Population Pharmacokinetics of Intravenous Ganciclovir and Oral Valganciclovir in a Pediatric Population To Optimize Dosing Regimens.

Ganciclovir is indicated for curative or preventive treatment of cytomegalovirus (CMV) infections. This study aimed to characterize ganciclovir pharmacokinetics, following intravenous ganciclovir and oral valganciclovir administration, to optimize dosing schemes. All children aged <18 years receiving ganciclovir or valganciclovir were included in this study. Pharmacokinetics were described using nonlinear mixed-effect modeling. Monte Carlo simulations were used to optimize the dosing regimen to maintain the area under the concentration-time curve (AUC) in the preventive or therapeutic target. Among the 105 children (374 concentration-time observations) included, 78 received intravenous (i.v.) ganciclovir, 19 received oral valganciclovir, and 6 received both drugs. A two-compartment model with first-order absorption for valganciclovir and first-order elimination best described the data. An allometric model was used to describe the bodyweight (BW) effect. Estimated glomerular filtration rate (eGFR) and medical status of critically ill children were significantly associated with ganciclovir elimination. Recommended doses were adapted for prophylactic treatment. To obtain a therapeutic exposure, doses should be increased to 40 mg/kg of body weight/day oral or 15 to 20 mg/kg/day i.v. in children with normal eGFR and to 56 mg/kg/day oral or 20 to 25 mg/kg/day i.v. in children with augmented eGFR. These doses should be prospectively confirmed, and therapeutic drug monitoring could be used to refine them individually. (This study has been registered at ClinicalTrials.gov under identifier NCT02539407.).

Population pharmacokinetics of intravenous and oral ciprofloxacin in children to optimize dosing regimens.

PURPOSE: This study aimed to characterize pharmacokinetics of intravenous and oral ciprofloxacin in children to optimize dosing scheme. METHODS: Children treated with ciprofloxacin were included. Pharmacokinetics were described using non-linear mixed-effect modelling and validated with an external dataset. Monte Carlo simulations investigated dosing regimens to achieve a target AUC0-24 h/MIC ratio ≥ 125. RESULTS: A total of 189 children (492 concentrations) were included. A two-compartment model with first-order absorption and elimination best described the data. An allometric model was used to describe bodyweight (BW) influence, and effects of estimated glomerular filtration rate (eGFR) and age were significant on ciprofloxacin clearance. CONCLUSION: The recommended IV dose of 10 mg/kg q8h, not exceeding 400 mg q8h, would achieve AUC0-24 h to successfully treat bacteria with MICs ≤ 0.25 (e.g. Salmonella, Escherichia coli, Proteus, Haemophilus, Enterobacter, and Klebsiella). A dose increase to 600 mg q8h in children > 40 kg and to 15 mg/kg q8h (max 400 mg q8h, max 600 mg q8h if augmented renal clearance, i.e., eGFR > 200 mL/min/1.73 m2) in children < 40 kg would be needed for the strains with highest MIC (16% of Pseudomonas aeruginosa and 47% of Staphylococcus aureus). The oral recommended dose of 20 mg/kg q12h (not exceeding 750 mg) would cover bacteria with MICs ≤ 0.125 but may be insufficient for bacteria with higher MIC and a dose increase according bodyweight and eGFR would be needed. These doses should be prospectively confirmed, and a therapeutic drug monitoring could be used to refine them individually.

Population Pharmacokinetics of Intravenous and Oral Acyclovir and Oral Valacyclovir in Pediatric Population To Optimize Dosing Regimens.

