Population pharmacokinetic-pharmacodynamic modeling of serum biomarkers as predictors of tumor dynamics following lenvatinib treatment in patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC)

Lenvatinib is a receptor tyrosine kinase (RTK) inhibitor targeting vascular endothelial growth factor (VEGF) receptors 1-3, fibroblast growth factor (FGF) receptors 1-4, platelet-derived growth factor receptor-α (PDGFRα), KIT, and RET that have been implicated in pathogenic angiogenesis, tumor growth, and cancer. The primary objective of this work was to evaluate, by establishing quantitative relationships, whether lenvatinib exposure and longitudinal serum biomarker data (VEGF, Ang-2, Tie-2, and FGF-23) are predictors for change in longitudinal tumor size which was assessed based on data from 558 patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC) receiving either lenvatinib or placebo treatment. Lenvatinib PK was best described by a 3-compartment model with simultaneous first- and zero-order absorption and linear elimination from the central compartment with significant covariates (body weight, albumin <30 g/dL, ALP>ULN, RR-DTC, RCC, HCC subjects, and concomitant CYP3A inhibitors). Except for body weight, none of the covariates have any clinically meaningful effect on exposure to lenvatinib. Longitudinal biomarker measurements over time were reasonably well defined by a PK/PD model with common EC50, Emax, and a slope for disease progression for all biomarkers. Longitudinal tumor measurements over time were reasonably well defined by a tumor growth inhibition Emax model, which in addition to lenvatinib exposure, included model-predicted relative changes from baseline over time for Tie-2 and Ang-2 as having significant association with tumor response. The developed PK/PD models pave the way for dose optimization and potential prediction of clinical response.

Lemborexant levels in breast milk after single doses in healthy, lactating women

AIMS

The aim of this study is to determine the cumulative amount of lemborexant (a competitive dual orexin receptor antagonist approved to treat adults with insomnia) excreted in human breast milk and the relative infant dose (RID) as a proportion of daily maternal dose.

METHODS

E2006-A001-010 was a single-centre, open-label study that enrolled lactating women (≥18 years) who breastfed for ≥5 weeks postpartum. After overnight fasting, subjects received a single 10-mg oral dose of lemborexant. Using a standardized electric pump, milk was sampled before and ≤240 h (10 days) after dosing; combined and total volume were recorded. The cumulative total amount of lemborexant excreted, fraction of dose excreted, daily infant dose and RID were calculated. Lemborexant concentration in human milk was assessed by liquid chromatography with tandem mass spectrometry.

RESULTS

Eight subjects completed the study. The mean cumulative total amount of lemborexant reached 0.0174 mg (coefficient of variation [CV] 54.5%; 0.174% of lemborexant 10 mg administered) in breast milk at 240 h (10 days); ~70% of excreted lemborexant accumulated in the first 24 h. For an infant weighing 6 kg, the daily infant dose was 0.00290 mg kg-1 (CV 54.5%) and the RID was 1.96% (CV 63.1%) of daily maternal dose. Mild treatment-emergent adverse events were reported in 4 subjects; these all resolved by end of study.

CONCLUSION

Trace quantities of lemborexant were found in human breast milk. Lemborexant was well tolerated by healthy lactating women.

First-in-Human Study of the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of E6742, a Dual Antagonist of Toll-like Receptors 7 and 8, in Healthy Volunteers

The first-in-human phase I study for E6742, a dual toll-like receptor (TLR) 7 and TLR8 antagonist, has been conducted to assess the safety, tolerability, and pharmacokinetics of E6742 in healthy volunteers. In a single ascending dose (SAD) study, 42 subjects received 10-800 mg of E6742 in the fasted state, as well as a 100-mg cohort in the fed state for evaluating the effect of food. In a multiple ascending dose (MAD) study, 18 subjects received 100-400 mg of E6742 twice daily for 7 days. E6742 was rapidly absorbed with a median t_max ranging from 1.50 to 2.50 hours across dose groups under the fasted condition, and eliminated with a median t_½ ranging from 2.37 to 14.4 hours. After multiple oral doses, a steady state was reached by day 7. In the SAD study, dose proportionality was observed for C_max , AUC_(0-t) , and AUC_(0-inf) values of E6742 up to 800 mg, but these values were slightly less than dose proportional at 10 mg. In the MAD study, the C_max and AUC_(0-12h)ss of E6742 appeared to be almost dose proportionally increased between 100 and 200 mg, while these parameters showed more than a dose proportional increase at 400 mg. In addition to safety and good tolerability, this study demonstrated cytokine concentrations in cultured peripheral blood in response to E6742 were suppressed in a dose-dependent manner. Further clinical studies targeting systemic lupus erythematosus patients are currently underway.

Phase 1 Single Ascending and Multiple Ascending Dose Studies of Phosphodiesterase-9 Inhibitor E2027: Confirmation of Target Engagement and Selection of Phase 2 Dose in Dementia With Lewy Bodies Trial

BACKGROUND

E2027 is a novel, highly selective and potent inhibitor of phosphodiesterase9 (PDE9) being evaluated as a treatment for dementia with Lewy bodies.

METHODS

Phase 1, randomized, double-blind, single ascending dose (SAD, n=96) and multiple ascending dose (MAD, n=68) studies evaluated E2027 doses (5 to 1200 mg) in healthy subjects. The impact of age, race (Japanese/non-Japanese), and food on pharmacokinetics (PK)/pharmacodynamics were evaluated. Serial cerebrospinal fluid (CSF) samples were collected to assess the target engagement.

RESULTS

E2027 PK profiles were biphasic (elimination half-life: ~30 hours. Approximately 3-fold accumulation was observed following multiple once-daily dosing. E2027 single doses of 50 to 400 mg resulted in mean maximum increases in CSF cyclic guanosine monophosphate ranging from 293% to 461% within 5.37 to 12.9 hours after dose administration to assess target engagement. Dose-response modelling of steady-state predose CSF cyclic guanosine monophosphate concentrations showed ≥200% increase from baseline is maintained with doses of ≥50 mg QD. The most common adverse events with E2027 were post-LP syndrome and back pain. PK profiles were similar between Japanese and non-Japanese. Higher exposure observed in fed versus fasted state was not considered clinically significant. PK exposure was higher in elderly subjects.

CONCLUSIONS

S.E2027 was well-tolerated following single and multiple administration. E2027 achieved maximal and sustained target engagement at 50 mg QD, the dose selected for the phase 2 clinical trial.

