Daptomycin Exposure Prediction With a Limited Sampling Strategy.

BACKGROUND: Daptomycin is a cyclic lipopeptide antibiotic used to treat serious infectious endocarditis caused by Staphylococcus aureus. The pharmacodynamic parameter correlating best with efficacy is the ratio of the estimated area under the concentration (AUC0-24)-time curve to the minimum inhibitory concentration. The aim of the study is to develop a limited sampling strategy to estimate AUC0-24 using a reduced number of samples. METHODS: Sixty-eight daptomycin AUC0-24 values were calculated for 50 White patients who underwent treatment for at least 5 consecutive days. Plasma concentrations were detected using a validated high-performance liquid chromatography-tandem mass spectrometry analytical method, with daptomycin-d5 as an internal standard. Multiple regression was used to evaluate the ability of 2 concentration-time points to predict the AUC0-24 calculated from the entire pharmacokinetic profile. Prediction bias was calculated as the mean prediction error, whereas prediction precision was estimated as the mean absolute prediction error. The development and validation datasets comprised 40 and 10 randomly selected patients, respectively. RESULTS: The AUC0-24 (mg*h/L) was best estimated using the daptomycin trough concentration and plasma concentrations detected 2 hours after dosing. We calculated a mean prediction error of 1.6 (95% confidence interval, -10.7 to 10.9) and a mean absolute prediction error of 11.8 (95% confidence interval, 5.3-18.3), with 73% of prediction errors within ±15%. CONCLUSIONS: An equation was developed to estimate daptomycin exposure (AUC0-24), offering clinical applicability and utility in generating personalized dosing regimens, especially for individuals at high risk of treatment failure or delayed response.

PEG 400 Ion Suppression in Busulfan Detection by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

BACKGROUND: Busulfan (Bu), an alkylating agent commonly used in chemotherapy and transplantation, exhibits high intraindividual pharmacokinetic variability and possible time-dependent variations in clearance, which complicate therapeutic drug monitoring. Numerous analytical methods have been developed to reduce analysis time and facilitate timely decision-making regarding treatment changes; however, the validation procedures rarely involve analysis of potentially interfering excipients. Macrogol 400 (PEG 400) should be considered as a possible interfering agent in the detection of plasma Bu levels, especially as an ionization suppressor. METHODS: Six intravenous formulations of Bu were compared with identify at least 1 common excipient (PEG 400). During the 176 therapeutic drug monitoring analyses of Bu, one of the PEG 400 specific mass-to-charge ratio transitions was determined using an instrumental method. After coelution with Bu and its internal standard (Bu-d8) was confirmed, all analyses were repeated using a different experimental setup free of ion suppression induced by PEG. The concentration-time profile of PEG 400 was also analyzed. RESULTS: The area under the curve obtained from the 2 data sets was compared and analyzed using Lin concordance correlation coefficient and Bland-Altman plot analysis. The results from the 2 analytical methods were comparable: PEG 400 negatively affected the Bu-d8 coefficient of variation but not the Bu/Bu-d8 ratio. CONCLUSIONS: The possible interference of PEG 400 should be thoroughly investigated, especially with respect to analytical methods that cannot be supported by correction of the stable isotopically labeled internal standard analog.

Pharmacokinetics of Venetoclax Co-Administered with Posaconazole in Patients with Acute Myeloid Leukemia.

The Food and Drug Administration currently approves the combination of hypomethylating agents (HMA), azacytidine or decitabine with venetoclax (VEN) for acute myeloid leukemia (AML) patients aged more than 75 years and for patients unsuitable for intensive chemotherapy. The risk of fungal infection in the early phase of treatment is not negligible; therefore, posaconazole (PCZ) is commonly administered as primary prophylaxis. A drug-drug interaction between VEN and PCZ is well known, but the trend of serum levels of venetoclax when both drugs are overlapped is not clear. In total, 165 plasma samples from 11 elderly AML patients receiving combined treatment with HMA, VEN and PCZ were analyzed by a validated analytical method (high-pressure liquid chromatography-tandem mass spectrometry). Venetoclax trough plasma concentrations were detected during the 3 days of ramp-up as well as on day 7 and day 12 of treatment when the exposure as the area under the plasma concentration-time curve and the accumulation ratio were also calculated. The results were compared with the expected data for 400 mg/dose VEN administered alone-the confirmed high inter-individual variability in pharmacokinetics suggests the need for therapeutic drug monitoring.

