[The reliability of Delta-T]. / De betrouwbaarheid van Delta-T.

BACKGROUND: In Dutch mental health care there is an ongoing debate about the benefits of rom and utility of benchmarking. Opinions vary regarding the reliability and validity of performance indicators.
AIM: Investigation of the reliability of the main indicator of Foundation Benchmark Mental Health Care (sbg), Delta-T, the indicator of treatment outcome.
METHOD: The reliability was established with two indices: the intraclass correlation coefficient (icc) for the agreement between repeated assessments of average treatment outcome and the consistency in rank order of mental health care providers over time.
RESULTS: The reliability of Delta-T proved to be excellent.
CONCLUSION: Reliability is a basic requirement, but only the first step in establishing the utility of Delta-T. Further investigation of its validity is ongoing, especially on how robust treatment outcome is for bias due to instrumentation, selection, and confounding by casemix composition. Ultimately, the usefulness of treatment outcome as indicator of quality of care needs to be demonstrated in practice.

Improved survival for sequentially as opposed to concurrently delivered neoadjuvant chemotherapy in non-metastatic breast cancer.

PURPOSE: The INTENS study was designed to determine whether delivering neoadjuvant chemotherapy at a higher dose in a shorter period of time improves outcome of breast cancer patients. METHODS: Women with newly diagnosed breast cancer were randomly assigned to neoadjuvant chemotherapy consisting of four cycles of doxorubicin and cyclophosphamide followed by four cycles of docetaxel (AC 60/600-T 100 mg/m2) or six cycles of TAC as triplet chemotherapy (75/50/500 mg/m2) every 3 weeks. The primary outcome was the pathologic complete response (pCR), with disease-free and overall survival as secondary endpoints. RESULTS: In total, 201 patients were included. The pCR rates were 28% for patients treated with AC-T and 19% for patients treated with TAC, with an odds ratio of 1.60 (95% CI 0.90-3.21). With a median follow-up of 6 years (range 0.04-8.41 years), the five-year disease-free survival was 81% for patients treated with sequentially AC-T and 71% for patients treated with concurrent triplet TAC chemotherapy with a stratified hazard ratio (HR) of 0.50 (95% CI 0.29-0.86). Five-year overall survival was 84% versus 76%, respectively, with a stratified HR of 0.55 (95% CI 0.29-1.03). CONCLUSIONS: No differences were observed between the two treatment arms with respect to pCR rate, but the sequentially delivered chemotherapy outperformed the triplet combination chemotherapy in terms of survival, despite a lower cumulative dose per agent. GOV nr NCT00314977.

Does Internet-based guided-self-help for depression cause harm? An individual participant data meta-analysis on deterioration rates and its moderators in randomized controlled trials.

BACKGROUND: Almost nothing is known about the potential negative effects of Internet-based psychological treatments for depression. This study aims at investigating deterioration and its moderators within randomized trials on Internet-based guided self-help for adult depression, using an individual patient data meta-analyses (IPDMA) approach. METHOD: Studies were identified through systematic searches (PubMed, PsycINFO, EMBASE, Cochrane Library). Deterioration in participants was defined as a significant symptom increase according to the reliable change index (i.e. 7.68 points in the CES-D; 7.63 points in the BDI). Two-step IPDMA procedures, with a random-effects model were used to pool data. RESULTS: A total of 18 studies (21 comparisons, 2079 participants) contributed data to the analysis. The risk for a reliable deterioration from baseline to post-treatment was significantly lower in the intervention v. control conditions (3.36 v. 7.60; relative risk 0.47, 95% confidence interval 0.29-0.75). Education moderated effects on deterioration, with patients with low education displaying a higher risk for deterioration than patients with higher education. Deterioration rates for patients with low education did not differ statistically significantly between intervention and control groups. The benefit-risk ratio for patients with low education indicated that 9.38 patients achieve a treatment response for each patient experiencing a symptom deterioration. CONCLUSIONS: Internet-based guided self-help is associated with a mean reduced risk for a symptom deterioration compared to controls. Treatment and symptom progress of patients with low education should be closely monitored, as some patients might face an increased risk for symptom deterioration. Future studies should examine predictors of deterioration in patients with low education.

