Longitudinal Analysis of the Effect of Inflammation on Voriconazole Trough Concentrations.

Voriconazole (VCZ) exhibits great inter- and intrapatient variability. The latter variation cannot exclusively be explained by concomitant medications, liver disease or dysfunction, and genetic polymorphisms in cytochrome P450 2C19 (CYP2C19). We hypothesized that inflammatory response in patients under VCZ medication might also influence this fluctuation in concentrations. In this study, we explored the association between inflammation, reflected by the C-reactive protein (CRP) concentration, and VCZ trough concentrations over time. A retrospective analysis of data was performed for patients with more than one steady-state VCZ trough concentration and a CRP concentration measured on the same day. A longitudinal analysis was used for series of observations obtained from many study participants over time. The approach involved inclusion of random effects and autocorrelation in linear models to reflect within-person cross-time correlation. A total of 50 patients were eligible for the study, resulting in 139 observations (paired VCZ and CRP concentrations) for the analysis, ranging from 2 to 6 observations per study participant. Inflammation, marked by the CRP concentration, had a significant association with VCZ trough concentrations (P < 0.001). Covariates such as age and interacting comedication ([es]omeprazole), also showed a significant correlation between VCZ and CRP concentrations (P < 0.05). The intrapatient variation of trough concentrations of VCZ was 1.401 (confidence interval [CI], 0.881 to 2.567), and the interpatient variation was 1.756 (CI, 0.934 to 4.440). The autocorrelation between VCZ trough concentrations at two sequential time points was calculated at 0.71 (CI, 0.51 to 0.92). The inflammatory response appears to play a significant role in the largely unpredictable pharmacokinetics of VCZ, especially in patients with high inflammatory response, as reflected by high CRP concentrations.

Long-term exposure to circulating platinum is associated with late effects of treatment in testicular cancer survivors.

BACKGROUND: The success of cisplatin-based (Platinol, Bristol-Myers Squibb Company, New York, NY, USA) chemotherapy for testicular cancer comes at the price of long-term and late effects related to healthy tissue damage. We assessed and modelled serum platinum (Pt) decay after chemotherapy and determined relationships between long-term circulating Pt levels and known late effects. PATIENTS AND METHODS: In 99 testicular cancer survivors, treated with cisplatin-based chemotherapy, serum and 24-h urine samples were collected during follow-up (1-13 years after treatment). To build a population pharmacokinetic model, measured Pt data were simultaneously analysed, together with cisplatin dose, age, weight and height using the NONMEM software. Based on this model, area under the curve between 1 and 3 years after treatment (Pt AUC1-3 years) was calculated for each patient. Predicted long-term Pt exposure was related to renal function and to late effects of treatment assessed median 9 (3-15) years after chemotherapy. RESULTS: Decay of Pt was best described by a two-compartment model. Mean terminal T1/2 was 3.7 (range 2.5-5.2) years. Pt AUC1-3 years correlated with cumulative cisplatin dose, and creatinine clearance before and 1 year after treatment. Patients with paraesthesia had higher Pt AUC1-3 years (30.9 versus 27.0 µg/l month) compared with those without paraesthesia (P = 0.021). Patients with hypogonadism, elevated LDL-cholesterol levels or hypertension also had higher Pt AUC1-3 years. CONCLUSIONS: Renal function before and after cisplatin treatment is an important determinant of long-term Pt exposure. Known long-term effects of testicular cancer treatment, such as paraesthesia, hypogonadism, hypercholesterolaemia and hypertension, are associated with long-term circulating Pt exposure.

Five year results of an international proficiency testing programme for measurement of antifungal drug concentrations.

