Evaluation of the effect of ritlecitinib on the pharmacokinetics of caffeine in healthy participants.

AIMS: This clinical study was conducted to evaluate the impact of ritlecitinib on the pharmacokinetics of caffeine, a cytochrome P450 1A2 (CYP1A2) substrate. METHODS: In this single-centre, single-arm, open-label, fixed-sequence study, healthy participants received a single 100-mg dose of caffeine on 2 separate occasions: on Day 1 of Period 1 as monotherapy and on Day 8 of Period 2 after oral administration of ritlecitinib 200 mg once daily for 8 days. Serial blood samples were collected and analysed using a validated liquid chromatography-mass spectrometry assay. Pharmacokinetic parameters were estimated by using a noncompartmental method. Safety was monitored by physical examination, vital signs, electrocardiograms and laboratory assessments. RESULTS: Twelve participants were enrolled and completed the study. Coadministration of caffeine 100 mg in the presence of steady-state levels of ritlecitinib (200 mg once daily) increased caffeine exposure compared with caffeine given alone. Area under the curve to infinity and maximum concentration of caffeine increased by approximately 165 and 10%, respectively, when coadministered with ritlecitinib. The ratios of the adjusted geometric means (90% confidence interval) for caffeine area under the curve to infinity and maximum concentration were 265.14% (234.12-300.26%) and 109.74% (103.90-15.91%), respectively, when caffeine was coadministered with steady-state ritlecitinib (test) compared with its administration alone (reference). Multiple doses of ritlecitinib when coadministered with a single dose of caffeine were generally safe and well tolerated in healthy participants. CONCLUSION: Ritlecitinib is a moderate inhibitor of CYP1A2 and can increase systemic exposures of CYP1A2 substrates.

The effect of itraconazole on the pharmacokinetics of lorlatinib: results of a phase I, open-label, crossover study in healthy participants.

Background The third-generation tyrosine kinase inhibitor lorlatinib is approved for the treatment of ALK-positive metastatic NSCLC. CYP3A plays a major role in lorlatinib metabolism; therefore, a drug-drug interaction study was warranted to evaluate the impact of the strong CYP3A inhibitor, itraconazole, on lorlatinib plasma exposure. Methods This phase 1, open-label, 2-period, crossover study estimated the effects of itraconazole on the plasma pharmacokinetics and safety of lorlatinib in healthy participants (NCT02838264). Single-dose lorlatinib 50 mg (n = 2), 75 mg (n = 2) and 100 mg (n = 12) was administered in Period 1. In Period 2, itraconazole oral solution 200 mg/day was administered on Days 1-11, and single-dose lorlatinib on Day 5. Blood samples were collected up to 168 h after lorlatinib dosing. Results During daily dosing with itraconazole (Period 2), the ratios of the adjusted geometric means for area under the plasma concentration-time profile extrapolated to infinity (AUCinf) and maximum plasma concentration (Cmax) of single-dose lorlatinib 100 mg were 141.79% (90% confidence interval, 128.71%, 156.21%) and 124.39% (110.20%, 140.41%), respectively, compared with Period 1 (lorlatinib alone). Lorlatinib was well tolerated alone and with itraconazole. No serious adverse events or withdrawals were reported. Conclusions Co-administration of itraconazole and lorlatinib increased the plasma exposure of lorlatinib relative to lorlatinib alone in healthy participants. Therefore, concomitant use of lorlatinib with strong CYP3A inhibitors should be avoided. If this combination is unavoidable, the starting dose of lorlatinib should be reduced from 100 mg to 75 mg.

The effects of ketoconazole and rifampin on the single-dose pharmacokinetics of crizotinib in healthy subjects.