Addition of zoledronic acid to neoadjuvant chemotherapy does not enhance tumor response in patients with HER2-negative stage II/III breast cancer: the NEOZOTAC trial (BOOG 2010-01).

BACKGROUND: The role of zoledronic acid (ZA) when added to the neoadjuvant treatment of breast cancer (BC) in enhancing the clinical and pathological response of tumors is unclear. The effect of ZA on the antitumor effect of neoadjuvant chemotherapy has not prospectively been studied before. PATIENTS AND METHODS: NEOZOTAC is a national, multicenter, randomized study comparing the efficacy of TAC (docetaxel, adriamycin and cyclophosphamide i.v.) followed by granulocyte colony-stimulating factor on day 2 with or without ZA 4 mg i.v. q 3 weeks inpatients withstage II/III, HER2-negative BC. We present data on the pathological complete response (pCR in breast and axilla), on clinical response using MRI, and toxicity. Post hoc subgroup analyses were undertaken to address the predictive value of menopausal status. RESULTS: Addition of ZA to chemotherapy did not improve pCR rates (13.2% for TAC+ZA versus 13.3% for TAC). Postmenopausal women (N = 96) had a numerical benefit from ZA treatment (pCR 14.0% for TAC+ZA versus 8.7% for TAC, P = 0.42). Clinical objective response did not differ between treatment arms (72.9% versus 73.7%). There was no difference in grade III/IV toxicity between treatment arms. CONCLUSIONS: Addition of ZA to neoadjuvant chemotherapy did not improve pathological or clinical response to chemotherapy. Further investigations are warranted in postmenopausal women with BC, since this subgroup might benefit from ZA treatment.

Prediction of successful revision surgery for mesh-related complaints after inguinal hernia and pelvic organ prolapse repair.

PURPOSE: With this retrospective case series, we aim to identify predictors for reduction of pain after mesh revision surgery in patients operated for inguinal hernia or pelvic organ prolapse with a polypropylene implant. Identifying these predictors may aid surgeons to counsel patients and select appropriate candidates for mesh revision surgery. METHODS: Clinical records before and after mesh revision surgery from 221 patients with chronic postoperative inguinal pain (CPIP) and 59 patients with pain after pelvic organ prolapse (POP) surgery were collected at two experienced tertiary referral centers. Primary outcome was patient reported improvement of pain after revision surgery. A multivariable logistic regression model was used to specify predictors for pain reduction. RESULTS: The multivariable logistic regression was performed for each patient group separately. Patients with CPIP had higher chances of improvement of pain when time between mesh placement and mesh revision surgery was longer, with an OR of 1.19 per year. A turning point in chances of risks and benefits was demonstrated at 70 months, with improved outcomes for patients with revision surgery ≥ 70 months (OR 2.86). For POP patients, no statistically significant predictors for reduction of pain after (partial) removal surgery could be identified. CONCLUSION: A longer duration of at least 70 months between implantation of inguinal mesh and revision surgery seems to give a higher chance on improvement of pain. Caregivers should not avoid surgery based on a longer duration of symptoms when an association between symptoms and the location of the mesh is found.

Phase I clinical and pharmacokinetic study of topotecan administered by a 24-hour continuous infusion.

PURPOSE: To determine the maximum-tolerable dose (MTD) and to investigate the pharmacokinetics and pharmacodynamics of topotecan in a phase I study. Topotecan is a novel semisynthetic derivative of the anticancer agent camptothecin and inhibits the intranuclear enzyme topoisomerase I. Broad preclinical activity rationalized further clinical evaluation. PATIENTS AND METHODS: In this phase I trial, topotecan was administered by 24-hour continuous infusion every 21 days to patients with solid malignant tumors. RESULTS: A total of 25 eligible patients, of whom 22 were pretreated, entered the study. They received the following dosages of topotecan: 2.5, 3.75, 5.60, 8.4, and 10.5 mg/m2 by 24-hour infusion. Reversible leukopenia and thrombocytopenia were dose-limiting, with mild anemia occurring regularly. Other toxicities, such as alopecia, mucositis, nausea, and vomiting were sporadic and mild. Responses were not observed. However, eight patients had stable disease. The plasma concentration-time curves were not compatible with standard linear pharmacokinetic models, and indications were found for the occurrence of nonlinear (saturation) kinetics at the dosages studied. CONCLUSION: The recommended dose for phase II studies is 8.4 mg/m2 when administered as a 24-hour infusion, which is well tolerated. Further studies will be necessary to account for the putative nonlinear behavior of the drug.

