Nebulized ceftazidime and amikacin in ventilator-associated pneumonia caused by Pseudomonas aeruginosa.

RATIONALE: In experimental pneumonia, nebulization of antibiotics provides high lung tissue concentrations and rapid bacterial killing. OBJECTIVES: To assess the efficacy and safety of nebulized ceftazidime and amikacin in ventilator-associated pneumonia caused by Pseudomonas aeruginosa. METHODS: Forty patients with ventilator-associated pneumonia caused by Pseudomonas aeruginosa were included in a randomized comparative phase II trial. Twenty patients infected with susceptible or intermediate strains received nebulized ceftazidime (15 mg·kg(-1)·3 h(-1)) and amikacin (25 mg·kg(-1)·d(-1)). Seventeen patients infected with susceptible strains received intravenous ceftazidime (90 mg·kg(-1)·d(-1), continuous administration) and amikacin (15 mg·kg(-1)·d(-1)). In three patients infected with intermediate strains, amikacin was replaced by ciprofloxacin (400 mg·12 h(-1)). MEASUREMENTS AND MAIN RESULTS: After 8 days of antibiotic administration, aerosol and intravenous groups were similar in terms of successful treatment (70 vs. 55%), treatment failure (15 vs. 30%), and superinfection with other microorganisms (15 vs. 15%). Antibiotic-induced changes in lung aeration, determined by computed tomography, were not different between groups (increase in gas volume, 159 ± 460 vs. 251 ± 583 ml; decrease in tissue volume, -58 [-77, 25] vs. -89 [-139, 5] ml). Acquisition of per-treatment antibiotic resistance was observed exclusively in the intravenous group. In the aerosol group, four patients infected with intermediate strains were successfully treated. Nebulization induced an obstruction of the expiratory filter in three patients. The obstruction caused cardiac arrest in one patient, who fully recovered after brief cardiopulmonary resuscitation. CONCLUSIONS: Nebulization and intravenous infusion of ceftazidime and amikacin provide similar efficiency for treating ventilator-associated pneumonia caused by Pseudomonas aeruginosa. Nebulization is efficient against intermediate strains and may prevent per-treatment acquisition of antibiotic resistance.

Relationships between plasma concentrations of morphine, morphine-3-glucuronide, morphine-6-glucuronide, and intravenous morphine titration outcomes in the postoperative period.

Although intravenous morphine titration (IMT) is widely used to control moderate to severe postoperative pain, the relationships between plasma concentrations of morphine and its metabolites, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), and IMT outcomes in the postanesthesia care unit (PACU) have not been yet investigated. IMT was administrated as a bolus of 2 or 3 mg every 5 min. Titration was interrupted in case of pain relief (visual analog score ≤30), adverse events, sedation, or failure of morphine titration. Blood samples were collected at the end of morphine titration to determine plasma concentration of morphine and its two metabolites. Data from 214 patients were analyzed; 143 (67%) of the patients achieved complete pain relief, 39 (18%) experienced adverse events, and 32 (15%) failure of morphine titration. At the end of titration, there were no significant differences in morphine, M6G, M3G concentrations between sedated and nonsedated patients (32 vs. 42 ng/mL (P = 0.07), 38 vs. 45 ng/mL (P = 0.51), 300 vs. 342 ng/mL (P = 0.29), respectively), or patients with or without adverse events (40 vs. 41 ng/mL (P = 0.95), 37 vs. 46 ng/mL (P = 0.51), 287 vs. 340 ng/mL (P = 0.72), respectively). Our study demonstrated a lack of relationship between plasma concentrations or ratios of morphine, M3G, and M6G, with IMT outcomes in PACU. This result suggests that the kinetics of morphine and its metabolites have limited value for explaining clinical effects of morphine in this clinical setting.

Comparison of lung tissue concentrations of nebulized ceftazidime in ventilated piglets: ultrasonic versus vibrating plate nebulizers.