OBJECTIVES: Since 2007 the Dutch Association for Quality Assessment in Therapeutic Drug Monitoring (KKGT) has organized an international interlaboratory proficiency testing (PT) programme for measurement of antifungal drugs in plasma. We describe the 5 year results of the laboratories' performance. METHODS: Twice a year, laboratories received a set of blind plasma samples containing low or high concentrations of fluconazole, itraconazole, hydroxyitraconazole, posaconazole, voriconazole and flucytosine. Participating laboratories were asked to report their results within 6 weeks after dispatch and provide details of their analytical methods. Results deviating >20% from the weighed-in concentration were considered inaccurate. Four-way ANOVA was performed to assess the effect of antifungal drug measured, concentration, analytical method and performing laboratory on the absolute inaccuracy. In 2012, a questionnaire based on the CLSI guidelines was dispatched with the request to provide input on sources of error. RESULTS: Fifty-seven laboratories (13 countries) reported 2251 results (287 fluconazole, 451 itraconazole, 348 hydroxyitraconazole, 402 posaconazole, 652 voriconazole and 111 flucytosine) in 5 years. Analyses were performed using HPLC (55.0%), LC-MS(/MS) (43.4%), UPLC (1.4%) or GC-MS (0.2%). Overall, 432 (19.2%) analyses were inaccurate. The performing laboratory was the only factor clearly associated with inaccuracies. The questionnaire results indicated that laboratories encounter significant problems analysing low concentrations (15.4% of all inaccuracies). CONCLUSIONS: Results of the PT programme suggest that one out of five measurements is inaccurate. The performing laboratory is the main determinant of inaccuracy, suggesting that internal quality assurance is pivotal in preventing inaccuracies, irrespective of the antifungal drug measured, concentration and analytical equipment.

Clinical validation of the analysis of linezolid and clarithromycin in oral fluid of patients with multidrug-resistant tuberculosis.

Linezolid plays an increasingly important role in the treatment of multidrug-resistant tuberculosis (MDR-TB). However, patients should be carefully monitored due to time- and dose-dependent toxicity. Clarithromycin plays a more modest role. Therapeutic drug monitoring may contribute to assessment of treatment regimens, helping to reduce toxicity while maintaining adequate drug exposure. Oral fluid sampling could provide a welcome alternative in cases where conventional plasma sampling is not possible or desirable. The aim of this study was to clinically validate the analysis of linezolid and clarithromycin and its metabolite hydroxyclarithromycin in oral fluid of patients with multidrug-resistant tuberculosis. Serum and oral fluid samples were simultaneously obtained and analyzed by using validated methods, after extensive cross-validation between the two matrices. Passing-Bablok regressions and Bland-Altman analysis showed that oral fluid analysis of linezolid and clarithromycin appeared to be suitable for therapeutic drug monitoring in MDR-TB patients. No correction factor is needed for the interpretation of linezolid oral fluid concentrations with a ratio of the linezolid concentration in serum to that in oral fluid of 0.97 (95% confidence interval [CI], 0.92 to 1.02). However, the clarithromycin concentration serum/clarithromycin concentration in oral fluid ratio is 3.07 (95% CI, 2.45 to 3.69). Analysis of hydroxyclarithromycin in oral fluid was not possible in this study due to a nonlinear relationship between the concentration in serum and that in oral fluid. In conclusion, the analysis of linezolid (no correction factor) and clarithromycin (correction factor of 3) in oral fluid is applicable for therapeutic drug monitoring in cases of multidrug-resistant tuberculosis as an alternative to conventional serum sampling. Easy sampling using a noninvasive technique may facilitate therapeutic drug monitoring for specific patient categories.

Dried blood spot analysis for therapeutic drug monitoring of linezolid in patients with multidrug-resistant tuberculosis.

Linezolid is a promising antimicrobial agent for the treatment of multidrug-resistant tuberculosis (MDR-TB), but its use is limited by toxicity. Therapeutic drug monitoring (TDM) may help to minimize toxicity while adequate drug exposure is maintained. Conventional plasma sampling and monitoring might be hindered in many parts of the world by logistical problems that may be solved by dried blood spot (DBS) sampling. The aim of this study was to develop and validate a novel method for TDM of linezolid in MDR-TB patients using DBS sampling. Plasma, venous DBS, and capillary DBS specimens were obtained simultaneously from eight patients receiving linezolid. A DBS sampling method was developed and clinically validated by comparing DBS with plasma results using Passing-Bablok regression and Bland-Altman analysis. This study showed that DBS analysis was reproducible and robust. Accuracy and between- and within-day precision values from three validations presented as bias and coefficient of variation (CV) were less than 17.2% for the lower limit of quantification and less than 7.8% for other levels. The method showed a high recovery of approximately 95% and a low matrix effect of less than 8.7%. DBS specimens were stable at 37°C for 2 months and at 50°C for 1 week. The ratio of the concentration of linezolid in DBS samples to that in plasma was 1.2 (95% confidence interval [CI], 1.12 to 1.27). Linezolid exposure calculated from concentrations DBS samples and plasma showed good agreement. In conclusion, DBS analysis of linezolid is a promising tool to optimize linezolid treatment in MDR-TB patients. An easy sampling procedure and high sample stability may facilitate TDM, even in underdeveloped countries with limited resources and where conventional plasma sampling is not feasible.