Acyclovir is an antiviral currently used for the prevention and treatment of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. This study aimed to characterize the pharmacokinetics (PK) of acyclovir and its oral prodrug valacyclovir to optimize dosing in children. Children receiving acyclovir or valacyclovir were included in this study. PK were described using nonlinear mixed-effect modeling. Dosing simulations were used to obtain trough concentrations above a 50% inhibitory concentration for HSV or VZV (0.56 mg/liter and 1.125 mg/liter, respectively) and maximal peak concentrations below 25 mg/liter. A total of 79 children (212 concentration-time observations) were included: 50 were taking intravenous (i.v.) acyclovir, 22 were taking oral acyclovir, and 7 were taking both i.v. and oral acyclovir, 57 for preventive and 22 for curative purposes. A one-compartment model with first-order elimination best described the data. An allometric model was used to describe body weight effect, and the estimated glomerular filtration rate (eGFR) was significantly associated with acyclovir elimination. To obtain target maximal and trough concentrations, the more suitable initial acyclovir i.v. dose was 10 mg/kg of body weight/6 h for children with normal renal function (eGFR ≤ 250 ml/min/1.73 m2) and 15 to 20 mg/kg/6 h for children with augmented renal clearance (ARC) (eGFR > 250 ml/min/1.73 m2). The 20-mg/kg/8 h dose for oral acyclovir and valacyclovir produced effective concentrations in more than 75% of children; however, a 15-mg/kg/6 h dose, if possible, is preferred. These doses should be prospectively confirmed, and therapeutic drug monitoring could be used to refine them individually. (This study has been registered at ClinicalTrials.gov under identifier NCT02539407.).

A meropenem pharmacokinetics model in patients with haematological malignancies.

BACKGROUND: Optimal dosing of antibiotics is critical in immunocompromised patients suspected to have an infection. Data on pharmacokinetics (PK) of meropenem in patients with haematological malignancies are scarce. OBJECTIVES: To optimize dosing regimens, we aimed to develop a PK population model for meropenem in this population. METHODS: Patients aged ≥18 years, hospitalized in the haematology department of our 1500 bed university hospital for a malignant haematological disease and who had received at least one dose of meropenem were eligible. Meropenem was quantified by HPLC. PK were described using a non-linear mixed-effect model and external validation performed on a distinct database. Monte Carlo simulations estimated the PTA, depending on renal function, duration of infusion and MIC. Target for free trough concentration was set at >4× MIC. RESULTS: Overall, 88 patients (181 samples) were included, 66 patients (75%) were in aplasia and median Modification of Diet in Renal Disease (MDRD) CLCR was 117 mL/min/1.73 m2 (range: 35-359). Initial meropenem dosing regimen ranged from 1 g q8h to 2 g q8h over 30 to 60 min. A one-compartment model with first-order elimination adequately described the data. Only MDRD CLCR was found to be significantly associated with CL. Only continuous infusion achieved a PTA of 100% whatever the MIC and MDRD CLCR. Short duration of infusion (<60 min) failed to reach an acceptable PTA, except for bacteria with MIC < 0.25 mg/L in patients with MDRD CLCR below 90 mL/min/1.73 m2. CONCLUSIONS: In patients with malignant haematological diseases, meropenem should be administered at high dose (6 g/day) and on continuous infusion to reach acceptable trough concentrations.

Addition of droperidol to prophylactic ondansetron and dexamethasone in children at high risk for postoperative vomiting. A randomized, controlled, double-blind study.

BACKGROUND: : The combination of dexamethasone (DEX), ondansetron (OND) and droperidol (DRO) is efficacious in preventing postoperative nausea and vomiting in adults, but has not been well assessed in children. METHODS: : Children undergoing elective surgery under general anaesthesia and considered at high risk for postoperative vomiting (POV) were randomly assigned to receive a combination of DEX, OND and placebo (Group A) or a combination of DEX, OND and DRO (Group B). The primary outcome was the incidence of POV during the first 24 hours after surgery. We hypothesized that the addition of DRO to the standard antiemetic prophylaxis would provide a further 15% reduction in the residual risk for POV. The secondary outcome considered was any adverse event occurring during the study. RESULTS: : One hundred and fifty-three children, aged three to 16 years, were randomized to Group A and 162 to Group B. The overall incidence of POV did not differ significantly between the two groups, with 16 patients in Group A (10.5%) and 18 in Group B (11.1%) presenting with one or more episodes of POV, P =0.86. Fewer patients presented with adverse events in Group A (2%) compared with Group B (8%), P =0.01. Drowsiness and headache were the principal adverse events reported. CONCLUSIONS: : The addition of DRO to a combination of OND and DEX did not decrease POV frequency below that obtained with the two-drug combination in children at high risk of POV, but increased the risk of drowsiness. The combination of DEX and OND should be recommended in children with a high risk of POV. CLINICAL TRIAL REGISTRATION.: NCT01739985.

