José Ramón Azanza

Development and validation of a sensitive method for the determination of ganciclovir in human plasma samples by reversed-phase high-performance liquid chromatography.

A rapid, sensitive, specific liquid chromatographic method has been developed for the determination of therapeutic levels of ganciclovir in human plasma. Plasma (1 ml) and acyclovir (I.S.) were treated with 50% trichloroacetic acid. The supernatant was neutralized with 2 M NaOH and purified with chloroform. The aqueous phase (80 microl) was analyzed by a 3-microm Hypersil ODS C18 column with 0.04 M triethylamine-0.1 M sodium dihydrogen phosphate monohydrate as the mobile phase (1 ml/min) and ultraviolet detection at 254 nm. Calibration was linear from 50 to 10000 ng/ml. Intra- and inter-day C.V. did no exceed 6.65%. The detection limit was about 10 ng/ml.

Improved selectivity in detection of polar basic drugs by liquid chromatography–electrospray ionization mass spectrometry: Illustration using an assay method for the determination of famotidine in human plasma

It is well to assume that bioanalytical chromatographic methods for the determination of polar basic drugs are developed and optimised according to a standardised procedure which involves two alternatives: (a) modifications in the sample preparation procedures, and (b) changes in the stationary phase of the chromatographic system. In this paper, a simple and rapid chromatographic procedure using a specific analytical detection method (ESI tandem mass spectrophotometric detection) in combination with a fast and efficient sample work-up procedure, protein precipitation, is presented. A demonstration of the entire chromatographic procedure is given for an HPLC method for the determination of famotidine in human plasma, a basic polar drug with poor solubility in organic solvents. In order to optimize the mass detection of famotidine, several parameters such as ionization mode, fragmentor voltage, m/z ratios of ions monitored, type of organic modifier and eluent additive, were investigated. Each analysis required 5 min. The calibration curve of famotidine in the range 1-200 ng/ml was linear with a correlation coefficient of 0.9992 (n = 6), and a detection limit a signal-to-noise ratio of 3 was approximately 0.2 ng/ml. The within- and between-day variations in the famotidine analysis were 5.2 (n = 6) and 6.7% (n = 18), respectively. The applicability of this method was also demonstrated for the analysis of plasma samples in a Phase-I human pharmacokinetic study.

Anidulafungin dosing in critically ill patients with continuous venovenous haemodiafiltration

BACKGROUND Anidulafungin is indicated as a first-line treatment for invasive candidiasis in critically ill patients. In the intensive care unit, sepsis is the main cause of acute renal failure, and treatment with continuous renal replacement therapy (CRRT) has increased in recent years. Antimicrobial pharmacokinetics is affected by CRRT, but few studies have addressed the optimal dosage for anidulafungin during CRRT. PATIENTS AND METHODS We included 12 critically ill patients who received continuous venovenous haemodiafiltration to treat acute renal failure. Anidulafungin was infused on 3 consecutive days, starting with a loading dose (200 mg) on Day 1, and doses of 100 mg on Days 2 and 3. Blood and ultradiafiltrate samples were collected on Day 3 (during steady-state) before, and at regular intervals after, the infusion had started. Anidulafungin concentrations were determined with HPLC. RESULTS On Day 3, peak plasma concentrations with the 100 mg dose were 6.2 ± 1.7 mg/L and 7.1 ± 1.9 mg/L in the arterial and venous samples, respectively. The mean, pre-filter trough concentration was 3.0 ± 0.6 mg/L. The mean AUC0-24 values for plasma anidulafungin were 93.9 ± 19.4 and 104.1 ± 20.3mg·h/L in the arterial and venous samples, respectively. There was no adsorption to synthetic surfaces, and the anidulafungin concentration in the ultradiafiltrate was below the limit of detection. CONCLUSION The influence of CRRT on anidulafungin elimination appeared to be negligible. Therefore, we recommend no adjustments to the anidulafungin dose for patients receiving CRRT.

Cost-effectiveness analysis of schizophrenia relapse prevention : an economic evaluation of the ZEUS (Ziprasidone-Extended-Use-In-Schizophrenia) study in Spain.