Therapeutic Drug Monitoring of Tacrolimus-Personalized Therapy in Heart Transplantation: New Strategies and Preliminary Results in Endomyocardial Biopsies.

Tacrolimus (TAC) is an immunosuppressant drug approved both in the US and in the EU, widely used for the prophylaxis of organ rejection after transplantation. This is a critical dose drug: low levels in whole blood can lead to low exposure and a high risk of acute rejection, whereas overexposure puts patients at risk for toxicity and infection. Both situations can occur at whole-blood concentrations considered to be within the narrow TAC therapeutic range. We assumed a poor correlation between TAC trough concentrations in whole blood and the incidence of acute rejection; therefore, we propose to study TAC concentrations in endomyocardial biopsies (EMBs). We analyzed 70 EMBs from 18 transplant recipients at five scheduled follow-up visits during the first year post-transplant when closer TAC monitoring is mandatory. We observed five episodes of acute rejection (grade 2R) in three patients (2 episodes at 0.5 months, 2 at 3 months, and 1 at 12 months), when TAC concentrations in EMBs were low (63; 62; 59; 31; 44 pg/mg, respectively), whereas concentrations in whole blood were correct. Our results are preliminary and further studies are needed to confirm the importance of this new strategy to prevent acute rejection episodes.

Hydroxychloroquine Blood Concentrations Can Be Clinically Relevant Also After Drug Discontinuation.

BACKGROUND AND OBJECTIVE: Hydroxychloroquine was widely used during the severe acute respiratory syndrome coronavirus 2 pandemic as an antiviral drug. Most previous pharmacokinetic/pharmacodynamic studies on hydroxychloroquine were conducted on healthy volunteers or patients receiving long-term therapy. There are no studies on the elimination of hydroxychloroquine after short-term treatments. Hydroxychloroquine is known to have a pro-arrhythmic effect through QT interval prolongation, but data in this setting are not conclusive. Our aims were to estimate the time needed for hydroxychloroquine concentrations (CHCQ) to drop to a safe concentration (500 ng/mL) after a short-term therapeutic cycle and to correlate the corrected QT interval with CHCQ. METHODS: We collected blood samples and electrocardiograms of patients who underwent short-term therapy with hydroxychloroquine during drug intake and after discontinuation. Hydroxychloroquine concentrations were determined by high-performance liquid chromatography-tandem mass spectrometry and analysed with a linear regression model to estimate the elimination time of the drug after its discontinuation. We conducted a multivariate analysis of the corrected QT interval correlation with CHCQ. RESULTS: Our data suggest that short-term hydroxychloroquine courses can generate significant CHCQ persisting above 500 ng/mL up to 16 days after discontinuation of treatment. Corrected QT interval prolongation significantly correlates with CHCQ. CONCLUSIONS: The study confirms the long half-life of hydroxychloroquine and its effect on the corrected QT interval even after short-term courses of the drug. This can inform the clinician using hydroxychloroquine treatments that it would be safer to start or re-initiate treatments with corrected QT interval-prolonging potential 16 days after hydroxychloroquine discontinuation.

Feasibility and Efficacy of a Pharmacokinetics-Guided Busulfan Conditioning Regimen for Allogeneic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide as Graft-versus-Host Disease Prophylaxis in Adult Patients with Hematologic Malignancies.