Placental transfer of maraviroc in an ex vivo human cotyledon perfusion model and influence of ABC transporter expression.

Nowadays, antiretroviral therapy is recommended during pregnancy to prevent mother-to-child transmission of HIV. However, for many antiretroviral drugs, including maraviroc, a CCR5 antagonist, very little data exist regarding placental transfer. Besides, various factors may modulate this transfer, including efflux transporters belonging to the ATP-binding cassette (ABC) transporter superfamily. We investigated maraviroc placental transfer and the influence of ABC transporter expression on this transfer using the human cotyledon perfusion model. Term placentas were perfused ex vivo for 90 min with maraviroc (600 ng/ml) either in the maternal-to-fetal (n = 10 placentas) or fetal-to-maternal (n = 6 placentas) direction. Plasma concentrations were determined by ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Fetal transfer rates (FTR) and clearance indexes (CLI) were calculated as ratios of fetal to maternal concentrations at steady state (mean values between 30 and 90 min) and ratios of FTR of maraviroc to that of antipyrine, respectively. ABC transporter gene expression levels were determined by quantitative reverse transcription (RT)-PCR and ABCB1 protein expression by Western blotting. For the maternal-to-fetal direction, the mean FTR and CLI were 8.0% ± 3.0 and 0.26 ± 0.07, respectively, whereas the mean CLI was 0.52 ± 0.23 for the fetal-to-maternal direction. We showed a significant inverse correlation between maraviroc CLI and ABCC2, ABCC10, and ABCC11 placental gene expression levels (P < 0.05). To conclude, we report a low maraviroc placental transfer probably involving ABC efflux transporters and thus in all likelihood associated with a limited fetal exposition. Nevertheless, these results would need to be supported by in vivo data obtained from paired maternal and cord blood samples.

Nonpublication and Selective Outcome Reporting of Oral Health Trials.

Less than one-quarter of oral health trials are registered in a public registry. However, no study has assessed the extent of study publication and selective outcome reporting bias in the field of oral health. We identified oral health trials registered between 2006 and 2016 in ClinicalTrials.gov. We assessed whether results of early discontinued trials, trials having an unknown status, and completed trials had been published and, among published trials, whether outcomes differed between the registered record and the corresponding publication. We included 1,399 trials, of which 81 (5.8%) were discontinued, 247 (17.7%) had an unknown status, and 1,071 (76.6%) were completed. The registration was prospective for 719 (51.9%) trials. Over half the registered trials were unpublished (n = 793, 56.7%). To explore the association between trials publication and characteristics of trials, we performed a multivariate logistic regression analysis. Trials conducted in the United States (P = 0.003) or Brazil (P < 0.001) were associated with increased odds of publication, whereas trials registered prospectively (P = 0.001) and industry-sponsored trials (P = 0.02) were associated with decreased odds. Among the 479 published trials with completed status, the primary outcomes of 215 (44.9%) articles differed from that registered. Major discrepancies consisted of the introduction of a new primary outcome in the published article (196 [91.2%]) and the transformation of a registered secondary outcome into a primary outcome (112 [52.1%]). In the remaining 264 (55.1%) trials, primary outcomes did not differ from that registered, but 141 (53.4%) had been registered retrospectively. Our study highlights the high rate of nonpublication and selective outcome reporting in the field of oral health. These results could alert sponsors, funders, authors of systematic reviews, and the oral health research community at large to combat the nondisclosure of trial results.

Joint population pharmacokinetic analysis of zidovudine, lamivudine, and their active intracellular metabolites in HIV patients.

