Proceedings of the Western Pharmacology Society最新文献

Persistent pulmonary hypertension of the newborn (PPHN) is a cardiopulmonary disorder characterized by systemic arterial hypoxemia secondary to elevated pulmonary vascular resistance with resultant shunting of pulmonary blood flow to the systemic circulation. PPHN is a serious illness that becomes progressively worse and is sometimes fatal. Management of the disease includes treatment of underlying causes, sedation and analgesia, maintenance of adequate systemic blood pressure, and ventilator and pharmacologic measures to increase pulmonary vasodilatation, decrease pulmonary vascular resistance, increase blood and tissue oxygenation, and normalize blood pH. Inhaled nitric oxide (NO) has been one of the latest measures to successfully treat PPHN. If all other treatments fail, extracorporeal membrane oxygenation (ECMO) can be used. Recently, preclinical and clinical studies have demonstrated the utility of the selective inhibitor of phosphodiesterase type 5 (PDE5), sildenafil, in decreasing pulmonary hypertension (HP). Sildenafil was first employed to offset rebound pulmonary hypertension in infants upon withdrawal of NO treatment. Later, several case reports demonstrated the effectiveness of sildenafil in the treatment of PPHN. Two randomized blinded studies with sildenafil in infants with PPHN were published in 2006. In both studies, the patients treated with sildenafil showed a steady improvement in pulse oxygen saturation over time. Likewise, the frequency death was lower in the groups treated with sildenafil. Recent evidence shows the utility of sildenafil in the treatment of PPHN. However, since existing data are limited there is an urgent need for multicenter blinded, placebo controlled, randomized trials.

The actions of nucleotides and hormones at endothelial cell (EC) receptors are known to result in the release of ATP that acts as a local hormone to facilitate release of mediators such as NO and PGI2. Stimulation of ECs with the P2Y1 receptor agonist 2-MeSATP leads to the rapid release of Ca2+ from stores consistent with a role for inositol trisphosphate (Ins-1,4,5-P3) in mediating the action of extracellular nucleotides. Guinea pig ECs were grown in primary culture. [3H]d-myo-inositol (30 Ci/mmol) labeling studies revealed maximal incorporation of radioactivity into [3H]Ins-1,4,5-P3 when glucose in the labeling buffer was lowered to 1 mM and non-radioactive inositol was added at 10 microM. Stimulation of EC for one sec led to the dose-dependent accumulation of [3H]Ins-1,4,5-P3 as well as [3H]IP4, [3H]IP5, and [3H]IP6. Unexpectedly, the metabolism of [3H]Ins-1,4,5-P3 to IP1 was disparat in stimulated versus un-stimulated cells. In [3H]d-Ins labeled stimulated EC or in homogenates derived from unlabeled, stimulated EC, dephosphorylation of [3H]Ins-1,4,5-P3 led to the exclusive formation of [3H]Ins-4-P1. Addition of on-nucleotide agonists such as bradykinin gave the same results suggesting that the dephosphorylation pathway for IP formation in EC is dependent on agonist stimulation and may be correlated with regulation of agonist responsiveness or heretofore unrecognized actions of IP isomers in stimulated versus unstimulated cells.

A genotyping approach for pharmacogenes such as CYP2C19 is often advocated to "personalise therapy", since individuals with the homozygous null allele genotype are poor metabolisers (PM) of many drugs. The genotype-phenotype relationship is a validated approach for S-mephenytoin, proguanil and omeprazole in young, healthy populations. However, this relationship may not be valid in patients with diseases such as cancer and congestive heart failure, or in old age. The high phenotypic discordance in the genotypic EM group means that in many clinical situations the true number of CYP2C19 poor metabolisers may be under-estimated if only genotypic approaches are used.

Fluconazole and itraconazole are antimycotics widely used in Mexico. However, limited information about their pharmacokinetics is available. It has been reported that physicochemical characteristics of these compounds are disparate, leading to different pharmacokinetic profiles. Moreover, it has been suggested that pharmacokinetics of some drugs may vary in Mexicans when compared with Caucasians due to reduced metabolism by CYP3A4. Based on these distinctions, it is important to carry out local studies in order to establish dosage regimens according the characteristics of each population. The purpose of this study was to compare the oral pharmacokinetics of fluconazole and itraconazole in Mexicans and to compare our results with those reported in other populations. Two groups of 16 subjects volunteered for this study that was approved by the Institutional Research and Ethics Committees. All subjects gave written informed consent for participation. After an overnight fast, volunteers received an oral dose of 100 mg fluconazole or itraconazole and blood samples were obtained at selected times over 96 hr. Plasma was obtained and analyzed by HPLC and pharmacokinetic parameters were obtained. As expected, fluconazole plasma levels were higher than itraconazole due to a lower volume of distribution. Additionally, less variability was observed for fluconazole. When data obtained in Mexicans was compared with those obtained in other populations, no differences were observed, suggesting that there are not interethnic differences in the pharmacokinetics of fluconazole and itraconazole.