Phase I and pharmacologic study of the combination paclitaxel and carboplatin as first-line chemotherapy in stage III and IV ovarian cancer.

PURPOSE: To determine the maximum-tolerated dose for the combination paclitaxel and carboplatin administered every 4 weeks and to gain more insight into the pharmacokinetics and pharmacodynamics of this combination in previously untreated ovarian cancer patients. PATIENTS AND METHODS: Thirty-five chemotherapy-naive patients with suboptimally debulked stage III (tumor masses > 3 cm) and stage IV ovarian cancer were entered onto this phase I trial in which paclitaxel was administered as a 3-hour intravenous (IV) infusion at dosages of 125 to 225 mg/m2 immediately followed by carboplatin over 30 minutes at dosages of 300 to 600 mg/m2. A total of six courses was planned, followed by a second-look laparoscopy/laparotomy. Patients with a response and/or minimal residual disease at second-look laparoscopy received three additional courses. Twenty-six patients participated in the pharmacokinetic part of the study. RESULTS: The most important hematologic toxicity encountered was neutropenia. Neutropenia was more pronounced for the higher dose levels (DLs) and was cumulative. Thrombocytopenia was mild in the first eight DLs, but increased during the treatment courses. Nonhematologic toxicities consisted mainly of vomiting, neuropathy, fatigue, rash, pruritus, myalgia, and arthralgia. Dose-limiting toxicities (DLTs) in this trial were neutropenic fever, thrombocytopenia that required platelet transfusions, and cumulative neuropathy. Of 33 patients assessable for response, 26 major responders (78%, 20 complete response [CR] and six partial response [PR]) were documented. The maximal concentration (Cmax) of paclitaxel and the area under the concentration-time curve (AUC) were not different from the historical data for paclitaxel as a single agent. Retrospective analysis using a modified Calvert formula showed that the measured carboplatin AUCs in plasma ultrafiltrate (pUF) were 30% +/- 3.4% less than the calculated carboplatin AUC. Neutropenia was more pronounced than could be expected on the basis of the historical times above a threshold concentration greater than 0.1 mumol/L (T > or = 0.1 mumol/L) or 0.05 mumol/L (T > or = 0.05 mumol/L), and thrombocytopenia was less than could be expected from historical sigmoidal Emax models. CONCLUSION: The combination of paclitaxel 200 mg/ m2 and carboplatin 550 mg/m2 every 4 weeks is a well-tolerated treatment modality. The paclitaxel-carboplatin combination is highly active in stage III (bulky) and stage IV ovarian cancer. No indications for a pharmacokinetic drug-drug interaction between carboplatin and paclitaxel were found.

Pharmacokinetics of paclitaxel and carboplatin in a dose-escalating and dose-sequencing study in patients with non-small-cell lung cancer. The European Cancer Centre.

PURPOSE: To investigate the pharmacokinetics and pharmacodynamics of paclitaxel (P) and carboplatin (C) in a sequence-finding and dose-escalating study in untreated non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Fifty-five chemotherapy-naive patients with NSCLC were entered onto the pharmacokinetic part of a large phase I trial in which P was administered as a 3-hour infusion at dosages of 100 to 250 mg/m2, and C over 30 minutes at dosages of 300 to 400 mg/m2. Patients were randomized for the sequence of administration, first C followed by P or vice versa. Each patient received the alternate sequence during the second and subsequent courses. RESULTS: The most important hematologic toxicity encountered-was neutropenia. Hematologic toxicity was not dependent on the sequence in which P and C were administered, but there was cumulative neutropenia. Nonhematologic toxicities consisted mainly of vomiting, myalgia, and arthralgia. No sequence-dependent pharmacokinetic interactions for the P area under the concentration-time curve (P-AUC), maximal plasma concentration (P-Cmax), or time above a threshold concentration of 0.1 mumol/L (P-T > or = 0.1 mumol/L) were observed. However, there was a significant difference for the metabolite 6 alpha-hydroxypaclitaxel AUC (6OHP-AUC). Higher 6OHP-AUCs were observed when C was administered before P. The mean plasma ultrafiltrate AUC of C (CpUF-AUC) at the dosage of 300 mg/m2 for the sequence C-->P was 3.52 mg/mL.min (range, 1.94 to 5.83) and 3.62 mg/mL.min for the sequence P-->C (range, 1.91 to 5.01), which is not significantly different (P = .55). Of 45 assessable patients, there were five major responders (three complete responders and two partial responders). Four of five responses occurred at dosages above dose level 4 (P 175 mg/m2 + C 300 mg/m2). The median survival duration was best correlated with the P dose (4.8 months for doses < 175 mg/m2 v 7.9 months for doses > or = 175 mg/m2, P = .07; P-T > or = 0.1 mumol/L, 4.8 months for < 15 hours v 8.2 months for > or = 15 hours, P = .06). CONCLUSION: There was no pharmacokinetic-sequence interaction between C and P in this study. A clear dose-response relation with respect to response rate and survival was observed. The pharmacokinetic parameter P-T > or = 0.1 mumol/L was related to improved survival in this study.