OBJECTIVE: To compare the efficiency of an Aeroneb Pro vibrating plate and an Atomisor MegaHertz ultrasonic nebulizer for providing ceftazidime distal lung deposition. DESIGN: In vitro experiments. One gram of cetazidime was nebulized in respiratory circuits and mass median aerodynamic diameter of particles generated by ultrasonic and vibrating plate nebulizers was compared using a laser velocimeter. In vivo experiments. Lung tissue concentrations and extrapulmonary depositions were measured in ten anesthetized ventilated piglets with healthy lungs that received 1 g of ceftazidime by nebulization with either an ultrasonic (n = 5), or a vibrating plate (n = 5) nebulizer. SETTING: A two-bed Experimental Intensive Care Unit of a University School of Medicine. INTERVENTION: Following sacrifice, 5 subpleural specimens were sampled in dependent and nondependent lung regions for measuring ceftazidime lung tissue concentrations by high-performance liquid chromatography. MEASUREMENTS AND RESULTS: Mass median aerodynamic diameters generated by both nebulizers were similar with more than 95% of the particles between 0.5 and 5 microm. Lung tissue concentrations were 553 +/- 123 [95% confidence interval: 514-638] microg g(-1) using ultrasonic nebulizer, and 452 +/- 172 [95% confidence interval: 376-528] microg g(-1) using vibrating plate nebulizers (NS). Extrapulmonary depositions were, respectively, of 38 +/- 5% (ultrasonic) and 34 +/- 4% (vibrating plate) (NS). CONCLUSIONS: Vibrating plate nebulizer is comparable to ultrasonic nebulizers for ceftazidime nebulization. It may represent a new attractive technology for inhaled antibiotic therapy.

Potentiation of fluindione or warfarin by dexamethasone in multiple myeloma and AL amyloidosis.

OBJECTIVES: Patients with primary systemic (AL) amyloidosis or multiple myeloma are frequently treated with cyclic dexamethasone (DXM) courses and often require oral anticoagulants. We previously reported a strong potentiation of oral anticoagulants with intravenous methylprednisolone and observed a similar potentiation with DXM in 3 patients, which led us to prospectively investigate the interaction between DXM and oral anticoagulants. METHODS: Nine patients with multiple myeloma (n=6) or AL amyloidosis (n=3), including 6 prospective patients, taking fluindione (n=8) or warfarin (n=1), were studied for a total of 10 cycles. DXM (40 mg/day for 4 days every 28 days) was administered alone (n=4) or with melphalan (n=5). One patient was studied for 2 consecutive cycles after a moderate increase in the international normalized ratio (INR) during the first course of DXM. International normalized ratio (INR) was measured serially during DXM administration. Plasma oral anticoagulant concentrations were measured for 5 cycles. RESULTS: The mean INR increased from 2.75 (range: 1.80-3.6) at baseline to 5.22 (3.09-7.07) after DXM. Oral anticoagulants were transiently stopped during 8 cycles and 1 mg oral vitamin K was given during 2. No serious bleeding was observed. Plasma oral anticoagulant concentrations increased after DXM administration. In controls receiving DXM without oral anticoagulants, DXM alone did not increase prothrombin time. CONCLUSION: High dose DXM can potentiate oral anticoagulants and elevate INR substantially. INR should therefore be monitored repeatedly during concomitant administration of these 2 drugs to allow individual adaptation of oral anticoagulant doses.

Very low blood hydroxychloroquine concentration as an objective marker of poor adherence to treatment of systemic lupus erythematosus.

BACKGROUND: Poor adherence to treatment is difficult to diagnose accurately. Hydroxychloroquine (HCQ) has a long elimination half-life and its concentration in whole blood can be measured easily. OBJECTIVE: To evaluate the utility of a very low blood HCQ concentration as a marker of poor compliance in patients with systemic lupus erythematosus (SLE). METHODS: HCQ concentrations were determined on a blinded basis in 203 unselected patients with SLE. At the end of the study, the patients were informed of the results and retrospectively interviewed about their adherence to treatment. RESULTS: 14 (7%) patients said that they had stopped taking HCQ (n = 8) or had taken it no more than once or twice a week (n = 6). Their mean (SD) HCQ concentration was 26 (46) ng/ml. range (0-129 ng/ml) By contrast, the other patients had a mean HCQ concentration of 1079 ng/ml range (205-2629 ng/ml). The principal barriers to adherence were related to HCQ treatment characteristics. Adherence subsequently improved in 10 of the 12 patients whose blood HCQ concentrations were remeasured. CONCLUSIONS: Very low whole-blood HCQ concentrations are an objective marker of prolonged poor compliance in patients with SLE. Regular drug assays might help doctors in detect non-compliance and serve as a basis for counselling and supporting these patients.