The population pharmacokinetic parameters of zidovudine (AZT), lamivudine (3TC), and their active intracellular metabolites in 75 naïve HIV-infected patients receiving an oral combination of AZT and 3TC twice daily as part of their multitherapy treatment in the COPHAR2-ANRS 111 trial are described. Four blood samples per patient were taken after 2 weeks of treatment to measure drug concentrations at steady state. Plasma AZT and 3TC concentrations were measured in 73 patients, and among those, 62 patients had measurable intracellular AZT-TP and 3TC-TP concentrations. For each drug, a joint population pharmacokinetic model was developed and we investigated the influence of different covariates. We then studied correlations between the mean plasma and intracellular concentrations of each drug. A one-compartment model with first-order absorption and elimination best described the plasma AZT concentration, with an additional compartment for intracellular AZT-TP. A similar model but with zero-order absorption was found to adequately described concentrations of 3TC and its metabolite 3TC-TP. The half-lives of AZT and 3TC were 0.81 h (94.8%) and 2.97 h (39.2%), respectively, whereas the intracellular half-lives of AZT-TP and 3TC-TP were 10.73 h (69%) and 21.16 h (44%), respectively. We found particularly a gender effect on the apparent bioavailability of AZT, as well as on the mean plasma and intracellular concentrations of AZT, which were significantly higher in females than in males. Relationships between mean plasma drug and intracellular metabolite concentrations were also highlighted both for AZT and for 3TC. Simulation with the model of plasma and intracellular concentrations for once- versus twice-daily regimens suggested that a daily dosing regimen with double doses could be appropriate.

Pregnancy-associated breast cancer is as chemosensitive as non-pregnancy-associated breast cancer in the neoadjuvant setting.

BACKGROUND: The aim of this study was to determine the chemosensitivity of pregnancy-associated breast cancer (PABC) in the neoadjuvant setting by comparing the observed pathological complete response (pCR) rate with the rate predicted by a validated nomogram. METHODS: Data from 48 PABC patients who received neoadjuvant chemotherapy (NACT) were collected. To predict the response rate to chemotherapy, we used well-calibrated logistic regression-based nomograms to calculate individual probability of pCR. RESULTS: Observed rates of pCR were concordant with predictions in the whole sample and in the analyzed subgroups. For the whole sample, the area under the receiver-operated curve (AUC) was 0.77 (95% CI 0.66-0.87). The calibration of predicted and observed probabilities was excellent. In the subgroup analyses (NACT initiated during pregnancy or postpartum, NACT with only anthracycline or both anthracycline and taxanes), discriminations assessed by AUC were significantly above 0.5, except for patients treated with anthracycline only. The interpretation was limited by a lack of power. CONCLUSION: Through the use of nomograms, our study demonstrates that PABC is as chemosensitive as non-PABC and suggests that taxanes should be part of the NACT regimen for PABC. Further studies are warranted to increase the power of the presented data.

Population pharmacokinetics of cefazolin in critically ill children infected with methicillin-sensitive Staphylococcus aureus.

OBJECTIVES: Cefazolin is one of curative treatments for infections due to methicillin-sensitive Staphylococcus aureus (MSSA). Both growth and critical illness may impact the pharmacokinetic (PK) parameters. We aimed to build a population PK model for cefazolin in critically ill children in order to optimize individual dosing regimens. METHODS: We included all children (age < 18 years, body weight (BW) > 2.5 kg) receiving cefazolin for MSSA infection. Cefazolin total plasma concentrations were quantified by high-performance liquid chromatography. A data modelling process was performed with the software MONOLIX. Monte Carlo simulations were used in order to attain the PK target of 100% fT > 4 ×MIC. RESULTS: Thirty-nine patients with a median (range) age of 7 (0.1-17) years and a BW of 21 (2.8-79) kg were included. The PK was ascribed to a one-compartment model, where typical clearance and volume of distribution estimations were 1.4 L/h and 3.3 L respectively. BW, according to the allometric rules, and estimated glomerular filtration rate (eGFR) on clearance were the two influential covariates. Continuous infusion with a dosing of 100 mg/kg/day to increase to 150 mg/kg/day for children with a BW < 10 kg or eGFR >200 mL/min/1.73m2 were the best schemes to reach the PK target of 100% fT> 4 ×MIC. CONCLUSIONS: In critically ill children infected with MSSA, continuous infusion seems to be the most appropriate scheme to reach the PK target of 100 % fT > 4 ×MIC in children with normal and augmented renal function.

