Association of cabozantinib pharmacokinetics, progression and toxicity in metastatic renal cell carcinoma patients: results from a pharmacokinetics/pharmacodynamics study.

BACKGROUND: Cabozantinib is a tyrosine kinase inhibitor with a substantial efficacy in metastatic renal cell carcinoma, and is associated with a challenging toxicity profile leading to frequent drug discontinuations. Whereas an exposure/safety relationship was demonstrated for this drug, an exposure/efficacy relationship is still unknown. PATIENTS AND METHODS: We carried out a monocentric, observational, pharmacokinetics/pharmacodynamics (PK/PD) study in patients with metastatic renal cell carcinoma (INDS MR 5612140520). We used measured blood concentrations of cabozantinib (Cmeas) to determine the area under the curve (AUC), apparent clearance (Cl/F) and residual blood concentration (Ctrough). Best overall response according to RECIST 1.1 and relevant toxicity (adverse event grade 3-4 or grade 2 requiring dose reduction or discontinuation) were assessed according to Cmeas, Ctrough, AUC and Cl/F. RESULTS: We enrolled 76 patients, including 35 who experienced disease progression and 30 with grade 3-4 toxicity. Patients with progressive disease had a significantly lower median Ctrough (406 versus 634 ng/ml, P = 0.001), Cl/F (2 versus 2.9 l/h, P = 0.002) and AUC (16 versus 20 µg h/ml, P = 0.037) compared with patients who had disease control as best response. Patients with relevant toxicity had a significantly higher Cmeas (732 versus 531 ng/ml, P = 0.006), Ctrough (693 versus 521 ng/ml, P = 0.005) and AUC (21 versus 16 µg h/ml, P = 0.046) compared with patients who did not experience any grade relevant toxicity. Receiver operating characteristic curves obtained from our study defined a threshold for drug efficacy of 536.8 ng/ml and of 617.7 ng/ml for toxicity. CONCLUSION: We first demonstrate the PK/PD relationship for cabozantinib. Severe toxicities are associated with a higher drug exposure, whereas inefficacy is associated with a lower drug exposure. Cabozantinib plasma drug monitoring may be useful to optimize clinical practice.

Effects of azacitidine in 93 patients with IDH1/2 mutated acute myeloid leukemia/myelodysplastic syndromes: a French retrospective multicenter study.

Isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) mutations in Myeloid Neoplams (MNs) exhibit DNA hypermethylation via 2-hydroxyglutarate (2HG) over-production. Clinical impact of azacitidine (AZA) remains inconsistent in IDH1/2-mutated MNs and the potential of serum 2HG as a suitable marker of response to AZA is unknown. To address these questions, we retrospectively analyzed 93 MNs patients (78 AML, 11 MDS, 4 CMML) with IDH1/2 mutations treated with AZA. After a median of 5 cycles of AZA, overall response rate was 28% (including 15% complete remission) and median OS was 12.3 months (significantly shorter in AML compared to MDS/CMML patients). In multivariate analysis of AML patients, DNMT3A mutation was associated with shorter OS while IDH1/2 mutation subtypes had no independent impact. No difference was observed in serum 2HG levels upon AZA treatment between responding and refractory patients suggesting that serum 2HG cannot be used as a surrogate marker of AZA response.

Prodrugs as drug delivery system in oncology.