Low blood concentration of hydroxychloroquine is a marker for and predictor of disease exacerbations in patients with systemic lupus erythematosus.

OBJECTIVE: To study the possible relationship between whole-blood hydroxychloroquine (HCQ) concentrations and clinical efficacy of HCQ in patients with systemic lupus erythematosus (SLE). METHODS: Whole-blood HCQ concentrations were measured, under blinded conditions, in 143 unselected patients with SLE who had been receiving HCQ 400 mg daily for at least 6 months. The relationship of these concentrations to current disease activity and to subsequent exacerbations during 6 months of followup was investigated. RESULTS: At baseline, 23 patients had active disease (mean +/- SD SLE Disease Activity Index 12.4 +/- 7.5). The mean whole-blood HCQ concentration in this group was significantly lower than that in the 120 patients with inactive disease (694 +/- 448 ng/ml versus 1,079 +/- 526 ng/ml; P = 0.001). Among the 120 patients who had inactive disease at baseline, the mean HCQ concentration at baseline in the 14 (12%) who had disease exacerbations during followup was significantly lower than that in the patients whose disease remained inactive. Multivariate logistic regression showed that the HCQ concentration was the only predictor of exacerbation (odds ratio 0.4 [95% confidence interval 0.18-0.85], P = 0.01). Receiver operating characteristic curve analysis showed that a whole-blood HCQ concentration cutoff of 1,000 ng/ml had a negative predictive value of 96% for exacerbation during followup. CONCLUSION: Low whole-blood HCQ concentrations are associated with SLE disease activity and are a strong predictor of disease exacerbation. Regular drug assaying and individual tailoring of treatment might help to improve the efficacy of HCQ treatment in patients with SLE.

Effect of widely used combinations of antiretroviral therapy on liver CYP3A4 activity in HIV-infected patients.

AIMS: To evaluate the effects of combined antiretroviral drugs (HAART) on liver CYP3A4 activity using the [(14)C-N-methyl]-erythromycin breath test (ERMBT). METHODS: HIV-infected patients (31 women, 30 men) with mean (+/- SD) age of 38 +/- 9 years were enrolled and underwent complete clinical and laboratory evaluation. Patients were divided into five groups and were treated with two nucleoside analogues (NAs) and one of the following: nelfinavir alone (n = 13), any ritonavir-boosted protease inhibitor with (n = 8) or without (n = 13) nevirapine, nevirapine alone (n = 15), or a third NA (n = 12). Three or four ERMBTs were performed 7 days prior to (D-7) and at the beginning of treatment (D0), D14 (only for patients taking nevirapine) and on D28. RESULTS: Mean baseline liver CYP3A4 activity displayed high interindividual variability (47%) but low intraindividual variability (15%). Women had 30% higher ERMBT values than men [2.7 +/- 1.3 vs. 1.9 +/- 0.7; 95% confidence interval (CI) 20.5, 49.5; P = 0.003]. The ERMBT data correlated with body weight, alpha- and beta-globulins and alanin aminotransferases (0.10 < r(s) < 0.20; P < 0.01). Whereas nevirapine had no effect on liver CYP3A4 activity, nelfinavir-based and ritonavir-boosted drug regimens inhibited it by 69% (95% CI 64.7, 72.9; P = 0.005) and by 95% (95% CI 93.3, 96.7; P = 0.001), respectively. CONCLUSION: Evaluation of the effect of HAART on liver CYP3A4 activity may aid in preventing inappropriate treatment regimens in HIV-infected patients.

Tubular transporters and clearance of adefovir.