Length of the treatment and number of doses per day as major determinants of child adherence to acute treatment.

OBJECTIVE: To determine the rate of aftercare adherence to prescriptions from a paediatric emergency department and to identify predictors for nonadherence. METHODS: Patients discharged from a French paediatric emergency department with at least one oral drug prescription were included. A telephone interview questionnaire was used to determine whether the child had received the treatments according to the prescription. Adherence was assessed according to three items: frequency of drug administration, length of treatment and drug administering method. Complete adherence was defined as adherence to the three items mentioned above, and nonadherent as nonadherent to at least one of the items. Influence of age, sex, pathology, language spoken at home, type of medical insurance, type of medication prescribed, diagnosis, dissatisfaction with the explanation of the medical problem, number of prescribed medications, length of the treatment and number of doses per day was assessed. RESULTS: One hundred and five telephone interviews were exploited. The children were 60 boys (57%) and 45 girls (43%). The ages of these 105 children were between 0.2 and 12 years. The most common diagnoses were asthma and pulmonary infection. Complete adherence with the prescription was 36.2%. Three factors were significantly associated with nonadherence (p < 0.05): length of treatment, number of doses per day and male sex. CONCLUSION: This study suggests that simplifying treatment schedules is an effective strategy for improving compliance in paediatric emergency departments.

Relationship between GSTP1 Ile(105)Val polymorphism and docetaxel-induced peripheral neuropathy: clinical evidence of a role of oxidative stress in taxane toxicity.

BACKGROUND: Glutathione-S-transferases (GST) regulate the cellular response to oxidative stress. We previously highlighted the importance of oxidative stress in taxane toxicity and therefore investigated the relationship between the GST isoforms M1, T1 and P1 gene polymorphisms and docetaxel (Taxotere)-induced peripheral neuropathy (DIPN). PATIENTS AND METHODS: The GSTM1 (null), GSTT1 (null) and GSTP1 (Ile(105)Val and Ala(114)Val) polymorphisms were determined in a cohort of cancer patients treated with docetaxel and entered in a clinical trial database. The relationship between GST polymorphisms and grade > or = 2 DIPN as primary end point was studied. RESULTS: Fifty-eight patients (median age 61 years) received a total of 261 cycles of docetaxel given as single agent. Patients with GSTP1 (105)Ile/(105)Ile genotype had a higher risk of developing a grade > or = 2 DIPN than did those with other GSTP1 genotypes (8 of 27 versus 2 of 31, respectively, odds ratio 6.11; 95% confidence interval 1.17-31.94; P = 0.03). In multivariate analysis, grade > or = 2 DIPN was strongly correlated with GSTP1 (105)Ile/(105)Ile genotype (P = 0.01) and the number of cycles (P = 0.03). CONCLUSION: We found a significant correlation between GSTP1 (105)Ile/(105)Ile genotype and the development of grade > or = 2 DIPN. This finding strongly suggests a role of oxidative stress in the pathophysiology of DIPN.

Guidelines of the French Society of Otorhinolaryngology (SFORL): Nonsteroidal anti-inflammatory drugs (NSAIDs) and pediatric ENT infections. Short version.