Busulfan (Bu) is an alkylating agent routinely used for conditioning regimens before allogeneic stem cell transplantation (allo-SCT). Bu shows wide pharmacokinetic (PK) variability among patients. Patients can have a higher systemic exposure (expressed as area under the curve [AUC]) with an increased risk of toxicity or a lower AUC with a higher probability of graft rejection and/or disease relapse. After i.v. administration, an optimal Bu therapeutic window (AUC target of 16,000 to 24,000 µM·minute) has been identified. The use of PK-guided Bu dosing leads to improved overall survival (OS) and progression-free survival (PFS) compared with fixed-dose administration in a variety of hematologic diseases. The aim of this study was to evaluate the outcomes and feasibility of a reduced-toxicity conditioning (RTC) regimen comprising thiotepa, Bu, and fludarabine (TBF) with therapeutic drug monitoring of Bu in patients with hematologic disorders. We report on 41 adult patients with myeloid or lymphoid malignancies who underwent an allo-SCT with a PK-guided Bu-based RTC regimen between January 2019 and October 2020. Patients received a total Bu dose to achieve a target AUC of 16,000 µM·minute in combination with Flu and thiotepa. The median time to absolute neutrophil count recovery and transfusion-independent platelet count recovery was 23 days (range, 15 to 42 days) and 29 days (range, 14 to 97 days), respectively. The cumulative incidence (CI) of nonrelapse mortality was 7% at 100 days and 13% at 1 year. Grade 3 liver toxicity was observed in 6 patients. One patient developed sinusoidal obstruction syndrome at day +27. Grade 3 mucositis occurred in 18 patients. Looking at grade ≥3 infections, the CI was 29% at 30 days, 34% at 60 days, 44% at 100 days, and 56% at 1 year. The 180-day CI of grade II-IV acute graft-versus-host disease (GVHD) was 15%, and the 1-year CI of overall chronic GVHD was 20%. With a median follow-up of alive patients of 14.4 months (range, 3.2 to 24 months), the CI of relapse at 1 year was 6%. The 1-year PFS was 81%, and 1-year OS was 84%. In conclusion, these data support the efficacy of PK-guided Bu dose in the context of a TBF conditioning regimen and the feasibility of therapeutic dosage monitoring of i.v. Bu for patients with hematologic diseases. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Daptomycin Pharmacokinetics and Pharmacodynamics in Patients on Methadone Substitution Therapy.

BACKGROUND AND OBJECTIVE: When administered for severe infections in intravenous drug users (IDUs) at a daily dose of 6 mg/kg, daptomycin displayed abnormal pharmacokinetic parameters compared with those seen in healthy volunteers; specifically, decreased trough and maximum concentrations (Ctrough; Cmax) and increased clearance (CL). The objective of this study was to evaluate the pharmacokinetics and pharmacodynamics of daptomycin administered at a daily dosage of 12 mg/kg for Staphylococcus aureus infective endocarditis (IE) in patients concomitantly treated with methadone, and to compare the results with those published in the literature for healthy controls treated with the same daily dose. METHODS: Antibiotic treatment included daptomycin (12 mg/kg daily) in combination with an antistaphylococcal ß-lactam (cefazolin 2 g three times a day). The minimum inhibitory concentration (MIC) of Staphylococcus aureus isolated through blood cultures was used to calculate pharmacokinetic and pharmacodynamic parameters such as the ratio of the area under the concentration-time curve over 24 h to the MIC (AUC0-24/MIC) and Cmax/MIC. RESULTS: Five IDUs hospitalized for IE were enrolled. The mean measured daptomycin Cmax and Ctrough were 54.1 µg/mL (CV: 0.32) and 8.7 µg/mL (CV: 0.59), respectively; the mean calculated AUC0-24 was 742.7 µg × h/mL (CV: 0.31). The estimated average volume of distribution at the steady state (Vd,ss) and the half-life (t1/2) were 316.5 mL/kg (CV: 0.53) and 14.4 h (CV: 0.30), respectively. The mean daptomycin clearance from plasma normalized for body weight (CLwp) was 17.3 mL/(h × kg) (CV: 0.33). The calculated average Cmax and AUC0-24 (183.7 µg/mL and 1277.4 µg × h/mL, respectively) were lower than and statistically significantly different from (p < 0.001 and p = 0.001, respectively) those expected for healthy volunteers. CONCLUSIONS: Treatment of Staphylococcus aureus IE in IDUs on methadone treatment requires the use of high daptomycin daily doses in order to achieve satisfactory pharmacodynamic parameters. Close monitoring of the daptomycin plasma concentration is suggested.

Comparison of Two Analytical Methods for Busulfan Therapeutic Drug Monitoring.

