Population Pharmacokinetics of Transdermal Fentanyl in Patients With Cancer-Related Pain

ABSTRACT

Determining the appropriate dose of transdermal fentanyl (TDF) for the alleviation of cancer pain requires determining the factors causing variations in serum fentanyl concentration after TDF treatment. The objective of this study was to identify these factors and incorporate them into a formula that can be used to predict serum fentanyl concentration after application of a TDF patch. Blood samples of cancer patients treated with a TDF patch for the alleviation of pain were collected at 24, 48, and 72 hours after application to evaluate population pharmacokinetics using the nonlinear mixed-effect model (NONMEM). Based upon this evaluation, Child-Pugh Score and use of a cytochrome P450 3A4 (CYP3A4) inducer were identified as the most significant factors in variations in serum fentanyl concentration and incorporated into the following Final Model formula: CL_fenta (L/h) = 3.53 × (15 ? Child-Pugh Score) × (1 + 1.38 × use or no use of CYP3A4 inducer). Bootstrap evaluation of the Final Model revealed a high convergence rate, suggesting that the model formula is a reliable and useful tool for determining TDF dose for the alleviation of cancer pain.     

Pharmacokinetics of Oxycodone After Intravenous and Subcutaneous Administration in Japanese Patients with Cancer Pain

ABSTRACT

In Japan, Oxycodone hydrochloride injection formulation has been approved in 2012. However, its pharmacokinetics has been poorly studied. The aim of this study is to evaluate the pharmacokinetics of oxycodone after intravenous and subcutaneous administration of oxycodone hydrochloride injection in Japanese patients with cancer pain. Noncompartmental analysis and population pharmacokinetic analysis were performed. We conducted a multicenter open-label study of oxycodone hydrochloride administered as constant infusion with the dose titrated individually according to the pain intensity in patients with cancer pain. Pharmacokinetic parameters for plasma oxycodone and its metabolites were estimated using pharmacokinetics of oxycodone was evaluated using a total of 344 plasma concentrations obtained from 89 patients. The estimated geometric mean clearance (CL) of oxycodone was 24.3 L per hour after constant intravenous infusion and 29.5 L per hour after constant subcutaneous infusion, respectively. Population pharmacokinetic analysis indicated that body surface area was the influencing factor on CL and there were no pharmacokinetic differences for CL between intravenous and subcutaneous infusion. These results provide important information for the clinical use of oxycodone injection.     

A Population Pharmacokinetic Analysis of the Influence of Nutritional Status of Digoxin in Hospitalized Korean Patients

Background

Safe and effective use of digoxin in hospitalized populations requires information about the drug’s pharmacokinetics and the influence of various factors on drug disposition. However, no attempts have been made to link an individual’s digoxin requirements with nutritional status.

Objectives

The main goal of this study was to estimate the population pharmacokinetics of digoxin and to identify the nutritional status that explains pharmacokinetic variability in hospitalized Korean patients.

Methods

Routine therapeutic drug-monitoring data from 106 patients who received oral digoxin at Seoul National University Bundang Hospital were retrospectively collected. The pharmacokinetics of digoxin were analyzed with a 1-compartment, open-label pharmacokinetic model by using a nonlinear mixed-effects modeling tool (NONMEM) and a multiple trough screening approach.

Results

The effect of demographic characteristics and biochemical and nutritional indices were explored. Estimates generated by using NONMEM indicated that the CL/F of digoxin was influenced by renal function, serum potassium, age, and percentage of ideal body weight (PIBW). These influences could be modeled by following the equation CL/F (L/h) = 1.36 × (creatinine clearance/50)^1.580 × K^0.835 × 0.055 × (age/65) × (PIBW/100)^0.403. The interindividual %CV for CL/F was 34.3%, and the residual variability (SD) between observed and predicted concentrations was 0.225 μg/L. The median estimates from a bootstrap procedure were comparable and within 5% of the estimates from NONMEM. Correlation analysis with the validation group showed a linear correlation between observed and predicted values.