OBJECTIVES: To present the guidelines of the French Society of Otolaryngology-Head and Neck Surgery concerning the use of non-steroidal anti-inflammatory drugs (NSAIDs) in pediatric ENT infections. METHODS: Based on a critical analysis of the medical literature up to November 2016, a multidisciplinary workgroup of 11 practitioners wrote clinical practice guidelines. Levels of evidence were classified according to the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) system: GRADE A, B, C or "expert opinion". The first version of the text was reworked by the workgroup following comments by the 22 members of the reading group. RESULTS: The main recommendations are: NSAIDs are indicated at analgesic doses (e.g. 20-30 mg/kg/day for ibuprofen) in combination with paracetamol (acetaminophen) in uncomplicated pediatric ENT infections (acute otitis media, tonsillitis, upper respiratory infections, and maxillary sinusitis) if: o pain is of medium intensity (visual analogue scale (VAS) score 3-5 or "Evaluation Enfant Douleur" (EVENDOL) child pain score 4-7) and insufficiently relieved by first-line paracetamol (residual VAS≥3 or EVENDOL≥4); o pain is moderate to intense (VAS 5-7 or EVENDOL 7-10). When combined, paracetamol and ibuprofen are ideally taken simultaneously every 6h. It is recommended: (1) o not to prescribe NSAIDs in severe or complicated pediatric ENT infections; (2) o to suspend NSAIDs treatment in case of unusual clinical presentation of the infection (duration or symptoms); (3) o not to prescribe NSAIDs for more than 72h.

Emerging therapeutic options for breast cancer chemotherapy during pregnancy.

BACKGROUND: Breast cancer is the commonest solid tumor observed during pregnancy. Anthracycline-based chemotherapy is feasible during the 2nd and 3rd trimesters of pregnancy, but few data are available on recent and highly active drugs taxanes, vinorelbine and anti-HER-2 agents in this setting. PATIENTS AND METHODS: We carried out a comprehensive review of reports documenting the use of taxanes, vinorelbine, trastuzumab and lapatinib during pregnancy in the English literature, in order to evaluate their safety profile in pregnant patients. RESULTS: Twenty-four pregnancies are described, in which no grade 3-4 maternal toxicity nor malformation in the offspring was reported. Whereas only one report studied the pharmacokinetics of paclitaxel (Taxol) during pregnancy, several preclinical reports indicate that the placental P-glycoprotein could prevent the transplacental transfer of taxanes and vinorelbine. The use of trastuzumab was associated with the occurrence of anhydramnios in three of six cases. CONCLUSION: The administration of recent drugs taxanes and vinorelbine seems feasible during the 2nd and 3rd trimesters of pregnancy, with a favorable toxicity profile. In contrast, anti-HER-2 agents may obscure the normal development of the fetal kidney, and should be avoided during pregnancy.

Pharmacokinetics and toxicity of docetaxel: role of CYP3A, MDR1, and GST polymorphisms.

OBJECTIVE: Patients initiating docetaxel chemotherapy were genotyped for CYP3A4, CYP3A5, MDR1, GSTM1, GSTT1, GSTM3, and GSTP1 to identify variability factors of docetaxel pharmacokinetics and toxicity. METHODS: Genotyping was performed by direct sequencing (CYP3A4), real-time polymerase chain reaction (CYP3A5), and polymerase chain reaction-restriction fragment length polymorphism (MDR1 and GST). The clearance and area under the curve of docetaxel were calculated by use of a Bayesian approach. Absolute neutrophil count was recorded twice weekly. RESULTS: With regard to the pharmacokinetic analysis, 58 patients were included. CYP3A4*1B carriers (*1A/*1B, n=4), who are also CYP3A5*1/*3 carriers, had a significantly higher clearance and lower dose-normalized area under the curve of docetaxel than those with the wild genotype (*1A/*1A, n=53): 55.2+/-13.5 L/h versus 37.3+/-11.7 L/h (P=.01) and 31.4+/-6.2 (microg . h/L)/(mg/m(2)) versus 52.7+/-18.2 (microg . h/L)/(mg/m(2)) (P=.005), respectively. No influence of MDR1 was evidenced. With regard to the pharmacodynamic analysis, febrile neutropenia occurred more frequently in GSTP1*A/*B carriers (31.6% versus 3.7% in *A/*A carriers and 0% in *A/*C, *B/*B, and *B/*C carriers) (P=.037). Grade 3 neutropenia occurred more frequently in 3435TT MDR1 genotype carriers: TT, 100%; CT, 77.3%; and CC, 54.5% (P=.046). No influence of GSTM1, GSTT1, or GSTM3 polymorphisms was evidenced on docetaxel toxicity. CONCLUSIONS: Patients carrying the CYP3A*1B allele may have enhanced docetaxel clearance and may be underexposed, whereas those carrying GSTP1*A/*B and 3435TT genotypes may have excessive hematologic toxicity. Further studies are warranted to determine the usefulness of genotyping before docetaxel treatment.

