Identification and human exposure prediction of two aldehyde oxidase-mediated metabolites of a methylquinoline-containing drug candidate.

1. Aldehyde oxidase (AO enzymes)-mediated oxidation predominantly occurs at a carbon atom adjacent to the nitrogen on aromatic azaheterocycles. In the current report, we identified that AO enzymes oxidation took place at both the C-2 and C-4 positions of the methylquinoline moiety of Compound A based on data from mass spectrometric analysis, AO enzymes "litmus" test, and comparison with authentic standards. 2. To assess the potential for inadequate coverage for these two AO enzyme-mediated metabolites in nonclinical safety studies, given concerns due to differences in AO enzymes expression between preclinical species and humans, the human circulating levels of the two AO enzyme-mediated metabolites were predicted prospectively using in vitro and in vivo models. Both formation clearance and elimination clearance of the two metabolites were predicted based on in vitro to in vivo correlation and comparison with in vivo data from rats. 3. The result showed that the 4-OH metabolite of Compound A would account for less than 3% of the total drug-related exposure in human plasma, while the exposure to the 2-oxo metabolite would be relatively high (∼70%). 4. The predicted human exposure levels for the two metabolites are in similar ranges as those observed in monkeys. These data taken together support the advancement to clinical development of Compound A.

Abuse Potential with Oral Route of Administration of a Hydrocodone Extended-Release Tablet Formulated with Abuse-Deterrence Technology in Nondependent, Recreational Opioid Users.

Objective: To compare the oral abuse potential of hydrocodone extended-release (ER) tablet developed with CIMA ® Abuse-Deterrence Technology with that of hydrocodone immediate release (IR). Design: Randomized, double-blind, placebo-controlled, crossover study. Setting and Patients: One study site in the United States; adult nondependent, recreational opioid users. Methods: After confirming their ability to tolerate and discriminate hydrocodone IR 45 mg from placebo, eligible participants were randomized to receive each of the following oral treatments once: finely crushed placebo, hydrocodone IR 45-mg powder, intact hydrocodone ER 45-mg tablet, and finely crushed hydrocodone ER 45-mg tablet. Primary pharmacodynamic measure was "at the moment" drug liking. Secondary measures included overall drug liking, drug effects (e.g., balance, positive, negative, sedative), pupillometry, pharmacokinetics, and safety. Results: Mean maximum effect (E max ) for "at the moment" drug liking was significantly lower for intact (53.9) and finely crushed hydrocodone ER (66.9) vs. hydrocodone IR (85.2; P < 0.001). Drug liking for intact hydrocodone ER was comparable to placebo (E max : 53.9 vs. 53.2). Secondary measures were consistent with these results, indicating that positive, negative, and sedative drug effects were diminished with intact and crushed hydrocodone ER tablet vs. hydrocodone IR. The 72-hour plasma concentration-time profile for each treatment mimicked its respective "at the moment" drug-liking-over-time profile. Incidence of adverse events was lower with intact hydrocodone ER (53%) vs. hydrocodone IR (79%) and finely crushed hydrocodone ER (73%). Conclusions: The oral abuse potential of hydrocodone ER (intact and finely crushed) was significantly lower than hydrocodone IR in healthy, nondependent, recreational opioid users. Hydrocodone ER was generally well tolerated.

Pharmacokinetics and excretion of (14)C-omacetaxine in patients with advanced solid tumors.

Background Omacetaxine mepesuccinate is indicated in adults with chronic myeloid leukemia resistant and/or intolerant to ≥ 2 tyrosine kinase inhibitor treatments. This phase I study assessed the disposition, elimination, and safety of (14)C-omacetaxine in patients with solid tumors. Methods The study comprised a 7-days pharmacokinetic assessment followed by a treatment period of ≤ six 28-days cycles. A single subcutaneous dose of 1.25 mg/m(2) (14)C-omacetaxine was administered to six patients. Blood, urine, and feces were collected through 168 h or until radioactivity excreted within 24 h was <1 % of the dose. Total radioactivity (TRA) was measured in all matrices and concentrations of omacetaxine, 4'-desmethylhomoharringtonine (4'-DMHHT), and cephalotaxine were measured in plasma and urine. For each treatment cycle, patients received 1.25 mg/m(2) omacetaxine twice daily for 7 days. Results Mean TRA recovered was approximately 81 % of the dose, with approximately half of the radioactivity recovered in feces and half in urine. Approximately 20 % of the dose was excreted unchanged in urine; cephalotaxine (0.4 % of dose) and 4' DMHHT (9 %) were also present. Plasma concentrations of TRA were higher than the sum of omacetaxine and known metabolites, suggesting the presence of other (14)C-omacetaxine-derived compounds. Fatigue and anemia were common, consistent with the known toxicity profile of omacetaxine. Conclusion Renal and hepatic processes contribute to the elimination of (14)C-omacetaxine-derived radioactivity in cancer patients. In addition to omacetaxine and its known metabolites, other (14)C-omacetaxine-derived materials appear to be present in plasma and urine. Omacetaxine was adequately tolerated, with no new safety signals.