The use of conventional chemotherapy in the treatment of cancer has been restricted by the lack of cell specificity, which causes toxicity regarding healthy cells resulting in limiting side effects responsible for low therapeutic efficiency. To overcome these drawbacks, the design of prodrugs has evolved and improved by covalently linking the drug through a degradable spacer. The use of these prodrugs as drug delivery systems, which are able to inactivate the drug during its biodistribution to specifically deliver the drug to its target, is an important breakthrough in cancer therapy. This strategy consisting in the covalent binding of a promoiety to daily used therapeutic compounds has been clinically proven in the design of targeted prodrugs leading enhanced therapeutic efficacy and increase of the therapeutic index. This review summarizes and compares several strategies that improve the therapeutic index of chemotherapy (i.e. conventional drugs) by their chemical transformation into prodrugs improving pharmacokinetic profiles and optimizing administration routes in comparison to the initial drug. This review provides an overview of the methods used to control the structure and function of prodrugs and, ultimately, their current and future potential in increasing the therapeutic index of daily used anticancer drugs. First, prodrugs' design and their activation within the tumor microenvironment or within the tumor cell will be exposed. Then, the different strategies used leading to these prodrugs will be presented.

Parameters for Stable Water-in-Oil Lipiodol Emulsion for Liver Trans-Arterial Chemo-Eembolization.

PURPOSE: Water-in-oil type and stability are important properties for Lipiodol emulsions during conventional trans-arterial chemo-embolization. Our purpose is to evaluate the influence of 3 technical parameters on those properties. MATERIALS AND METHODS: The Lipiodol emulsions have been formulated by repetitive back-and-forth pumping of two 10-ml syringes through a 3-way stopcock. Three parameters were compared: Lipiodol/doxorubicin ratio (2/1 vs. 3/1), doxorubicin concentration (10 vs. 20 mg/ml) and speed of incorporation of doxorubicin in Lipiodol (bolus vs. incremental vs. continuous). The percentage of water-in-oil emulsion obtained and the duration until complete coalescence (stability) for water-in-oil emulsions were, respectively, evaluated with the drop-test and static light scattering technique (Turbiscan). RESULTS: Among the 48 emulsions formulated, 32 emulsions (67%) were water-in-oil. The percentage of water-in-oil emulsions obtained was significantly higher for incremental (94%) and for continuous (100%) injections compared to bolus injection (6%) of doxorubicin. Emulsion type was neither influenced by Lipiodol/doxorubicin ratio nor by doxorubicin concentration. The mean stability of water-in-oil emulsions was 215 ± 257 min. The emulsions stability was significantly longer when formulated using continuous compared to incremental injection (326 ± 309 vs. 96 ± 101 min, p = 0.018) and using 3/1 compared to 2/1 ratio of Lipiodol/doxorubicin (372 ± 276 vs. 47 ± 43 min, p = <0.0001). Stability was not influenced by the doxorubicin concentration. CONCLUSION: The continuous and incremental injections of doxorubicin in the Lipiodol result in highly predictable water-in-oil emulsion type. It also demonstrates a significant increase in stability compared to bolus injection. Higher ratio of Lipiodol/doxorubicin is a critical parameter for emulsion stability too.

Organoids as preclinical models to improve intraperitoneal chemotherapy effectiveness for colorectal cancer patients with peritoneal metastases: Preclinical models to improve HIPEC.

BACKGROUND: Peritoneal metastases (PM), corresponding to tumor implants into the peritoneal cavity, are associated with impaired prognosis and low responsiveness to systemic chemotherapy. A new therapeutic approach has dramatically changed the prognosis of patients with PM from colorectal cancer (CRC), consisting in the association of a complete cytoreductive surgery followed by intraperitoneal chemotherapy associated to hyperthermia (HIPEC). Many drugs have been administered intraperitoneally, but no clear consensus has been approved. Therefore, relevant preclinical models are essentials for the efficient translation of treatments option into affected patients. METHOD: Organoids, the last generation of preclinical models, were used to rationalize and improve intraperitoneal chemotherapy. We tested several cytotoxics, combination, effect of hyperthermia, exposure duration and frequency. RESULTS: Organoids were a representative model of response to chemotherapies used for the treatment of PM from CRC; 460mg/m2 of oxaliplatin being the most efficient cytotoxic treatment. Repeated incubations with oxaliplatin; mimicking cycles of intraperitoneal treatment, resulted in an increased efficacy. CONCLUSION & DISCUSSION: Organoids are relevant models to study the chemosensitivity of peritoneal metastases from CRCs. These models could be used for large scale drug screening strategies or personalized medicine, for colorectal carcinoma but also for PM from other origins.