PURPOSE: To investigate the potential effects of strong CYP3A inhibitor ketoconazole and strong CYP3A inducer rifampin on the pharmacokinetics of crizotinib in human. METHODS: Two separate open-label, 2-period, 2-treatment, 1-sequence, crossover, single-dose studies were conducted in healthy subjects with and without ketoconazole or rifampin. Series of plasma samples were collected after each crizotinib dose to determine concentration of crizotinib and its metabolite PF-06260182. Relevant pharmacokinetic (PK) parameters for crizotinib and PF096269182 were estimated by standard non-compartmental analysis (NCA) method. RESULTS: Co-administration of a single 150-mg oral dose of crizotinib with the strong CYP3A inhibitor ketoconazole resulted in an area under the plasma-concentration curve extrapolated to infinity (AUC0-inf) 3.2-fold that for crizotinib alone. Co-administration of a single 250-mg crizotinib dose with the strong CYP3A inducer rifampin caused an 82 % decrease in crizotinib AUC0-inf. Respective increases and decreases in systemic exposure to the crizotinib metabolite PF-06260182 following co-administration of ketoconazole and rifampin were greater than those seen for crizotinib. CONCLUSIONS: These findings suggest that CYP3A plays an important role in the metabolism of both crizotinib and PF-06260182, with the extent of this role being greater for PF-06260182. There were no serious adverse events or deaths and no dose reductions or temporary or permanent discontinuations due to drug-related adverse events in either study.

Metabolism, excretion and pharmacokinetics of [14C]crizotinib following oral administration to healthy subjects.

1. Crizotinib (XALKORI®), an oral inhibitor of anaplastic lymphoma kinase (ALK) and mesenchymal-epithelial transition factor kinase (c-Met), is currently approved for the treatment of patients with non-small cell lung cancer that is ALK-positive. 2. The metabolism, excretion and pharmacokinetics of crizotinib were investigated following administration of a single oral dose of 250 mg/100 µCi [(14)C]crizotinib to six healthy male subjects. 3. Mean recovery of [(14)C]crizotinib-related radioactivity in excreta samples was 85% of the dose (63% in feces and 22% in urine). 4. Crizotinib and its metabolite, crizotinib lactam, were the major components circulating in plasma, accounting for 33% and 10%, respectively, of the 0-96 h plasma radioactivity. Unchanged crizotinib was the major excreted component in feces (∼ 53% of the dose). In urine, crizotinib and O-desalkyl crizotinib lactam accounted for ∼ 2% and 5% of the dose, respectively. Collectively, these data indicate that the primary clearance pathway for crizotinib in humans is oxidative metabolism/hepatic elimination. 5. Based on plasma exposure in healthy subjects following a single dose of crizotinib and in vitro potency against ALK and c-Met, the crizotinib lactam diastereomers are not anticipated to contribute significantly to in vivo activity; however, additional assessment in cancer patients is warranted.

Assessment of the Effects of Abrocitinib on the Pharmacokinetics of Probe Substrates of Cytochrome P450 1A2, 2B6 and 2C19 Enzymes and Hormonal Oral Contraceptives in Healthy Individuals.

BACKGROUND AND OBJECTIVE: Abrocitinib is an oral small-molecule Janus kinase (JAK)-1 inhibitor approved for the treatment of moderate-to-severe atopic dermatitis. In vitro studies indicated that abrocitinib is a weak time-dependent inhibitor of cytochrome P450 (CYP) 2C19/3A and a weak inducer of CYP1A2/2B6/2C19/3A. To assess the potential effect of abrocitinib on concomitant medications, drug-drug interaction (DDI) studies were conducted for abrocitinib with sensitive probe substrates of these CYP enzymes. The impact of abrocitinib on hormonal oral contraceptives (ethinyl estradiol and levonorgestrel), as substrates of CYP3A and important concomitant medications for female patients, was also evaluated. METHODS: Three Phase 1 DDI studies were performed to assess the impact of abrocitinib 200 mg once daily (QD) on the probe substrates of: (1) 1A2 (caffeine), 2B6 (efavirenz) and 2C19 (omeprazole) in a cocktail study; (2) 3A (midazolam); and (3) 3A (oral contraceptives). RESULTS: After multiple doses of abrocitinib 200 mg QD, there is a lack of effect on the pharmacokinetics of midazolam, efavirenz and contraceptives. Abrocitinib increased the area under the concentration time curve from 0 to infinity (AUCinf) and the maximum concentration (Cmax) of omeprazole by approximately 189 and 134%, respectively. Abrocitinib increased the AUCinf of caffeine by 40% with lack of effect on Cmax. CONCLUSIONS: Based on the study results, abrocitinib is a moderate inhibitor of CYP2C19. Caution should be exercised when using abrocitinib concomitantly with narrow therapeutic index medicines that are primarily metabolized by CYP2C19 enzyme. Abrocitinib is a mild inhibitor of CYP1A2; however, the impact is not clinically relevant, and no general dose adjustment is recommended for CYP1A2 substrates. Abrocitinib does not inhibit CYP3A or induce CYP1A2/2B6/2C19/3A and does not affect the pharmacokinetics of contraceptives. CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov registration IDs: NCT03647670, NCT05067439, NCT03662516.