BACKGROUND AND OBJECTIVES: Busulfan (Bu) is an old drug, but is still well recommended as an alkylating agent during conditioning therapy, before hematopoietic stem cell transplantation. Although its dose administration is standardized and based on patient weight, therapeutic drug monitoring is required in order to maintain its exposure [as area under the concentration-time curve (AUC) from 0 to infinity AUC0-∞] within a narrow therapeutic range and, if necessary, to adjust the dose with as short a lead time as possible. The aim of the study is to evaluate the agreement (as calculated AUC) between a gold standard analytical method and a new one that is faster and easier. METHODS: We analyzed 221 plasma samples from 37 children (0.25-16 years; 4-62.5 kg) and 11 adults (21-59 years; 45-80 kg), corresponding to 52 AUC values (ng h/mL). The drug exposure was calculated, simultaneously, by two validated analytical methods. The reference method was a high-performance liquid chromatography (HPLC) assay combined with an ultraviolet detector (UV). The test method had a triple quadrupole mass spectrometer (MS) as detector; the clean-up procedures of the samples were different and faster. RESULTS: The agreement between the two methods (reference and test) was evaluated in terms of Bu exposure differences based on Lin's concordance correlation coefficient (CCC) and represented by the Bland-Altman plot. The CCC between the AUC of the two methods was excellent (0.868; 95% CI: 0.802-0.935). The precision of the measures (expressed by Pearson's italic "r") was 0.872, and the accuracy (accounted by the bias correction factor) was 0.996. CONCLUSIONS: We can conclude that the HPLC-MS/MS assay represents a very good alternative to the reference.

Development and validation of a combined enzymatic-digestion/mass spectrometry assay for Tacrolimus quantitation in cardiac biopsies.

Recent studies report strategies for analysing immunosuppressive drugs in brain, liver and renal tissue, mostly in animals: we developed and validated a two steps combined enzymatic digestion/mass spectrometry assay to quantify Tacrolimus (TAC) in heart biopsies. Our aims were to avoid sample loss and sample contamination during the laboratory preparation, and to limit matrix effects in the electrospray ionization source (ESI) of the mass spectrometer. Enzymatic tissue digestion followed by a liquid-liquid drug extraction in the same vial of reaction allowed us to reach both our aims. The assay was assessed for selectivity, matrix effect, linearity, Lower Limit of Quantification (LLOQ) and Detection (LOD), accuracy and precision, according to the "Guideline on Bioanalytical Method Validation (EMA). A stable isotopically labelled (SIL) analogue (13CD2-TAC) was used as internal standard. The chromatographic separation of the analyte took 6 min. The observed linear range of quantification was 0.0162-0.520 ng in terms of TAC added to the biopsies (by 50 µL of the corresponding working solutions). The limit of detection and the lower limit of quantification (LLOQ) were 0.008 and 0.0162 ng, respectively. Both the mobile phases contained ammonium acetate and formic acid that promote the formation of ammoniated precursor ions that can be easily fragmented ([M + NH4]+, TAC m/z 821.3; 13CD2-TAC m/z 824.3). The calibration curves were generated by plotting analyte-to-internal standard peak area ratios versus TAC amount (ng) added to the biopsies, and using a weighted (1/x) linear regression. Curves were not forced to pass through the origin. Swine hearts were employed as blank matrix for all the analytical method validation procedures but, after approval by the ethics committee (by "Fondazione IRCCS Policlinico San Matteo": Protocol 20190032933), TAC was also quantified in endomyocardial biopsies from informed and consenting heart transplant patients. The study was funded by Fondazione IRCCS Policlinico San Matteo (RC08017617), as a part of the clinical studies on the maintenance of immunosuppressive therapy in cardiac transplant patients. Tacrolimus concentrations in patients biopsies were expressed as ratio between the detected amount of TAC (ng) in the tissue and the weight of the tissue itself (mg).

In vitro and in vivo quantification of chloroprocaine release from an implantable device in a piglet postoperative pain model.

BACKGROUND: The pharmacokinetic properties and clinical advantages of the local anesthetic chloroprocaine are well known. Here, we studied the pharmacokinetic profile of a new hydrogel device loaded with chloroprocaine to investigate the potential advantages of this new strategy for postoperative pain (POP) relief. MATERIALS AND METHODS: We performed both in vitro and in vivo analyses by considering plasma samples of four piglets receiving slow-release chloroprocaine. To quantify chloroprocaine and its inactive metabolite 4-amino-2-chlorobenzoic acid (ACBA), a HPLC-tandem mass spectrometry (HPLC-MS/MS) analytical method was used. Serial blood samples were collected over 108 hours, according to the exposure time to the device. RESULTS: Chloroprocaine was consistently found to be below the lower limit of quantification, even though a well-defined peak was observed in every chromatogram at an unexpected retention time. Concerning ACBA, we found detectable plasma concentrations between T0 and T12h, with a maximum plasma concentration (Cmax) observed 3 hours after the device application. In the in vitro analyses, the nanogel remained in contact with plasma at 37°C for 90 minutes, 3 hours, 1 day, and 7 days. Chloroprocaine Cmax was identified 1 day following exposure and Cmin after 7 days, respectively. Additionally, ACBA reached the Cmax following 7 days of exposure. CONCLUSION: A thorough review of the literature indicates that this is the first study analyzing both in vivo and in vitro pharmacokinetic profiles of a chloroprocaine hydrogel device and is considered as a pilot study on the feasibility of including this approach to the management of POP.

