Clinical Pharmacology for Lynkuet
Mechanism of Action
LYNKUET is a neurokinin 1 (NK1) and neurokinin 3 (NK3) receptor antagonist. Inhibition of Substance P and Neurokinin B through antagonism of NK1 and NK3 receptor signaling on kisspeptin/neurokinin B/dynorphin (KNDy) neurons can modulate neuronal activity in thermoregulation associated with hot flashes.
Elinzanetant has higher affinity for human NK1 receptors (pKi values of 8.7 to 10.2) and NK3 receptors (pKi values of 8.0 to 8.8) than for human NK2 receptors (pKi values of approximately 6.0).
Pharmacodynamics
Cardiac Electrophysiology
No clinically relevant prolongation of the QTc interval was observed after single oral administration of elinzanetant at doses up to 5 times the maximum recommended dose. However, QTc prolongation effect of elinzanetant when coadministered with strong CYP3A4 inhibitors has not been sufficiently characterized.
Pharmacokinetics
Elinzanetant Cmax and AUC increased in a greater than dose-proportional manner (20% to 50%) over the dose range from 40 to 160 mg once daily (0.33 to 1.33 times the highest recommended dose).
Elinzanetant steady state plasma concentrations were reached in 5 to 14 days after daily dosing.
Elinzanetant accumulation is <2-fold at the approved recommended dosage.
Absorption
Elinzanetant median (min-max) time to maximum plasma concentration (Tmax) is 1.0 hours (1-2.5 hours) at steady state. Elinzanetant absolute bioavailability is 52% following oral administration.
Effect of Food
No clinically significant differences in elinzanetant pharmacokinetics were observed following administration with a highcalorie, high-fat meal containing approximately 1000 calories (500-600 calories from fat, 250 calories from carbohydrates, and 150 calories from protein).
Distribution
The mean volume of distribution after intravenous administration at steady state of elinzanetant is 137 L. The plasma protein binding of elinzanetant is 99.7%. The blood-to-plasma ratio is between 0.6 and 0.7.
Elimination
Elinzanetant elimination half-life was approximately 45 hours in women with vasomotor symptoms. The clearance of elinzanetant after a single intravenous dose was 8.77 L/h.
Metabolism
Elinzanetant is primarily metabolized by CYP3A4 to yield three major active metabolites, M18/21, M27, and M30/34. These metabolites have similar potency for the human NK1 and NK3 receptors as compared to elinzanetant. The ratio of these metabolites to parent in plasma is approximately 0.39.
Excretion
Following a single oral dose of radiolabeled elinzanetant in healthy subjects, approximately 90% of the dose was recovered in feces (50% unchanged) and less than 1% with urine.
Specific Populations
No clinically significant differences in the pharmacokinetics of LYNKUET were observed based on race.
Patients with Renal Impairment
In patients with mild (eGFR 60 to <90 mL/min) renal impairment, mean elinzanetant Cmax increased 1.9-fold and AUC increased 1.6-fold. In patients with moderate (eGFR 30 to <60 mL/min) renal impairment, mean elinzanetant Cmax increased 1.8-fold and AUC increased 1.7-fold. In patients with severe (eGFR< 30 mL/min) renal impairment, mean elinzanetant Cmax increased 1.2-fold and AUC increased 1.1-fold.
Population pharmacokinetic analysis of the clinical trial data indicate similar exposure of elinzanetant in patients with mild and moderate renal impairment compared to patients with normal renal function.
Elinzanetant has not been studied in patients with end-stage renal disease (eGFR <15 mL/min) [see Use in Specific Populations (8.7)].
Patients with Hepatic Impairment
In patients with Child-Pugh Class A (mild) hepatic impairment, mean elinzanetant Cmax increased 1.2-fold and AUC(0-24) increased 1.5-fold. In patients with Child-Pugh Class B (moderate) hepatic impairment, mean elinzanetant Cmax and AUC(0-24) increased by 2.3-fold.
Elinzanetant has not been studied in patients with Child-Pugh Class C (severe) hepatic impairment [see Use in Specific Populations (8.6)].
Drug Interaction Studies
Clinical Studies and Model-Informed Approaches
No clinically significant differences in elinzanetant pharmacokinetics were observed when used concomitantly with esomeprazole (proton pump inhibitor). No clinically significant differences in the pharmacokinetics of the following oral drugs were observed when used concomitantly with elinzanetant: tamoxifen (substrate of CYP2D6, CYP3A4 and P-gp) and rosuvastatin (substrate of BCRP, OATP1B1/OATP1B3, and OAT3).
Strong CYP3A4 and P-gp inhibitors: Elinzanetant Cmax increased approximately 3.3-fold and AUC increased 6.3-fold following concomitant use with itraconazole 200 mg (strong CYP3A4 and P-gp inhibitor).
Moderate CYP3A4 Inhibitors: Elinzanetant Cmax and AUC are predicted to increase 2.0-fold and 3.0-fold, respectively, following concomitant use of elinzanetant 120 mg with erythromycin (moderate CYP3A4 inhibitor). PBPK predictions after co-administration of 60 mg elinzanetant [(see Dosage and Administration (2.3)] with the moderate CYP3A4 inhibitor erythromycin showed a 1.4-fold increase of elinzanetant AUC and no increase for Cmax when compared to 120 mg, the regular recommended elinzanetant dosage.
Weak CYP3A4 Inhibitors: Elinzanetant Cmax is predicted to increase 1.3-fold and AUC increase 1.5-fold following concomitant use with cimetidine (weak CYP3A4 inhibitor).
Moderate to Strong CYP3A4 Inducers: Elinzanetant Cmax reduced by 44% and AUC reduced by 64% following concomitant use with carbamazepine (moderate to strong CYP3A4 inducer) 600 mg administered twice daily.
Sensitive CYP3A4 Substrates: Elinzanetant increased midazolam (sensitive CYP3A4 substrate) Cmax 1.5-fold and AUC 1.8-fold.
In Vitro Studies
Cytochrome P450 (CYP450) Enzymes: Elinzanetant and its metabolites M18/21, M27, and M30/M34 inhibited CYP3A4 but did not inhibit CYP1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, or 2J2, or induce CYP1A2, 2B6, 2C19, or 3A4 at clinically relevant concentrations.
Transporter systems: Elinzanetant is a substrate for P-gp but not for OATP1A2, OATP2B1, BCRP, OATP1B1, OATP1B3, or MRP4. Elinzanetant and its metabolites M18/21, M27, and M30/M34 inhibited P-gp, BCRP, and BSEP in vitro but did not inhibit OAT1, OAT3, OCT1, OCT2, MATE2-K, or MRP2.