Evaluation of the Effect of Lorlatinib on CYP2B6, CYP2C9, UGT, and P-Glycoprotein Substrates in Patients with Advanced Non-Small Cell Lung Cancer.

BACKGROUND AND OBJECTIVE: Lorlatinib is a tyrosine kinase inhibitor approved for the treatment of advanced anaplastic lymphoma kinase-positive non-small cell lung cancer. This study assessed the effect of steady-state lorlatinib on the metabolic enzymes cytochrome P450 (CYP) 2B6, CYP2C9, and uridine 5'-diphospho-glucuronosyltransferase (UGT) and the P-glycoprotein (P-gp) transporter. METHODS: Thirty-two patients received a single oral dose of a probe drug on Day - 2 to determine the pharmacokinetics of the probe drug alone. Starting on Day 1, patients received 100 mg oral lorlatinib daily. On Day 15, a single oral dose of the probe drug was administered concurrently with lorlatinib. Pharmacokinetic parameters for these probe substrates were assessed. RESULTS: Plasma exposures of all probe substrates were reduced by lorlatinib compared with the probe alone. The greatest reduction in area under the plasma concentration-time curve from time zero to infinity (AUC∞) and maximum (peak) plasma drug concentration (Cmax) (67% and 63% decrease, respectively) was observed with the P-gp probe substrate fexofenadine. Lorlatinib coadministration also decreased the AUC∞ and Cmax of bupropion (CYP2B6 probe substrate) by 25% and 27%, tolbutamide (CYP2C9 probe substrate) by 43% and 15%, and acetaminophen (UGT probe substrate) by 45% and 28%, respectively. CONCLUSIONS: Lorlatinib is a net moderate inducer of P-gp and a weak inducer of CYP2B6, CYP2C9, and UGT after steady state is achieved with daily dosing. Medications that are P-gp substrates with a narrow therapeutic window should be avoided in patients taking lorlatinib; no dose modifications are needed with substrates of CYP2B6, CYP2C9, or UGT. CLINICALTRIALS: gov: NCT01970865.

No effect of a single supratherapeutic dose of lersivirine, a next-generation nonnucleoside reverse transcriptase inhibitor, on corrected QT interval in healthy subjects.

The objective of this study was to investigate the effect of a supratherapeutic dose of lersivirine (LRV) on corrected QT (QTc) interval using Fridericia's equation (QTcF) in healthy subjects. In this randomized, single-dose, placebo- and active-controlled 3-way crossover study, healthy adult males (n = 48) were randomized to receive LRV (2,400 mg), moxifloxacin (400 mg), or placebo for each treatment period. Triplicate 12-lead electrocardiogram measurements were performed, PK samples were collected, and vital signs were measured. Adverse event monitoring and safety laboratory testing were performed. All subjects were white (mean age, 39 years; body mass index [BMI], 25.6 kg/m(2)) and completed the study. Following LRV administration, the upper bound of the 90% confidence interval (CI) for time-matched adjusted mean differences to placebo QTcF at each time point postdose was below the regulatory threshold of 10 ms, satisfying the criteria for a negative thorough QT/QTc study. The highest upper bound of QTcF 90% CI occurred at 6 h for LRV (3.32 ms; 90% CI, 1.47 to 5.17 ms). The study was deemed adequately sensitive as the lower bound of the 90% CI for the adjusted mean QTcF differences between moxifloxacin and placebo at the moxifloxacin historical T(max) of 3 h was >5 ms (15.29 ms; 90% CI, 13.44 to 17.14 ms). There was no statistically significant relationship between LRV exposure and placebo-adjusted change from baseline QTcF or clinically significant changes in QRS complex, pulse rate (PR) interval, heart rate, or blood pressure. LRV (2,400 mg) did not prolong the QTcF interval, and no clinically relevant electrocardiogram or vital sign changes were observed in healthy subjects.