Evaluation of moxifloxacin for the treatment of tuberculosis: 3 years of experience.

Moxifloxacin (MFX) is a powerful second-line anti-tuberculosis (TB) agent, but the optimal dose has not yet been established and long-term safety data are scarce. We retrospectively reviewed the medical charts of TB patients treated at the Tuberculosis Centre Beatrixoord, University Medical Centre Groningen (Haren, the Netherlands) receiving MFX 400 mg once daily as part of their TB treatment between January 1 2006 and January 1 2009. Safety data and drug-drug interactions were evaluated. Efficacy was predicted based on the area under the concentration-time curve up to 24 h post-dosage (AUC(0-24h))/minimal inhibitory concentration (MIC) ratio. 89 patients were treated with a median dose of 6.9 mg · kg(-1) MFX once daily for a median period of 74 days. Discontinuation of therapy occurred in only three patients due to gastrointestinal side-effects and hypersensitivity. Pharmacokinetic analysis showed an AUC(0-24h)/MIC ratio <100 in eight out of 16 patients. A large variation in protein binding affected the unbound AUC(0-24h) considerably. These data show that MFX treatment was well tolerated in 89 patients receiving a dose of 400 mg once daily for a prolonged period. Considering the variability in (un)bound AUC(0-24h)/MIC ratio, therapeutic drug monitoring is recommended in selected patients (i.e. rifampicin co-medication; MIC ≥ 0.25 mg · L(-1)) to assess optimal therapy.

Pharmacokinetics of rifampin and clarithromycin in patients treated for Mycobacterium ulcerans infection.

In a randomized controlled trial in Ghana, treatment of Mycobacterium ulcerans infection with streptomycin (SM)-rifampin (RIF) for 8 weeks was compared with treatment with SM-RIF for 4 weeks followed by treatment with RIF-clarithromycin (CLA) for 4 weeks. The extent of the interaction of RIF and CLA combined on the pharmacokinetics of the two compounds is unknown in this population and was therefore studied in a subset of patients. Patients received CLA at a dose of 7.5 mg/kg of body weight once daily, rounded to the nearest 125 mg. RIF was administered at a dose of 10 mg/kg, rounded to the nearest 150 mg. SM was given at a dose of 15 mg/kg once daily as an intramuscular injection. Plasma samples were drawn at steady state and analyzed by liquid chromatography-tandem mass spectroscopy. Pharmacokinetic parameters were calculated with the MW/Pharm (version 3.60) program. Comedication with CLA resulted in a 60% statistically nonsignificant increase in the area under the plasma concentration-time curve (AUC) for RIF of 25.8 mg x h/liter (interquartile ratio [IQR], 21.7 to 31.5 mg x h/liter), whereas the AUC of RIF was 15.2 mg x h/liter (IQR, 15.0 to 17.5 mg x h/liter) in patients comedicated with SM (P = 0.09). The median AUCs of CLA and 14-hydroxyclarithromycin (14OH-CLA) were 2.9 mg x h/liter (IQR, 1.5 to 3.8 mg x h/liter) and 8.0 mg x h/liter (IQR, 6.7 to 8.6 mg x h/liter), respectively. The median concentration of CLA was above the MIC of M. ulcerans, but that of 14OH-CLA was not. In further clinical studies, a dose of CLA of 7.5 mg/kg twice daily should be used (or with an extended-release formulation, 15 mg/kg should be used) to ensure higher levels of exposure to CLA and an increase in the time above the MIC compared to those achieved with the currently used dose of 7.5 mg/kg once daily.

Intravenous voriconazole after toxic oral administration.