E2027 Cardiac Safety Evaluation With Concentration-Response Modeling of ECG Data to Inform Dose Selection in Studies in Patients With Dementia With Lewy Bodies

BACKGROUND

E2027 is a novel, highly selective and potent inhibitor of phosphodiesterase 9 in development for dementia with Lewy bodies. Cardiac safety assessments for emerging agents are essential to avoid drug-induced QT interval prolongation, which may predispose individuals to potentially fatal ventricular arrhythmias. To evaluate the cardiac safety of E2027 and to inform dose selection for the phase 2 study of E2027 in dementia with Lewy bodies, we evaluated concentration-response modeling of pooled electrocardiogram data.

PATIENTS AND METHODS

A post hoc concentration-QTc analysis evaluated potential QT effects using data from 2 randomized, double-blind studies in healthy subjects: a single ascending dose (SAD) study and a multiple ascending dose (MAD) study. Daily E2027 doses ranged from 5 to 1200 mg.

RESULTS

A linear mixed-effects model was used to establish the relationship between plasma concentrations of E2027 and change from the baseline of QTcF (ΔQTcF). A significant but shallow relationship was observed in the estimated slope of the concentration-ΔQTcF: 0.002 ms/ng/mL (90% confidence interval: 0.0007-0.0031) with a small, nonsignificant treatment effect-specific intercept of -0.6 ms. Based on this pooled concentration-QTc analysis, an effect on the QTcF interval >10 ms can be excluded up to E2027 plasma concentrations of ∼3579 ng/mL, corresponding to a dose at least 4-fold larger than the 50 mg phase 2 dose.

CONCLUSION

This pooled post hoc analysis evaluating cardiac safety of E2027 demonstrated that clinically concerning QTcF prolongation and related cardiac complications are highly unlikely with proposed E2027 doses planned for phase 2.

Effect of alcohol coadministration on the pharmacodynamics, pharmacokinetics, and safety of lemborexant: A randomized, placebo-controlled crossover study

BACKGROUND

Lemborexant is a dual orexin receptor antagonist approved to treat insomnia in adults in several countries including the USA, Canada, and Japan.

AIMS

This study was conducted to investigate effects of lemborexant and alcohol coadministration on postural stability, cognitive performance, and the pharmacokinetics, safety, and tolerability of lemborexant.

METHODS

This was a Phase 1, double-blind, placebo-controlled, four-period crossover study in 32 healthy adults. Individuals were randomized into one of four treatment sequences to receive single doses of placebo, lemborexant 10 mg (LEM10), alcohol (males, 0.7 g/kg; females, 0.6 g/kg), and LEM10 plus alcohol, each separated by a 14-day washout. Postural stability (body sway) was measured by ataxiameter and a cognitive performance assessment battery evaluated four domains of attention and memory.

RESULTS

Pharmacodynamic outcomes were analyzed for the 18 participants who completed all four treatments. Change from baseline in body sway showed no significant differences between lemborexant plus alcohol versus alcohol alone. Compared with alcohol alone, coadministration of lemborexant with alcohol showed additive negative effects on cognitive performance domains, corresponding approximately with peak plasma lemborexant concentrations (median = 1.5 h). Cognitive performance was also impaired with lemborexant alone at 0.5 and 2 h in this experimental paradigm with morning dosing. Alcohol increased plasma lemborexant exposure by 70% based on area under the curve to 72 h, and increased peak plasma lemborexant concentrations by 35%. The most commonly reported treatment-emergent adverse event was somnolence.

CONCLUSION

Coadministration of lemborexant with alcohol showed additive negative effects on cognitive measures, but not on postural stability, compared with alcohol alone. Lemborexant exposure was increased with alcohol. Lemborexant alone or with alcohol was well tolerated. Patients are advised not to consume alcohol with lemborexant.

Intravenous Perampanel as an Interchangeable Alternative to Oral Perampanel: A Randomized, Crossover, Phase I Pharmacokinetic and Safety Study

Intravenous (IV) drug administration enables treatment of epilepsy when oral administration is temporarily not feasible. Perampanel is a once‐daily antiseizure medication currently available as oral formulations. Study 050 (NCT03376997) was an open‐label, randomized, single‐dose, crossover study to evaluate the interchangeability of oral and IV perampanel in healthy subjects (N = 48). Bioequivalence of single 12‐mg doses of IV (30‐, 60‐, or 90‐minute infusion) and oral perampanel, ≥6 weeks apart, was assessed. Analyses indicated bioequivalence of area under the plasma concentration–time curve extrapolated to infinity for 30‐ and 60‐minute IV infusions and oral perampanel doses (geometric mean ratio [90% confidence interval], 0.93 [0.84–1.02] and 1.03 [0.97–1.09], respectively); however, IV maximum observed drug concentration (C_max) values were 1.35‐ to 1.61‐fold higher than C_max. Simulated plasma concentration–time profiles using pooled pharmacokinetic data further supported oral and IV perampanel interchangeability in two scenarios: 12‐mg per day IV dosing during a temporary 7‐day switch from oral steady‐state maintenance therapy, and treatment initiation with 2‐mg perampanel. Thirty‐four (70.8%) subjects experienced treatment‐related adverse events. The IV perampanel safety profile was similar to that of oral perampanel without new safety concerns. Perampanel IV infusions may be a suitable temporary alternative to oral perampanel for treatment maintenance and/or initiation.

Effects of Lemborexant on the Pharmacokinetics of Oral Contraceptives: Results From a Phase 1 Drug-Drug Interaction Study in Healthy Females

Lemborexant is a dual orexin receptor antagonist approved in multiple countries including the United States, Canada, and Japan for the treatment of insomnia in adults. As women of childbearing potential may be prescribed insomnia drugs, a drug‐drug interaction study was conducted. This single‐center, open‐label, fixed‐sequence study examined potential drug‐drug interactions between lemborexant and an oral contraceptive (OC) in healthy females (18–44 years, n = 20). The purpose of this study was to determine the effect of lemborexant 10 mg (at steady state) on the pharmacokinetics of a single dose of OC (0.03 mg ethinyl estradiol and 1.5 mg norethindrone acetate), assess the effect of a single dose of OC on lemborexant pharmacokinetics, and evaluate safety and tolerability of lemborexant and OC coadministration. Ethinyl estradiol maximum plasma drug concentration was not altered by lemborexant coadministration; area under the curve from zero time to the last quantifiable concentration was slightly increased, by 13%. No clinically relevant effects on norethindrone acetate pharmacokinetics were observed. Coadministration of OC with lemborexant had no clinically relevant effect on the steady‐state pharmacokinetics of lemborexant. Adverse events were consistent with the known safety profile. These results support the conclusion that lemborexant and OC can be coadministered without dose adjustment.

