average, 1,093 mL/minute), with renal clearance accounting for less than 0.02% of the total. The only circulating metabolite detected in humans is the 17β carboxylic acid derivative of fluticasone propionate, which is formed through the CYP3A4 pathway. This metabolite has 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 humans.
Excretion
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.
Salmeterol:
Terminal half-life estimates for salmeterol for Fluticasone Propionate/Salmeterol MDPI were approximately 12.6 hours.
The xinafoate moiety has no apparent pharmacologic activity. The xinafoate moiety is highly protein bound (greater than 99%) and has a long elimination half-life of 11 days.
Metabolism
Salmeterol base is extensively metabolized by hydroxylation.
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.
Excretion
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.
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 another fluticasone propionate and salmeterol MDPI, the combination of HFA‑propelled fluticasone propionate and salmeterol inhalation aerosol, fluticasone propionate MDPI, HFA‑propelled fluticasone propionate inhalation aerosol, 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. Fluticasone Propionate/Salmeterol MDPI is not approved in pediatric patients younger than 12 years.
Geriatric and Pediatric Patients: No pharmacokinetic studies have been performed with Fluticasone Propionate/Salmeterol MDPI in pediatric or geriatric patients. A subgroup analysis was conducted to compare patients aged 12-17 (n=15) and ≥18 (n=23) years following administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI. No overall differences in fluticasone propionate and salmeterol pharmacokinetics were observed.
Male and Female Patients: A subgroup analysis was conducted to compare male (n=21) and female (n=16) patients following administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI. No overall differences in fluticasone propionate and salmeterol pharmacokinetics were observed.
Patients with Renal Impairment: The effect of renal impairment of the pharmacokinetics of Fluticasone Propionate/Salmeterol MDPI has not been evaluated.
Patients with Hepatic Impairment: Formal pharmacokinetic studies using Fluticasone Propionate/Salmeterol MDPI have not been conducted in patients with hepatic 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 [see Use in Specific Populations (8.6)].
Drug Interaction Studies
In a single-dose trial, the presence of salmeterol did not alter fluticasone propionate exposure.
No studies have been performed with Fluticasone Propionate/Salmeterol MDPI to investigate the effect of fluticasone propionate on salmeterol pharmacokinetics when given in combination.
Drug Interaction Studies with Another Fluticasone Propionate/Salmeterol MDPI Product:
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.
Strong CYP3A4 Inhibitors: Fluticasone propionate is a substrate of CYP3A4. Coadministration of fluticasone propionate and ritonavir, a strong CYP3A4 inhibitor, is not recommended based upon a multiple-dose, crossover drug interaction trial in 18 healthy subjects [see Drug Interactions (7.1)]. 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 AUC0-τ averaged 8.43 pg•h/mL (range: 4.2 to 18.8 pg•h/mL). However, the fluticasone propionate Cmax and AUC0-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 7 days of coadministration of ritonavir (100 mg twice daily) with fluticasone propionate aqueous nasal spray (200 mcg once daily). This significant increase in plasma fluticasone propionate exposure resulted in a significant decrease (86%) in serum cortisol AUC.
Ketoconazole: 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.
In a placebo-controlled, crossover drug interaction trial in 20 healthy male and female subjects, coadministration of salmeterol (50 mcg twice daily) and ketoconazole, a strong CYP3A4 inhibitor, (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 administration alone and placebo administration.
Erythromycin: 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.
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.