Adefovir is transported by the organic anion transporter (OAT1) and the multidrug resistant protein (MRP2, 4 and 5). We studied adefovir clearance in rat after inhibition of transporters by probenecid and in mutant transport-deficient (TR-) rats, in which MRP2 is lacking. After treatment by probenecid or placebo, pharmacokinetics of adefovir 10mg/kg was studied via population nonlinear mixed effect modeling. The fraction of drug excreted in the urine was low. Renal clearance of adefovir was significantly lower (P < 0.05) in probenecid TR- rats (0.03+/-0.02l/h) than in normal control (0.09+/-0.05l/h), in normal probenecid (0.10+/-0.07l/h) and in TR- control rats (0.13+/-0.07l/h). In vivo in rats MRP2 mutation alone did not affect adefovir clearance suggesting that MRP2 does not play a critical role in the secretion of adefovir. Additional pharmacological inhibition of transporters decreased renal clearance, which may reflect inhibition of compensating transport mechanisms activated when MRP2 is lacking.

[Tubular transporters OAT1 and MRP2 and clearance of adefovir]. / Effet de l'inhibition des transporteurs OAT1 et MRP2 sur la clairance de l'adéfovir.

Adefovir is transported by the organic anion transporter (OAT1) and the multidrug resistant protein (MRP2, 4 and 5). We studied adefovir clearance in rat after inhibition of transporters by probenecid and in TR- rats, in which MRP2 is lacking. After treatment by probenecid or placebo, pharmacokinetics of adefovir 10 mg/kg was studied via population modeling (NONMEM). The fraction of drug excreted in the urine was low. Renal clearance of adefovir was significantly lower (P < 0.05) in probenecid TR- rats (0.03 +/- 0.02 l/hour) than in normal control (0.09 +/- 0.05 l/hour), in normal probenecid (0.10 +/- 0.07 l/hour) and in TR- control rats (0.13 +/- 0.07 l/hour). In vivo in rats MRP2 mutation alone did not affect adefovir clearance suggesting that MRP2 does not play a critical role in the secretion of adefovir. Additional pharmacological inhibition of transporters decreased renal clearance, which may reflect inhibition of compensating transport mechanisms activated when MRP2 is lacking.

Atenolol administration via a nasogastric tube after abdominal surgery: an unreliable route.

beta-adrenoceptor antagonists, especially atenolol, reduce perioperative cardiac morbidity. Because there are no data on the bioavailability of atenolol given by nasogastric tube in the postoperative period, we assessed the efficacy of this route of administration in 18 patients scheduled for abdominal surgery. We found a 36% reduction in the area under the atenolol concentration curve and a 46% reduction in the peak concentration of atenolol in the postoperative period compared with preoperative values. In addition, patients had more rapid mean heart rates on the second postoperative day compared with the day before surgery. We conclude that the administration of atenolol via nasogastric tube in the postoperative period does not result in adequate plasma concentrations.

Pharmacokinetic-pharmacodynamic study of apomorphine's effect on growth hormone secretion in healthy subjects.

Apomorphine (APO) stimulates growth hormone (GH) release via dopamine D2 receptors (DRD2). There is no specific study assessing the relationship between APO pharmacokinetic (PK) and the pharmacodynamic (PD) response e.g. GH release. The objective of the study is the PK-PD modelling of APO in healthy subjects. This is a randomized crossover study with s.c. administration of 5, 10, and 20 micro g/kg of APO in 18 healthy subjects. APO concentrations were modelled according to both a bi-compartmental model with zero-order absorption and a bi-compartmental model with first-order absorption. PK-PD relationship was modelled in accordance with the Emax Hill equation using plasma concentrations of APO calculated according to the bi-compartmental model with zero-order absorption. Modelled parameters were very similar to the experimental parameters. PK of APO was linear and there was no significant difference between the tested doses for AUC0--> infinity and Cmax (normalised to the dose 1 micro g/kg), t1/2alpha and t1/2beta. These parameters expressed as mean (CV%: SD/mean) were: 17.2 (26.9) ng/mL.min, 0.26 (33.3) ng/mL, 17.1 (54.2) and 45.2 (20.6) min, respectively (n = 53). An anticlockwise hysteresis loop (effect function of APO plasma concentration) appeared for each dose and each subject. The predicted and measured GH concentrations for all subjects and times were similar whatever the dose (P > 0.27). Emax values were 246 (121), 180 (107), 205 (139) ng/mL, respectively, and EC50 were 0.98 (48.1), 1.70 (62.3), 3.67 (65.2) ng/mL, respectively at dose 5, 10, and 20 micro g/kg (P < 10-4). APO and GH concentrations were predicted with good accuracy using bi-compartmental with zero-order absorption PK model and sigmoid Emax PD model, respectively.