Metabolite profiling of 14C-omacetaxine mepesuccinate in plasma and excreta of cancer patients.

Omacetaxine mepesuccinate (hereafter referred to as omacetaxine) is a protein translation inhibitor approved by the US Food and Drug Administration for adult patients with chronic myeloid leukemia with resistance and/or intolerance to two or more tyrosine kinase inhibitors. The objective was to investigate the metabolite profile of omacetaxine in plasma, urine and faeces samples collected up to 72 h after a single 1.25-mg/m2 subcutaneous dose of 14C-omacetaxine in cancer patients. High-performance liquid chromatography mass spectrometry (MS) (high resolution) in combination with off-line radioactivity detection was used for metabolite identification. In total, six metabolites of omacetaxine were detected. The reactions represented were mepesuccinate ester hydrolysis, methyl ester hydrolysis, pyrocatechol conversion from the 1,3-dioxole ring. Unchanged omacetaxine was the most prominent omacetaxine-related compound in plasma. In urine, unchanged omacetaxine was also dominant, together with 4'-DMHHT. In feces very little unchanged omacetaxine was found and the pyrocatechol metabolite of omacetaxine, M534 and 4'-desmethyl homoharringtonine (4'-DMHHT) was the most abundant metabolites. Omacetaxine was extensively metabolized, with subsequent renal and hepatic elimination of the metabolites. The low levels of the metabolites found in plasma indicate that the metabolites are unlikely to contribute materially to the efficacy and/or toxicity of omacetaxine.

Characterization of the Pharmacokinetics and Mass Balance of a Single Oral Dose of Trofinetide in Healthy Male Subjects.

BACKGROUND AND OBJECTIVE: Trofinetide is the first drug to be approved for the treatment of Rett syndrome, a neurodevelopmental disorder. The purpose of the study is to fully characterize the metabolic and excretion profiles of trofinetide in humans. METHODS: This Phase 1, open-label, single-dose trial conducted in healthy male adults was designed to characterize the pharmacokinetics of trofinetide (absorption, metabolism, and excretion), mass balance of [14C]-trofinetide, and safety profile of trofinetide following administration of an oral 12-g dose administered as a mixture of trofinetide and [14C]-trofinetide. Blood, urine, and fecal samples were collected at prespecified timepoints. The pharmacokinetics of trofinetide were assessed in blood and urine samples using high-performance liquid chromatography (HPLC) with tandem mass spectrometric detection. Bioanalysis of radioactivity was conducted in blood, plasma, urine, and fecal samples using liquid scintillation counting. Metabolite profiling was conducted in blood, plasma, urine, and fecal samples using HPLC with liquid scintillation counting of chromatographic fractions. Safety and tolerability, including treatment-emergent adverse events (TEAEs), were assessed. RESULTS: Blood concentration-time profiles of trofinetide and total radioactivity were almost superimposable up to ~12 h after dosing. Urine concentration-time profiles of trofinetide and total radioactivity were similar. Trofinetide was rapidly absorbed into the circulation with an initial rapid decline (half-life [t½] alpha ~2.6 h), followed by a relatively slow terminal elimination phase (t½ beta ~20 h). The blood-to-plasma total radioactivity ratios were 0.529-0.592, indicating a lack of affinity for the cellular portion of blood. Renal excretion accounted for 83.8% of the administered radiochemical dose; 15.1% was recovered in feces. Urine and fecal recovery of radioactivity accounted for 99% of the administered dose at 168 h after dosing. Parent [14C]-trofinetide was the major radiolabeled entity in blood and plasma (88.4% and 93.1% in area under the concentration-time curves from 0 to 12 h [AUC0-12] in pooled blood and plasma samples, respectively) and the major entity excreted in urine (91.5% in 0-48-h pooled urine samples) and in feces (52.7% in 0-192-h pooled fecal samples). Only small levels of metabolites were present. In blood and plasma, only two minor metabolites were identified (each metabolite ≤ 2.24% of the AUC0-12 pool). These two metabolites were also observed in urine and fecal samples (≤ 2.41% of dose). In feces, one additional metabolite (0.84% of dose) was identified. Two mild TEAEs were reported in two participants and were not considered related to trofinetide. There were no clinically meaningful changes in individual laboratory parameters, vital signs, physical findings, or electrocardiogram results. CONCLUSIONS: Metabolic and excretion profiles confirm that trofinetide undergoes minimal hepatic or intestinal metabolism and is primarily excreted unchanged in the urine. Trofinetide containing radiolabeled [14C]-trofinetide was well tolerated.