Phase I study of temsirolimus in combination with cetuximab in patients with advanced solid tumours.

BACKGROUND: Preclinical studies suggest synergistic antitumour effects of mammalian target of rapamycin (mTOR) inhibitor such as temsirolimus combined with anti-EGFR monoclonal antibody such as cetuximab. METHODS: Temsirolimus (T) and cetuximab (C) were combined and escalated in cohorts of patients with advanced or metastatic solid tumours, respectively from 15 to 25 mg and 150-250 mg/m2, until the maximum tolerated dose (MTD) was determined. Effort was made in the expansion cohort to enrol patients harbouring a molecular aberration in the human epidermal growth factor receptor (EGFR) and/or phosphoinositide 3-kinase (PI3K) pathways. Paired biopsies were optional to evaluate pathway modulation. RESULTS: Among 39 patients enrolled, three experienced dose-limiting toxicities (DLTs): pulmonary embolism (C200 + T20), stomatitis (C250 + T20) and acneiform rash (C250 + T25). The weekly C 250 mg/m2 and T 25 mg dose level was selected as the MTD. The most common treatment-related adverse events were: acneiform rash (97%), oral mucositis (82%), fatigue (59%), nausea (41%) and diarrhoea (36%). The median progression-free survival (PFS) and overall survival (OS) were respectively 2.0 months [95% CI: 1.8, 3.5] and 7.5 months [95% CI: 5.5, 11.9]. Among all patients, partial responses (PRs) and stable diseases (SDs) were observed in 2 (5.1%) and 18 patients (46.2%), respectively. The objective response rate (ORR) in patients with a molecular aberration was 2/14 (14%), versus 0/24 in those without molecular aberration. CONCLUSIONS: Combination of T + C showed significant but manageable toxicities. Due to modest clinical activity, further evaluation is not recommended. Molecular selection could potentially increase the objective response rate and should be implemented during drug development.

Stabilization Improves Theranostic Properties of Lipiodol®-Based Emulsion During Liver Trans-arterial Chemo-embolization in a VX2 Rabbit Model.

PURPOSE: To demonstrate that stability is a crucial parameter for theranostic properties of Lipiodol®-based emulsions during liver trans-arterial chemo-embolization. MATERIALS AND METHODS: We compared the theranostic properties of two emulsions made of Lipiodol® and doxorubicin in two successive animal experiments (One VX2 tumour implanted in the left liver lobe of 30 rabbits). Emulsion-1 reproduced one of the most common way of preparation (ratio of oil/water: 1/1), and emulsion-2 was designed to obtain a water-in-oil emulsion with enhanced stability (ratio of oil/water: 3/1, plus an emulsifier). The first animal experiment compared the tumour selectivity of the two emulsions: seven rabbits received left hepatic arterial infusion (HAI) of emulsion-1 and eight received HAI of emulsion-2. 3D-CBCT acquisitions were acquired after HAI of every 0.1 mL to measure the densities' ratios between the tumours and the left liver lobes. The second animal experiment compared the plasmatic and tumour doxorubicin concentrations after HAI of 1.5 mg of doxorubicin administered either alone (n = 3) or in emulsion-1 (n = 6) or in emulsion-2 (n = 6). RESULTS: Emulsion-2 resulted in densities' ratios between the tumours and the left liver lobes that were significantly higher compared to emulsion-1 (up to 0.4 mL infused). Plasmatic doxorubicin concentrations (at 5 min) were significantly lower after HAI of emulsion-2 (19.0 µg/L) than emulsion-1 (275.3 µg/L, p < 0.01) and doxorubicin alone (412.0 µg/L, p < 0.001), and tumour doxorubicin concentration (day-1) was significantly higher after HAI of emulsion-2 (20,957 ng/g) than in emulsion-1 (8093 ng/g, p < 0.05) and doxorubicin alone (2221 ng/g, p < 0.01). CONCLUSION: Stabilization of doxorubicin in a water-in-oil Lipiodol®-based emulsion results in better theranostic properties.

