Pasireotide for intramuscular use is formulated as microspheres for long-acting release. After a single injection, the plasma pasireotide concentration shows an initial burst release on the injection day, followed by a dip from Day 2 to Day 7, then a slow increase to the maximum concentration around Day 21, and a slow declining phase over the next weeks, concomitant with the terminal degradation phase of the polymer matrix of the dosage form.
Absorption and Distribution
No studies have been conducted to evaluate the absolute bioavailability of pasireotide in humans. Food effect is unlikely to occur since SIGNIFOR LAR is administered via a parenteral route.
In healthy volunteers, pasireotide administered as SIGNIFOR LAR is widely distributed with large apparent volume of distribution (Vz/F > 100 L). Distribution between blood and plasma is concentration-independent and shows that pasireotide is primarily located in the plasma (91%). Plasma protein binding is moderate (88%) and independent of concentration.
Pasireotide has low passive permeability and is likely to be a substrate of P-glycoprotein (P-gp), but the impact of P-gp on the ADME (absorption, distribution, metabolism, excretion) of pasireotide is expected to be low. In clinical testing in healthy volunteers, P-gp inhibition did not affect the rate or extent of pasireotide availability [see Drug Interactions (7.1)]. At therapeutic dose levels, pasireotide is not expected to be a substrate of BCRP (breast cancer resistance protein), OCT1 (organic cation transporter 1), or OATP (organic anion-transporting polypeptides) 1B1, 1B3, or 2B1.
Elimination
Metabolism and Excretion
Pasireotide was shown to be highly metabolically stable in human liver and kidney microsomes. In healthy volunteers, pasireotide in its unchanged form is the predominant form found in plasma, urine and feces. Somatropin may increase CYP450 enzymes and, therefore, suppression of GH secretion by somatostatin analogs including pasireotide may decrease the metabolic clearance of compounds metabolized by CYP450 enzymes.
Pasireotide is eliminated mainly via hepatic clearance (biliary excretion) with a small contribution of the renal route. In a human ADME study with subcutaneous SIGNIFOR with a single dose 0.6 mg, 55.9 ± 6.63% of the radioactivity dose was recovered over the first 10 days post dosing, including 48.3 ± 8.16% of the radioactivity in feces and 7.63 ± 2.03% in urine.
The apparent clearance (CL/F) of SIGNIFOR LAR in healthy volunteers is on average 4.5-8.5 L/hour.
Steady-State Pharmacokinetics
PK steady-state for SIGNIFOR LAR is achieved after 3 monthly doses. Following multiple intramuscular doses every 4 weeks (every 28 days), SIGNIFOR LAR demonstrates approximately dose-proportional PK exposures (steady-state trough; Ctrough, ss) in the dose range of 10 mg to 60 mg every 4 weeks.
Special Populations
Population PK analyses of SIGNIFOR LAR suggest that race, gender, and body weight do not have clinically relevant influence on circulating levels of pasireotide. No dose adjustment is required for demographics.
Pediatric Patients
No studies have been performed in pediatric patients [see Use in Specific Populations (8.4)].
Geriatric Patients
Age is not a significant covariate in the population PK analysis. Therefore age is not expected to significantly impact circulating levels of pasireotide.
Efficacy and safety data on patients older than 65 years are limited [see Use in Specific Populations (8.5)].
Hepatic Impairment
In a clinical study with a single subcutaneous dose of 600 µg pasireotide in subjects with impaired hepatic function (Child-Pugh A, B, and C), subjects with moderate and severe hepatic impairment (Child-Pugh B and C) showed significantly higher exposures than subjects with normal hepatic function. Upon comparing with the control group, AUCinf was increased by 12%, 56%, and 42%; and Cmax was increased by 3%, 46%, and 33% respectively, in the mild, moderate, and severe hepatic impairment groups [see Use in Specific Populations (8.6), Dosage and Administration (2.5)].
Renal Impairment
Clinical studies have not been performed in patients with renal impairment. However, renal clearance has a minor contribution to the elimination of pasireotide in humans. Renal function (creatinine clearance and estimated glomerular filtration rate) is not a covariate in the population PK analysis. Therefore, renal function is not expected to significantly impact the circulating levels of pasireotide [see Use in Specific Populations (8.7)].