An overview of the clinical pharmacology of topotecan.

Topotecan (Hycamtin; SmithKline Beecham Pharmaceuticals, Philadelphia, PA), a topoisomerase I inhibitor, is a semisynthetic camptothecin that has been structurally modified for increased water solubility. The closed lactone ring predominates at acidic pH, but the reverse reaction of the parent into the metabolite predominates at physiologic pH. The pharmacokinetic profile of topotecan is usually characterized by a two-compartment model and is linear in the dose range of 0.5 to 3.5 mg/m2. Following intravenous administration for 5 days at doses of 0.5 to 1.5 mg/m2/d as a 30-minute infusion, topotecan has a volume of distribution of approximately 130 L. Mean plasma clearance for topotecan (total) was approximately 1,000 mL/min with a plasma half-life of 2 to 3 hours. Renal clearance is an important determinant of topotecan elimination, with approximately 30% of the dose excreted in the urine. In three phase I studies in which the schedule of five daily doses every 21 or 28 days was investigated, all found 1.5 mg/m2/d to be the maximum tolerated dose. Neutropenia (reversible and noncumulative over time) was the major dose-limiting toxicity; fevers and infections were infrequently reported. The magnitude of topotecan exposure was correlated to the observed myelosuppression.

Clinical pharmacology of carboplatin administered in combination with paclitaxel.

The clinical pharmacology of carboplatin (C) administered with paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) (P) was investigated in two phase I studies undertaken in 83 previously untreated patients with either non-small cell lung cancer or ovarian cancer. Carboplatin was administered over 30 minutes and paclitaxel over 3 hours. Both agents were given every 4 weeks. Non-small cell lung cancer patients were randomized to two administration sequences, either carboplatin followed by paclitaxel (C-->P) or the reverse (P-->C). Each patient received the alternate sequence during the second and subsequent courses. Ovarian cancer patients uniformly received paclitaxel before carboplatin. Platinum concentrations in plasma ultrafiltrate were measured via flameless atomic absorption spectrometry, and 122 concentration-time curves were obtained. For non-small cell lung cancer patients, the mean area under the concentration-time curve (AUC) per 300 mg/m2 carboplatin was 3.52 mg/mL x min (range, 1.94 to 5.83) for the sequence C-->P and 3.62 mg/mL x min (range, 1.91 to 5.01) for the sequence P-->C. No sequence-dependent effect was observed (P > .5). For ovarian cancer patients, the mean AUC per 300 mg/m2 carboplatin was 3.83 mg/mL x min (range, 2.72 to 6.10), showing no difference when compared with data derived from non-small cell lung cancer patients (P = .13). In addition, the carboplatin AUC was not influenced by increasing paclitaxel doses from 100 to 250 mg/m2. Neutropenia was the principal toxicity, and anemia was frequent. However, there was a striking lack of thrombocytopenia. Modeling of the relationship between the carboplatin AUC and the decrease in platelets revealed a 50% decrease in platelets at a carboplatin AUC (AUC50) of 6.3 mg/mL x min. This contrasts with historical data documenting a carboplatin AUC50 of 4.0 mg/mL x min. Our findings suggest that there is a considerable interaction of both drugs at the cellular level, with at least an additive effect of carboplatin on the main hematologic toxicity of paclitaxel (ie, neutropenia). There is also a protective effect exerted by paclitaxel on carboplatin-related toxicity (ie, thrombocytopenia). The clear protective effect of paclitaxel in this combination suggests that it is possible to reduce the dose interval to 3 weeks. Studies are in progress to test this hypothesis and to investigate the underlying pharmacologic interactions.