Effect of hepatic impairment on pharmacokinetics, safety, and tolerability of lemborexant

Lemborexant, a dual orexin receptor antagonist, is approved in the United States, Japan, and Canada for the treatment of insomnia in adults. This phase I, multicenter, open‐label, parallel‐group study assessed the impact of mild or moderate hepatic impairment (HI) on lemborexant pharmacokinetics and metabolism. The pharmacokinetics, tolerability, and safety of lemborexant were evaluated in subjects with mild (Child–Pugh class A) or moderate (Child–Pugh class B) HI and healthy age‐, sex‐, and body mass index (BMI)‐matched control subjects (n = 8 subjects/group). Subjects received a single oral dose of lemborexant 10 mg (LEM10). Blood samples were collected up to 312 hours post dosing for lemborexant pharmacokinetics assessments. Median time to maximum plasma concentration was similar across all groups. Compared with healthy subjects, exposure measures (maximum plasma concentration [C_max] and area under the curve extrapolated to infinity [AUC_0‐inf]) increased by ~58% (C_max) and ~25% (AUC_0‐inf) in subjects with mild HI and ~22% (C_max) and ~54% (AUC_0‐inf) in subjects with moderate HI. Clearance decreased by 20% and 35% in subjects with mild and moderate HI, respectively, versus healthy subjects. Lemborexant unbound fraction was similar in all groups (range: 0.060–0.065). All treatment‐emergent adverse events (TEAEs) were mild in severity; no serious TEAEs occurred. In conclusion, following a single LEM10 dose, lemborexant exposure was similar in subjects with mild HI and increased in subjects with moderate HI versus healthy subjects. No dose adjustment is required in subjects with mild HI. Dosing in subjects with moderate HI should be restricted to 5 mg. Lemborexant was well tolerated in all groups.

Effect of severe renal impairment on pharmacokinetics, safety, and tolerability of lemborexant

The primary aim of this study was to examine the effect of severe renal impairment (SRI) on the pharmacokinetics of lemborexant, a dual orexin receptor antagonist indicated for the treatment of insomnia. A phase 1 multicenter, single‐dose, open‐label, parallel‐group study was conducted in subjects with SRI not requiring dialysis (estimated glomerular filtration rate 15–29 ml/min/1.73 m²; n = 8) compared with demographically matched healthy subjects with normal renal function (n = 8). Plasma levels of lemborexant and its metabolites were measured over 240 h following a single oral 10‐mg dose administered in the morning. Relative to subjects with normal renal function, lemborexant maximum plasma concentration (C_max) was similar, whereas area under the plasma concentration–time curve from zero to time of last quantifiable concentration (AUC_(0‐t)) and AUC from zero to infinity (AUC_(0‐inf)) were about 1.5‐fold higher in subjects with SRI. The geometric mean ratios (90% confidence interval) were 104.8 (77.4–142.0), 150.5 (113.2–200.3), and 149.8 (113.1–198.6) for C_max, AUC_(0‐t), and AUC_(0‐inf), respectively. In both groups, the median lemborexant time to C_max (t_max) was 1 h, and the mean unbound fraction of lemborexant was ~7%. For the M4, M9, and M10 metabolites, C_max was reduced ~20% and exposure (AUC_(0‐t) and AUC_(0‐inf)) was ~1.4‐ to 1.5‐fold higher in subjects with SRI versus healthy subjects; t_max was delayed ~1.5–2 h for M4 and M10. All treatment‐emergent adverse events were mild or moderate. Lemborexant pharmacokinetics were not sufficiently altered to warrant a dose adjustment for subjects with renal impairment.

Evaluation of the CYP3A and CYP2B6 Drug-Drug Interaction Potential of Lemborexant

Lemborexant is approved for treating insomnia and is under investigation for treating irregular sleep‐wake rhythm disorder. Based on in vitro drug‐drug interaction (DDI) characteristics, phase 1, open‐label DDI studies were conducted to evaluate lemborexant's cytochrome P450 3A (CYP3A) and CYP2B6 interaction potential. Interactions between lemborexant 10 mg and strong and moderate CYP3A inhibitors (itraconazole and fluconazole), a strong CYP3A inducer (rifampin), and CYP3A (midazolam) and CYP2B6 substrates (bupropion) were evaluated. Coadministration of lemborexant with itraconazole or fluconazole resulted in 1.4‐ to 1.6‐fold and 3.7‐ to 4‐fold increases in lemborexant maximum observed concentration (C_max) and area under the concentration‐time curve from zero time extrapolated to infinity (AUC_0‐inf), respectively. Coadministration of lemborexant with rifampin resulted in >90% decreases in lemborexant C_max and AUC_0‐inf. Midazolam exposure was not affected. Coadministration of lemborexant with bupropion resulted in 49.9% and 45.5% decreases in S‐bupropion C_max and AUC_0‐inf, respectively.Comparison of estimated exposures for patients in phase 3 trials who were/were not receiving concomitant weak CYP3A inhibitors substantiated the DDI pharmacokinetic findings. Lemborexant was generally well tolerated in the phase 1 studies. In summary, lemborexant does not affect the pharmacokinetics of CYP3A substrates and has potential to induce CYP2B6. Consistent with in vitro findings, moderate and strong CYP3A inhibitors and inducers affected the pharmacokinetics of lemborexant; hence, patients taking lemborexant 5 or 10 mg should avoid coadministration with moderate and strong CYP3A inhibitors and inducers.