Trofinetide is the first approved treatment for Rett syndrome, a rare genetic condition that affects brain development. Study aims were to look at how a single oral dose of trofinetide is absorbed into the bloodstream, to see whether trofinetide's chemical structure is changed once in the body, and to see how trofinetide and any metabolites (chemically altered trofinetide) are removed from the body. Safety and tolerability of trofinetide were also assessed. Eight healthy adult men took a single oral 12-g dose administered as a mixture of ¹⁴C-radiolabeled and nonlabeled trofinetide. Researchers collected blood, urine, and stool samples at regular intervals for up to 10 days postdose to measure levels of trofinetide and its metabolites. Trofinetide was rapidly absorbed (time to maximum concentration was 2 h postdose) and was primarily present in the blood as the unaltered compound. Concentrations decreased rapidly during the first 24 h postdose and more slowly thereafter. Most of the dose was recovered in urine with a lower amount in stool samples (83.8% and 15.1% of the radiochemical dose, respectively). Total recovery in urine and stool samples was 99%, primarily as the chemically unaltered compound. Only low levels of three trofinetide metabolites were detected. Two metabolites were found in blood, urine, and stool samples, while one metabolite was found in stool samples only. Two mild treatment-emergent adverse events, considered to be unrelated to trofinetide, were reported. In summary, trofinetide is rapidly absorbed, minimally metabolized, and mainly removed from the body in the urine as the unchanged drug.

Metabolite profiling of bendamustine in urine of cancer patients after administration of [14C]bendamustine.

Bendamustine is an alkylating agent consisting of a mechlorethamine derivative, a benzimidazole group, and a butyric acid substituent. A human mass balance study showed that bendamustine is extensively metabolized and subsequently excreted in urine. However, limited information is available on the metabolite profile of bendamustine in human urine. The objective of this study was to elucidate the metabolic pathways of bendamustine in humans by identification of its metabolites excreted in urine. Human urine samples were collected up to 168 h after an intravenous infusion of 120 mg/m(2) (80-95 µCi) [(14)C]bendamustine. Metabolites of [(14)C]bendamustine were identified using liquid chromatography (high-resolution)-tandem mass spectrometry with off-line radioactivity detection. Bendamustine and a total of 25 bendamustine-related compounds were detected. Observed metabolic conversions at the benzimidazole and butyric acid moiety were N-demethylation and γ-hydroxylation. In addition, various other combinations of these conversions with modifications at the mechlorethamine moiety were observed, including hydrolysis (the primary metabolic pathway), cysteine conjugation, and subsequent biotransformation to mercapturic acid and thiol derivatives, N-dealkylation, oxidation, and conjugation with phosphate, creatinine, and uric acid. Bendamustine-derived products containing phosphate, creatinine, and uric acid conjugates were also detected in control urine incubated with bendamustine. Metabolites that were excreted up to 168 h after the infusion included products of dihydrolysis and cysteine conjugation of bendamustine and γ-hydroxybendamustine. The range of metabolic reactions is generally consistent with those reported for rat urine and bile, suggesting that the overall processes involved in metabolic elimination are qualitatively the same in rats and humans.

Dose proportionality of fentanyl buccal tablet in doses ranging from 600 to 1300 microg in healthy adult subjects: a randomized, open-label, four-period, crossover, single-centre study.

Fentanyl buccal tablet (FBT) is indicated for the treatment of breakthrough pain in patients who are already receiving, and who are tolerant to, opioid therapy for underlying, persistent cancer pain. Breakthrough pain may be severe or excruciating, and some patients may require high doses of rapid-onset opioids to obtain adequate analgesia. The objective of this study was to assess the dose proportionality of FBT over a range of 600-1300 microg in healthy subjects. This was a randomized, open-label, four-period, crossover, single-centre study of FBT (Fentora) conducted in healthy adult subjects who were not tolerant to opioids. The study included 120 men and women aged 18-45 years with a body mass index of 20-30 kg/m2 who had no clinically significant findings on medical and psychiatric histories, physical examination, ECG or standard clinical laboratory tests, and who had a negative urine screen for drugs and alcohol. Eligible subjects were randomized to one of four dose sequences: ABDC, BCAD, CDBA and DACB, where A, B, C and D were FBT doses from lowest to highest (600, 1000, 1200 and 1300 microg). Each dose of FBT was separated by a minimum of 7 days. Naltrexone 50 mg was administered to block the opioid receptor-mediated effects of fentanyl. Plasma fentanyl concentration was measured through 72 hours after placement of FBT. The main outcome measures, maximum plasma fentanyl concentration (C(max)) and area under the plasma drug concentration versus time curve from time zero to infinity (AUC(infinity)), were analysed to determine dose proportionality. Other pharmacokinetic parameters were also evaluated. Dose proportionality was concluded if the two-sided 90% confidence intervals (CIs) for the slopes of the C(max) versus dose and AUC(infinity) versus dose curves were completely contained within the range of 0.711-1.289. The safety and tolerability of FBT were assessed throughout the study. The slope for C(max) versus dose was 0.8627 (90% CI 0.7730, 0.9525), and the slope for AUC(infinity) versus dose was 0.9330 (90% CI 0.8738, 0.9922). Given that the CIs for C(max) and AUC(infinity) were within the predefined range of 0.711-1.289, dose proportionality was concluded over the 600-1300 microg range. The mean dose-normalized plasma fentanyl concentration reached 80% of C(max) within 25 minutes; plasma fentanyl concentration was maintained at this level for 3 hours after dose. No unexpected safety or tolerability concerns were noted in the naltrexone-blocked healthy subjects. Seventy-four subjects (68%) experienced adverse events (AEs); all were mild (56 [51%]) or moderate (18 [17%]). The most common AEs were nausea, dizziness and headache. No serious AEs were reported. The dose proportionality of FBT from 600-1300 microg was shown in healthy subjects. Based on the data, when FBT is titrated up to 1300 microg, a predictable and linear increase in systemic exposure can be expected. Currently, FBT is approved up to 800 microg. This study provides pharmacokinetic data to support a potential, expanded therapeutic dose range of FBT.

