Absorption: In a study that compared the relative bioavailability of Lazanda and an oral transmucosal fentanyl citrate product, the bioavailability of fentanyl from Lazanda was approximately 20% higher. Fentanyl is absorbed from the nasal mucosa following intranasal administration of Lazanda, with median Tmax values ranging from 15-21 min after administration of a single dose. Cmax and AUC values for fentanyl following administration of Lazanda increase linearly over the 100- to 800-mcg dose range. 

Mean plasma concentration versus time profiles are presented in Figure 1. Mean pharmacokinetic parameters are presented in Table 3.

In a pharmacokinetic study that evaluated multiple-dose pharmacokinetics of Lazanda when two doses of Lazanda are administered in the same nostril and are separated by a 1, 2 or 4 h time lapse, Cmax2 (Cmax after second administration) was greater than Cmax1 (Cmax after first administration), by 30% when Lazanda was administered 1 h apart, by 25% when Lazanda was administered 2 h apart and by 10% when Lazanda was administered 4 h apart. Based on these results and based on Tmax range of Lazanda observed across pharmacokinetic studies, and frequency of breakthrough pain episodes in a cancer population, a waiting period of 2 h between two consecutive doses of Lazanda is recommended [see Dosage and Administration (2)]. 

In a pharmacokinetic study to evaluate differences in Lazanda absorption in individuals with induced allergic (seasonal) rhinitis, no clinically meaningful differences were observed in rate or extent of exposure to fentanyl, when compared to the Asymptomatic (Unchallenged) state, indicating that presence of allergic rhinitis does not affect Lazanda absorption. This study also assessed differences in Lazanda absorption, if any, when co-administered with oxymetazoline, a nasal decongestant in subjects undergoing treatment for seasonal allergic rhinitis. Mean Cmax values for Treated arm (Rhinitis treated with oxymetazoline) were about 32% and 40% lower and mean AUCt values were about 10% and 17% lower for Ragweed and Tree pollen induced cohorts respectively as compared to the Asymptomatic arm in each cohort. In addition, mean Tmax of Lazanda in the Treated arm was 0.75 h (range 0.08-3 h) for the Ragweed pollen induced cohort and 1.25 h (range 0.08-3 h) for Tree pollen induced cohort as compared to 0.25 h (0.17-1 h) and 0.33 h (0.17-2 h) for the Asymptomatic arm in each cohort respectively. These results indicate that co-administration with oxymetazoline leads to lower peak plasma concentrations and delayed Tmax of Lazanda [see Drug Interactions (7.2)]. 

Distribution: Fentanyl is highly lipophilic. The plasma protein binding of fentanyl is 80% to 85%. The main binding protein is alpha-1-acid glycoprotein, but both albumin and lipoproteins contribute to some extent. The mean volume of distribution at steady state (Vss) was 4 L/kg.

Metabolism: The metabolic pathways following intranasal administration of Lazanda have not been characterized in clinical studies. The progressive decline of fentanyl plasma concentrations results from the uptake of fentanyl in the tissues and biotransformation in the liver. Fentanyl is metabolized in the liver and in the intestinal mucosa to norfentanyl by cytochrome P450 3A4 isoform. In animal studies, norfentanyl was not found to be pharmacologically active. 

Elimination: The disposition of fentanyl following intranasal administration of Lazanda has not been characterized in a mass balance study. Fentanyl is primarily (more than 90%) eliminated by biotransformation to N-dealkylated and hydroxylated inactive metabolites. Less than 7% of the administered dose is excreted unchanged in the urine, and only about 1% is excreted unchanged in the feces. The metabolites are mainly excreted in the urine, while fecal excretion is less important.

The total plasma clearance of fentanyl following intravenous administration is approximately 42 L/h.