Taxol metabolism by human liver microsomes: identification of cytochrome P450 isozymes involved in its biotransformation.

The biotransformation of taxol by human liver was investigated in vitro with microsomes isolated from adult and developing human tissues. In vitro, no metabolism was detected with kidney microsomes, whereas two metabolites were generated by liver microsomes. The most prominent metabolite, termed M5, corresponded to an hydroxylation at the C6 position on the taxane ring, while the other metabolite, termed M4, corresponded to an hydroxylation at the para-position on the phenyl ring at the C3'-position of the C13 side chain. These two taxol derivatives have been shown to be the major metabolites recovered in bile from a patient infused with taxol. Several approaches have been used to identify the cytochrome P450 (CYP) isozymes involved in these reactions. No positive correlation was observed between the in vitro synthesis of these two metabolites, suggesting that two cytochrome P450 isozymes could be involved, although they could not be distinguished by their apparent affinities (Km approximately 15 microM). The formation of metabolite M4 was substantially reduced both by antibody directed against CYP3A and by the addition of CYP3A substrates such as orphenadrine, erythromycin, troleandomycin, and testosterone. Conversely, the formation of metabolite M5 remained unaffected by antibodies against CYP3A and by CYP3A substrates but was sensitive to diazepam inhibition, a preferential substrate of CYP2C. Correlation between CYP2C content or diazepam demethylation and the synthesis of metabolite M5 was highly positive. The formation of metabolite M4 developed during the early postnatal period. In contrast, the synthesis of metabolite M5 rose only after 3 months of age. These data clearly implicate CYP3A in the formation of metabolite M4 and CYP2C in the synthesis of metabolite M5. Microsomes from patients treated with barbiturates and benzodiazepines increased the formation of metabolite M4 to the level of metabolite M5, demonstrating that drug interactions could modify the human metabolism of taxol.

Development and validation of a LC-MS/MS method for the quantification of tenofovir and emtricitabine in seminal plasma.

Accurate and sensitive liquid-chromatography tandem mass spectrometry method for the quantification of tenofovir and emtricitabine in seminal plasma has been developed and full validated. Molecules were separated by high-performance liquid chromatography on an Atlantis T3 C18 column using a gradient of deionized water and methanol, including 0.05% formic acid (250µl/min) and detected by electrospray ionisation/tandem mass spectrometry in positive ion mode. The method was validated over a clinical range of 3.13-1000ng/mL for tenofovir and 6.25-2000ng/mL for emtricitabine. Inter and intra-assay precisions were <9.37% for tenofovir and<10.88% for emtricitabine, and accuracies were between 0.48% and 8.43% for tenofovir, and between 0.64% and 13.87% for emtricitabine. The developed method was successfully applied for analysing tenofovir and emtricitabine concentrations in seminal plasma samples from a clinical study. The use of tandem mass spectrometry can be a suitable method for the analysis of this kind of matrices, providing high sensitivity and specificity to the analysis.

Tolerance of efavirenz in children.

OBJECTIVE: To extend the limited knowledge of efavirenz tolerance in children. METHOD: An observational study of 33 children given efavirenz combined with various others agents and followed in a single institution. RESULTS: Fifteen (42%) of the children presented at least one clinically discernable side effect, cutaneous (n = 5), nervous system (n = 10), or both (n = 2). Intolerance led to treatment interruption in seven children but the main symptom was transitory dizziness or other signs similar to those observed in adults. CONCLUSION: Early, often transient nervous system side effects require careful preparation with the child and his family to avoid premature and inadequate withdrawal from treatment.