Armodafinil and modafinil have substantially different pharmacokinetic profiles despite having the same terminal half-lives: analysis of data from three randomized, single-dose, pharmacokinetic studies.

BACKGROUND AND OBJECTIVE: Armodafinil, a non-amphetamine, wakefulness-promoting medication, is the R- and longer-lasting isomer of racemic modafinil. Armodafinil has been shown to improve wakefulness in patients with excessive sleepiness (ES) associated with treated obstructive sleep apnoea, shift work disorder or narcolepsy. In comparison with modafinil, armodafinil maintains higher plasma concentrations later in the day in healthy subjects. The objective of this analysis was to characterize the pharmacokinetic parameters related to those higher concentrations. METHODS: Data from three randomized studies in healthy adult subjects receiving single doses of either armodafinil (50, 100, 200, 250, 300 or 400 mg) or modafinil (400 mg) were pooled, and subsequently dose-normalized to a 200 mg dose for each drug. Non-compartmental pharmacokinetic parameters were assessed. RESULTS: Armodafinil and modafinil both had a mean single-dose terminal elimination half-life of approximately 13 hours, with similar mean maximum plasma drug concentration (C(max)) and median time to C(max) values. After reaching C(max), plasma concentrations appeared to decline in a monophasic manner with armodafinil, but in a biphasic manner with modafinil due to the initial rapid elimination of its S-isomer. As a result, mean area under the plasma drug concentration versus time curve (AUC) from time zero to the time of the last measurable concentration (AUC(last)) and AUC from time zero to infinity (AUC(infinity)) values were 33% and 40% higher, respectively, with armodafinil compared with modafinil on a milligram-to-milligram basis. CONCLUSIONS: Despite similar half-lives, plasma concentrations following armodafinil administration are higher late in the day than those following modafinil administration on a milligram-to-milligram basis. The different pharmacokinetic profile of armodafinil may result in improved wakefulness throughout the day in patients with ES compared with modafinil.

Pharmacokinetic profile of armodafinil in healthy subjects: pooled analysis of data from three randomized studies.

BACKGROUND AND OBJECTIVES: Armodafinil (R-modafinil) is the R- and longer-lasting isomer of the racemic compound modafinil, a wakefulness-promoting medication. Armodafinil is eliminated approximately three times more slowly than the S-isomer of racemic modafinil. Published studies have demonstrated the efficacy of armodafinil for treating excessive sleepiness associated with obstructive sleep apnoea, shift work disorder and narcolepsy. The objectives of this study were to describe the pharmacokinetic profile, tolerability and safety of armodafinil in healthy subjects. METHODS: Pooled pharmacokinetic data from three separate randomized studies in 119 healthy subjects who received single or multiple (once daily for up to 14 days) oral doses of armodafinil ranging between 50 and 400 mg were analysed. The impact of food on the single-dose pharmacokinetic profile of armodafinil was also assessed in subjects following an overnight fast and after the consumption of a standard fatty meal. RESULTS: Armodafinil was readily absorbed and exhibited linear pharmacokinetics over the 50-400 mg dose range. Peak plasma concentrations were reached around 2 hours after administration in the fasted state. Food had no effect on the overall bioavailability of armodafinil; however, the peak concentration was delayed by approximately 2-4 hours. In the multiple-dose study, dose proportionality was confirmed by linear regression analyses of the log-transformed area under the plasma concentration versus time curve (AUC) and maximum plasma concentration (Cmax) values as a function of dose. After reaching the peak, plasma concentrations of armodafinil declined in a monophasic manner, with a mean elimination half-life of approximately 15 hours. Steady state appeared to be reached within 7 days. At steady state, the systemic exposure to armodafinil was 1.8 times that observed after single-dose administration. Armodafinil was generally well tolerated, the most frequent adverse events being headache, dizziness and nausea. CONCLUSIONS: In the present analysis, armodafinil exhibited linear pharmacokinetics over the dose range of 50-400 mg. While food affected the rate but not the extent of absorption, peak plasma concentrations were reached in approximately 2 hours when the drug was taken on an empty stomach. With once-daily dosing, steady state appeared to be reached within 7 days. After reaching peak plasma levels, concentrations of armodafinil declined monophasically, with a mean elimination half-life of around 15 hours. Armodafinil was generally well tolerated.

Interaction profile of armodafinil with medications metabolized by cytochrome P450 enzymes 1A2, 3A4 and 2C19 in healthy subjects.