In a male patient with rhinocerebral invasive aspergillosis, prolonged high-dosage oral administration of voriconazole led to hepatotoxicity combined with a severe cutaneous reaction while intravenous administration in the same patient did not. High concentrations in the portal blood precipitate liver enzyme abnormalities, and therefore, oral administration of voriconazole may have a hepatotoxicity profile different from that of intravenous (i.v.) administration. Intravenously administered voriconazole might still be an option after oral-voriconazole-induced toxicity has resolved.

pH adjustment of human blood plasma prior to bioanalytical sample preparation.

pH adjustment in bioanalytical sample preparation concerning ionisable compounds is one of the most common sample treatments. This is often done by mixing an aliquot of the sample with a proper buffer adjusted to the proposed pH. The pH of the resulting mixture however, does not necessarily have to be the same as the pH of the used buffer due to the significant buffer capacity of the sample. Calculation methods from titration technology were adapted and applied to this problem. The acid-base characteristics of human blood plasma and serum samples were determined and used to calculate the pH of buffer-plasma mixtures. Based on these parameters and the characteristics of the used buffers, two alternative methods were described to prepare buffers that lead to the proposed pH when mixed in the right volume ratio with human plasma samples. The resulting pH of several mixtures of different buffers with human blood plasma were in good accordance with the calculated pH. The proposed calculation methods and recommended buffer preparation methods may lead to more robust bioanalytical methods.

New practical algorithm for modelling analyte recovery in bioanalytical reversed phase and mixed-mode solid phase extraction.

Solid phase extraction (SPE) is a widely used method for sample cleanup and sample concentration in bioanalytical sample preparation. A few methods to model the retention behaviour on SPE cartridges have been described previously but they are either not applicable to ionised species or are not suitable when using multiple wash and elution steps with solvents differing in volume, modifier concentration and acidity. Furthermore, these models were not applied to mixed mode SPE sorbents. In order to overcome these limitations a new SPE modelling algorithm was proposed. The retention behaviour was determined directly on the SPE cartridge by connecting the cartridge online with an HPLC system using a simple but suitable device that was developed and described. The results from these online experiments were used to model the elution behaviour using a quadratic retention function combined with an exponentially modified Gaussian peak shape model to predict analyte recovery under different wash and elution conditions. The validity of the proposed algorithm was tested using practical SPE experiments with an aqueous test mixture as well as with spiked human plasma. Different sequential wash and elution steps were performed using solvents differing in volume and composition. The predicted band shape and recoveries in each collected step were in good agreement with the results obtained from practical experiments. The proposed algorithm is very useful for the description of the SPE behaviour of the analytes on the actual used SPE cartridge and can be used in structural and automated SPE method development.

Reconsideration of sample pH adjustment in bioanalytical liquid-liquid extraction of ionisable compounds.

Liquid-liquid extraction (LLE) is widely used as a simple and robust sample preparation technique in bioanalytical sample preparation. When extracting ionisable compounds, most bioanalysts adjust the pH of the sample to achieve fully unionized compounds. Usually, a generally accepted rule is applied to adjust the pH of the aqueous phase, known as the pKa+/-2 rule, depending on the acid/base characteristics of the analyte. By taking a closer look at the general equations that describe the extraction behaviour of ionisable compounds, we extended this pH adjustment rule by taking the distribution ratio and the volume of both liquid phases into account. By choosing an extraction pH based on this extended rule, the selectivity of the extraction can be influenced without loss of recovery. As a measure of this selectivity, two equations were proposed to indicate the ability of the extraction system to discriminate between two compounds. Also, milder extraction pH can be used for pH labile analytes. To use this new rule quantitatively, a new calculation method for the determination of the distribution ratio was derived. These calculations were based on normalized recoveries making this method less susceptible to errors in absolute recovery determination. The proposed equations were supported by demonstrating that careful pH adjustment can lead to higher selectivity. The main conclusion was that a closer look at the extraction pH in bioanalytical methods extends the possibilities of obtaining a higher selectivity or the possibilities of extracting pH labile analytes at milder pH conditions without loss of recovery.

Phase I study of the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 with 5-fluorouracil and leucovorin: a safe combination.