Antineoplastic busulfan encapsulated in a metal organic framework nanocarrier: first in vivo results.

Nanoparticles of a mesoporous iron(iii) trimesate MIL-100 nanocarrier encapsulating high amounts of the challenging antineoplastic busulfan were administered to rats and compared with the commercial Busilvex®. Large differences in serum concentration of both busulfan and trimesate revealed the great impact of drug encapsulation both on the drug and on nanoparticle pharmacokinetics during the first 24 h of administration.

Variation in transplacental transfer of tyrosine kinase inhibitors in the human perfused cotyledon model.

BACKGROUND: The use of tyrosine kinase inhibitors (TKis) during pregnancy in humans remains rare, and little data are available on their transplacental passage. Erlotinib and gefitinib are the first-line targeted therapy in case of stage IV nonsmall-cell lung cancer with an EGFR-activating mutation. There are no data available regarding the comparative use of these TKis in pregnant patients. We aimed to compare the transplacental transfer of gefitinib, imatinib and erlotinib, using the ex vivo method of human perfused cotyledon, and to determine the placental accumulation of TKis. MATERIALS AND METHODS: Term placentas were perfused after delivery with gefitinib, imatinib and erlotinib at targeted maternal concentrations around the steady-state plasma trough concentration (i.e. 500, 1000 and 1500 ng/ml, respectively). Samples from fetal and maternal circulations were collected in order to monitor TKis concentrations. Main transfer parameters such as fetal transfer rate (FTR), clearance index (CI) and placental uptake were assessed. RESULTS: Mean FTR of gefitinib, imatinib and erlotinib were 16.8%, 10.6% and 31.4%, respectively. Mean CI of gefitinib, imatinib and erlotinib were 0.59, 0.48 and 0.93, respectively. Placental uptake in cotyledon was 0.030% %, 0.010% and 0.003% for gefitinib, imatinib and erlotinib, respectively, corresponding to a mean mass of 27.7 µg for gefitinib, 15.7 µg for imatinib and 6.8 µg for erlotinib. CONCLUSION: The results suggest that TKis cross the placenta at therapeutic level. Particularly, erlotinib crosses the placenta at a higher rate than gefitinib or imatinib. All of them have a very low placental uptake. These data may suggest that gefitinib should be preferred to erlotinib for the treatment of pregnant woman with lung cancer harboring an EGFR-activating mutation, during the second and third trimesters of pregnancy.

Efficacy and safety of gefitinib during pregnancy: case report and literature review.

The incidence of lung cancer is rising in pregnancy, which is diagnosed on stage III-IV in 98%. Almost half of these patients are non-smokers, who are associated with more epidermal growth factor receptor (EGFR)-mutated lung cancer. As cytotoxic chemotherapy is associated with poor outcome for mothers and prematurity for children this will probably lead to repeatedly question the use of EGFR-Tyrosine kinase inhibitors (TKI) (i.e. gefitinib and erlotinib) during pregnancy for EGFR-mutated lung cancer. EGFR-TKIs are recommended as the first line targeted therapy in case of advanced non small cell lung carcinoma (NSCLC) with an activating EGFR mutation but not recommended during pregnancy due to lack of data. We report clinical and pharmacological data for gefitinib during pregnancy in both the mother and fetus and resume the literature on the subject. A 33-year-old pregnant mother exhibited a disseminated EGFR-mutated lung carcinoma with respiratory distress at 26 weeks of pregnancy. Gefitinib administration was associated with rapid maternal respiratory improvement allowing a planned cesarian section on week 35, giving birth to a healthy baby (2575g) with regular development at 24 months of follow-up. The mother exhibited a progression-free survival of 42 weeks with an overall survival of 22 months. Gefitinib residual concentration was found in cord blood at 25.7ng/mL, confirming a transplacental transfer, but at only 20% of the maternal concentration measured at the same time (i.e. 127.1ng/mL). Gefitinib concentration in amniotic fluid, which represents chronic fetal exposure to the drug, was also 20% of the maternal residual concentration (16.9ng/mL) and reflected no fetal accumulation of the drug, despite both long half time elimination of gefitinib (i.e. 48h) and long time exposure (i.e. 55 days). This low transplacental transfer is an important report, as potential side effect toxicity on the fetus is likely correlated to gefitinib blood concentration.