Limited-sampling models for anticancer agents.

Pharmacokinetic parameters of antineoplastic drugs are usually generated from concentration/time profiles obtained after multiple venipunctures. With limited-sampling models (LSM) this number can be reduced to between one and three timed plasma samples. LSMs may facilitate population pharmacokinetic/pharmacodynamic studies, which eventually may lead to a dosing strategy based on the characteristics of the individual patient. In this article, the development, validation and application of several LSMs reported in the literature are reviewed.

A limited-sampling model for the pharmacokinetics of carboplatin administered in combination with paclitaxel.

PURPOSE: Carboplatin doses are often determined by using modified Calvert formulas. It has been observed that the area under the concentration versus time curve (AUC) for free carboplatin is lower than expected when modified formulas are used for carboplatin/paclitaxel chemotherapy combination regimens. By using limited-sampling models, the carboplatin AUC actually reached can easily be verified, and the dose adjusted accordingly. METHODS: In this report, we describe the development and validation of a limited-sampling model for carboplatin from 77 pharmacokinetic curves, when carboplatin is used in combination with paclitaxel. RESULTS: The following single-point model was selected as optimal: AUC carboplatin (min mg(-1) ml(-1)) = 418. c(2.5 h)(mg/ml) + 0.43 (min mg(-1) ml(-1)), where c(2.5 h) is the concentration (mg/ml) of carboplatin 2.5 h after the start of a 30-min infusion. This model proved to be unbiased (mean prediction error = 3.4 +/- 1.6%) and precise (root mean square error = 10.1 +/- 1.5%). CONCLUSIONS: The proposed model can be very useful for ongoing and future carboplatin/paclitaxel studies aimed to optimise and individualize treatment.

The use of the Calvert formula to determine the optimal carboplatin dosage.

Carboplatin is a chemotherapeutic agent frequently used in the treatment of various malignancies. The myelotoxicity and clinical efficacy of carboplatin correlate with the clearance of the drug, which is correlated to the glomerular filtration rate (GFR). Dosing of this agent based solely upon the patients body surface area is therefore not accurate enough; the GFR, and thus the clearance of carboplatin differ in each patient irrespective of the body area. Consequently, some patients undergo a higher systemic exposure, expressed as the area under the plasma concentration/time curve (AUC), than others when dosages of carboplatin are given on the basis of the body surface area. A high AUC correlates with increased toxicity, thus increasing the risks of the treatment, but in the case of a low AUC the therapeutical efficacy decreases. This indicates that an individual dosing strategy is warranted to obtain the optimal AUC. In this article, the development and application of a simple equation, known as the Calvert formula, are discussed. This formula can be used to calculate the carboplatin dose accurately in order to obtain a target AUC by using only the GFR. The formula is: dose (mg) = AUC (mg ml-1 min) x [GFR (ml/min) + 25 (ml/min)]. This formula has proven to be, in both retrospective and prospective studies, a reliable tool to calculate the optimal dose of carboplatin Future studies should determine the value of the creatinine clearance as a measure for the GFR.

Validation of a limited sampling model for carboplatin in a high-dose chemotherapy combination.

A limited sampling model for the estimation of the carboplatin area under the concentration versus time curve (AUC), as developed by Sørensen et al., was validated prospectively for the use in a high-dose combination chemotherapy schedule. The model allows an estimation of the AUC on the basis of only one timed plasma drug concentration, sampled at exactly 2.75 h after a 1-h carboplatin infusion. Pharmacokinetic curves were obtained from nine patients receiving carboplatin (400 mg/m2 per day) combined with cyclophosphamide (1500 mg/m2 per day), thiotepa (120 mg/m2 per day), and mesna (3 g/day) for 4 consecutive days. Peripheral blood stem-cell transplantation (PBSCT) was performed 3 days later to restore hematopoiesis. Using this combination of high doses, the model proved to be unbiased (MPE -3.40%; SE, 1.22%) and highly precise [root mean squared prediction error (RMSE), 5.15%; SE, 0.17%] for estimation of the AUC during 4 consecutive days. The validated limited sampling model provides a starting point for future pharmacokinetic studies in a larger population of patients, which might lead to more insight into the relationships with the pharmacodynamic outcome of carboplatin and may help in achieving more rational dosing of patients on the basis of an AUC determination.

