Vapor phase Beckmann rearrangement using high silica zeolite catalyst

Vapor phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam has been studied using high silica zeolite catalysts. Catalysts with different crystal sizes and gel-ageing times have been activated by ionic exchange in different conditions by means of a highly basic solution and a nearly neutral solution both containing ammonium salts. Samples have been calcined at different temperatures in order modify the number of defective sites. We observed that samples exchanged by means of a highly basic solution (pH > 10)1,2 and calcined at a relatively lower temperature (450 C) show the most interesting catalytic results. X-ray powder diffraction patterns of these samples show2 retention of the unit cell symmetry (orthorhombic cell) if compared to the dried sample. NH3-TPD confirms the low acidity of high silica zeolites, however a higher amount of desorbed ammonia is observed for the samples exchanged at higher pH and calcined at 450 C. Due to silanol nests the IR spectra of the same samples show the formation of Si\u2013NH2 bonds which are absent in the same material exchanged by other methods. Such sites seem to promote the high stability of the high silica zeolite catalysts also to the regeneration which is needed to remove the heavy carbonaceous compounds from the catalyst surface

Identification of acute myocardial infarction from electronic healthcare records using different disease coding systems

Objective: To evaluate positive predictive value (PPV) of different disease codes and free text in identifying acute myocardial infarction (AMI) from electronic healthcare records (EHRs). Design: Validation study of cases of AMI identified from general practitioner records and hospital discharge diagnoses using free text and codes from the International Classification of Primary Care (ICPC), International Classification of Diseases 9th revision-clinical modification (ICD9-CM) and ICD-10th revision (ICD-10). Setting: Population-based databases comprising routinely collected data from primary care in Italy and the Netherlands and from secondary care in Denmark from 1996 to 2009. Participants: A total of 4 034 232 individuals with 22 428 883 person-years of follow-up contributed to the data, from which 42 774 potential AMI cases were identified. A random sample of 800 cases was subsequently obtained for validation. Main outcome measures: PPVs were calculated overall and for each code/free text. 'Best-case scenario' and 'worst-case scenario' PPVs were calculated, the latter taking into account non-retrievable/non-assessable cases. We further assessed the effects of AMI misclassification on estimates of risk during drug exposure. Results: Records of 748 cases (93.5% of sample) were retrieved. ICD-10 codes had a 'best-case scenario' PPV of 100% while ICD9-CM codes had a PPV of 96.6% (95% CI 93.2% to 99.9%). ICPC codes had a 'best-case scenario' PPV of 75% (95% CI 67.4% to 82.6%) and free text had PPV ranging from 20% to 60%. Corresponding PPVs in the 'worst-case scenario' all decreased. Use of codes with lower PPV generally resulted in small changes in AMI risk during drug exposure, but codes with higher PPV resulted in attenuation of risk for positive associations. Conclusions: ICD9-CM and ICD-10 codes have good PPV in identifying AMI from EHRs; strategies are necessary to further optimise utility of ICPC codes and free-text search. Use of specific AMI disease codes in estimation of risk during drug exposure may lead to small but significant changes and at the expense of decreased precision

Drug-drug interactions and statin therapy

No abstract availabl

Age-related changes in pharmacodynamics: focus on drug acting on cetral nervous and cardiovascular systems

Aging is characterized by progressive impairment of functional capacities of all system organs, reduction in homeostaticmechanisms, and altered response to receptor stimulation. These age-related physiologic changes influence both pharmacokinetics andpharmacodynamics of drugs in elderly patients. Pharmacokinetic and pharmacodynamics changes as well as polypharmacy and comorbiditiesmay alter significantly the effect of pharmacological treatment with advancing age. With the same drug concentration at thesite of action, significant differences in the response to several drugs have been observed in older patients as compared to younger patients.Elderly patients are particularly suceptibles to the effects of frequently prescribed drugs acting on central nervous system, such asbenzodiazepines, antidepressants, antipsychotics and lithium, with high potential for adverse drug reactions. Moreover, in older patientsincreased sensitivity to warfarin resulting in increased risk of bleeding has been previously documented. On the other hand, reduced effectivenessof conventional doses of cardiovascular drugs, such as diuretics and -blockers, has been observed. Due to pharmacodynamicchanges, therefore, dose adjustment of the above mentioned cardiovascular and psychotropic drugs is recommended in elderly. Cliniciansshould be aware of the age-related physiologic changes affecting several organ systems and their implications on the effect of drugs thatare commonly prescribed to elderly patients.This review focuses on the main age-related pharmacodynamics changes of drugs acting on central nervous system and cardiovascularsystem, which are the most frequently prescribed medications in older patients

"Stopped-flow desorption" analysis of the nature of strongly adsorbed species during n-butane oxidation in a flow reactor