Population Pharmacokinetics and Exposure-Response Analyses for the Most Frequent Adverse Events Following Treatment With Lemborexant, an Orexin Receptor Antagonist, in Subjects With Insomnia Disorder

Lemborexant is a novel orexin receptor antagonist approved in the United States and Japan for the treatment of insomnia. This article describes the population pharmacokinetics (PK) of lemborexant and the relationship of its daily steady-state exposure (Cav,ss ) to the probability of most frequent treatment-emergent adverse events (TEAEs). The 12 230-observation, 1892-subject PK data set included data from 12 clinical studies with predominantly female subjects (66%) ranging in age from 18 to 88 years and from 37 to 168 kg in body weight. The 1664-subject exposure-response data set included data from 3 late-stage studies. Lemborexant pharmacokinetics were described by a 3-compartment model with combined first- and zero-order absorption with lag time and linear elimination. Oral clearance decreased with increasing body mass index (exponent, -0.428), increasing alkaline phosphatase levels (exponent, -0.118), and was 26% lower in the elderly (≥65 years). Across the adverse event analysis, the frequency of subjects experiencing TEAEs during active treatment ranged from approximately 3% to 8%, in the range estimated for placebo. With and without adjustment for age, lemborexant exposure (Cav,ss ) was not a clinically meaningful linear predictor of the probability of specific TEAEs: somnolence, nasopharyngitis, flu/influenza, urinary tract infection, upper respiratory tract infection, or headache. Given the small effect sizes of covariates of the PK model and a low degree of association of lemborexant TEAEs and exposure over the range of phase 3 (therapeutic) 5- and 10-mg doses, lemborexant can be safely administered without the need for dose adjustment.

Effect of gastric acid-reducing agents on the pharmacokinetics and efficacy of lemborexant

Lemborexant is a dual orexin receptor antagonist approved for treating insomnia. As the solubility of lemborexant is pH-sensitive, the impact of the gastric acid-reducing agent (ARA), famotidine, on lemborexant pharmacokinetics was evaluated in a Phase 1 study. Additionally, post hoc analysis of data from Phase 3 studies examined the potential effect of concomitant ARAs on patient-reported/subjective sleep onset latency (sSOL) in subjects with insomnia. Coadministration of lemborexant 10 mg with famotidine decreased the maximum observed concentration by 27% and delayed time of maximum observed concentration by 0.5 hours. Famotidine did not affect overall lemborexant exposure based on comparison of area under the concentration curves. Concomitant ARA use in the Phase 3 studies did not impact the effect of lemborexant on sSOL; the change from baseline during the last 7 nights of 1 month of treatment with lemborexant 10 mg was -17.1 minutes with vs -17.9 minutes without ARAs. Collectively, these results indicate that lemborexant can be coadministered with ARAs.

Pharmacokinetics, Pharmacodynamics, and Safety of the Dual Orexin Receptor Antagonist Lemborexant: Findings From Single-Dose and Multiple-Ascending-Dose Phase 1 Studies in Healthy Adults

Lemborexant, a dual orexin receptor antagonist, is approved for the treatment of insomnia and is under investigation for treating other sleep disorders. Here we summarize pharmacokinetic, pharmacodynamic, and safety data from 3 randomized, double‐blind, placebo‐controlled phase 1 studies: single ascending doses in healthy adults (Study 001; 1‐200 mg; N = 64), multiple ascending doses in healthy and elderly adults (Study 002; 2.5‐75 mg; N = 55), and multiple doses in healthy white and Japanese adults (Study 003; 2.5‐25 mg; N = 32). Lemborexant exposure increased with increasing dose. The time to maximum concentration ranged from approximately 1 to 3 hours for the 5‐ and 10‐mg doses. The mean effective half‐life was 17 hours for lemborexant 5 mg and 19 hours for lemborexant 10 mg. The plasma concentration at 9 hours postdose was 27% of the maximum concentration following multiple dosing with lemborexant 10 mg. There were no clinically relevant effects on next‐morning residual sleepiness (Karolinska Sleepiness Scale, Digital Symbol Substitution Test, Psychomotor Vigilance Test) for doses through 10 mg/day, indicating no effect of residual plasma concentrations on next‐day residual effects. Lemborexant was well tolerated across the doses tested. There were no clinically relevant effects of age, sex, or race on lemborexant pharmacokinetics, pharmacodynamics, or safety. These results suggest that lemborexant at doses through 25 mg provides an overall pharmacokinetic, pharmacodynamic, and safety profile suitable for obtaining the target pharmacologic effect supporting treatment of insomnia while minimizing residual effects during wake time.

A phase I/II study of lenvatinib (LEN) plus everolimus (EVE) in recurrent and refractory pediatric solid tumors, including CNS tumors

10527

Background: Proangiogenic signaling pathways cooperate with mTOR-mediated regulation of cell growth and maintenance to drive development of many pediatric cancers. We report results of the phase 1 dose escalation for LEN + EVE in pediatric patients (pts) with recurrent solid and CNS tumors conducted by Children’s Oncology Group. Methods: Dose escalation was conducted using a rolling-6 design. Pts received LEN + EVE orally once daily in continuous 28-day cycles. Dose determination was based on toxicity (CTCAE v4.03) during cycle 1. Pharmacokinetics (PK) of plasma LEN and EVE were monitored. Results: 17 pts were enrolled (9 male; 8 female). Median (range) age was 10 (3–21) years; 8 pts had CNS tumors. 17 were evaluable for dose-limiting toxicity (DLT). Enrollment started at dose level 1 (DL 1; LEN 11 mg/m2 + EVE 3 mg/m2) and, after treatment of 3 pts, was initially de-escalated to DL –1 (LEN 8 mg/m2 + EVE 3 mg/m2) due to DLT of proteinuria in 1 pt and self-resolving headache in another who, on review, did not meet the definition of DLT. No pts enrolled at DL –1 (n = 5) experienced DLT. Overall, DLTs were observed in 2 of the first 6 patients enrolled at DL 1: the initial pt with proteinuria and 1 more pt with hypertriglyceridemia and hypercholesteremia. Because 2 pts had reversible DLT of different categories not related to Cmax or AUC, the DL 1 cohort was expanded to enroll an additional 6 pts, none of whom had DLT. Thus, 2/12 pts experienced DLT at DL 1. Overall, most common treatment-emergent adverse events (TEAEs; ≥ 50% of pts) were diarrhea, hypertension, hypertriglyceridemia, vomiting, abdominal pain, headache, and hypothyroidism. 47% of pts had ≥ 1 treatment-related TEAE grade ≥ 3; the most frequent was proteinuria (n = 2). On cycle 1 day 15, mean (SD) Cmax (ng/mL) for LEN at DL –1 and DL 1, respectively, was 314 (150) and 359 (270), and mean (SD) AUC0-8h (hr•ng/mL) for LEN was 1570 (935) and 1780 (1100). Taking all toxicities and PK into account, no further dose escalation was recommended. Best overall response in pts with measurable disease was 2/11 stable disease, 7/11 progressive disease, and 2/11 not evaluable. Conclusions: The recommended phase 2 dose of LEN + EVE in children with solid and CNS tumors was LEN 11 mg/m2 + EVE 3 mg/m2, with maximum daily doses capped at 18 mg and 5 mg, respectively. The toxicity profile was no more than additive to single-agent therapy. PK exposure was comparable with children on single-agent LEN and to adults receiving LEN + EVE. Enrollment to the phase 2 portion (Ewing sarcoma, high-grade glioma, and rhabdomyosarcoma strata) is ongoing. Clinical trial information: NCT03245151.