A chronic pain patient prescribed 20 mg of methadone per day was seen at the Emergency Department within one hour following a witnessed intentional 200 mg ingestion. In addition, he was taking the serotonin re-uptake inhibitor antidepressant drugs, sertraline and venlafaxine as prescribed. Methadone is also a serotonin re-uptake inhibitor which has been involved in serotonin toxicity reactions. Initially, no symptoms of narcotic overdose (depressed central nervous system, respiration, or blood pressure) could be distinguished, and the standard narcotic urine screen was negative. No decontamination or antagonist therapy was given, and the patient was discharged to a psychiatric unit for observation. At 5 hours post-ingestion he presented in a panic with hallucinations and elevated blood pressure, pulse, and respiration. These symptoms are characteristic of serotonin syndrome which is often described as mental status changes, autonomic hyperactivity, and neuromuscular abnormalities. At 10 hours post-ingestion the patient was found unconscious. He had aspirated stomach contents into his lungs. His respiration, blood pressure, and pulse were all severely depressed. He never regained conciousness, and he died 5 days later. The medical examiner's finding was probable acute methadone intoxication. In this case serotonin syndrome appears to have opposed and delayed typical narcotic symptoms. Methadone has additional pharmacologic and toxicologic properties which may complicate the assessment and treatment in overdose situations.

Pharmacogenetics dates back more than 2,000 years to observations by Pythagoras, however it was not until the 1950s when some enzyme polymorphisms (e.g., N-acetyltransferase, G6PD) were discovered that the term was coined by Vogel. Pharmacogenetics then went into decline as being too esoteric a subject. In the 1970s the discovery of the CYP2D6 polymorphism and its resultant effect on drug toxicity and response led to many observations of pharmacogenetic-based variations in pharmacokinetics. These and other discoveries and the subsequent ability to genotype led to the term pharmacogenomics. Today, there are an increasing number of genes for which polymorphisms have been identified that are associated with variable drug response whether it be at the drug metabolizing enzyme, transporter or receptor level and, mainly through a candidate genes(s) approach. Increasing use of genome-wide analysis is identifying hitherto unpredictable new genes associated with disease and drug response. Although some old and most new drugs coming onto the market have a "pharmacogenomic footprint", the clinical and practical usefulness of pharmacogenomics has been generally lacking. To date, clinical translation of pharmacogenetics has focused on narrow therapeutic index drugs for toxicity (e.g., azathioprine) and more recently for efficacy and toxicity (e.g., warfarin) purposes. Pharmacogenetics and genomics will be advanced through lower cost, rapid whole genome sequencing methods combined with sophisticated algorithms allowing individualised dosage recommendations but not necessarily their adoption. However, complicating this is the influence of changes in gene expression by environmental and genetic factors. Therefore translation of pharmacogenetics into "personalised medicine" will depend on many factors including clinical relevance, environmental-genetic interactions, cost and education.

Mexico City is among the world's largest metropolitan city centers and one of the most difficult and challenging cities in which to drive a motor vehicle. During peak transit hours and maximum congestion, numerous accidents occur, many of them fatal. The aim of the study presented here was to analyze the levels of select indicators against oxidative stress and levels of biogenic amines as a consequence of accident or altercation and fear deaths. Eighteen cases were studied (sixteen males, two females). Subjects ranged from twelve to eighty-one years of age. Nine of the deaths studied were the result of motor vehicle or subway accidents. Eight of the eighteen deaths were the result of a violent altercation, while one of the deaths resulted from a drug overdose and cardiac arrest. Biopsies of cadaver putamen were homogenized and analyzed for Tryptophan (Trp), 5-hydroxyindole acetic acid (5-HIAA), Dopamine (DA), and Glutathione (GSH) levels by fluorometric methods. Trp, 5-HIAA, DA, and GSH levels showed an increase in the subjects who's death was caused by violent altercation combined with fear, while DA levels showed significant differences in all accident groups. This data suggest that biogenic amines in cadaver putamen tissue, such as DA, can be telling biochemical markers, indicative of altercation and fear deaths.