Conclusions

The use of this model in routine therapeutic drug monitoring requires that certain conditions be met which are consistent with the conditions of the subpopulations in the present study. Therefore, further studies are needed to clarify the effects of nutritional status on digoxin pharmacokinetics. The present study established important sources of variability in digoxin pharmacokinetics and highlighted the relationship between pharmacokinetic parameters and nutritional status in hospitalized Korean patients.     

Population Pharmacokinetics Study of Nemonoxacin Among Chinese Patients With Moderate Hepatic Impairment

Purpose

Nemonoxacin is a novel C-8-methoxy nonfluorinated quinolone that has been approved for the treatment of community-acquired pneumonia (CAP) in adults. The goals of this study were to evaluate the pharmacokinetic (PK) and population PK parameters of nemonoxacin and to provide the appropriate dose adjustment recommendations for patients with hepatic impairment.

Safety and Efficacy of Once-Daily Hydromorphone Extended-Release Versus Twice-Daily Oxycodone Hydrochloride Controlled-Release in Chinese Patients With Cancer Pain: A Phase 3, Randomized,Double-Blind,Multicenter Study

Noninferiority of the efficacy of once-daily hydromorphone hydrochloride extended-release (hydromorphone ER) compared with twice-daily oxycodone hydrochloride controlled-release (oxycodone CR) was investigated in this randomized, double-blind study in Chinese patients with moderate to severe cancer pain requiring strong oral opioid analgesics. Randomization (1:1) to hydromorphone ER (8–32 mg) or oxycodone CR (10–40 mg) was followed by dose titration (up to 8 days) and dose maintenance (28 days, weekly visits). Primary endpoint was change from baseline to end of study in “worst pain in the past 24 hours” of Brief Pain Inventory (Short Form) score on last observation carried forward (per protocol set). A total of 137 of 260 randomized patients completed maintenance phase (hydromorphone ER: n = 70; oxycodone CR: n = 67); per protocol set: 81 patients. Mean age was 53.1 years (range: 18–70 years; males: 65.3%); most common Eastern Cooperative Oncology Group performance status = 2. Least square mean difference between 2 treatment groups for primary endpoint using analysis of covariance (baseline score, covariate) was ?.1 (95% confidence interval: ?1.3, 1.1), with upper bound of 95% confidence interval <1.5 (predefined noninferiority margin). Most common reason for deaths was disease progression (hydromorphone ER: 6.3%; oxycodone CR: 12.7%). Treatment-emergent adverse events were comparable between treatment groups. Hydromorphone ER was noninferior to oxycodone CR in alleviating cancer pain and was well tolerated.PerspectiveThis article demonstrates clinical noninferiority of the efficacy of once-daily hydromorphone ER compared with twice-daily oxycodone CR in alleviating cancer pain in Chinese patients, with comparable safety profiles between the 2 treatment groups. Thus, a treatment option with the potential for a reduced dosing frequency exists for health care providers and patients.     

Pharmacokinetic Effects of Diphenhydramine or Oxycodone in Simulated Acetaminophen Overdose

Objectives: To determine the effects of co‐ingested diphenhydramine (DPH) or oxycodone (OXY) on the absorption kinetics of simulated acetaminophen (APAP) overdose. Methods: This was an institutional review board–approved, prospective crossover study of ten healthy human volunteers ingesting 5 grams of APAP, 5 grams of APAP + 250 mg of DPH (APAP+DPH), or 5 grams of APAP + 0.5 mg/kg of OXY (APAP+OXY). Serum APAP concentrations (APAPs) were measured hourly from zero through eight hours and again at 24 hours, and basic noncompartmental pharmacokinetic parameters were compared. Results: For APAP alone, the mean parameters were: maximum APAP concentration ([APAP]_max) 71.8 μg/mL, time to peak [APAP] (t_max) 1.71 hours, and area under the receiver operating characteristic curve (AUC_0–8) 318.3 μg‐hr/mL. For APAP+DPH, the mean parameters were: [APAP]_max 67.6 μg/mL, t_max 1.90 hours, and AUC_0–8 297.7 μg‐hr/mL. For APAP+OXY, the parameters were: [APAP]_max 42.9 μg/mL, t_max 2.87 hours, and AUC_0–8 232.1 μg‐hr/mL. Compared with APAP alone, APAP+OXY had a 27% lower AUC, a 40% lower [APAP]_max, and a 68% longer t_max. Co‐ingested DPH had no significant effect on APAP absorption, except a 6% decrease in the AUC. Conclusions: Co‐ingested OXY, but not DPH, delayed absorption of APAP. This suggests a potential role for activated charcoal administration beyond one hour postingestion after mixed ingestions that include OXY.     