A phase I/II study of eribulin mesilate (ERI) plus irinotecan (IRI) in children with refractory or recurrent solid tumors

10535

Background: ERI is an inhibitor of microtubule dynamics. IRI is used to treat pediatric sarcomas. In the pediatric preclinical testing program, ERI was well tolerated and had promising activity compared with vincristine (a common chemotherapeutic for pediatric cancers) for various solid tumors ( in vivo xenograft panels). Methods: Children with relapsed/refractory solid tumors (excluding active central nervous system tumors) were enrolled. Prior treatment with IRI was allowed. Dose escalation was conducted for 2 schedules with the primary objective (phase 1) of determining the maximum tolerated dose and the recommended phase 2 dose: (A) ERI 1.4 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle) + IRI 20 or 40 mg/m2 IV infusion (Days 1–5 of 21-day cycle); (B) ERI 1.4 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle) + IRI 100 or 125 mg/m2 IV infusion (Days 1 + 8 of 21-day cycle). Safety and pharmacokinetic parameters were assessed. Results: 13 patients (pts) were enrolled (median age: 9 years [range: 3–17]); 4 pts had rhabdomyosarcoma (RMS), 2 had non-RMS soft tissue sarcoma, 2 had Ewing sarcoma, 2 had hepatoblastoma, 2 had nephroblastoma, and 1 had neuroblastoma. Overall, 7 pts previously received IRI. No dose-limiting toxicities (DLTs) were reported for either schedule. At data cut-off (July 14, 2019), 4 pts (with Ewing sarcoma, neuroblastoma, RMS, or hepatoblastoma) continued treatment (A, n = 2; B, n = 2) and 9 pts discontinued treatment (primarily for radiographic progression, n = 7 [A, n = 4; B, n = 3]). All pts experienced ≥1 treatment-emergent adverse event (TEAE); the most common any grade TEAE was neutropenia (n = 10; A, n = 5; B, n = 5). 11 pts had grade ≥3 TEAEs (A, n = 6; B, n = 5); the most frequent grade ≥3 TEAE was neutropenia (n = 9; A, n = 5; B, n = 4). No pt withdrew ERI or IRI due to an AE; 3 pts had dose reductions for ERI (A, n = 1; B, n = 2) and 3 pts had dose interruption of ERI (A, n = 2; B, n = 1) due to AEs. No pt had dose reductions for IRI, and 3 pts had dose interruption of IRI (A, n = 2; B, n = 1) due to AEs. 3 deaths occurred; 2 deaths were the result of tumor progression (A, n = 1; B, n = 1), and the cause of 1 was unknown (B). 1 pt with neuroblastoma treated according to schedule A had a partial response. Systemic exposures of ERI, IRI, and SN-38 (IRI active metabolite) were similar between schedules and doses. Conclusions: No DLTs were observed. Toxicity was manageable. Administration of IRI treatment on Days 1–5 is widely used in pediatric cancers; enrollment for phase 2 is ongoing with treatment Schedule A (ERI 1.4 mg/m2 Days 1 + 8 of 21-day cycle; IRI 40 mg/m2 Days 1–5 of 21-day cycle). Clinical trial information: NCT03245450.

An Open-Label Phase 1 Study to Determine the Effect of Lenvatinib on the Pharmacokinetics of Midazolam, a CYP3A4 Substrate, in Patients with Advanced Solid Tumors

BACKGROUND AND OBJECTIVE

Lenvatinib is a multikinase inhibitor that inhibits enzyme activity but induces gene expression of cytochrome P450 3A4 (CYP3A4), an important enzyme for drug metabolism. We evaluated the impact of lenvatinib on CYP3A4 using midazolam as a probe substrate in patients with advanced solid tumors. The primary objective was to determine the pharmacokinetic effects of lenvatinib on midazolam, and the secondary objective was to assess the safety of lenvatinib.

METHODS

This multicenter, open-label, nonrandomized, phase 1 study involved patients with advanced cancer that progressed after treatment with approved therapies or for which no standard therapies were available.

RESULTS

Compared with baseline, coadministration of lenvatinib decreased the geometric mean ratio of the area under the concentration-time curve for midazolam on day 1 to 0.914 (90% confidence interval [CI] 0.850-0.983) but increased it on day 14 to 1.148 (90% CI 0.938-1.404). Coadministration of lenvatinib also decreased the geometric mean ratio of the maximum observed concentration for midazolam on day 1 to 0.862 (90% CI 0.753-0.988) but increased it on day 14 to 1.027 (90% CI 0.852-1.238). There was little change in the terminal elimination phase half-life of midazolam when administered with lenvatinib. The most common treatment-related adverse events were hypertension (20.0%), fatigue (16.7%), and diarrhea (10.0%).

CONCLUSIONS

Coadministration of lenvatinib had no clinically relevant effect on the pharmacokinetics of midazolam, a CYP3A4 substrate. The adverse events were consistent with the known safety profile of lenvatinib, and no new safety concerns were identified. CLINICALTRIALS.

GOV IDENTIFIER

NCT02686164.

Pharmacokinetic/pharmacodynamic drug-drug interactions of avatrombopag when coadministered with dual or selective CYP2C9 and CYP3A interacting drugs

AIMS

Avatrombopag, a thrombopoietin receptor agonist, is a substrate of cytochrome P450 (CYP) 2C9 and CYP3A. We assessed three drug-drug interactions of avatrombopag as a victim with dual or selective CYP2C9/3A inhibitors and inducers.

METHODS

This was a three-part, open-label study. Forty-eight healthy subjects received single 20 mg doses of avatrombopag alone or with one of 3 CYP2C9/3A inhibitors or inducers: fluconazole 400 mg once daily for 16 days, itraconazole 200 mg twice daily on Day 1 and 200 mg once daily on Days 2-16, or rifampicin 600 mg once daily for 16 days. Pharmacokinetics, pharmacodynamics (platelet count) and safety of avatrombopag were evaluated.