AbstractObjective: The aim of this study was to estimate the cost-effectiveness of schizophrenia relapse prevention in Spain using data from the ZEUS (Ziprasidone-Extended-Use-in-Schizophrenia) study. Methods: Treatment of schizophrenia was modeled over 1 year using a retrospective deterministic model from the Spanish National Health System (NHS) perspective (year 2005). The primary outcome was the probability of relapse occurring within a 52-week period of treatment with daily doses of ziprasidone 40–160mg versus placebo. Data were obtained from a randomised, double-blind clinical trial (n = 218 patients). Antipsychotic cost, concomitant medications to treat adverse events (for example extrapyramidal symptoms) and medical costs associated with adverse events were derived from the clinical trial results and a Spanish health cost database. The average cost of a relapse admitted to hospital in Spain (€3421) was obtained from a retrospective study. Results: The probability of psychosis relapse was 0.77 with placebo, and 0.43, 0.35, 0.36 and 0.38 with ziprasidone daily doses of 40, 80, 160mg and average dose, respectively (p < 0.01 vs placebo in all cases). The average annual incremental cost per relapse avoided was €186 for the average dose, ranging from a saving of €557 (80 mg/day) to an incremental cost of €1015 (160 mg/day), and was ower in all cases than the minimum cost of a relapse (€2830). Conclusions: According to this evaluation, psychosis relapse prevention with ziprasidone is cost effective compared with no treatment from the Spanish NHS perspective. Ziprasidone therapy avoids a considerable number of relapses at a reasonable cost, producing cost savings.

Granulicatella adiacens breast implant-associated infection

The 1st reported case of breast implant-associated infection due to Granulicatella adiacens, formerly known as nutritionally variant streptococci, Streptococcus adiacens, and Abiotrophia adiacens is presented. Microbiology and previously reported cases of infections by this organism are reviewed.

Determination of ketorolac enantiomers in plasma using enantioselective liquid chromatography. Application to pharmacokinetic studies

SummaryA direct HPLC method for quantification of the (R) and (S) enantiomers of ketorolac in human plasma for pharmacokinetics studies has been developed. Naproxen sodium [S(+) enantiomer] was used as an internal standard. Plasma samples (1 mL) were vortexed for 30 sec with methyltert-butyl ether, followed by centrifugation at 2000 g for 8 min. The aqueous phase was acidified (pH 1) by adding 1 mL of 2N HCl and back-extracted with 5 mL methyltert-butyl ether. The organic phase was evaporated, and the residue was dissolved in 200 μL of mobile phase. 25 μL were chromatographed on a α1-acid glycoprotein column (Chiral-AGP, 100×4 mm I.D.), using a mobile phase with 8.5% propan-2-ol in phosphate buffer (0.09M NaH2PO4.H2O, 0.01M Na2HPO4, 0.002M Dimethyloctylamine; pH 5.5). Calibration range was 20–20000 ng mL−1 for (R)- and (S)-ketorolac. The LOQ was 5 ng mL−1 for both enantiomers. The sensitivity could be extended to 1 ng mL−1 with the same precison by increasing the injection volume to 100 μL.The method is reproducible, accurate, and stereospecific. The inter-assay and intra-assay CVs were <11.40% and <9.30% for (R)- and (S)-ketorolac respectively. Under the conditions employed, no racemization was observed.

Farmacología de los azoles

Azole antifungals have different pharmacokinetic characteristics: complete oral absorption for Voriconazole, and to a lesser extent for fluconazole. The absorption of posaconazole and itraconazole increases with food intake. All of them have high tissue distribution with low plasma concentrations, especially low in the case of posaconazole and itraconazole. Posaconazole and itraconazole have high plasmatic protein binding and consequently both have a very low free fraction. Elimination of azole antifungals is through a metabolic pathway with CYP450 isoenzymes, and has a non linear pharmacokinetics with a high risk of interation with other drugs since azoles have the ability of CYP450 isoenzymes inhibition. Possibly the parameter that defines more precisely their efficacy is AUIC with an optimum value near 20, although cut-off values must be defined since some azoles may have difficulty to reach this value.