Evaluation of Proton Pump Inhibitor Esomeprazole on Crizotinib Pharmacokinetics in Healthy Participants.

Crizotinib is a small-molecule, multitargeted tyrosine kinase inhibitor that exhibits decreased aqueous solubility at a higher pH. This open-label, randomized, phase 1 study (NCT01549574) evaluated the effect of multiple doses of the proton pump inhibitor esomeprazole on the pharmacokinetics (PK) of crizotinib and the safety of crizotinib with or without esomeprazole in healthy adults. Participants received a single 250-mg crizotinib dose after overnight fast or a single 250-mg crizotinib dose following esomeprazole 40 mg/day for 5 days. After a washout of ≥14 days, participants crossed over to the alternate treatment. Blood samples for plasma analysis were taken up to 144 hours after crizotinib dosing and relevant PK parameters estimated. Safety was assessed in all participants receiving ≥1 dose of study medication. Fifteen participants were evaluable for PK and safety for each treatment. Coadministration with esomeprazole resulted in a slight decrease (≈10%) in the crizotinib geometric mean area under the plasma concentration-time profile from time 0 to infinity (adjusted geometric mean ratio, 89.81% [90% confidence interval, 79.05-102.03]). Coadministration of esomeprazole did not affect peak crizotinib exposure. Adverse events (AEs) occurred in similar numbers between treatments; no serious or severe AEs occurred. The most common AE was diarrhea. Although esomeprazole decreased total exposure of crizotinib, it is not considered clinically meaningful, and dose modification is not required when crizotinib is coadministered with agents that affect gastric pH.

Evaluation of the absolute oral bioavailability of the anaplastic lymphoma kinase/c-ROS oncogene 1 kinase inhibitor lorlatinib in healthy participants.

PURPOSE: Lorlatinib is a third-generation tyrosine kinase inhibitor currently approved for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer. This open-label, phase 1, randomized two-sequence, two-treatment, two-period, crossover study investigated the absolute oral bioavailability of lorlatinib in healthy participants. METHODS: Eligible participants were randomized to receive two treatments in one of two sequences: lorlatinib 100 mg single oral dose followed by lorlatinib 50 mg intravenous (IV) dose, or lorlatinib IV dose followed by lorlatinib oral dose, each with at least a 10-day washout between successive lorlatinib doses. Blood samples for pharmacokinetics were collected for up to 144 hours (h) after dosing. Validated liquid chromatographic-tandem mass spectrometry was used to determine plasma concentrations of lorlatinib and its benzoic acid metabolite PF-06895751. RESULTS: In total, 11 participants were enrolled (mean age 37.6 years, all male). The adjusted geometric mean (90% confidence interval) for the absolute oral bioavailability was 80.78% (75.73-86.16%). Using non-compartmental analysis, the estimated arithmetic mean elimination plasma half-life of lorlatinib was 25.5 and 27.0 h after the oral and IV doses, respectively. No deaths, serious adverse events (AEs), or severe AEs were reported, and most treatment-emergent AEs were mild in severity, with two events of transaminase increase of moderate severity. All treatment-emergent AEs were resolved by the end of the study. CONCLUSION: Both oral and IV lorlatinib were well-tolerated in healthy participants and oral lorlatinib is highly bioavailable after oral administration.

Assessment of the Effects of Inhibition or Induction of CYP2C19 and CYP2C9 Enzymes, or Inhibition of OAT3, on the Pharmacokinetics of Abrocitinib and Its Metabolites in Healthy Individuals.