Comparative pharmacokinetics and pharmacodynamics of intravenous and oral nefopam in healthy volunteers.

To determine the pharmacokinetic, subjective effects of a single 20 mg dose of nefopam administered either intravenously or orally in healthy volunteers, twenty-four healthy Caucasian men received 20 mg nefopam orally+placebo intravenous infusion and placebo orally+intravenous infusion of 20 mg nefopam with one week interval, in a double-blind, double-dummy cross-over study. Nefopam and desmethyl-nefopam plasma concentrations were measured by HPLC with UV detection up to 48 hr after drug administration. Self-rating questionnaires (Mood and vigilance Visual Analogue Scales, Addiction Research Centre Inventory) and drug safety were investigated. The F value (bioavailability) of the parent drug was 0.36+/-0.13. The AUCoral/AUCiv ratio of nefopam+desmethyl-nefopam was 0.62+/-0.23. The half-life of nefopam was similar whether administered orally (5.1+/-1.3 hr) or intravenously (5.1+/-0.6 hr). The half-life of desmethyl-nefopam was two to three times longer than that of the parent molecule (orally: 10.6+/-3.0 versus 5.1+/-1.3 hr, P<10(-4) and intravenously: 15.0+/-2.4 versus 5.1+/-0.6 hr, P<10(-4)). As assessed by the Addiction Research Centre Inventory, no evidence of abuse liability in healthy, drug-naive volunteers was observed. On visual analogue scales, volunteers rated themselves as more drowsy, less alert, less energetic and less anxious after oral compared to intravenous administration. The AUC0-->24 hr of anxiety and energy parameters were not different after oral and intravenous administration: 90+/-142 versus 35+/-84 (P=0.27) and 66+/-74 versus 46+/-54 mm x hr (P=0.36), respectively. The AUC0-->24 hr of drowsiness and alertness parameters were significantly greater after oral than after intravenous administration: 68+/-65 versus 27+/-30 (P=0.005) and 54+/-63 versus 28+/-48 mm x hr (P=0.03), respectively. A clockwise hysteresis loop was observed for drowsiness in 16 out of 24 volunteers after oral administration. The results suggest that in healthy volunteers desmethyl-nefopam may contribute to the pharmacodynamic effects of single dose nefopam solution administered orally. This study shows a rather low bioavailability of nefopam given in intravenous solution when administered orally. Nevertheless, when the main metabolite desmethyl-nefopam is taken into account, the ratio of the areas under the curves is almost doubled.

Dopaminergic drug response and the genotype (Taq IA polymorphism) of the dopamine D2 receptor.

The genotype of the receptor with which a particular drug interacts may be a between- subject factor that modifies the pharmacodynamic and consequently the therapeutic response to drugs. Subjects with A1 allele (Taq IA restriction fragment length polymorphism) of the gene encoding for the dopamine D2 receptor (DRD2) seem to express lower number of DRD2 compared to subjects who do not have this allele. We investigated whether subjects homozygous for the A1 allele of the DRD2 gene have decreased response to DRD2 stimulation by apomorphine when compared with those homozygous for the A2 allele. Two hundred and two Caucasian subjects were genotyped for DRD2 Taq IA polymorphism, 6.9 % had the genotype A1A1 and 65% A2A2. Nine homozygous subjects/group were selected for the apomorphine study. Five, 10 and 20 &mgr;g/kg of apomorphine were administered subcutaneously according to a randomized crossover design. The main pharmacodynamic criterion was the plasma growth hormone increase induced by apomorphine. Secondarily, we measured oral temperature responses and yawns in response to apomorphine. Plasma apomorphine concentrations were similar for the two matched and only genotypically different groups. Apomorphine dose-dependently increased serum growth hormone concentration, and significant effect of time, dose by time interaction but no effect of genotype or genotype by dose interaction was shown. Apomorphine decreased body temperature, significant effect of dose, time, dose by time interaction but no effect of genotype or genotype by dose interaction were observed. The number of apomorphine-induced yawns increased dose-dependently but no significant difference between groups occurred. Thus, in this study apomorphine-induced responses were not modified by DRD2 Taq IA polymorphism although the power of the study could be insufficient to detect subtle differences.