Pharmacokinetics and pharmacodynamics of topotecan administered daily for 5 days every 3 weeks.

Topotecan is a novel semisynthetic derivative of the anticancer agent camptothecin and inhibits the intranuclear enzyme topoisomerase I. The lactone structure of topotecan, which is in equilibrium with the inactive ring-opened hydroxy acid, is essential for this activity. The open form predominates at physiological pH. We performed a pharmacokinetic study as part of a phase I study in patients with various types of solid tumors, where topotecan was administered in a 30-min infusion daily on 5 consecutive days every 3 weeks. The plasma kinetics of topotecan could be described best using an open two-compartment model with t1/2(alpha) and t1/2(beta) of 8.1 (range 0.3 to 40.7) min and 132 (range 49 to 286) min, respectively. The plasma concentration-time profiles of the metabolite, however, could be described using a one-compartment model with t1/2(formation) of 29.0 (range 5.6-99.5) min and t1/2 (elimination of 123.2 (range 32-265) min, respectively. The lactone was the predominate form during the first hour from the start of infusion, but was rapidly converted into its ring-opened structure. The elimination rate of topotecan was independent of the dose. There were linear relationships between the dose (mg m-2 day-1), the area under the plasma concentration versus time curve (AUC) of topotecan and its metabolite, the total AUC, peak plasma lactone concentrations, and the time period that the topotecan concentrations remained above 10 nM. Different models were used to correlate pharmacokinetic and pharmacodynamic parameters. The percentage decrease in absolute neutrophil count (ANC) was related to these parameters and plots were well fitted by linear and sigmoidal Emax models.

A single 24-hour plasma sample does not predict the carboplatin AUC from carboplatin-paclitaxel combinations or from a high-dose carboplatin-thiotepa-cyclophosphamide regimen.

PURPOSE: It has been observed that the area under the free carboplatin concentration in plasma ultrafiltrate versus time curve (AUC) is related to toxicity and tumour response. For this reason, it can be important to measure the carboplatin AUC and subsequently adjust the dose to achieve a predefined target AUC. The use of limited sampling strategies enables relatively simple measurement and calculation of actual carboplatin AUCs. METHODS: We studied the performance of a limited sampling model, based on a single 24-h sample (the Ghazal-Aswad model). in 52 patients who received carboplatin in two different chemotherapy regimens (a carboplatin-paclitaxel combination and a high-dose carboplatin-thiotepa-cyclophosphamide combination). RESULTS: The measured mean AUC in our population was 4.1 min x mg/ml (median 3.9, range 1.9 6.3, SD 1.0 min x mg/ml). With the limited sampling model, the predicted mean AUC was 4.4 min x mg/ml (median 4.2, range 2.4-8.4, SD 1.2 min x mg/ml). Statistical analysis revealed that the model was slightly biased (MPE%, 6.5%), but imprecise (RMSE%, 20.6%) in our study population. CONCLUSION: Although easy and attractive to use, the Ghazal-Aswad formula is not precise enough to predict the carboplatin AUC, and needs to be evaluated prospectively in other patient populations.

Evaluation of formulas using the serum creatinine level to calculate the optimal dosage of carboplatin.

Carboplatin is a chemotherapeutic agent frequently used in the treatment of various malignancies. An individual dosing strategy has been recommended to yield the most optimal exposure, expressed as the area under the concentration-time curve (AUC). The formula developed by Calvert et al. (dose = target-AUC x [GFR + 25]) can be used to achieve this. However, due to the inconvenient [51Cr]-ethylenediamine-tetraacetic acid ([51Cr]-EDTA)-based measurement of the glomerular filtration rate (GFR), its application in the clinic has thus far been limited. Chatelut and co-workers have recently proposed a formula to estimate carboplatin clearance using the serum creatinine concentration. We retrospectively tested the Chatelut equation and the Calvert formula using either the creatinine clearance based on 24-h urine collection or the creatinine clearance based on the formula of Cockcroft and Gault. The latter equations were shown to predict the carboplatin clearance reasonably well, although systematic overprediction and underprediction occurred. However, the formula proposed by Chatelut and co-workers had no significant bias and was precise. It is proposed that this formula be used to calculate the optimal carboplatin dosage after prospective validation has been performed.