We performed a phase I study with the thrombospondin-1-mimetic angiogenesis inhibitor ABT-510 combined with 5-fluorouracil and leucovorin (5-FU/LV) to determine safety profile and assess pharmacokinetic interactions. Patients with advanced solid malignancies received LV 20 mg/m(2) followed by 5-FU 425 mg/m(2) both administered intravenously in 15 min daily for 5 days every 4 weeks. ABT-510 was administered subcutaneously twice daily continuously from day 2 onwards. Blood and urine samples for pharmacokinetic analyses were collected at days 1, 5 and 22. Twelve patients received a total of 45 cycles of 5-FU/LV combined with ABT-510. ABT-510 dose levels studied were 50 and 100 mg. The combination was well tolerated, with a toxicity profile comparable to that of 5-FU/LV alone. At the dose levels studied no significant pharmacokinetic interactions were observed. These data indicate that ABT-510 administered twice daily subcutaneously can be safely combined with 5-FU/LV administered daily for 5 days, every 4 weeks.

Comparison of urine and oral fluid as matrices for screening of thirty-three benzodiazepines and benzodiazepine-like substances using immunoassay and LC-MS(-MS).

Benzodiazepines are the most frequently detected medicinal drugs in drivers. The use of benzodiazepines is associated with an increased road accident risk. In this study, the presence of benzodiazepines detected by liquid chromatography-(tandem) mass spectrometry [LC-MS(-MS)] in oral fluid and urine samples obtained from drivers stopped during a roadside survey was compared. In addition, the sensitivity and selectivity of enzyme multiplied immunoassay technique (EMIT II Plus) relative to LC-MS(-MS) was determined for both matrices. A total number of 1,011 urine samples were collected and screened for benzodiazepines using immunoassay (IA) (EMIT II Plus; cutoff 300 ng/mL). In the IA-positive (n = 25) and a group of randomly selected negative urine samples (n = 79), the presence or absence of benzodiazepines was confirmed by LC-MS-MS after deglucuronidation. The corresponding oral fluid samples (n = 101, 3 samples omitted), were analyzed by LC-MS(-MS) and IA (EMIT II Plus; cutoff 10 ng/mL). The presence of benzodiazepines was demonstrated by LC-MS-(MS) in all IA-positive urine samples, but in only four corresponding oral fluid samples. Concentrations in oral fluid were, one substance excepted, lower than in urine. The sensitivity and specificity of EMIT II Plus were better by using urine as matrix for screening of benzodiazepines than by using oral fluid. The results show that benzodiazepines are detectable in oral fluid. More research has to be done to determine the pharmacokinetic profile of the different benzodiazepines in oral fluid and to study the relationship between dose, concentration (in oral fluid and blood), and impairment.

New practical algorithm for modelling retention times in gradient reversed-phase high-performance liquid chromatography.

Computer models have been widely used to predict the chromatographic behaviour of liquid chromatography systems. With the introduction of mass spectrometric detection and the use of lower mobile phase flow rates with conventional LC equipment, the influence of the dwell volume on the shape of the gradient curve becomes an issue in predicting the retention times. A new straight forward algorithm is proposed for the modelling of retention times in reversed-phase LC, taking the effect of the dwell volume on the gradient shape into account. The results show that the dwell volume has a large effect at lower flow rates and on the retention times of the analytes eluting at the end of fast gradient curves. The proposed model is able to make reliable predictions and can be helpful in LC-MS method development.

Drug use and the severity of a traffic accident.

Several studies have showed that driving under the influence of alcohol and/or certain illicit or medicinal drugs increases the risk of a (severe) crash. Data with respect to the question whether this also leads to a more severe accident are sparse. This study examines the relationship between the use of alcohol, illicit drugs and/or medicinal drugs and the severity of an accident within a group of drivers that were involved in a crash in The Netherlands. Blood samples of 993 drivers, collected in the period from October 1998 through September 1999, were linked to accident characteristics as available from the National Transport Research Centre. The outcome measure was the severity of the accident. An accident was considered severe when the accident had resulted in hospital admission or death. All the blood samples obtained after the accident were screened for the presence of alcohol, illicit drugs (opiates, amphetamines and amphetamine-like substances, cocaine and metabolites, methadone, cannabinoids) and medicinal drugs (benzodiazepines, barbiturates and tricyclic antidepressants). The strength of the associations between exposure to the different classes of alcohol/drugs/medicines and the severity of the accident was evaluated using logistic regression analysis and were expressed as odds ratios (OR), adjusted for age, gender, time of the day, day of the week and urban area. The most frequently detected drugs were cannabinoids, benzodiazepines and cocaine. Our results showed no clear association between the use of alcohol, illicit drug and/or medicinal drug use and the severity of the accident. Given the process of obtaining blood samples from drivers involved in accidents and the retrospective nature of the study, we cannot rule out the occurrence of selection bias. Therefore, our findings need further confirmation.