Influence of the multidrug transporter P-glycoprotein on the intracellular pharmacokinetics of vandetanib.

Efflux transporters play an important role in the resistance of tumor cells against anticancer agents. Interaction between these transporters, including P-glycoprotein (P-gp), and drugs might influence their pharmacological properties and toxicities. The aim of this study was to investigate whether vandetanib (Caprelsa(®)), a small tyrosine kinase inhibitor, could interact with the multidrug transporter P-gp. Interaction of vandetanib with the P-gp was investigated using the parental cell line (IGROV1) and the P-gp doxorubicin-resistant (IGROV1-DXR) cell line, derived from the parental drug-sensitive IGROV1 cells. Cytotoxicity tests were assessed in both cell lines to examine the impact of P-gp on the cell survival after a vandetanib treatment. The effects of P-gp on vandetanib intracellular pharmacokinetics were investigated. To this aim, we developed a quantitative liquid chromatography tandem mass spectrometry to quantify vandetanib in cell medium. Results showed that overexpression of P-gp confers resistance to vandetanib in the IGROV1-DXR cell line. Using a LC-MS/MS assay validated in cell medium, cellular pharmacokinetic studies revealed that in cells overexpressing the P-gp intracellular concentrations of vandetanib were decreased compared to parental cell line. For the first time, vandetanib is described as a substrate of P-gp. In tumor cells, P-gp could be responsible for cellular resistance to vandetanib. It may be relevant to the clinical efficacy of vandetanib. Moreover, interaction of vandetanib with P-gp could modify the pharmacodynamics of other conventional chemotherapeutics, substrates of P-gp. It could impact on the overall response to anticancer therapy.

Performance of alfentanil target-controlled infusion in normal and morbidly obese female patients.

BACKGROUND: Available alfentanil pharmacokinetic (PK) sets for target-controlled infusion (TCI) were derived from populations with normal BMI. The performance and accuracy of the models devised by Maitre and colleagues and Scott and colleagues were evaluated in a population including morbidly obese patients. METHODS: Alfentanil TCI using Maitre and colleagues' model was administered to 10 obese and six non-obese women (BMI 19.5-57.4 kg m(-2)) undergoing laparoscopic surgery. The initial effect-site target concentration was 100 ng ml(-1). Alfentanil arterial plasma concentrations were sampled from TCI onset to 220 min after its termination. Stanpump(®) software calculated predicted alfentanil concentrations. Data were analysed with a non-linear mixed-effect model (NONMEM, version 7.2), including calculations of the median performance error (MDPE) and the median absolute performance error (MDAPE). Scott and colleagues' model was evaluated retrospectively. RESULTS: Using Maitre and colleagues' model, MDPE and MDAPE (range) for the whole population were 13.3% and 23.9%, respectively. With Scott and colleagues' model, MDPE and MDAPE were -30.7% and 50.1%, respectively. We created a three-compartment model with BMI as the covariate (CL), yielding MDPE 1.1% and MDAPE 30.6%. CONCLUSIONS: Maitre and colleagues' PK set underestimated the predicted concentrations in our mixed-weighted population, but its bias and accuracy were acceptable for clinical application. Scott and colleagues' model was inaccurate. The NONMEM model seemed to be more accurate during the infusion and for high concentrations, but it needs to be validated in a larger population.

