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Aim The objective of this analysis was to characterize the population pharmacokinetics (PK) of fevipiprant in asthma patients and to evaluate the effect of baseline covariates on the PK of fevipiprant. Methods PK data from 1281 healthy subjects or asthma patients were available after single or once daily dosing of fevipiprant. Population PK analysis was conducted to describe fevipiprant plasma concentration data using a non-linear mixed effect modeling approach. Results Fevipiprant PK was described by a two-compartment model with first-order absorption and first-order elimination. Exploration of fevipiprant PK in the population from the phase III studies revealed an over-dispersed and skewed distribution. This unusual distribution was described using Tukey’s g-and-h distribution (TGH) on the between-subject variability of apparent clearance (CL/F). The model identified a significant impact of disease status on CL/F, with the value in healthy subjects being 62% higher than that in asthma patients. Bodyweight, age and renal function showed statistically significant impact on fevipiprant clearance; however, compared with a typical asthma patient, the simulated difference in steady-state exposure was at most 16%. Conclusion Fevipiprant PK was described by a two-compartment model with first-order absorption and first-order elimination. The TGH distribution was appropriate to describe the over-dispersed and skewed PK data as observed in the current studies. Asthma patients had approximately 37% higher exposure than healthy subjects did. Other covariates changed exposure by at most 16%.

Asciminib is an investigational, first-in-class, specifically targeting the ABL myristoyl pocket (STAMP) inhibitor of BCR-ABL1 with a new mechanism of action compared with approved ATP-competitive tyrosine kinase inhibitors. This report describes the findings from 2 phase 1 studies assessing the pharmacokinetic (PK) profile of a single dose of asciminib (40 mg) in individuals with impaired renal function (based on absolute glomerular filtration rate; NCT03605277) or impaired hepatic function (based on Child-Pugh classification; NCT02857868). Individuals with severe renal impairment exhibited 49%-56% higher exposure (area under the curve [AUC]), with similar maximum plasma concentration (Cmax ), than matched healthy controls. Based on these findings, as per the protocol, the PK of asciminib in individuals with mild or moderate renal impairment was not assessed. In individuals with mild and severe hepatic impairment, asciminib AUC was 21%-22% and 55%-66% higher, respectively, and Cmax was 26% and 29% higher, respectively, compared with individuals with normal hepatic function. Individuals with moderate hepatic impairment had similar asciminib AUC and Cmax than matched healthy controls. The increase in asciminib AUC and Cmax in the mild hepatic impairment cohort was mainly driven by 1 participant with particularly high exposure. Asciminib was generally well tolerated, and the safety data were consistent with its known safety profile. In summary, these findings indicate that renal or hepatic impairment has no clinically meaningful effect on the exposure or safety profile of asciminib, and support its use in patients with varying degrees of renal or hepatic dysfunction.

Asciminib, a first-in-class, Specifically Targeting the Abelson kinase Myristoyl Pocket (STAMP) inhibitor with the potential to overcome resistance to adenosine triphosphate-competitive tyrosine kinase inhibitors, is being investigated in leukemia as monotherapy and in combination with tyrosine kinase inhibitors including imatinib. This phase 1 study in healthy volunteers assessed the pharmacokinetics of asciminib (40 mg single dose) under 2 conditions: when taken with imatinib (steady state; 400 mg once daily) and a low-fat meal (according to imatinib prescription information), or when taken as single-agent under different food conditions. Asciminib plus imatinib with a low-fat meal increased asciminib area under the plasma concentration-time curve from time 0 to infinity and maximum plasma concentration (geometric mean ratios [90% confidence interval], 2.08 [1.93-2.24] and 1.59 [1.45-1.75], respectively) compared with asciminib alone under the same food conditions. Asciminib plus food decreased asciminib area under the plasma concentration-time curve from time 0 to infinity compared with asciminib taken under fasted conditions (geometric mean ratios: low-fat meal, 0.7 [0.631-0.776]; high-fat meal, 0.377 [0.341-0.417]). Asciminib plus imatinib was well tolerated with no new safety signals. Overall, coadministration of asciminib with imatinib and a low-fat meal results in a moderate increase in asciminib exposure compared with asciminib alone under the same food condition. Food itself decreases asciminib exposure, indicating that single-agent asciminib should be administered in the fasted state to prevent potential suboptimal exposures.

Ranolazine and metformin may be frequently co-administered in subjects with chronic angina and co-morbid type 2 diabetes mellitus (T2DM). The potential for a drug-drug interaction was explored in two phase 1 clinical studies in subjects with T2DM to evaluate the pharmacokinetics and safety of metformin 1000 mg BID when administered with ranolazine 1000 mg BID (Study 1, N = 28) or ranolazine 500 mg BID (Study 2, N = 25) as compared to metformin alone. Co-administration of ranolazine 1000 mg BID with metformin 1000 mg BID resulted in 1.53- and 1.79-fold increases in steady-state metformin Cmax and AUCtau , respectively; co-administration of ranolazine 500 mg BID with metformin 1000 mg BID resulted in 1.22- and 1.37-fold increases in steady-state metformin Cmax and AUCtau , respectively. Co-administration of ranolazine and metformin was well tolerated in these T2DM subjects, with no serious adverse events or drug-related adverse events leading to discontinuation. The most common adverse events were nausea, diarrhea, and dizziness. These findings are consistent with a dose-related interaction between ranolazine and metformin, and suggest that a dose adjustment of metformin may not be required with ranolazine 500 mg BID; whereas, the metformin dose should not exceed 1700 mg of total daily dose when using ranolazine 1000 mg BID.