Development of an optimal sampling strategy for clinical pharmacokinetic studies of the novel anthracycline disaccharide analogue MEN-10755.

AIM: MEN-10755 is a novel anthracycline analogue that has shown an improved therapeutic efficacy over doxorubicin in animal models, especially in gynaecological and lung cancers and is currently under clinical development for the treatment of solid tumours. The aim of the project was to develop an optimal sampling strategy for MEN-10755 to provide an efficient basis for future pharmacokinetic/pharmacodynamic investigations. METHODS: Data from 24 patients who participated in a phase I clinical pharmacokinetic study of MEN-10755 administered as a short i.v. infusion were included. Individual pharmacokinetic values were calculated by fitting the plasma concentration data to a two-compartment model using nonlinear least-squared regression (KINFIT, Ed 3.5). Population pharmacokinetic analysis was carried out using (a) the traditional standard two-stage method (STS) based on all data (KINFIT-ALL), (b) the iterative two-stage Bayesian (IT(2)B) population modelling algorithm (KINPOP), and (c) the STS method using KINFIT and using four optimally timed plasma concentrations (KINFIT-OSS4). Determinant (D) optimal sampling strategy (OSS) was used to evaluate the four most information-rich sampling times. The pharmacokinetic parameters V(c) (l), k(el) (h(-1)), k(12) (h(-1)) and k(21) (h(-1)) calculated using KINPOP served as a model for calculation of four D-optimal sampling times. D-optimal sampling data sets were analysed using KINFIT-OSS4 and compared with the population model obtained by the traditional standard two-stage approach for all data sets (KINFIT-ALL). RESULTS: The optimal sampling times were: the end of the infusion, and 1.5 h, 3.8 h and 24 h after the start of the infusion. The four-point D-optimal sampling design determined in this study gave individual parameter estimates close to the basic standard estimates using the full data set. CONCLUSION: Because accurate estimates of pharmacokinetic parameters were achieved, the four-point D-optimal sampling design may be very useful in future studies with MEN-10755.

Outcome of local application of amifostine (WR-1065) on epirubicin-induced oral mucositis. A phase II study.

BACKGROUND: Intravenous administration of amifostine reduces chemotherapy-induced toxicity. Preclinical experiments showed a reduction in radiation-induced mucositis after local application of the active metabolite of amifostine (WR-1065). This study evaluated the effect of local application of WR-1065 on chemotherapy-induced oral mucositis. PATIENTS AND METHODS: Non-small cell lung cancer patients treated with gemcitabine and epirubicin every 3 weeks for a maximum of five cycles were included. WR-1065 was administered during the second and third cycle as an oral rinse. Oral mucositis evaluation included WHO toxicity grading, a validated oral mucositis assessment scale (OMAS) and a questionnaire. RESULTS: Twenty-four patients were evaluated for at least one control and one rinse cycle. Mucositis scores, pain and feeding difficulties increased from day 1 to day 15, and were not significantly different between the control and rinse cycles. Local application of WR-1065 leads to detectable quantities of WR-1065 in epithelial mucosa cells. A negative correlation between the WR-1065 concentration and OMAS score was found. CONCLUSION: No clinical detectable influence of WR-1065 on oral mucositis was found.

Quantitative analysis of 33 benzodiazepines, metabolites and benzodiazepine-like substances in whole blood by liquid chromatography-(tandem) mass spectrometry.