Efficacy of intraventricular amikacin treatment in pan-resistant Pseudomonas aeruginosa postsurgical meningitis.

BACKGROUND: We describe a case of pan-resistant Pseudomonas aeruginosa postsurgical meningitis associated with the presence of an external ventricular device. We changed therapy twice; finally, by using amikacin and a continuous infusion of cefepime, we obtained clinical improvement. CASE PRESENTATION: A female patient, who underwent surgery for a cavernous angioma, presented with meningitis. Cerebrospinal fluid culture revealed a multidrug-resistant Pseudomonas aeruginosa, initially sensitive only to colistin. We successfully used intrathecal amikacin and intravenous cefepime continuous infusion plus intravenous amikacin after two previous ineffective therapeutic approaches. CONCLUSION: The evaluation of the antibiotic concentration and the bactericidal activity in cerebrospinal fluid may contribute to the choice of the drug in cases of multidrug-resistant meningitis.

Bioengineered gold nanoparticles targeted to mesenchymal cells from patients with bronchiolitis obliterans syndrome does not rise the inflammatory response and can be safely inhaled by rodents.

The use of gold nanoparticles (GNPs) as drug delivery system represents a promising issue for diseases without effective pharmacological treatment due to insufficient local drug accumulation and excessive systemic toxicity. Bronchiolitis obliterans syndrome (BOS) represents about 70% of cases of chronic lung allograft dysfunction, the main challenge to long-term lung transplantation. It is believed that due to repeated insults to epithelial bronchiolar cells local inflammatory response creates a milieu that favors epithelial-mesenchymal transition and activation of local mesenchymal cells (MCs) leading to airway fibro-obliteration. In a previous work, we engineered GNPs loaded with the mammalian target of rapamycin inhibitor everolimus, specifically decorated with an antibody against CD44, a surface receptor expressed by primary MCs isolated from bronchoalveolar lavage of BOS patients. We proved in vitro that these GNPs (GNP-HCe) were able to specifically inhibit primary MCs without affecting the bronchial epithelial cell. In the present work, we investigated the effect of these bioengineered nanoconstructs on inflammatory cells, given that a stimulating effect on macrophages, neutrophils or lymphocytes is strongly unwanted in graft airways since it would foster fibrogenesis. In addition, we administered GNP-HCe by the inhalatory route to normal mice for a preliminary assessment of their pulmonary and peripheral (liver, spleen and kidney) uptake. By these experiments, an evaluation of tissue toxicity was also performed. The present study proves that our bioengineered nanotools do not rise an inflammatory response and, under the tested inhalatory conditions that were used, are non-toxic.

Bioequivalence of a New Oral Levosulpiride Formulation Compared With a Standard One in Healthy Volunteers.

BACKGROUND: A monocentric, single-dose, open-label, 2-way, crossover randomized study was conducted by the San Matteo Phase I Clinical Trial Unit and Experimental Therapy (Pavia, Italy) to assess the bioequivalence and the systemic tolerability of a new oral formulation of levosulpiride (tablet 25 mg: test) versus a commercially available formulation on the Italian market (tablet 25 mg: reference). METHODS: Thirty-five healthy adult volunteers, men (n = 19) and women (n = 16), aged between 18 and 55 years were screened and 32 of them were enrolled in the study. After having signed the written informed consent, each subject received a single oral dose of Test or Reference product with 250 mL of natural mineral water, in fasting conditions, interspersed with a 6-day washout period Blood samples were collected up to 36 hours after drug administration: the drug plasma levels were determined by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. The pharmacokinetic parameters included peak plasma concentration (Cmax), time corresponding to Cmax (tmax), area under the plasma concentration-time curve from zero to infinity (AUC0-∞) or to the last sampling time assessment (AUC0-36), the elimination rate constant (ke), and the terminal half-life (t1/2). Safety was measured by pre- and post-treatment specific biochemical investigations, physical examination, electrocardiogram, occurrence of adverse events, and any information on patients' withdrawal. RESULTS: The geometric mean ratio Test/Reference (90% confidence interval) for levosulpiride was 103.0% (95.8-110.8) for AUC0-36, 103.6% (95.9-111.9) for AUC0-∞, and 104.3% (94.9-114.6) for Cmax. ke and t1/2 were 0.07 (SD: 0.02) and 9 hours (8-12) for both the formulations. Clearance (L/h) was 29.6 (±13.5) and 30.7 (±14.2) for the test and the reference product, respectively. CONCLUSIONS: Because the acceptance criteria required by the drug regulatory agency (European Medicines Agency, EMA) for bioequivalence prescribe limits of 80%-120% for untransformed data and 80%-125% for "ln" transformed data, we can confirm that the 2 formulations are bioequivalent, in terms of the rate and extent of absorption.