BACKGROUND AND OBJECTIVE: Abrocitinib is a Janus kinase 1-selective inhibitor for the treatment of moderate-to-severe atopic dermatitis. Abrocitinib is eliminated primarily by metabolism involving cytochrome P450 (CYP) enzymes. Abrocitinib pharmacologic activity is attributable to the unbound concentrations of the parent molecule and 2 active metabolites, which are substrates of organic anion transporter 3 (OAT3). The sum of potency-adjusted unbound exposures of abrocitinib and its 2 active metabolites is termed the abrocitinib active moiety. We evaluated effects of CYP inhibition, CYP induction, and OAT3 inhibition on the pharmacokinetics of abrocitinib, its metabolites, and active moiety. METHODS: Three fixed-sequence, open-label, phase I studies in healthy adult volunteers examined the drug-drug interactions (DDIs) of oral abrocitinib with fluvoxamine and fluconazole, rifampin, and probenecid. RESULTS: Co-administration of abrocitinib with fluvoxamine or fluconazole increased the area under the plasma concentration-time curve from time 0 to infinity (AUCinf) of the unbound active moiety of abrocitinib by 91% and 155%, respectively. Co-administration with rifampin decreased the unbound active moiety AUCinf by 56%. The OAT3 inhibitor probenecid increased the AUCinf of the unbound active moiety by 66%. CONCLUSIONS: It is important to consider the effects of DDIs on the abrocitinib active moiety when making dosing recommendations. Co-administration of strong CYP2C19/2C9 inhibitors or CYP inducers impacted exposure to the abrocitinib active moiety. A dose reduction by half is recommended if abrocitinib is co-administered with strong CYP2C19 inhibitors, whereas co-administration with strong CYP2C19/2C9 inducers is not recommended. No dose adjustment is required when abrocitinib is administered with OAT3 inhibitors. CLINICAL TRIALS REGISTRATION IDS: NCT03634345, NCT03637790, NCT03937258.

Pharmacokinetics of Lorlatinib After Single and Multiple Dosing in Patients with Anaplastic Lymphoma Kinase (ALK)-Positive Non-Small Cell Lung Cancer: Results from a Global Phase I/II Study.

BACKGROUND: Lorlatinib demonstrated efficacy (including intracranial activity) in patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) in a phase I/II study (NCT01970865). BACKGROUND AND OBJECTIVE: This analysis describes the pharmacokinetics (PK) of lorlatinib following single and multiple dosing. METHODS: This ongoing, multicenter, open-label, single-arm, phase I/II trial enrolled patients with ALK-positive or c-ros oncogene 1 (ROS1)-positive advanced NSCLC. In phase I, patients received escalating doses of lorlatinib (10-200 mg orally once daily) and twice-daily doses of 35, 75, and 100 mg in continuous 21-day cycles. In phase II, lorlatinib was administered at a starting dose of 100 mg once daily in continuous 21-day cycles. Parameters investigated included the potential for lorlatinib to inhibit/induce cytochrome P450 (CYP) 3A; the absorption/metabolism of lorlatinib and its major metabolite PF-06895751; and differences in these parameters between Asian and non-Asian patients. RESULTS: Data were available for 54 patients from phase I and 275 patients from phase II. Lorlatinib plasma exposure increased dose proportionally after single doses of 10-200 mg, and slightly less than dose proportionally after multiple doses. Lorlatinib clearance increased following multiple dosing compared with single dosing, indicating autoinduction. The area under the concentration-time curve from time zero to time τ (the dosing interval; AUCτ) of PF-06895751 was approximately 80% higher than that of lorlatinib after multiple dosing. Lorlatinib exhibited brain penetration. Furthermore, no overt differences in single- and multiple-dose PK parameters between the Asian and non-Asian patients were observed. CONCLUSIONS: Lorlatinib is highly brain penetrant and exhibits autoinduction after multiple dosing. There appears to be no inherent differences in lorlatinib PK between healthy subjects and cancer patients, or between Asian and non-Asian patients. ClinicalTrials.gov NCT01970865.

Phase 1 Study Evaluating the Effects of the Proton Pump Inhibitor Rabeprazole and Food on the Pharmacokinetics of Lorlatinib in Healthy Participants.