BACKGROUND AND OBJECTIVE: Armodafinil, a wakefulness-promoting agent, is the pure R-enantiomer of racemic modafinil. The objective of this article is to summarize the results of three clinical drug-interaction studies assessing the potential for drug interactions of armodafinil with agents metabolized by cytochrome P450 (CYP) enzymes 1A2, 3A4 and 2C19. Study 1 evaluated the potential for armodafinil to induce the activity of CYP1A2 using oral caffeine as the probe substrate. Study 2 evaluated the potential for armodafinil to induce gastrointestinal and hepatic CYP3A4 activity using intravenous and oral midazolam as the probe substrate. Study 3 evaluated the potential for armodafinil to inhibit the activity of CYP2C19 using oral omeprazole as the probe substrate. METHODS: Healthy men and nonpregnant women aged 18-45 years with a body mass index of

Bioequivalence following buccal and sublingual placement of fentanyl buccal tablet 400 microg in healthy subjects.

BACKGROUND AND OBJECTIVE: The fentanyl buccal tablet (FBT) is formulated to enhance the rate and extent of fentanyl absorption across the buccal mucosa. FBT is indicated for the management of breakthrough pain (a transient flare of pain on a background of chronic pain otherwise controlled by treatment with opioids) in patients with cancer who are already receiving and who are tolerant to opioid therapy for their underlying persistent cancer pain. This study assessed the bioequivalence of a single 400-microg dose of FBT following buccal (i.e. above a molar tooth between the upper gum and cheek) and sublingual (i.e. placed under the tongue) placement in order to provide an alternative option to patients. METHODS: Healthy subjects were randomized to receive one FBT 400 microg buccally and sublingually (with naltrexone to minimize opioid effects) in an open-label, crossover design. Bioequivalence, as determined from the maximum plasma drug concentration (C(max)) and the area under the plasma drug concentration-time curve from time 0 to infinity (AUC(infinity)), was established if the 90% confidence interval (CI) for the ratio of the means of sublingual/buccal values fell within the range of 0.80 to 1.25. RESULTS: Ninety subjects were enrolled (67 men, 23 women; median age 24 years), and 78 completed the study. The criteria for bioequivalence were met for both C(max) and AUC(infinity) for the two sites of tablet placement: sublingual/buccal ratio for C(max) = 0.868 (90% CI 0.815, 0.924); sublingual/buccal ratio for AUC(infinity) = 0.947 (90% CI 0.901, 0.995). Buccal and sublingual placement resulted in similar values for both AUC from time 0 to t(max') (AUC(tmax')), where t(max') is the median time to C(max) of a single 400-microg dose of FBT administered buccally (mean [SD]: 0.35 [0.16] ng . h/mL buccal; 0.35 [0.16] ng . h/mL sublingual) and for time to C(max) (median [range]: 0.75 [0.33-3.13] hours buccal; 0.78 [0.17-3.00] hours sublingual). FBT was generally well tolerated following placement at both sites in healthy volunteers administered naltrexone. CONCLUSION: The results of this study support sublingual FBT placement as a viable alternative to buccal placement in patients who may require an alternate administration site.

Absolute and relative bioavailability of fentanyl buccal tablet and oral transmucosal fentanyl citrate.

This study assessed the absolute and relative bioavailabilities and transmucosal and gastrointestinal absorbency of fentanyl buccal tablet (FBT) and oral transmucosal fentanyl citrate (OTFC). In a randomized crossover design, 26 healthy subjects received FBT 400 microg (transmucosal), FBT 800 microg (oral), OTFC 800 microg (transmucosal), and fentanyl 400 microg (intravenous). The transmucosal FBT had the highest absolute bioavailability (0.65) compared with the oral FBT (0.31) or transmucosal OTFC (0.47). More fentanyl was absorbed transmucosally from FBT than OTFC (48% vs 22%). Median t(max) values were shorter following the transmucosal FBT (47 minutes) than the oral FBT (90 minutes) or the transmucosal OTFC (91 minutes). Transmucosal administration of FBT compared with dose-normalized OTFC resulted in higher total systemic fentanyl exposure, higher early systemic exposure, and higher C(max). The rate and extent of fentanyl absorption were greater following administration of FBT compared to OTFC. An approximately 30% smaller dose of FBT achieved systemic exposures comparable to OTFC.

Single-dose and steady-state pharmacokinetics of fentanyl buccal tablet in healthy volunteers.

This study evaluated the single-dose and steady-state pharmacokinetics of fentanyl buccal tablet 400 microg in healthy adult volunteers. After receiving naltrexone 50 mg to block opioid receptor-mediated effects of fentanyl, subjects received fentanyl buccal tablet 400 microg on day 1, then every 6 hours from day 4 to day 9 (21 doses). Naltrexone 50 mg was administered every 12 hours throughout the study. Plasma fentanyl concentrations were determined for 72 hours after administration of fentanyl buccal tablet 400 microg on day 1 and the last dose of fentanyl buccal tablet 400 microg on day 9. Following single- and multiple-dose administration of fentanyl buccal tablet, the median time to maximum concentration (tmax) was 52.2 and 49.8 minutes, respectively. Peak plasma concentration of fentanyl (Cmax) was 0.88 ng/mL for the single-dose regimen and 1.77 ng/mL for the multiple-dose regimen. Steady state was reached within 5 days, consistent with the observed median half-life of approximately 22 hours following multiple doses. Observed accumulation of fentanyl after multiple doses of fentanyl buccal tablet was slightly greater than would be expected based on the single-dose data. This was attributed to the redistribution of fentanyl from a deep tissue compartment into the plasma. This study indicates that fentanyl buccal tablet has predictable pharmacokinetics following multiple-dose administration.