RESULTS

Coadministration of a single 20-mg dose of avatrombopag with fluconazole at steady-state resulted in 2.16-fold increase of AUC of avatrombopag, prolonged terminal elimination phase half-life (from 19.7 h to 39.9 h) and led to a clinically significant increase in maximum platelet count (1.66-fold). Itraconazole had a mild increase on both avatrombopag pharmacokinetics and pharmacodynamics compared to fluconazole. Coadministration of rifampicin caused a 0.5-fold decrease in AUC and shortened terminal elimination phase half-life (from 20.3 h to 9.84 h), but has no impact on maximum platelet count. Coadministration with interacting drugs was found to be generally safe and well-tolerated.

CONCLUSIONS

The results from coadministration of fluconazole or itraconazole suggest that CYP2C9 plays a more predominant role in metabolic clearance of avatrombopag than CYP3A. To achieve comparable platelet count increases when avatrombopag is coadministered with CYP3A and CYP2C9 inhibitors, an adjustment in the dose or duration of treatment is recommended, while coadministration with strong inducers is not currently recommended.

Abstract 5050: Pharmacodynamic and pharmacokinetic relationship of single agent E7449 in patients with advanced solid tumors or B-cell malignancies

E7449 is a small-molecule inhibitor of poly (ADP-ribose) polymerase (PARP). Preclinical studies reported antitumor activity of single-agent E7449 in BRCA-deficient in vivo models. An open-label, multicenter, phase 1 study was completed to determine the maximum tolerated dose (MTD), safety, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antitumor activity of single-agent E7449. The MTD was determined to be 600 mg/day (n = 8). Treatment-emergent adverse events led to drug withdrawal in 1 patient and dose interruption in 2 patients at this dose level. E7449 treatment at the MTD was associated with substantial and sustained dose-dependent PARP inhibition. The overall response rate was 7.1% (2 confirmed partial responses [PR]) and durable stable disease (≥23 weeks) was observed in 21.4% of patients. Here we report additional PD and PK results from this trial.

Patients in this study (N=28) were ≥ 18 years and had measurable, confirmed, advanced solid tumors or B-cell lymphoma that had progressed after approved treatment. Patients received E7449 at 50, 100, 200, 600, or 800 mg/day. Food effect was examined in an MTD expansion cohort. PD assessments included measurement of PARP activity and comet assay to determine the extent of DNA damage.

In the food-effect cohort (n=13), PARP inhibition (up to 90%) was sustained during treatment with the MTD of E7449 600 mg/day up to 24 hours post-dose. Peak E7449 plasma concentrations were delayed by 2 hours in fed patients compared with fasted patients. In the PK/PD analysis set, peak plasma concentrations of E7449 were observed at 2 hours following a single dose, and coincided with the lowest levels of poly (ADP-ribose) (PAR; up to 90% inhibition). Of note, while E7449 exposure was highest at the 800 mg dose, the lowest PAR levels were observed at the 600 mg dose. At the time of observed responses, the 2 patients with confirmed PR demonstrated greater than 90% PAR inhibition from baseline. E7449 did not cause a change in the level of DNA damage that could be detected by the comet assay. DNA damage levels remained similar to the damage seen in healthy donors. No significant changes in percent DNA in the electrophoresis comet tail by dose or E7449 plasma concentration were observed.

In conclusion, continuous E7449 dosing at 600 mg/day was associated with sustained PARP inhibition. Dose-dependent PARP inhibition was observed and the greatest PARP inhibition occurred at the 600 mg dose. Peak E7449 plasma concentration appeared to coincide with maximal PARP inhibition. These results support E7449 dosing at 600 mg/day.

Citation Format: Pallavi Sachdev, Shannon McGrath, Robert Shumaker, Jagadeesh Aluri, Claudio Savulsky. Pharmacodynamic and pharmacokinetic relationship of single agent E7449 in patients with advanced solid tumors or B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5050. doi:10.1158/1538-7445.AM2017-5050

Pharmacokinetics, Pharmacodynamics, Pharmacogenomics, Safety, and Tolerability of Avatrombopag in Healthy Japanese and White Subjects

Avatrombopag, an orally administered, small-molecule thrombopoietin receptor (c-Mpl) agonist, is currently in clinical development for the potential treatment of severe thrombocytopenia in patients with chronic liver disease undergoing an elective procedure. The objectives of this study were to characterize and compare the pharmacokinetics (including the food effect) and pharmacodynamics (platelet count) of avatrombopag following single doses in Japanese and white subjects. Following single dosing under fasted and fed conditions, mean peak concentrations occurred at 5 to 8 hours and subsequently declined with a half-life of 16 to 18 hours in Japanese and white subjects. Administration with food did not alter the rate or extent of avatrombopag absorption but substantially reduced pharmacokinetic variability relative to the fasted state. CYP2C9 polymorphism (*2, *3) was associated with higher pharmacokinetic variability but not with any clinically important effect on variability in platelet response. Plasma exposures of avatrombopag increased in a dose-proportional manner over the dose range tested. After a single dose, platelet count increased in a dose-related manner, reaching a maximum by day 11 and returning to baseline levels by day 27. No clinically important differences were found when avatrombopag pharmacokinetics and pharmacodynamics were compared between Japanese and white subjects. Administration of avatrombopag was generally well tolerated.

Effect of rifampicin on the pharmacokinetics of lenvatinib in healthy adults

Background and Objectives

Lenvatinib is an oral, multitargeted tyrosine kinase inhibitor under clinical investigation in solid tumours. This study evaluated the influence of P-glycoprotein (P-gp) inhibition (single-dose rifampicin) and simultaneous cytochrome P450 3A4 (CYP3A4)/P-gp induction (multiple-dose rifampicin) on lenvatinib pharmacokinetics.

Methods

This Phase I, single-centre, single-dose (lenvatinib mesylate 24 mg), open-label, sequential study enrolled 15 healthy volunteers. Three regimens were administered over three periods: Period (P) 1 (Days 1–8), P2 (Days 15–22) and P3 (Days 29–50), with a 14-day (first dose) and 28-day (second dose) washout period after lenvatinib mesylate administration (Day 1, Day 15 and Day 43). In P2, a single oral dose of rifampicin (600 mg) was coadministered with lenvatinib. In P3, rifampicin was administered daily (600 mg) for 21 days (Days 29–49). Serial blood samples were collected, and plasma concentrations of total (protein bound + unbound) and free (unbound) lenvatinib and total metabolites (M1, M2, M3 and M5) were measured by validated high-performance liquid chromatography/tandem mass spectrometry.