Changes in total plasma and serum N-glycome composition and patient-controlled analgesia after major abdominal surgery.

Systemic inflammation participates to the complex healing process occurring after major surgery, thus directly affecting the surgical outcome and patient recovery. Total plasma N-glycome might be an indicator of inflammation after major surgery, as well as an anti-inflammatory therapy response marker, since protein glycosylation plays an essential role in the inflammatory cascade. Therefore, we assessed the effects of surgery on the total plasma N-glycome and the association with self-administration of postoperative morphine in two cohorts of patients that underwent major abdominal surgery. We found that plasma N-glycome undergoes significant changes one day after surgery and intensifies one day later, thus indicating a systemic physiological response. In particular, we observed the increase of bisialylated biantennary glycan, A2G2S[3,6]2, 12 hours after surgery, which progressively increased until 48 postoperative hours. Most changes occurred 24 hours after surgery with the decrease of most core-fucosylated biantennary structures, as well as the increase in sialylated tetraantennary and FA3G3S[3,3,3]3 structures. Moreover, we observed a progressive increase of sialylated triantennary and tetraantennary structures two days after surgery, with a concomitant decrease of the structures containing bisecting N-acetylglucosamine along with bi- and trisialylated triantennary glycans. We did not find any statistically significant association between morphine consumption and plasma N-glycome.

Human Genetic Variability Contributes to Postoperative Morphine Consumption.

UNLABELLED: High interindividual variability in postoperative opioid consumption is related to genetic and environmental factors. We tested the association between morphine consumption, postoperative pain, and single nucleotide polymorphisms (SNPs) within opioid receptor µ 1 (OPRM1), catechol-O-methyltransferase (COMT), uridine diphosphate glucose-glucuronosyltransferase-2B7, and estrogen receptor (ESR1) gene loci to elucidate genetic prediction of opioid consumption. We analyzed 20 SNPs in 201 unrelated Caucasian patients who underwent abdominal surgery and who were receiving postoperative patient-controlled analgesia-administered morphine. Morphine consumption and pain intensity were dependent variables; age and sex were covariates. A haplotype of 7 SNPs in OPRM1 showed significant additive effects on opioid consumption (P = .007); a linear regression model including age and 9 SNPs in ESR1, OPRM1, and COMT explained the highest proportion of variance of morphine consumption (10.7%; P = .001). The minimal model including 3 SNPs in ESR1, OPRM1, and COMT explained 5% of variance (P = .007). We found a significant interaction between rs4680 in COMT and rs4986936 in ESR1 (P = .007) on opioid consumption. SNPs rs677830 and rs540825 of OPRM1 and rs9340799 of ESR1 were nominally associated with pain Numeric Rating Scale scores. Combinations of genetic variants within OPRM1, COMT, and ESR1 better explain variability in morphine consumption than single genetic variants. Our results contribute to the development of genetic markers and statistical models for future diagnostic tools for opioid consumption/efficacy. PERSPECTIVE: This article presents the efforts dedicated to detect correlations between the genetic polymorphisms and the clinical morphine effect self-administered by patients using a patient-controlled analgesia pump after major surgery. The clinical effect is expressed in terms of morphine consumption and pain scores. REGISTERED ON CLINICALTRIALS.GOV: NCT01233752.

Influence of the oral dissolution time on the absorption rate of locally administered solid formulations for oromucosal use: the flurbiprofen lozenges paradigm.