Lorlatinib is approved worldwide as treatment for anaplastic lymphoma kinase-positive and c-ros oncogene 1-positive non-small cell lung cancer. The objectives of this phase 1, open-label crossover study (NCT02569554) in healthy adult participants were to determine (1) the effects of the proton pump inhibitor (PPI) rabeprazole on lorlatinib pharmacokinetics (PK), (2) the effects of a high-fat meal on lorlatinib PK, and (3) the relative bioavailability of an oral solution to tablet formulation of lorlatinib under fasted conditions. Participants were followed on-study for ≥50 days after the first dose of lorlatinib. Participants received treatments over 4 periods, with a washout of ≥10 days between consecutive lorlatinib doses. Twenty-seven participants were enrolled and received lorlatinib, and all were assessed for PK and safety. Results showed no effect of multiple doses of rabeprazole on the total plasma exposure of a single oral dose of lorlatinib 100-mg tablets. The results also indicated that a high-fat meal had no effect on lorlatinib PK after a single 100-mg oral dose. In addition, the relative bioavailability of lorlatinib oral solution compared with lorlatinib tablets was complete (approximately 108%). The safety profile of lorlatinib was consistent with that reported in previous studies, and most treatment-related adverse events were mild to moderate. These data indicate that lorlatinib can be administered with drugs that modify gastric acid, including PPIs, without restriction. These results also confirm that lorlatinib can be administered regardless of food intake.

Effects of Hepatic Impairment on the Pharmacokinetics of Abrocitinib and Its Metabolites.

Abrocitinib, an oral once-daily Janus kinase 1 selective inhibitor, is under development for treatment of atopic dermatitis. This phase 1, nonrandomized, open-label, single-dose study (NCT03626415) investigated the effect of hepatic impairment on pharmacokinetics (PK), safety, and tolerability of abrocitinib and its metabolites after a 200-mg oral dose. Twenty-four subjects with varying degrees of hepatic function (normal, mild, and moderate impairment) were enrolled (N = 8/group). Active moiety PK parameters were calculated as the sum of unbound PK parameters for abrocitinib and its active metabolites. For abrocitinib, the ratios (percentages) of adjusted geometric means for area under the concentration-time curve from time 0 extrapolated to infinite time (AUCinf ) and maximum plasma concentration (Cmax ) were 133.33 (90% confidence interval [CI], 86.17-206.28) and 94.40 (90%CI, 62.96-141.55), respectively, for subjects with mild hepatic impairment vs normal hepatic function. The corresponding comparisons of ratios (percentages) for AUCinf and Cmax were 153.99 (90%CI, 99.52-238.25) and 105.53 (90%CI, 70.38-158.24), respectively, for subjects with moderate hepatic impairment. Exposures of the metabolites were generally lower in subjects with hepatic impairment. For abrocitinib active moiety, the ratios (percentages) of adjusted geometric means of unbound AUCinf were 95.74 (90%CI, 72.71-126.08) and 114.82 (90%CI, 87.19-151.20) in subjects with mild and moderate impairment vs normal hepatic function, respectively. Abrocitinib was generally safe and well tolerated. Hepatic impairment had no clinically relevant effect on the PK and safety of abrocitinib and the exposure of abrocitinib active moiety. These results support the use of abrocitinib without dose adjustment in subjects with mild or moderate hepatic impairment.

Palbociclib (PD-0332991) pharmacokinetics in subjects with impaired renal function.

PURPOSE: This publication describes an evaluation of the impact of different degrees of renal impairment on the pharmacokinetics and safety of palbociclib after a single 125-mg oral dose. METHODS: Thirty-one subjects were assigned to different renal function groups. Serial blood sampling for pharmacokinetics was performed up to 120 h and 168 h post-palbociclib dose for subjects with normal and impaired renal function, respectively. A separate blood sample was collected at pre-dose and 8 h after dosing to measure plasma protein binding. Plasma palbociclib was measured using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Plasma protein binding samples were processed by equilibrium dialysis and measured by a validated LC-MS/MS method. RESULTS: Plasma palbociclib exposure was higher in subjects with renal impairment than in subjects with normal renal function; however, there were no marked differences in exposure across subjects with mild, moderate, and severe renal impairment. Total plasma exposure AUCinf increased by 39%, 42%, and 31% with mild, moderate, and severe renal impairment, respectively, relative to subjects with normal renal function. Peak exposure Cmax increased by 17%, 12%, and 15% for mild, moderate, and severe impairment, respectively. There was no obvious trend in the mean fu with worsening renal function. The PBPK model adequately described palbociclib exposure observed in subjects with moderate or severe renal impairment from this study. CONCLUSION: Palbociclib was safe and well-tolerated in a small population of subjects with normal and impaired renal function after a single oral 125 mg dose. No dose adjustment is required in patients with renal impairment.