Results

Single-dose rifampicin (P-gp inhibition) increased area under the plasma concentration–time curve from time zero to infinity (AUC_0–∞) of free and total lenvatinib by 32 and 31 %, respectively. Multiple-dose rifampicin (simultaneous P-gp and CYP3A4 induction) decreased lenvatinib AUC_0–∞ (total: 18 %; free: 9 %). Treatment-emergent adverse events were mild or moderate and occurred in 7 subjects (47 %).

Conclusion

Lenvatinib exposure was increased by P-gp inhibition; however, based on free concentrations, simultaneous P-gp and CYP3A4 induction results met the prespecified bioequivalence 90 % confidence interval. Overall, the magnitude of these changes was relatively small, and likely not clinically meaningful.

Influence of hepatic impairment on lenvatinib pharmacokinetics following single-dose oral administration

This open-label, single-dose study assessed lenvatinib pharmacokinetics (PK) in subjects with normal hepatic function (n = 8) and mild, moderate, or severe hepatic impairment (n = 6 each). Subjects received 10 mg oral lenvatinib, except those with severe hepatic impairment (5 mg). Plasma and urine samples were collected over 14 days; free and total lenvatinib and its metabolites were analyzed using validated chromatography/spectrometry. PK parameters were estimated using noncompartmental analysis. There were no clinically meaningful effects of mild or moderate hepatic impairment on lenvatinib PK. Dose-normalized Cmax for free lenvatinib was 7.0, 3.7, 5.7, and 5.6 ng/mL in subjects with normal hepatic function, mild, moderate, and severe hepatic impairment, respectively. There was no consistent trend, although dose-normalized Cmax was lower for all subjects with hepatic impairment. AUCs increased 170% and t1/2 increased (37 versus 23 hours) in subjects with severe hepatic impairment. Changes in exposure based on total plasma concentrations were generally less than those based on free concentrations, suggesting changes in plasma protein binding in subjects with severe hepatic impairment. Lenvatinib was generally well tolerated. Subjects with severe hepatic impairment should begin lenvatinib treatment at a reduced dose of 14 mg versus 24 mg for subjects with normal liver function and subjects with mild or moderate hepatic impairment.

Effects of Ketoconazole on the Pharmacokinetics of Lenvatinib (E7080) in Healthy Participants

BACKGROUND

Lenvatinib is an oral, multitargeted, tyrosine kinase inhibitor under clinical investigation in solid tumors. In vitro evidence indicates that lenvatinib metabolism may be modulated by ketoconazole, an inhibitor of CYP3A4 and p-glycoprotein.

METHODS

In this Phase I, single-center, randomized, open-label, two-period, crossover study, healthy adults (18-55 years; N = 18) were randomized to one of two sequences (ketoconazole → placebo or vice versa). Ketoconazole (400 mg) or placebo was administered orally once daily for 18 days; a 5 mg dose of lenvatinib was orally administered on Day 5 of each treatment period. Blood samples were collected over 14 days and lenvatinib plasma concentrations measured by high-performance liquid chromatography/tandem mass spectrometry.

RESULTS

Systemic exposure to lenvatinib increased slightly (15-19%) with coadministration of ketoconazole. Although the 90% confidence interval (CI) for area under the plasma concentration-time curve (AUC) was within the prespecified bioequivalence interval of 80-125%, C_max slightly exceeded the 125% CI bound (134%). No changes in t_max, t_lag, or t_½ were observed. Thirteen subjects (72%) experienced treatment-emergent adverse events (11 mild, 2 moderate), most commonly headache (22%) and diarrhea (17%).

CONCLUSIONS

Lenvatinib exposure was slightly increased by ketoconazole; however, the magnitude of the change was relatively small, and likely not clinically meaningful.

Abstract A5: Effects of rifampin on the pharmacokinetics (PK) of lenvatinib (L) in healthy participants

Background: L is an orally administered multitargeted tyrosine kinase inhibitor of VEGF receptors 1, 2, 3; FGF receptors 1, 2, 3, 4; PDGFR-β; RET; and KIT under clinical investigation in solid tumors at doses of 24 mg/d. This study in volunteers assessed the influence of P-glycoprotein (Pgp) inhibition (single-dose R) and simultaneous CYP3A4 and Pgp induction (multiple-dose R) on L PK parameters.

Methods: This was a single-center, single-dose, open-label, sequential, 3-period study. Subjects were administered 3 regimens with a 14-day washout between each treatment. Subjects received a single oral dose of L 24 mg on Day 1 (Period 1), Day 15 (Period 2), and Day 43 (Period 3). In Period 2 on Day 15, subjects received a single oral dose of rifampin 600 mg coadministered with L. In Period 3, subjects received oral rifampin 600 mg/d for 21 days (Days 29 to 49).

Results: 15 subjects were enrolled and completed the study. Single-dose rifampin increased free (unbound) L AUC0-∞ (32%) and Cmax (30%). Multidose rifampin decreased free L AUC0-∞ (9%) without a corresponding decrease in Cmax; mean t1/2(free L) decreased by ∼2.5 h (to ∼17 h) following single-dose rifampin and by ∼5 h following multidose R. The 90% confidence intervals (CIs) of the geometric least squares (GLS) mean ratios for Cmax and AUCs were above the upper CI boundary of the prespecified bioequivalence interval of 80%-125% following a single rifampin dose but within the prespecified bioequivalence interval following multidose R. Headache (n=3, 20%) was the most frequently reported treatment-emergent adverse event (TEAE); 5 subjects reported mild or moderate treatment-related TEAEs (n=5, 33%) most frequently nausea (n=3, 20%) and diarrhea (n=2, 13%).

Conclusions: L exposure was increased by single-dose rifampin but decreased by multiple rifampin doses. The magnitude of these changes was relatively small and likely not clinically meaningful.