Flurbiprofen is a nonsteroidal anti-inflammatory agent preferentially used for local oromucosal treatment of painful and/or inflammatory conditions of the oropharynx such as gingivitis, stomatitis, periodontitis, pharyngitis and laryngitis. In this study, we have investigated the bioavailability of a new generic formulation of flurbiprofen lozenges developed by Epifarma Srl, compared to the originator Benactiv Gola® taken as reference. Within the framework of a formal bioequivalence study, we investigated in particular the putative influence of oral dissolution time (i.e. the time spent suckling the lozenge from its intake to complete dissolution) on the absorption rate, and the contribution of this factor to the total variability of plasma flurbiprofen during absorption. We found that the amount of flurbiprofen absorbed into the systemic circulation is not significantly higher for the test drug compared to that of the reference product. We observed that the length of oral dissolution time is inversely correlated to 10-min flurbiprofen plasma levels in the test but not in the reference formulation. We estimated that oral dissolution time accounts for about 14% of overall variability in flurbiprofen plasma 10 min after test drug administration.

Clinical pharmacokinetics of morphine and its metabolites during morphine dose titration for chronic cancer pain.

BACKGROUND: Pain is one of the most prevalent and distressing symptoms in patients with cancer. There is evidence from observational studies that many patients do not get adequate relief. Although data in the literature confirm the effectiveness of most opioid drugs for the treatment of chronic pain, there is limited information about opioid titration. METHODS: The aim of this study was to evaluate the clinical pharmacokinetics of morphine (M) and their correlation with pharmacodynamic results (effective daily dose of M and side effects) during the M titration phase, in the management of chronic cancer pain. Fifty-two consecutive patients were administered Oramorph (Molteni Farmaceutici, Scandicci, Florence, Italy; beginning with 5 mg every 6 hours), to maintain pain intensity at low levels (visual analog scale <4). M, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G) plasma concentrations were determined by a mass spectrometric assay. RESULTS: Expected pharmacokinetic parameters were based on a pharmacokinetic profile extrapolated from 39 patients: M total clearance varied between 1.5 and 6.42 L·h(-1)·kg(-1); the median apparent volume of M distribution was 25.0 L/kg, and the elimination half-life was 4.4 hours. Over the entire period of treatment, a weak correlation between M and M3G or M6G concentrations was found, but the metabolite ratio (M3G/M6G) remained quite stable for each patient and at different sampling times. At the end of titration, the M6G/M ratio was significantly higher in the patients whose effective M concentration was below the median (5.2 ng/mL), than in patients in whom the concentration was above the median (M6G/M: 13.0 and 9.0, respectively). CONCLUSIONS: This article presents the pharmacokinetic profiles of M and its metabolites: their concentration ratio could help clinicians to optimize individual therapies and tailor the dose to individual needs. Our results indicate that the relationship between M6G and M could represent a potentially useful parameter to personalize M dosing.

Genetic variability at COMT but not at OPRM1 and UGT2B7 loci modulates morphine analgesic response in acute postoperative pain.

PURPOSE: To investigate interindividual variability in response to pain treatment, we characterized postoperative patients for morphine metabolism and for COMT, OPRM1 and UGT2B7 polymorphisms. METHODS: A total of 109 patients treated with morphine were genotyped by DNA sequencing for 12 DNA polymorphisms of the COMT, OPRM1 and UGT2B7 genes. The plasma concentration of morphine and of M3G/M6G metabolites were evaluated by means of reversed phase high-performance liquid chromatography coupled with mass spectrometry. RESULTS: An association between average morphine consumption during the first 24 postoperative hours by patient-controlled analgesia (PCA) and COMT haplotypes was found. Specifically, patients with the diplotype for average pain intensity (APS/APS) required the lowest morphine doses compared to the other subjects (p = 0.011). The APS haplotype contains an adenine corresponding to methionine, instead of valine, at position 158 of the COMT protein. Met/Met homozygous patients consumed significantly lower morphine doses than other subjects (p = 0.014); accordingly, Val158Met genotyping alone might be used in the clinical setting to predict PCA morphine need. Considering both COMT Val158Met and OPRM1 A118G polymorphisms, carriers of both the Met/Met and AA genotypes required less morphine than other subjects, although the difference was not significant. The analysis of UGT2B7 revealed the occurrence of two common haplotypes (G_C_C_A_C and A_T_T_G_T) that did not prove to be related with plasma morphine and M3G/M6G concentration. CONCLUSIONS: By considering COMT, OPRM1, and UGT2B7 genotypes, as well as pharmacokinetic results, only COMT polymorphisms appear to be predictive of morphine need in postoperative pain therapy.