Absorption of fentanyl from fentanyl buccal tablet in cancer patients with or without oral mucositis: a pilot study.

BACKGROUND AND OBJECTIVES: Patients with cancer, particularly those undergoing chemotherapy or radiotherapy, may develop oral mucositis. This is the first study to investigate the absorption profile of fentanyl buccal tablet (FBT) - an effervescent formulation of fentanyl indicated for the management of breakthrough pain in opioid-tolerant cancer patients - in patients with or without oral mucositis. METHODS: In this open-label study, patients with or without oral mucositis self-administered a single 200 microg dose of FBT by placing the tablet between the upper gum and cheek above a molar tooth. Venous blood samples for measurement of plasma fentanyl concentrations were collected at regular intervals up to 8 hours following FBT administration. Parameters of interest included maximum plasma concentration (C(max)), time to reach C(max) (t(max)), area under the plasma concentration-time curve from time zero to 8 hours (AUC(8)), and AUC from time zero to the median t(max) (AUC(tmax)(')). Adverse events were monitored throughout the study. Oral mucosal examinations and measurements of vital signs were performed at intervals up to 8 hours following FBT administration. RESULTS: Sixteen patients, 8 with and 8 without oral mucositis, received FBT and completed the study. The severity of oral mucositis was mild in the patients exhibiting this condition. Median C(max) values were comparable: 1.14 ng/mL (range 0.26-2.69 ng/mL) in patients with mucositis, and 1.21 ng/mL (range 0.21-2.34 ng/mL) in patients without mucositis. The t(max) was not significantly different in the two groups: median t(max) was 25.0 min (range 15-45 min) in patients with mucositis and 22.5 min (range 10-121 min) in patients without mucositis. Median AUC(tmax') values were 0.17 ng . h/mL (range 0.04-0.52 ng . h/mL) in patients with mucositis, and 0.20 ng . h/mL (range 0.00-0.65 ng . h/mL) in patients without mucositis. The corresponding AUC(8) values were 2.05 ng . h/mL (range 1.16-3.83 ng . h/mL) and 1.55 ng . h/mL (range 0.74-3.07 ng . h/mL), respectively. FBT was generally well tolerated in this small group. No application site adverse events or changes in oral mucosal assessments were reported. CONCLUSION: The absorption profile of a single dose of FBT 200 microg was similar in patients with or without mild oral mucositis. The compound was generally well tolerated.

Effect of Food on the Pharmacokinetics of Single- and Multiple-Dose Hydrocodone Extended Release in Healthy Subjects.

BACKGROUND AND OBJECTIVES: Food intake can alter the pharmacokinetics of certain medications, including changes in their oral bioavailability, which is of particular concern for extended-release (ER) opioids because of the high drug loads. Two randomized, open-label studies assessed the effect of food on the pharmacokinetics of single and multiple doses of hydrocodone ER formulated with CIMA® Abuse-Deterrence Technology. METHODS: Healthy subjects in fed and fasted states received single 90-mg doses of hydrocodone ER (Studies 1 and 2) or multiple doses of hydrocodone ER (45 mg twice daily on days 2-3, 60 mg twice daily on days 4-5, 90 mg twice daily on days 6-10, and 90 mg once in the morning on day 11) (Study 2). Naltrexone was administered to minimize opioid-related adverse events. Pharmacokinetic parameters included maximum hydrocodone plasma concentration (C max) and area under the concentration-versus-time curve from time 0 to infinity (AUC0-∞) in Study 1 (day 1) and for one dosing interval at steady state (AUCτ,ss) in Study 2 (day 11). Before conducting the multiple-dose study, single-dose data were fitted with a population pharmacokinetic methodology. RESULTS: In total, 40 subjects were randomized to Study 1 and 43 subjects were randomized to Study 2. While overall exposure (AUC0-∞) was relatively similar (least squares mean ratio [90% CI]: 1.11 [1.06-1.16]), results indicated that the single-dose C max was 40% higher under fed versus fasted conditions (least squares mean ratio [90% CI]: 1.40 [1.31-1.51]; Study 1). Modeling of single-dose data predicted that the effect of food would be much less at steady state [predicted fed:fasted C max at steady state (C max,ss) and AUCτ,ss ratios of 1.18 and 1.09, respectively]. The multiple-dose study results validated these predicted ratios and indicated that the steady-state 90% CIs were within 0.80-1.25 for the fed:fasted C max,ss (1.14 [1.07-1.21]) and AUCτ,ss (1.11 [1.04-1.17]) parameters, indicating that clinically meaningful food effects at steady state are not expected. CONCLUSION: No evidence of an effect of food was found on the pharmacokinetics of hydrocodone ER after multiple days of twice-daily dosing.