Population Pharmacokinetics Study of Contezolid (MRX-I), a Novel Oxazolidinone Antibacterial Agent,in Chinese Patients

PurposeContezolid (MRX-I) is a novel oxazolidinone with potent in vitro activity against gram-positive pathogens. The aim of this study was to establish the dose-pharmacokinetic (PK) exposure-pharmacodynamic (PD)–response relationship and to quantitatively evaluate the variability of MRX-I after continuous oral administration of 600 mg BID and 800 mg BID for 14 days under fed conditions in patients with skin and skin structure infections. Another goal was to evaluate the 2 dosing regimens against methicillin-resistant Staphylococcus aureus infections based on PK/PD analysis.MethodsPK data from healthy volunteers and patients were pooled to develop a population PK model using a nonlinear mixed effect modeling method. Monte Carlo simulations were used to predict probability of target attainment (PTA) and cumulative fraction of response after single oral administration of 600 and 800 mg of MRX-I under fed conditions.FindingsThe PK profile of oral administration of MRX-I was described by using a 2-compartment model with first-order elimination. Absorption of MRX-I may be affected by food intake. Type of volunteers could affect absorption constant rate and volume of distribution in the peripheral compartment, and weight could affect volume of distribution in the central department. No obvious effect on PK parameters was identified for other factors such as age, sex, creatinine clearance, concomitant medicine, and baseline diseases. Based on Monte Carlo simulation, MRX-I 600 or 800 mg BID up to 14 days on ordinary fed status could produce satisfactory efficacy against methicillin-resistant S aureus, with cumulative fraction of response >90% for fAUC_0–24/MIC targeted at 2.3. At MIC ≤2.0 μg/mL for MRX-I 600 mg BID, or at MIC ≤4.0 μg/mL for MRX-I 800 mg BID, with continuous administration for 14 days at fed status, both regimens could obtain satisfactory clinical and antibacterial efficacy, with PTA >90%. Hence, the MRX-I regimen of 800 mg BID for 7–14 days can be recommended for confirmative clinical trials in patients with skin and skin structure infections.ImplicationsPK profiles of MRX-I were well captured by using a 2-compartment PK model, and disease status, food intake, and weight were found to significantly affect PK profiles. A dosing regimen of 800 mg BID for 7–14 days with ordinary food intake was recommended for pivotal study based on simulated fAUC_0–24/MIC and PTA values. Results suggest that dose adjustments are not necessary for patient sex in confirmatory studies. Chinese Clinical Trial Registration identifier: CTR20140056.     

Pharmacokinetics and Pharmacodynamics of Levornidazole in Patients With Intra-abdominal AnaerobicInfection

Purpose

The pharmacokinetic (PK) and pharmacodynamic characteristics of levornidazole were studied in patients with intra-abdominal anaerobic infection to provide the rationale of new clinical dosing regimen of levornidazole.