The Bioequivalence of Tafamidis 61-mg Free Acid Capsules and Tafamidis Meglumine 4 × 20-mg Capsules in Healthy Volunteers.

Tafamidis, a non-nonsteroidal anti-inflammatory benzoxazole derivative, acts as a transthyretin (TTR) stabilizer to slow progression of TTR amyloidosis (ATTR). Tafamidis meglumine, available as 20-mg capsules, is approved in more than 40 countries worldwide for the treatment of adults with early-stage symptomatic ATTR polyneuropathy. This agent, administered as an 80-mg, once-daily dose (4 × 20-mg capsules), is approved in the United States, Japan, Canada, and Brazil for the treatment of hereditary and wild-type ATTR cardiomyopathy in adults. An alternative single solid oral dosage formulation (tafamidis 61-mg free acid capsules) was developed and introduced for patient convenience (approved in the United States, United Arab Emirates, and European Union). In this single-center, open-label, randomized, 2-period, 2-sequence, crossover, multiple-dose phase 1 study, the rate and extent of absorption were compared between tafamidis 61-mg free acid capsules (test) and tafamidis meglumine 80-mg (4 × 20-mg) capsules (reference) after 7 days of repeated oral dosing under fasted conditions in 30 healthy volunteers. Ratios of adjusted geometric means (90%CI) for the test/reference formulations were 102.3 (98.0-106.8) for area under the concentration-time profile over the dosing interval and 94.1 (89.1-99.4) for the maximum observed concentration, satisfying prespecified bioequivalence acceptance criteria (90%CI, 80-125). Both tafamidis regimens had an acceptable safety/tolerability profile in this population.

Evaluation of hepatic impairment on pharmacokinetics and safety of crizotinib in patients with advanced cancer.

PURPOSE: This phase 1 study evaluated the effect of hepatic impairment on pharmacokinetics and safety of crizotinib in patients with advanced cancer. METHODS: Patients were dosed according to hepatic function classified by modified National Cancer Institute Organ Dysfunction Working Group criteria and group assignment [normal (A1 and A2), mild (B), moderate (C1 and C2), or severe (D)]. Primary pharmacokinetic endpoints included area under the concentration-time curve as daily exposure (AUCdaily) and maximum plasma concentration (Cmax) at steady state. Safety endpoints included types, incidence, seriousness, and relationship to crizotinib of adverse events. RESULTS: The AUCdaily and Cmax in patients with normal liver function were 7107 ng h/mL and 375.1 ng/mL (A1) and 5422 ng h/mL and 283.9 ng/mL (A2), respectively. The AUCdaily and Cmax ratios of adjusted geometric means for Groups B, C2, and D versus Group A1 were 91.12 and 91.20, 114.08 and 108.87, and 64.47 and 72.63, respectively. Any grade treatment-related adverse events (TRAEs) occurred in 75% of patients; grade 3/4 TRAEs occurred in 25%, including fatigue (6%), hyponatremia (5%), and hyperbilirubinemia (3%). CONCLUSIONS: No adjustment to the approved 250 mg twice daily (BID) dose of crizotinib is recommended for patients with mild hepatic impairment. The recommended dose is 200 mg BID for patients with moderate hepatic impairment, and the dose should not exceed 250 mg daily for patients with severe hepatic impairment. Adverse events appeared consistent among the hepatic impairment groups. CLINICAL TRIAL REGISTRATION NO: NCT01576406.

Lack of pharmacokinetic and pharmacodynamic interactions between a smoking cessation therapy, varenicline, and warfarin: an in vivo and in vitro study.