Comparison of equivalent doses of fentanyl buccal tablets and arteriovenous differences in fentanyl pharmacokinetics.

BACKGROUND: The fentanyl buccal tablet (FBT) is designed to enhance the rate and extent of fentanyl absorption through the buccal mucosa. AIM: To evaluate the bioequivalence of microg-equivalent doses of FBT administered as single and multiple tablets and assess differences in the arterial and venous pharmacokinetics of FBT in healthy volunteers. METHODS: Twenty-seven healthy adults, aged 19-45 years, participated in the randomised, open-label, three-period, crossover study. In the first two periods, FBT was administered as four 100 microg tablets simultaneously or one FBT 400 microg to assess bioequivalence. Venous blood samples were obtained over a 72-hour period to measure plasma fentanyl concentrations. In the third period, arterial and venous blood samples were obtained simultaneously from before administration of one FBT 400 microg through 4 hours after administration to evaluate the impact of arterial versus venous sampling on the pharmacokinetic profile. As subjects were not opioid tolerant, naltrexone was administered to block opioid receptor-mediated effects of fentanyl. Adverse events were recorded throughout. RESULTS: Maximum plasma concentration (C(max)) and area under the plasma concentration-time curve from time zero to infinity (AUC(infinity)) on average were approximately 12% and 13% higher, respectively, for FBT administered as four 100 microg tablets simultaneously compared with one FBT 400 microg. Maximum plasma concentrations in the arterial circulation were approximately 60% higher and occurred 15 minutes earlier than those measured from the venous circulation. No serious adverse events were reported during the study. CONCLUSION: Despite small differences in C(max) and AUC(infinity) (on average 12% and 13%, respectively), FBT administered as four 100 microg tablets simultaneously compared with one 400 microg tablet did not meet the criteria for bioequivalence. An increased surface area exposure with four tablets compared with one tablet may account for the slightly higher maximum concentrations observed with four 100 microg tablets. A substantially higher C(max) was reached earlier in the arterial than in the venous circulation.

Pharmacokinetic properties of fentanyl effervescent buccal tablets: a phase I, open-label, crossover study of single-dose 100, 200, 400, and 800 microg in healthy adult volunteers.

BACKGROUND: The fentanyl effervescent buccal tablet (FEBT) is designed to enhance the rate and extent of the absorption of fentanyl, an opioid, through the buccal mucosa. OBJECTIVES: The purposes of this study were to assess the dose proportionality of FEBT in healthy volunteers over the potential therapeutic dose range (100-800 microg) and characterize the pharmacokinetic (PK) profile of 4 doses (100, 200, 400, and 800 microg) of FEBT. METHODS: This Phase I, randomized, open-label, 4-period crossover study was conducted at Radiant Research, Honolulu, Hawaii. Healthy adult volunteers with intolerance to opioids were randomly assigned to receive 1 of 4 single-dose sequences of FEBT: 100, 200, 400, and 800 microg (selected to encompass the anticipated therapeutic dose range), with each successive administration separated by a washout period of >or=7 days. Naltrexone hydrochloride (50-mg tablet) was administered-15 and 3 hours before and 9 hours after FEBT administration to block opioid receptor-mediated effects of fentanyl. Plasma fentanyl concentrations were measured from venous samples obtained over 72 hours after FEBT administration. Early fentanyl exposure was assessed using AUC from time 0 to 0.75 hour (the median T(max) of the reference dose [100 microg]) (AUC(0-Tmax')). Adverse events (AEs) were monitored and recorded throughout the study by medically qualified personnel. RESULTS: Thirty-two subjects (26 men, 6 women; mean [SD] age, 29.3 [7.2] years [range, 19-44 years]; mean [SD] weight, 74.7 [10.7] kg) were enrolled. Median T was between 35 and 45 minutes after FEBT administration. AUC(0-infinity) and C(max) increased approximately linearly with increasing doses of FEBT. Mean plasma fentanyl concentrations decreased from C(max) in a biexponential manner at the 100- and 200-microg doses and decreased in a triexponential manner at the 800-mug dose. Despite the triexponential decrease in the mean profile observed with the 400-microg dose, a biexponential decrease was observed in approximately half of the individual profiles. AUC(0-Tmax') ranged from 0.09 ng x h/mL with the 100-microg dose to 0.52 ng x h/mL with the 800-microg dose. The most commonly reported AEs in the 100-, 200-, 400-, and 800-microg dose groups were as follows: application-site erythema, 3, 3, 4, and 3 subjects, respectively; nausea, 3, 2, 5, and 4 subjects; somnolence, 3, 2, 3, and 2 subjects; and headache, 3, 2, 1, and 4 subjects. None of the AEs were serious. CONCLUSIONS: In this study of the dose proportionality of FEBT in healthy volunteers, the PK profile of FEBT was characterized by a high early systemic exposure of fentanyl (0.09-0.52 ng x h/mL). Dose-dependent parameters (C(max) and AUC) increased in an approximately dose-proportional manner from 100 to 800 microg FEBT.

Effects of Renal Impairment and Hepatic Impairment on the Pharmacokinetics of Hydrocodone After Administration of a Hydrocodone Extended-Release Tablet Formulated With Abuse-Deterrence Technology.