Pharmacokinetics of Single-dose Ertugliflozin in Patients With Hepatic Impairment

Purpose

Ertugliflozin, an oral, highly selective inhibitor of the sodium-glucose cotransporter 2, is approved in the United States and the European Union for the treatment of adults with type 2 diabetes mellitus. Hepatic impairment may affect, to varying degrees, the absorption, metabolism, and excretion of drugs and may be associated with a lower plasma protein binding compared with that in healthy individuals. This study was conducted to assess the effect of hepatic impairment on the pharmacokinetic (PK), safety, and tolerability profiles of ertugliflozin after administration of a single, 15-mg oral dose.

Perspectives on Intravenous Oxycodone for Control of Postoperative Pain

Intravenous (IV) analgesia has particular advantages in the immediate postoperative period. For example, IV administration results in a faster onset of pain relief and results in more predictable pharmacokinetics than does administration by other routes. It also allows for convenient dosing before or during surgery, permitting the initiation of effective analgesia in the early phase of the postoperative period. In addition, when patients are able to tolerate oral intake, they can be switched from IV to oral dosing based on maintaining the predictable analgesia established by the IV route. IV morphine is widely used for the control of postoperative pain, but there is a trend toward the use of oxycodone. Oxycodone (which may be mediated partly through kappa‐ as well as mu‐opioid receptors) offers several potential advantages. Published studies comparing IV oxycodone to other IV opioids for postsurgical pain report that oxycodone is a safe and effective analgesic. Some studies show that IV oxycodone may be associated with greater pain control, fewer or less severe adverse events, and faster onset of action, although the results are not consistent across all studies. Oxycodone has been reported to be safe in the geriatric and other special populations when adequate clinical adjustments are made. Thus, the clinical reports and oxycodone's pharmacologic profile make intravenous oxycodone a potentially important “new” old drug for postoperative pain control.     

Fentanyl Tolerance in the Treatment of Cancer Pain: A Case of Successful Opioid Switching From Fentanyl to Oxycodone at a Reduced Equivalent Dose

Opioids are not generally deemed to have an analgesic ceiling effect on cancer pain. However, there have been occasional reports of tolerance to opioid development induced by multiple doses of fentanyl. The authors report a case of suspected tolerance to the analgesic effect of opioid, in which an increasing dose of fentanyl failed to relieve the patient's cancer pain symptoms, but opioid switching to oxycodone injections enabled a dose reduction to below the equivalent dose conversion ratio. The patient was a 60-year-old man diagnosed with pancreatic body carcinoma with multiple metastases. The base dose consisted of 12 mg/day of transdermal fentanyl patches (equivalent to 3.6 mg/day, 150 μg/h fentanyl injection), and rescue therapy consisted of 10 mg immediate-release oxycodone powders. Despite the total daily dose of fentanyl reaching 5.6 mg (equivalent to 560 mg oral morphine), the analgesic effect was inadequate; thus, an urgent adjustment was necessary. Due to the moderate dose of fentanyl, the switch to oxycodone injection was done incrementally at a daily dose equivalent to 25% of the fentanyl injection. The total dose of oxycodone was replaced approximately 53.5% of the dose of fentanyl prior to opioid switching.     

Breakthrough Cancer Pain in Patients With Abdominal Visceral Cancer Pain

Objective

The objective of this study was to assess the characteristics of breakthrough cancer pain (BTcP) in patients with abdominal cancer pain, and the eventual factors associated with its presentation.

Population pharmacokinetic investigation of disopyramide by mixed effect modelling using routine clinical pharmacokinetic data in Japanese patients

OBJECTIVE: To estimate the population pharmacokinetic parameters of disopyramide using non-linear mixed effects modelling. METHOD: A total of 148 serum levels from 109 patients (61 males and 48 females) receiving disopyramide were collected. RESULTS: The final pharmacokinetic model was Cl (L/h)=3.75.TBW0.567.AGE-0.374.Conc(-0.719).1.48(DOSE>or=5), Vd (L/kg)=4.13 and k(a) (h-1)=0.363, where Cl is total body clearance, Vd is apparent volume of distribution, k(a) is absorption rate constant, TBW is total bodyweight (kg), AGE is age (years), Conc is the concentration of disopyramide (microg/mL), and DOSE>or=5=1 for patient received 5 mg/kg/day of disopyramide dosage or over and 0 otherwise. CONCLUSION: Application of the findings in this study to patient care may permit selection of an appropriate initial maintenance dosage to achieve target disopyramide concentrations and the desired therapeutic effect.     