Cyclosporine exhibits pharmacokinetic and pharmacodynamic variability in renal transplant recipients (RTR) attributed to P-glycoprotein (P-gp), an ABCB1 efflux transporter that influences bioavailability and intracellular distribution. Data on race and sex influences on P-gp in RTR are lacking. We investigated sex and race influences on cyclosporine pharmacokinetics and ABCB1 gene expression in peripheral blood mononuclear cells (PBMC). Fifty-four female and male African American and Caucasian stable RTR receiving cyclosporine and mycophenolic acid completed a 12-hour study. ABCB1 gene expression was assessed in PBMCs pre-dose and 4 hours after cyclosporine. Statistical analysis used mixed effects models on transformed, normalized ABCB1 expression and cyclosporine pharmacokinetics. Sex and race differences were observed for the dose-normalized area under the concentration curve (AUC0-12 /Dose) [P = .0004], apparent clearance [P = .0004] and clearance/body mass index (CL/BMI) [P = .027] with slowest clearance and greatest drug exposure in females. Sex and race differences were found pre-dose and 4 hours for ABCB1 [P

GS-9667, a new selective, partial agonist of the A(1) adenosine receptor (AR), may represent an effective therapy for Type 2 diabetes (T2DM) and dyslipidemia via lowering of free fatty acids (FFA). The objectives of the studies were to evaluate the effects of single and multiple doses of GS-9667 on plasma FFA concentrations, its pharmacokinetics (PK) and safety/tolerability. Two studies were conducted. In the single ascending dose study, healthy, non-obese, and obese subjects received a single oral dose of GS-9667 (30-1,800 mg). In the multiple, ascending dose study, healthy, obese subjects received GS-9667 (600-2,400 mg QD, 1,200 mg BID, or 600 mg QID) for 14 days. Blood and urine samples were collected for lipid profiling and PK analyses. The ECG, vital signs, and subject tolerability were monitored. Doses of GS-9667 ≥300 mg caused dose-dependent reductions in FFA levels that were reproducible over 14 days without evidence of desensitization or rebound. All doses were well tolerated. GS-9667 was rapidly absorbed and distributed; Steady-state concentrations were achieved within 3-5 days. The A(1) AR partial agonist GS-9667 reduced plasma FFA, exhibited linear kinetics, and was well-tolerated in healthy non-obese and obese subjects.

The authors review the basic pharmacology and potential for adverse drug-drug interactions (DDIs) of bosentan and ambrisentan, the 2 endothelin receptor antagonists currently approved for pulmonary arterial hypertension (PAH) treatment. Bosentan, an endothelin (ET) receptor-type ET(A) and ET(B) antagonist, is metabolized to active metabolites by and an inducer of cytochrome P450 (CYP)2C9 and CYP3A. Ambrisentan, a selective ET(A) receptor antagonist, is metabolized primarily by uridine 5'diphosphate glucuronosyltransferases (UGTs) 1A9S, 2B7S, and 1A3S and, to a lesser extent, by CYP3A and CYP2C19. Drug interactions observed with bosentan DDI studies have demonstrated a potential for significant clinical implications during PAH management: bosentan is contraindicated with cyclosporine A and glyburide, and additional monitoring/dose adjustments are required when coadministered with hormonal contraceptives, simvastatin, lopinavir/ritonavir, and rifampicin. As bosentan carries a boxed warning regarding risks of liver injury and showed dose-dependant increases in serum aminotransferase abnormalities, drug interactions that increase bosentan exposure are of particular clinical concern. Ambrisentan DDI studies performed to date have shown only one clinically relevant DDI, an interaction with cyclosporine A that requires ambrisentan dose reduction. As the treatment of PAH moves toward multimodal combination therapy, scrutiny should be placed on ensuring that drug combinations achieve maximal clinical benefit while minimizing side effects.

Renal transplant recipients exhibit variability in mycophenolic acid (MPA) and MPA glucuronide (MPAG) pharmacokinetics, which are influenced by clinical and demographic factors. Racial influence on MPA and MPAG pharmacokinetics was investigated in 53 patients: 17 African American males, 22 Caucasian males, and 14 females receiving mycophenolate mofetil (MMF) and cyclosporine. A 12-hour steady-state pharmacokinetic study was conducted. Enterohepatic circulation of MPA was characterized by a second plasma concentration peak and was included in a novel statistical model with MPAG. MPA clearance in African American males was 26.5 ± 14.4 L/h versus 17.9 ± 6.1 L/h in Caucasian males (P = .035) and 16.1 ± 4.6 L/h in Caucasian females (P = .024) with no difference noted in MPA troughs. Enterohepatic circulation occurred less frequently in African American males (23%) compared with Caucasian males (42%) and Caucasian females (50%) (P > .05). Cyclosporine exposure was correlated with MPA and MPAG pharmacokinetics, whereas creatinine clearance influenced MPAG pharmacokinetics. A racial difference was noted with more rapid MPA clearance in African American males compared with Caucasians. The results support differential MPA dosing and the role of therapeutic drug monitoring in addition to considering the influence of renal function and concurrent immunosuppressives on MPA and MPAG pharmacokinetics.