A first-in-human phase I study of MORAb-004 (M4), a humanized monoclonal antibody recognizing endosialin (TEM-1), in patients with solid tumors

3016

Background: Endosialin (TEM-1) is a membrane glycoprotein on the cell surface of activated mesenchymal cells (e.g. pericytes, fibroblasts and mesenchymal tumor cells) and on a subset of human cancers. It is involved in the development of tumor vasculature, stromal/tumor organization and PDGFRb signaling. M4 is a humanized IgG monoclonal antibody which targets TEM-1. Preclinical studies suggest that M4 may have single agent activity via inhibition of the tumor microenvironment and by direct effects on tumors expressing this target. Methods: A phase I dose escalation study in patients (pts) with advanced solid tumors was conducted to evaluate the safety, pharmacokinetic profile and preliminary efficacy of M4 administered intravenously on a weekly schedule; final results are presented. Results: 36 pts refractory to therapy were treated at 10 dose levels (0.0625 to 16 mg/kg administered i.v. on a weekly schedule). Drug-related adverse events (AE) observed were primarily infusion toxicity (grade 1 and 2 fever, chills, headache, myalgia). The MTD was determined to be 12 mg/kg. DLT of grade 3 vomiting was observed at 16 mg/kg. Preliminary pharmacokinetic (PK) analyses demonstrate M4 accumulation beginning at 4 mg/kg, and that elimination mechanisms are saturable beginning at 0.25 mg/kg. Exposure (AUC) increases in a greater than dose-proportional manner, with the apparent t1/2 increasing proportionally with dose. Tumor shrinkage (Minor/mixed tumor responses, mR) were seen in four pts (soft tissue sarcoma (2), hepatocellular carcinoma, pancreatic neuroendocrine tumor). Each mR was associated with prolonged disease stabilization in these pts (6-14 months). A cohort (n=4) of pts with refractory colorectal carcinoma demonstrated disease stabilization (15-24 weeks). Analysis of archival tumor revealed TEM-1 stromal staining in all cases with tumor cell expression noted on a subset of tumors of mesenchymal origin. Conclusions: In this phase I study, M4 was tolerated up to 12 mg/kg (MTD) and early signs of potential activity were observed. Expanded cohorts of 1-12 mg/kg are ongoing to further define an optimal dose.

Pharmacokinetics and pharmacodynamics of argatroban in combination with a platelet glycoprotein IIB/IIIA receptor antagonist in patients undergoing percutaneous coronary intervention

The pharmacokinetic-pharmacodynamic (PK-PD) relationship of argatroban, administered in combination with a platelet glycoprotein IIb/IIIa receptor antagonist, was characterized in patients undergoing percutaneous coronary intervention (PCI). Plasma argatroban and activated clotting times (ACTs) were assessed periprocedurally in 152 patients administered argatroban (250- or 300-microg/kg bolus, then 15-microg/kg/min infusion) in combination with abciximab or eptifibatide during PCI. The PK and PK-PD models were developed utilizing a sequential population approach in NONMEM. Population PK estimates for clearance, central volume, and peripheral volume were 22.0 L/h, 11.0 L, and 13.0 L, respectively (coefficients of variation [CVs] </= 10%). By covariate analysis, clearance increased linearly with body weight. Plasma argatroban and ACT effect were well described using a sigmoidal E(max) model. For argatroban in combination with platelet glycoprotein IIb/IIIa receptor blockade in patients undergoing PCI, population PK parameters are consistent with values reported for argatroban in healthy subjects. A predictable relationship exists between argatroban concentration and effect in this setting.

A population pharmacokinetic-pharmacodynamic and logistic regression analysis of lotrafiban in patients

OBJECTIVE

Our objective was to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of lotrafiban, an oral glycoprotein IIb/IIIa inhibitor, in patients with a recent myocardial infarction, unstable angina, transient ischemic attack, or stroke.

METHODS

A 12-week, double-blind, multi-center, placebo-controlled, parallel-group, phase II study of lotrafiban (the Anti-platelet Useful Dose Study) was conducted in patients. Lotrafiban or placebo was administered as a twice daily oral dose at four dose levels (5-100 mg) for 12 weeks with daily doses of aspirin (300-325 mg). The pharmacokinetics of lotrafiban were characterized with the use of a population approach and were described by a two-compartment model with first order absorption and first order elimination. The pharmacodynamic data, ex vivo platelet aggregation, were described with the use of a direct effect inhibitory sigmoidal model with a baseline. The relationship between the severity of bleeding episodes and predicted steady-state lotrafiban exposure was characterized by logistic regression.

RESULTS

Pharmacokinetic analysis showed that increasing age and decreasing creatinine clearance resulted in increased exposure to lotrafiban. The concentration-effect relationship was steep, with near complete inhibition of platelet aggregation at lotrafiban concentrations in excess of 20 ng/mL. Logistic regression showed that at exposures that exceeded approximately 835 ng. h/mL, the severity of adverse bleeding events increased considerably; this suggested that dosing recommendations should be generated to minimize the likelihood of patients having an area under the plasma concentration-time curve from 0 to 24 hours in excess of this value.

CONCLUSIONS

Patients whose age exceeded 65 years or whose creatinine clearance was less than 60 mL/min should be given a lower dose of lotrafiban than younger patients with good renal function.

Bioavailability of pseudoephedrine from controlled release formulations in the presence of guaifenesin in human volunteers

A multiple-dose bioequivalence study with six healthy human volunteers was conducted. The bioavailability of an experimental controlled release tablet containing pseudoephedrine was compared with a marketed controlled release pseudoephedrine capsule in a three-way crossover study. Plasma samples, collected serially after oral drug administration, were analyzed for pseudoephedrine content using a specific HPLC method with UV detection. The bioavailability parameters, area under the concentration-time curve (AUC), maximum plasma concentration Cmax, and time to peak (Tmax) were obtained from the plasma concentration-time data. Additionally, model independent pharmacokinetic parameters were estimated. Analysis of variance of the data revealed no statistically significant differences between the test and the reference formulation. The presence of guaifenesin in the sustained release tablet did not influence pseudoephedrine bioavailability. The relative bioavailability of the tablet dosage form with respect to the capsule was found to be 100.8%. Classical and Westlake 95% confidence limits as well as the two one-sided t test, proposed by Schuirmann, and the Anderson-Hauck power analysis supported the inference that the two formulations demonstrated comparable bioavailabilty, even in the presence of guaifenesin. Using a non-linear regression program, it was found that the pharmacokinetics of pseudoephedrine followed a simple one-compartment disposition model with no lag time. Additionally, an in vitro-in vivo correlation, based on the estimation of cumulative relative fraction absorbed, was developed between the absorption of pseudoephedrine in humans and the in vitro dissolution time.