Malnutrition is a health problem in Mexico. It has been established that malnutrition may produce important changes in the pharmacological response to drugs, since changes in the pharmacodynamics and pharmacokinetics may occur. It has been described that a reduction of plasma proteins and in hepatic enzymes may occur. Due to these changes, absorption, distribution and elimination of drugs can be modified. Nimesulide is a non-steroidal anti-inflammatory agent that is widely used. This drug is importantly bound to plasma proteins and is metabolized through cytochrome P-450, two systems that are altered in malnutrition. In order to establish if malnutrition can modify the pharmacokinetics of nimesulide, a comparison of pharmacokinetic parameters obtained in control and protein-calorie malnourished rats was carried out. Two groups of 7 rats were employed in this study. At 45 days of age, group 1 received a standard balanced diet for 4 weeks, whereas, group 2 received a low protein diet for the same period. Then, rats received an oral dose of 10 mg/kg nimesulide and blood samples were drawn at selected times for 12 hr. Nimesulide whole blood levels were determined by HPLC and the pharmacokinetic parameters; Cmax 1.18 +/- 0.13 and 1.03 +/- 0.10 microg/ml, tmax 5.25 +/- 1.03 and 7.48 +/- 1.09 h and AUC12h 8.64 +/- 1.19 and 8.27 +/- 0.85 microg x h/ml were obtained. We conclude that malnutrition does not modify the oral pharmacokinetics of nimesulide.

Human breast cancer cells (MDA-MB-435s) secrete a nucleoside diphosphate kinase (NDPK-B) as a phosphoprotein capable of converting diphosphate nucleosides to triphosphate nucleotides for one round in the absence of a phosphoryl donor. Incubation of the partially purified NDPK-B (Nm23-H2 by Western blot) from [gamma32P]Pi-labeled cells with non-radioactive ADP results in the formation of [gamma32P]ATP (Proc. West. Pharmacol. Soc. 44: 61-63, 2001). The presence of a secreted protein that can maintain ATP levels in the vicinity of capillary and lymph vessels may support cancer metastasis in several ways based on the known actions of ATP at P2Y receptors: facilitate intravasation of breast cancer cells that migrate from a solid tumor, support their extravasation at a distal site, and stimulate angiogenesis. The putative role of angiostatin (AS) as an ATP-synthase inhibitor led us to test the notion that AS blocks NDPK-B activity. Addition of commercial AS (kringles 1-4) did not alter enzyme activity. However, AS produced by us and never lyophilized, blocked NDPK activity in a dose-dependent fashion consistent with the notion that extracellular ATP generation by tumor cells may be important to the development of metastases. The ability of 0.5 mg/ml angiostatin to block NDPK-B activity to approximately 75% of control activity compared poorly with the polyphenol inhibitors of. The catechin gallates, theaflavins and ellagic acid inhibited NDPK-B completely with the rank order of potency: EA > theaflavins > EGCG > ECG > PAPS. Our results suggest that the biological activity of angiostatin as a putative metastasis inhibitor may be in part the result of nm23 inhibition and that the production, lyophilization, packaging or storage of commercial angiostatin leads to the alteration of its biological activity against NDPK-B. Ellagic acid is a potent (IC50 = 10.5 microM) NDPK-B inhibitor that may prove useful in elucidating the role of cancer-cell secreted NDPK-B in tumor development.

Valvular myofibroblasts (VMFs) are present in large numbers in the cardiac valve. Although the functional roles of VMFs in vivo remain to be determined, evidence suggests the cells' ability to contract in vitro. Since Ca2+ is important in the contractility of many cell types, we examined Ca2+ responses induced by different agonists in normal and rheumatic VMFs. The agonists used were histamine, adenosine triphosphate (ATP) and 5-hydroxytryptamine (5-HT), all of which are important mediators in cardiac function. Cytosolic Ca2+ concentrations ([Ca2+]i) in fura-2-loaded VMFs were measured with ratiometric fluorescence microscopy. VMFs were challenged with a single concentration of each agonist in either Ca2+-containing (+Ca) or Ca2+-free (-Ca) physiological salt solution (PSS). From the resulting Ca2+ response, area under curve (AUC) was calculated from the point of drug addition (i.e., baseline) until the response reached the first peak (i.e., maximum). Our data show that more Ca2+ was mobilized in normal than in rheumatic VMFs, suggesting possible Ca2+-mobilizing dysfunction in the initial phase of a response under disease conditions. The most prominent difference was observed with 5-HT stimulation in +Ca PSS, where normal VMFs showed significantly greater AUC than rheumatic VMFs. The investigation of agonist-induced Ca2+ signaling characteristics in VMFs may provide information pertaining to Ca2+-associated changes and their consequences in cardiac valvular diseases.