Ranolazine and metformin may be frequently co-administered in subjects with chronic angina and co-morbid type 2 diabetes mellitus (T2DM). The potential for a drug-drug interaction was explored in two phase 1 clinical studies in subjects with T2DM to evaluate the pharmacokinetics and safety of metformin 1000 mg BID when administered with ranolazine 1000 mg BID (Study 1, N = 28) or ranolazine 500 mg BID (Study 2, N = 25) as compared to metformin alone. Co-administration of ranolazine 1000 mg BID with metformin 1000 mg BID resulted in 1.53- and 1.79-fold increases in steady-state metformin Cmax and AUCtau , respectively; co-administration of ranolazine 500 mg BID with metformin 1000 mg BID resulted in 1.22- and 1.37-fold increases in steady-state metformin Cmax and AUCtau , respectively. Co-administration of ranolazine and metformin was well tolerated in these T2DM subjects, with no serious adverse events or drug-related adverse events leading to discontinuation. The most common adverse events were nausea, diarrhea, and dizziness. These findings are consistent with a dose-related interaction between ranolazine and metformin, and suggest that a dose adjustment of metformin may not be required with ranolazine 500 mg BID; whereas, the metformin dose should not exceed 1700 mg of total daily dose when using ranolazine 1000 mg BID.

GS-9667, a new selective, partial agonist of the A(1) adenosine receptor (AR), may represent an effective therapy for Type 2 diabetes (T2DM) and dyslipidemia via lowering of free fatty acids (FFA). The objectives of the studies were to evaluate the effects of single and multiple doses of GS-9667 on plasma FFA concentrations, its pharmacokinetics (PK) and safety/tolerability. Two studies were conducted. In the single ascending dose study, healthy, non-obese, and obese subjects received a single oral dose of GS-9667 (30-1,800 mg). In the multiple, ascending dose study, healthy, obese subjects received GS-9667 (600-2,400 mg QD, 1,200 mg BID, or 600 mg QID) for 14 days. Blood and urine samples were collected for lipid profiling and PK analyses. The ECG, vital signs, and subject tolerability were monitored. Doses of GS-9667 ≥300 mg caused dose-dependent reductions in FFA levels that were reproducible over 14 days without evidence of desensitization or rebound. All doses were well tolerated. GS-9667 was rapidly absorbed and distributed; Steady-state concentrations were achieved within 3-5 days. The A(1) AR partial agonist GS-9667 reduced plasma FFA, exhibited linear kinetics, and was well-tolerated in healthy non-obese and obese subjects.

Systemic candidiasis causes significant mortality in patients despite amphotericin B (AMB) therapy. Mycograb C28Y variant, a human recombinant antibody fragment to heat shock protein 90, is closely related to Mycograb, which showed a survival advantage in combination with AMB in a phase III human trial. The Mycograb C28Y variant could potentially increase the antifungal effect of AMB. In our study, the interaction between AMB-desoxycholate (DAMB) and the Mycograb C28Y variant was characterized in vitro by using a checkerboard method. Quantitative cultures of kidneys, livers, and spleens of neutropenic mice with systemic Candida albicans infections were used to assess the in vivo interaction between 1.4 mg/kg of body weight/day of DAMB and 0.15, 1.5, and 15 mg/kg/day of the Mycograb C28Y variant after 1, 3, and 5 days of therapy. DAMB and Mycograb C28Y variant monotherapies, vehicle, and a no-treatment arm served as controls. Also, single- and multidose pharmacokinetics for the Mycograb C28Y variant were determined. Indifference or synergy between DAMB and the Mycograb C28Y variant was seen in two trials by the checkerboard method. The pharmacokinetics of the Mycograb C28Y variant was best described by a 2-compartment model with a median serum t 1/2 α of ∼0.198 h and a t 1/2 β of ∼1.77 h. In mice, DAMB together with the Mycograb C28Y variant was no more effective than AMB alone ( P > 0.05 by analysis of variance). The Mycograb C28Y variant alone had no antifungal activity. We therefore conclude that the Mycograb C28Y variant in combination with DAMB offered no benefit over DAMB monotherapy in a neutropenic murine model of systemic candidiasis.

TO THE EDITOR: In a letter to the editor, Dr. I. Tasci raises the question regarding potential drug–drug interactions of tegaserod, which might be related to its inhibitory effect on cytochrome P450 (CYP) isoenzymes CYP1A2 and CYP2D6.