A quantitative method using high-performance liquid chromatography-mass spectrometry (LC-MS, ion trap) after matrix supported liquid-liquid extraction is described for the simultaneous determination in whole blood of 33 benzodiazepines including metabolites and benzodiazepine-like substances. The limits of detection (LOD) range from 0.0001 to 0.0126 mg/l. Linearity is satisfactory for all compounds. The extraction recoveries for the benzodiazepines in whole blood are between 60 and 91%, desmethyldiazepam, OH-bromazepam and brotizolam excepted. Selectivity, accuracy and precision are satisfactory for clinical and forensic purposes.

[Non-fatal rupture of a cocaine packet in a man with the 'bodypacker' syndrome]. / Niet-fatale ruptuur van een cocaïnebolletje bij een man met 'bodypacker'-syndroom.

A 24-year-old patient was admitted to the intensive care unit because he had swallowed about 20 cocaine packets 48 hours before admission; he also complained of abdominal cramps, perspiration and dizziness. The patient reported that he had not defecated since swallowing the packets. Abdominal X-ray revealed only coprotasis. On conservative therapy with bowel irrigation, two packets were eliminated, after which a second abdominal X-ray revealed several cocaine packets in the colon. Four days afterwards, the cocaine packets in the colon had not progressed despite adequate bowel irrigation. The patient now showed signs of mild cocaine intoxication (hallucinations and tachycardia). It was therefore decided to perform a laparotomy. Via a sigmoidotomy, 7 intact packets were removed; another 3 had already ruptured and were empty. The rupture of 3 cocaine packets in this patient was probably not fatal because of the sedation with midazolam and because the patient had diarrhoea as a result of the extensive irrigation, so that a large proportion of the cocaine was probably not absorbed. This case also shows that the presence of foreign bodies cannot be established adequately by an abdominal X-ray if there is coprostasis.

Simultaneous determination of rifampicin, clarithromycin and their metabolites in dried blood spots using LC-MS/MS.

INTRODUCTION: Rifampicin (RIF) and clarithromycin (CLR) are common drugs for the treatment of infections like Mycobacterium tuberculosis and Mycobacterium ulcerans. Treatment for these diseases are long-term and the individual pharmacokinetic variation, drug-drug interactions or non-adherence may introduce sub-therapeutic exposure or toxicity. The application of therapeutic drug monitoring (TDM) can be used to ensure efficacy and avoid toxicity. With the use of dried blood spot (DBS), TDM may be feasible in rural areas. During DBS method development, unexpected interactions or matrix effects may be encountered due to endogenous components in the blood. Another complication compared to plasma analysis is that RIF can form chelate complexes with ferric ions or can bind with hemes, which are potentially present in the extracts of dried blood spots. METHODS: The investigation focused on the interaction between RIF and the endogenous components of the DBS. The use of ethylenediaminetetraacetic acid (EDTA) and deferoxamine (DFX) as chelator agents to improve recoveries and matrix effects were investigated. A rapid analytical method was developed and validated to quantify RIF and CLR and their active metabolites desacetyl rifampicin (DAc-RIF) and 14-hydroxyclarythromcin (14OH-CLR) in DBS samples. A clinical application study was performed in tuberculosis patients by comparing DBS concentrations with plasma concentrations. RESULTS: The interaction between RIF and the DBS matrix was avoided using the complexing agents EDTA and DFX, which improved recoveries and matrix effects. The developed sample procedure resulted in a simple and fast method for the simultaneous quantification of RIF, CLR and their metabolites in DBS samples. High stability was observed as all four substances were stable at ambient temperature for 2 months. Deming regression analysis of the clinical application study showed no significant differences for RIF, DAc-RIF, CLR and 14OH-CLR between patient plasma and DBS analysis. The slopes of the correlation lines between DBS and plasma concentrations of RIF, DAc-RIF, CLR and 14OH-CLR were 0.90, 0.99, 0.80 and 1.09 respectively. High correlations between plasma and DBS concentrations were observed for RIF (R(2)=0.9076), CLR (R(2)=0.9752) and 14OH-CLR (R(2)=0.9421). Lower correlation was found for DAc-RIF (R(2) of 0.6856). CONCLUSION: The validated method is applicable for TDM of RIF, CLR and their active metabolites. The stability of the DBS at high temperatures can facilitate the TDM and pharmacokinetic studies of RIF and CLR even in resource limited areas. The role of EDTA and DFX as complexing agents in the extraction was well investigated and may provide a solution for potential applications to other DBS analytical methods.