Barriers to Pain Management among Lithuanian Cancer Patients

Objectives: The objectives of this study are (1) to describe Lithuanian cancer patients' barriers to pain management as well as pain management outcomes, (2) to check the reliability and validity of the questionnaires used in Lithuanian for the first time, and (3) to formulate patient‐centered recommendations for better cancer pain management. Methods: Thirty patients from the Pain Clinic of Kaunas University of Medicine Hospital responded to the Lithuanian versions of: (1) Brief Pain Inventory pain scale, (2) Barriers Questionnaire‐II, (3) Hospital Anxiety and Depression Scale, (4) Modified version of the Perceived Involvement in Care Scale, and (5) Medication Adherence Report Scale. Results: The translated questionnaires had fear internal consistency reliability and construct validity. Reported average (standard deviation [SD]) pain intensity among Lithuanian cancer patients was 3.9 (1.30) on a scale 0–10. The mean (SD) scores of anxiety and depression among the surveyed patients were 8.7 (4.86) and 7.5 (5.05) on a scale 0–21, respectively. The percentage of the patients, who reported stopping taking pain medicine because of its side effects, was 33.3%. The biggest patients' concerns were about physiological consequences and harmful effects of opioid use. The average (SD) level of perceived communication among Lithuanian patients was 3.1 (0.95) on a scale 0–5, whereas the average level (SD) of self‐reported adherence to pain medication among Lithuanians was 13.0 (3.65) on a scale 4–20. Conclusions: The authors believe, that to improve cancer pain management in Lithuania (1) more attention should be paid to psychological status of patients, (2) patients should be more educated about the need and consequences of opioid use for cancer pain, and (3) adherence to pain management regimens should be improved.     

Population Pharmacokinetics Analysis of Quetiapine Extended-release Formulation in Japanese Patients with Bipolar Depression

PurposeThe objectives of this study were to explore covariates of plasma quetiapine concentrations after oral administration of quetiapine extended-release formulation (XR), and to examine the exposure–response relationship in Japanese patients with bipolar depression, using population pharmacokinetics (PopPK) modeling.MethodsIn a multicenter, randomized, double-blind, placebo-controlled study of quetiapine XR in patients with bipolar depression, plasma for the measurement of quetiapine concentration was collected at weeks 2, 4, 8, 12, 20, 28, and 52 during oral administration of 150 or 300 mg once daily of quetiapine XR before bedtime. A PopPK model of quetiapine XR was developed using nonlinear mixed-effects modeling with first-order conditional estimation with interactions. The exposure–response relationship was examined using post-hoc exposures. The post-hoc AUC estimate was plotted against the change in the Montgomery-Åsberg Depression Rating Scale (ΔMADRS) total score from baseline to 8 weeks following once-daily doses at 300 mg.FindingsThe final PopPK analysis dataset contained 322 patients and 1162 observations (cutoff data at week 28; cutoff date, February 2016). The plasma quetiapine concentration–time profile in patients with bipolar depression after oral administration of quetiapine XR was represented well using a 1-compartment with first-order absorption model. Covariate analysis led to the selection of γ-glutamyl transpeptidase on apparent oral clearance and body weight on apparent volume of distribution as covariates. The final population mean values of apparent oral clearance and apparent volume of distribution were 87.7 L/h and 277 L, respectively, and the interindividual %CVs were 32.6% and 75.0%, respectively.ImplicationsThe effects of covariates on PK parameters were not large compared with the interindividual variability. In addition, there was no clear relationship between the AUC and ΔMADRS. ClinicalTrials.gov identifier: NCT01725308.