High Serum Cholesterol Levels Are Associated with Herpes Zoster Infection after Heart Transplantation

Sun and Singh reported that statins might improve morbidity and mortality attributable to sepsis or infection in organ transplant recipients (1). Statins have antiviral effects against HIV-1(2), BK virus, cytomegalovirus, Epstein-Barr virus and hepatitis C (1). Cholesterol is required for varicella zoster virus (VZV) cell entry (3, 4). The relationship between cholesterol serum levels and risk of VZV post-transplant infection, if any, is unknown. We performed a case-control analysis to test the hypothesis that serum cholesterol is associated with an increased risk of zoster in heart transplant patients. We studied patients who underwent heart transplantation at Mayo Clinic from January 1994 through June 2006, from one-month pre- through 12-months post-transplantation. Details of this cohort have been previously reported (5, 6). Cases were patients diagnosed with post-transplantation zoster. For each case, three individually matched controls with no history of zoster, matched by age, gender, and transplantation year, were randomly selected. The degree of likeness between cases and controls was assessed using conditional logistic regression. Initial analysis compared mean serum cholesterol level within the first post-transplantation year in cases and controls. A second analysis compared serum cholesterol level within the month before the zoster episode in cases with the mean serum cholesterol level within the first post-transplantation year in cases. Twelve patients developed zoster at a median of 170 days after transplantation. One patient had disseminated zoster, and another eye involvement. Cases and controls had a median age of 59 years; 91 and 94%, respectively, were male. There were no differences between cases and controls in the following variables (univariate conditional logistic regression, Wald χ2 test): Use of antiviral prophylaxis (p,0.38) or statins (p,0.21) during the first post-transplantation year, reason for transplantation (p,0.96), diabetes (p,0.99), dyslipidemia (p,0.48), or BMI (p,0.58). There was no difference in mean serum cholesterol level in the first post-transplantation year between cases (mean 208.83 ± 49.3 mg/dl) and controls (mean 204.13 ± 31.63 mg/dl). However, mean cholesterol levels of cases within one month before the zoster episode were significantly higher (mean 241.08 ± 56.05 mg/dl) than those of the same patients within the first post-transplant year (p,0.007), or those in control patients within the first post-transplant year (p,0.0251). Cholesterol may play a role in the reactivation and spread of VZV in vivo. While no epidemiological studies have examined the relationship between serum cholesterol and zoster, a relationship between statins and infection risk has been reported (1). Statins have immunomodulatory (7), and direct antimicrobial effects (2). Depletion of cholesterol in membranes of inflammatory cells or reduced isoprenylation of signaling proteins are other possible mechanisms. HSV DNA in the brain, coupled with apolipoprotein E allele e4, has been suggested to confer an increased risk for Alzheimer’s disease. Cholesterol-lowering statins have recently been linked with a reduced risk of Alzheimer’s disease, possibly by reducing the neuronal spread of HSV-1 (8). It is biologically plausible that serum cholesterol levels are causally linked to the occurrence of zoster infections after heart transplantation.

Possible interaction between cyclosporine and josamycin: A description of three cases

Clinical Pharmacology and Therapeutics (1992) 51, 572–575; doi:10.1038/clpt.1992.65

A fast reverse-phase high performance liquid chromatographic tandem mass spectrometry assay for the quantification of clindamycin in plasma and saliva using a rapid resolution package.

A new method for the quantitative analysis of clindamycin in human plasma and saliva by liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) has been developed using a rapid resolution C18 column (2.1 mm x 30 mm x 3.5 microm). A simple deproteinization procedure was applied to the samples before analysis. Multiple reaction monitoring (MRM) mode of precursor-product ion transitions for clindamycin (425.1/126.1) and the internal standard, lincomycin (407.2/126.0) was used. Chromatographic separation was achieved at 0.6 ml/min in less than 1.5 min, with improved peak resolution and sensitivity between drug and internal standard. The assay exhibited a linear dynamic range between 0.05 and 15.0 microg/ml and gave a determination coefficient of 0.991 or better. The limit of quantification of the method was 10 ng/ml in both biological samples. Intra-day and inter-day precision ranged from 7.5% to 11.5%. Good accuracy was observed for both the intra-day and inter-day assays (R.S.D. below +/-4%). The suitability of the developed method for the analysis of clindamycin in plasma and saliva samples was demonstrated by the measure of clindamycin in samples taken up to 6h after oral and intravenous administration of this drug in infectious patients.