This study investigated the effect of varenicline on the pharmacokinetics and pharmacodynamics of a single dose of warfarin in 24 adult smokers and compared these findings with data generated using human in vitro systems. Subjects were randomized to receive varenicline 1 mg twice a day or placebo for 13 days and then switched to the alternative treatment after a 1-week washout period. A single dose of warfarin 25 mg was given on day 8 of each treatment period, and serial blood samples were collected over 144 hours postdose. Pharmacokinetic parameters for both (R)- and (S)-warfarin and international normalized ratio (INR) values were determined. Varenicline was assessed as an inhibitor and inducer of human cytochrome P450 activities using liver microsomes and hepatocytes, respectively. Consistent with the in vitro data, no alteration in human pharmacokinetics of warfarin enantiomers was observed with varenicline treatment. The 90% confidence intervals for the ratios of area under the concentration-time curve from zero hours to infinity and peak plasma concentrations were completely contained within 80% to 125%. Warfarin pharmacodynamic parameters, maximum INR, and the area under the prothrombin (INR)-time curve, were also unaffected by steady-state varenicline. Concomitant administration of varenicline and warfarin was well tolerated. Consequently, warfarin can be safely administered with varenicline without the need for dose adjustment.

Effect of food on the bioavailability of palbociclib.

PURPOSE: This phase I study estimated the effect of food on bioavailability of palbociclib (IBRANCE®), and a selective inhibitor of cyclin-dependent kinase 4/6 approved for oncology indications has pH-dependent solubility and high permeability. METHODS: In this randomized, four-sequence, four-period crossover study, 28 healthy volunteers received a single 125-mg dose of palbociclib (free-base capsule) following an overnight fast or (1) after a high-fat/-calorie meal, (2) after a low-fat/-calorie meal, and (3) between two moderate-fat/standard-calorie meals. Pharmacokinetic samples were collected predose and serially ≤144 h postdose; palbociclib concentrations were measured using validated high-performance liquid chromatography tandem mass spectrometry. Pharmacokinetic data were analyzed using a noncompartmental approach based on a mixed-effects model. RESULTS: Median time to maximum concentration was 8 h for all conditions. Exposure (AUCinf and C max) increased slightly in the fed versus fasted conditions; ratios (90% CIs) of the adjusted geometric mean relative to the fasted condition ranged from 111.8 (104.3-119.9%) to 120.6% (112.6-129.1%) for AUCinf and from 124.0 (108.4-141.9%) to 137.8% (120.6-157.5%) for C max due mainly to three subjects with significantly lower exposure (low liers) in the fasted condition. Pharmacokinetic variability was reduced in the fed (AUCinf, 23-27%; C max, 21-24%) versus fasted (AUCinf, 39%; C max, 73%) conditions. In a supplemental analysis excluding the three low liers, food intake did not affect palbociclib exposure. CONCLUSIONS: Food intake modestly increased palbociclib exposure while greatly reducing pharmacokinetic variability. For subjects with normal absorption, food intake did not affect palbociclib exposure. Thus, palbociclib should be administered with food. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01904747.

Impact of Acid-Reducing Agents on the Pharmacokinetics of Palbociclib, a Weak Base With pH-Dependent Solubility, With Different Food Intake Conditions.

Palbociclib free base capsule is a weak base drug with highly pH-dependent solubility. In vitro and in vivo studies evaluated the impact of acid-reducing agents on exposure of palbociclib and determined whether the impact, if any, can be mitigated by food. A drug-drug interaction study (study 1) was conducted first under fasted conditions and showed that coadministration of multiple doses of the proton-pump inhibitor rabeprazole substantially reduced palbociclib mean area under the concentration-time curve from time 0 to infinity and maximum observed plasma concentration by 62% and 80%, respectively. In vitro assessment suggested that the presence of bile salt mixed micelles to mimic the fed state can significantly enhance the solubility of palbociclib. Subsequently, study 2 was conducted under fed conditions and demonstrated that coadministration of rabeprazole decreased palbociclib maximum observed plasma concentration by 41% but had limited impact on area under the concentration-time curve from 0 to infinity (13% decrease). This study also showed that the histamine-2 receptor antagonist famotidine and local antacid with staggered dosing had no impact on palbociclib exposure under fed conditions. Food intake effectively mitigated the impact of acid-reducing agents on palbociclib exposure. Palbociclib free base capsule should be taken with food, and acid-reducing agent use does not need to be avoided.