Two open-label, single-dose, parallel-group studies assessed effects of renal and hepatic impairment on the pharmacokinetics of a hydrocodone extended-release (ER) formulation developed with the CIMA Abuse-Deterrence Technology platform. Forty-eight subjects with normal renal function or varying degrees of renal impairment received hydrocodone ER 45 mg (study 1); 16 subjects with normal hepatic function or moderate hepatic impairment received hydrocodone ER 15 mg (study 2). Blood samples were obtained predose and through 144 hours postdose. Mean maximum observed plasma hydrocodone concentration (Cmax ) in subjects with normal renal function, mild, moderate, and severe impairment, and end-stage renal disease was 28.6, 33.4, 42.4, 36.5, and 31.6 ng/mL, and mean area under the plasma hydrocodone concentration-versus-time curve from time 0 to infinity (AUC0-∞ ) was 565, 660, 973, 983, and 638 ng·h/mL, respectively. Incidence of adverse events was 57%, 38%, 44%, 33%, and 56%, respectively. Mean Cmax with normal hepatic function and moderate impairment was 10.1 and 13.0 ng/mL, and mean AUC0-∞ was 155 and 269 ng·h/mL, respectively. Incidence of adverse events was 38% in both groups. Altered systemic exposure in renally or hepatically impaired populations (up to ∼70% higher) should be considered when titrating to an effective dose of hydrocodone ER.

Dose proportionality of a hydrocodone extended-release tablet formulated with abuse-deterrence technology.

BACKGROUND AND OBJECTIVE: This open-label, crossover study evaluated the dose proportionality of a hydrocodone extended-release (ER) tablet employing the CIMA(®) Abuse-Deterrence Technology platform. METHODS: Healthy volunteers were randomized to receive single doses of hydrocodone ER 15, 30, 45, 60, and 90 mg separated by a minimum 14-day washout. Subjects received naltrexone to minimize opioid-related adverse events (AEs). Blood samples were collected for 72 h after each hydrocodone administration. Pharmacokinetic measures included maximum observed plasma hydrocodone concentration (C max) and area under the plasma concentration-time curve from time zero to infinity (AUC∞). Dose proportionality was concluded if the confidence interval (CI) of the slope of the regression line for C max and AUC∞ versus dose fell within 0.875-1.125. RESULTS: In total, 60 subjects were evaluable for pharmacokinetics. The mean C max was 12.6, 20.7, 30.3, 41.2, and 62.5 ng/mL and the mean AUC∞ was 199, 382, 592, 766, and 1189 ng.h/mL for hydrocodone ER 15, 30, 45, 60, and 90 mg, respectively. C max and AUC∞ increased linearly with increasing dose. The 90 % CIs of the slope of the regression line for C max (0.880-0.922) and AUC∞ (0.984-1.026) indicated systemic exposure to hydrocodone increased in a dose-proportional manner. In these naltrexone-blocked subjects, no increased incidence of AEs was apparent with increasing dose. CONCLUSION: Hydrocodone exposure increased in a dose-proportional manner after administration of hydrocodone ER 15-90 mg tablets in healthy, naltrexone-blocked subjects.

Pharmacokinetic and pharmacodynamic profile of bendamustine and its metabolites.

PURPOSE: Bendamustine is a unique alkylating agent indicated for the treatment of chronic lymphocytic leukemia and rituximab-refractory, indolent B cell non-Hodgkin's lymphoma. Despite the extensive experience with bendamustine, its pharmacokinetic profile has only recently been described. This overview summarizes the pharmacokinetics, pharmacokinetic/pharmacodynamic relationships, and drug-drug interactions of bendamustine in adult and pediatric patients with hematologic malignancies. METHODS: A literature search and data on file (including a human mass balance study, pharmacokinetic population analyses in adult and pediatric patients, and modeling analyses) were evaluated for inclusion. RESULTS: Bendamustine concentrations peak at end of intravenous infusion (~1 h). Subsequent elimination is triphasic, with the intermediate t 1/2 (~40 min) as the effective t 1/2 since the final phase represents <1 % of the area under the curve. Bendamustine is rapidly hydrolyzed to monohydroxy-bendamustine and dihydroxy-bendamustine, which have little or no activity. Cytochrome P450 (CYP) 1A2 oxidation yields the active metabolites γ-hydroxybendamustine and N-desmethyl-bendamustine, at low concentrations, which contribute minimally to cytotoxicity. Minor involvement of CYP1A2 in bendamustine elimination suggests a low likelihood of drug-drug interactions with CYP1A2 inhibitors. Systemic exposure to bendamustine 120 mg/m(2) is comparable between adult and pediatric patients; age, race, and sex have been shown to have no significant effect on systemic exposure in either population. The effect of hepatic/renal impairment on bendamustine pharmacokinetics remains to be elucidated. Higher bendamustine concentrations may be associated with increased probability of nausea or infection. No clear exposure-efficacy response relationship has been observed. CONCLUSIONS: Altogether, the findings support dosing based on body surface area for most patient populations.