Busulfan pharmacokinetics following intravenous and oral dosing regimens in children receiving high-dose myeloablative chemotherapy for high-risk neuroblastoma as part of the HR-NBL-1/SIOPEN trial.

INTRODUCTION: Busulfan is widely used in a neuroblastoma setting, with several studies reporting marked inter-patient variability in busulfan pharmacokinetics and pharmacodynamics. The current study reports on the pharmacokinetics of oral versus intravenous (IV) busulfan in high-risk neuroblastoma patients treated on the European HR-NBL-1/SIOPEN study. METHODS: Busulfan was administered four times daily for 4 days to children aged 0.7-13.1 years, either orally (1.45-1.55 mg/kg) or by the IV route (0.8-1.2mg/kg according to body weight strata). Blood samples were obtained prior to administration, 2, 4, and 6h after the start of administration on dose 1. Busulfan analysis was carried out by gas chromatography-mass spectrometry and data analysed using a NONMEM population pharmacokinetic approach. RESULTS: Busulfan plasma concentrations obtained from 38 patients receiving IV busulfan and 25 patients receiving oral busulfan, were fitted simultaneously using a one-compartment pharmacokinetic model. Lower variability in drug exposure was observed following IV administration, with a mean busulfan area under the plasma concentration versus time curve (AUC) of 1146 ± 187 µM.min (range 838-1622), as compared to 953 ± 290 µM.min (range 434-1427) following oral busulfan. A total of 87% of children treated with IV busulfan achieved AUC values within the target of 900-1500 µM.min versus 56% of patients following oral busulfan. Busulfan AUC values were significantly higher in HR-NBL-1/SIOPEN trial patients who experienced hepatic toxicity or veno-occlusive disease (VOD) (1177 ± 189 µM.min versus 913 ± 256 µM.min; p=0.0086). Further stratification based on route of administration suggested that the incidence of hepatic toxicity was related to both high busulfan AUC and oral drug administration. CONCLUSION: The reduced pharmacokinetic variability and improved control of busulfan AUC observed following IV administration support its utility within the ongoing HR-NBL-1/SIOPEN trial.

Safety and quality assurance of chemotherapeutic preparations in a hospital production unit: acceptance sampling plan and economic impact.

OBJECTIVE: The opportunity to apply a sampling plan was evaluated. Costs were computed by a microcosting study. SETTING: In 2003, a sampling plan was defined to reduce the number of chemotherapy quality controls while preserving the same level of quality. Recent qualitative and quantitative changes led us to define a second sampling plan supplemented by an economic evaluation to determine the cost and cost-savings of quality control. METHODS: The study considers preparation produced during four semesters classified into three groups. The first one includes drugs produced below 200 batches a semester. Group 2, those for which the lot of preparation lots would have been rejected twice among these four semesters. Group 3, those would have been accepted (≥3 'acceptable lot'). A single sampling plan by attributes was applied to this group with an acceptance quality level of 1.65% and a lot tolerance percent defective below 5%. A micro-costing study was conducted on quality control, from the sampling to the validation of the results. RESULTS: Among 39 cytotoxic drugs, 11 were sampled which enabled to avoid a mean of 17,512 control assays per year. Each batch of the 28 non-sampled drugs was however analyzed. Costs were estimated at 2.98€ and 5.25€ for control assays depending of the analytical method. The savings from the application of the sampling plans was 153,207€ in 6 years. CONCLUSION: The sampling plan allowed maintaining constancy in number of controls and the level of quality with significant costsavings, despite a substantial increase in drugs to assay and in the number of preparations produced.

Liposomal formulation of a glycerolipidic prodrug for lymphatic delivery of didanosine via oral route.