The presence and the evolution as a function of time of strongly adsorbed species during n-butane oxidation in a flow reactor was studied by "stopped-flow desorption" experiments and by thermogravimetric and Fourier-transform infrared analyses on a (VO)2P2O 7 catalyst highly active/selective in the conversion of n- butane to maleic anhydride. In particular, the presence of an adsorbed species was found which desorbs as crotona1dehyde only at temperatures around 100 K higher than the reaction temperature (573 K). The parallel increase in the amount of this species formed with the change in catalytic behavior (a decrease in the rate of n-butane depletion with a parallel increase in the rate of maleic anhydride formation) suggests that due to the reduced turnover number, the formation of strongly adsorbed species causes catalyst deactivation by site blocking, but at the same time allows controlled reactivity of the surface which prevents the consecutive oxidation of maleic anhydride to carbon oxides. \ua9 1987 Elsevier Science Publishers B.V

Clinically significant drug interactions with newer antidepressants

After the introduction of selective serotonin reuptake inhibitors (SSRIs),other newer antidepressants with different mechanisms of action have beenintroduced in clinical practice. Because antidepressants are commonlyprescribed in combination with other medications used to treat co-morbidpsychiatric or somatic disorders, they are likely to be involved in clinicallysignificant drug interactions. This review examines the drug interaction profilesof the following newer antidepressants: escitalopram, venlafaxine, desvenlafaxine,duloxetine, milnacipran, mirtazapine, reboxetine, bupropion,agomelatine and vilazodone.In general, by virtue of a more selective mechanism of action and receptorprofile, newer antidepressants carry a relatively low risk for pharmacodynamicdrug interactions, at least as compared with first-generation antidepressants,i.e. monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressantsREVIEWARTICLE CNS Drugs 2012; 26 (1): 39-671172-7047/12/0001-0039/$49.95/0\uaa 2012 Adis Data Information BV. All rights reserved.(TCAs). On the other hand, they are susceptible to pharmacokinetic druginteractions. All new antidepressants are extensively metabolized in the liverby cytochrome P450 (CYP) isoenzymes, and therefore may be the target ofmetabolically based drug interactions. Concomitant administration of inhibitorsor inducers of the CYP isoenzymes involved in the biotransformationof specific antidepressants may cause changes in their plasma concentrations.However, due to their relatively wide margin of safety, the consequences ofsuch kinetic modifications are usually not clinically relevant. Conversely, somenewer antidepressants may cause pharmacokinetic interactions through theirability to inhibit specific CYPs.With regard to this, duloxetine and bupropionare moderate inhibitors of CYP2D6. Therefore, potentially harmful drug interactionsmay occur when they are coadministered with substrates of theseisoforms, especially compounds with a narrow therapeutic index. The othernew antidepressants are only weak inhibitors or are not inhibitors of CYPisoforms at usual therapeutic concentrations and are not expected to affect thedisposition of concomitantly administered medications.Although drug interactions with newer antidepressants are potentially, butrarely, clinically significant, the use of antidepressants with a more favourabledrug interaction profile is advisable. Knowledge of the interaction potential ofindividual antidepressants is essential for safe prescribing and may help cliniciansto predict and eventually avoid certain drug combinations

From Big Data to Smart Data for Pharmacovigilance: The Role of Healthcare Databases and Other Emerging Sources

In the last decade 'big data' has become a buzzword used in several industrial sectors, including but not limited to telephony, finance and healthcare. Despite its popularity, it is not always clear what big data refers to exactly. Big data has become a very popular topic in healthcare, where the term primarily refers to the vast and growing volumes of computerized medical information available in the form of electronic health records, administrative or health claims data, disease and drug monitoring registries and so on. This kind of data is generally collected routinely during administrative processes and clinical practice by different healthcare professionals: from doctors recording their patients' medical history, drug prescriptions or medical claims to pharmacists registering dispensed prescriptions. For a long time, this data accumulated without its value being fully recognized and leveraged. Today big data has an important place in healthcare, including in pharmacovigilance. The expanding role of big data in pharmacovigilance includes signal detection, substantiation and validation of drug or vaccine safety signals, and increasingly new sources of information such as social media are also being considered. The aim of the present paper is to discuss the uses of big data for drug safety post-marketing assessmen

Surface characterization of a grafted vanadium-titanium dioxide catalyst

Surface properties of a low-content vanadium catalyst, prepared by grafting a high-surface-area TiO 2 (anatase) support, have been studied by means of diffuse reflectance, e.s.r. and F.t.i.r. spectroscopy, t.p.d. and its catalytic activity by butadiene oxidation. It has been found that the grafting reaction of vanadium occurs on all surface OH groups of TiO 2, leaving exposed Ti 4+ cations. Vanadium sites are isolated on the surface and have labile oxidative and coordinative states. Moreover, they interact cooperatively with titanium sites. Evidence for other vanadium species (surface, interstitial or reticular) has not been found