Pharmacokinetics and metabolism of docetaxel administered as a 1-h intravenous infusion.

Docetaxel, a taxane antitumor agent, was administered to 24 patients by a 1-h intravenous infusion at a dose level of 100 mg/m(2) with pharmacokinetic monitoring. The plasma concentration-versus-time data were fitted with a three-compartment model. The mean area under the curve (AUC) for docetaxel was 3.1 +/- 0.9 h. mg/l and the clearance was 34.8 +/- 9.3 l/h per m(2). There was considerable interpatient pharmacokinetic variability. In 33% of the patient population, metabolites were detected in plasma samples collected 5-30 min after the end of the infusion. The cyclized oxazolidinedione metabolite M4 was most frequently present and was detected in 8 out of 24 patients with maximal concentrations between 0.022 and 0.23 mg/l. Logistic regression analysis was performed to predict M4 docetaxel metabolism. In the final model, alanine aminotransferase and alkaline phosphatase levels were the strongest predictors. No relationship was found between M4 metabolism and percentage decrease in neutrophil count in this study. Three patients with high M4 concentrations in plasma during course 1 suffered from most pronounced fluid retention (grade 2-3) after two to five courses.

Pharmacokinetics and pharmacodynamics of topotecan given on a daily-times-five schedule in phase II clinical trials using a limited-sampling procedure.

Topotecan is a novel semisynthetic derivative of the anticancer agent camptothecin and inhibits the intranuclear enzyme topoisomerase I. The lactone structure of topotecan, which is in equilibrium with the inactive ring-opened hydroxy acid, is essential for this activity. We performed a pharmacokinetics study as part of phase II clinical trials in patients with various types of solid tumors, giving topotecan at 1.5 mg/m2 per day by 30-min infusion for 5 consecutive days, with courses being repeated every 3 weeks. Previously validated limited-sampling models, using concentration measurements in samples obtained 2 h after infusion, were used to calculate the area under the plasma concentration-time curves (AUCs) for both chemical forms. Samples were obtained from a total of 36 patients over 136 treatment days. The mean AUC of the closed-ring form (AUC(closed)) was 8.74 (range 2.3-16.3 microM min per day, and the mean AUC of the ring-opened form (AUC(open)) was 11.5 (range 3.2-46.0) microM min per day (interpatient variability 34-61%). In each patient the AUC values achieved on the 1st day of administration were similar to and, thus, predictive for those achieved during the following days, with a day-to-day variation of 7.39% being recorded for the AUC(closed) and that of 12.6% for the AUC(open). There was no drug accumulation during the 5 consecutive treatment days of each cycle. However, despite the large interpatient pharmacokinetic variability, the importance of regular drug monitoring on this schedule can be questioned, as the pharmacodynamic variability was relatively small.

Tailor-made chemotherapy for cancer patients.

Dosages of anticancer agents are usually calculated from a uniform standard-the body surface area (BSA). Although the BSA is proportionate to many physiological functions, it is however only partially related to the overall drug clearance. Consequently, a wide variability in drug exposure and drug concentrations can be found between patients, by which some experience little toxicity, while others may show severe toxic symptoms. It seems clear that monitoring of plasma drug concentrations can be a useful tool to further optimize current cancer chemotherapy. The problem that pharmacokinetic parameters are usually generated from concentration-time profiles obtained after multiple venepunctures can be reduced by applying limited sampling models (LSM). Other tailor-made dosing strategies include the Calvert formula for carboplatin dosing and strategies based on the characteristics of the individual patient. It can be concluded that the determination of pharmacokinetic parameters and adjustment of the drug dose in each patient to a predefined 'target' value with an optimal therapeutic outcome, could contribute substantially to improvement of current chemotherapeutic treatment.