Didanosine is a polar drug with poor membrane absorption and high hepatic first pass metabolism. This study aimed at developing a lipidic formulation of a glycerolipidic prodrug of didanosine in order to improve its bioavailability. In the course of a preformulation study, the glycerolipidic prodrug of didanosine was characterized by microscopy, DSC and XRDT. In anhydrous conditions, the prodrug displayed a polymorphic behaviour similar to that of triglycerides. Then, we evaluated three types of lipidic formulations (emulsions, mixed micelles and liposomes) in order to encapsulate the prodrug. Solubilities in water - even in the presence of taurocholate micelles - but also in some oils were very low (max 244 microg/mL) as the prodrug was found to be amphiphilic (log P=2). On the contrary, the prodrug was found to be perfectly incorporated in dipalmitoylphosphatidylcholine (DPPC) multilamellar liposomes up to a ratio of 1:5 (mol:mol) prodrug:DPPC as suggested by HPLC-UV and DSC experiments. Moreover, these liposomes could be freeze-dried whereas the chemical integrity of the prodrug was preserved. Then, the freeze-dried liposomal preparation could be formulated as gastro-resistant capsules to prevent didanosine from acidic degradation. Further experiments are on the way to evaluate in vitro the absorption of prodrug incorporated in liposomes by enterocytes.

Elevated plasma ferritin and busulfan pharmacodynamics during high-dose chemotherapy regimens in children with malignant solid tumors.

Hepatic veno-occlusive disease (HVOD) is a frequent complication during hematopoietic stem-cell transplantation (HSCT). A strong relationship has been demonstrated between busulfan exposure and HVOD for busulfan-cyclophosphamide and allogeneic HSCT in adults. Busulfan disposition after the first intake was studied in 77 children treated for solid malignancies with high-dose busulfan-containing regimens and autologous HSCT. Busulfan was combined with cyclophosphamide and melphalan (n=30), melphalan (n=27), and thiotepa (n=20). No relationship was observed between busulfan exposure and HVOD. In contrast, plasma ferritin at baseline was higher in patients with HVOD (750 ng/ml (20-3,110)) compared with those without HVOD (189 ng/ml (8-3,967), P=0.012). Multivariate analysis showed that a ferritin level exceeding 300 ng/ml was the only risk factor for HVOD with an odds ratio of 4.0 (confidence interval 95% (1.5-11.2), P=0.0071). A high ferritin level at baseline was explained by the diagnosis of neuroblastoma, related treatments and transfusions.

Evaluation of the pharmacokinetic profile and analgesic efficacy of oral morphine after total hip arthroplasty.

BACKGROUND AND OBJECTIVE: Oral morphine may be useful for postoperative pain relief, but few studies have tested its use after in-hospital surgery. METHODS: We evaluated clinical efficacy and the pharmacokinetic parameters of oral morphine after total hip arthroplasty. We recruited 60 patients who had total hip arthroplasty under general anaesthesia. The patients were randomized to receive placebo, 10 mg morphine sulphate or 20 mg morphine sulphate orally every 4 h for 24 h. The oral administration was started 3 h after the morphine-loading dose in the Post Anaesthesia Care Unit and then patients used intravenous morphine patient-controlled analgesia for 24 h. Pain score at rest (scored by patients on a visual analogue scale), sedation, nausea, vomiting and urinary retention were monitored. In 11 additional total hip arthroplasty patients, we determined the pharmacokinetics of morphine and its metabolites after oral administration of 20 mg morphine sulphate every 4 h for 16 h. RESULTS: The amount of morphine administered via patient-controlled analgesia over 24 h was reduced in the 20-mg group compared with that in the placebo group (19.0 +/- 2.7 mg vs. 33.0 +/- 5.5 mg; P = 0.03). No significant morphine-sparing effect was observed in the 10-mg group. Pain scores and side-effects were similar in all groups. The pharmacokinetic study revealed a limited and slow absorption of morphine. CONCLUSION: Despite a limited absorption of oral morphine postoperatively, high doses of oral morphine have a significant analgesic effect after total hip arthroplasty.