Current Clinical Pharmacology - Volume 11, Issue 1, 2016

Surgical removal of a tumor may, ironically, unleash prometastatic effects that enhance cancer recurrence and metastatic disease. The patient’s physiologic response to the surgical trauma may increase tumor cell growth and invasiveness while diminishing the immune system’s ability to eliminate residual disease. At the same time anaesthetic drugs used to accomplish the surgery may also have important effects on cancer cells and the immune system. Those combined effects potentially lead to sooner recurrence of local or metastatic cancer, and, ultimately, decreased survival. This review explores current research on the influences of surgery and anaesthesia on tumor cells, the immune system, and cancer recurrence. Although a substantial body of evidence sheds much light on the nature of these processes and is at times suggestive of how they might be relevant in clinical practice that literature also reveals a foundation of data that remain largely preclinical with as yet insufficient human study to support clinical recommendations. The tantalizing possibility that anaesthetic care of the surgical oncology patient might affect long term oncologic outcome remains unproven speculation, awaiting prospective human study.

Catalase is responsible for converting hydrogen peroxide (H2O2) into water and oxygen in cells. This enzyme has high affinity for hydrogen peroxide and can protect the cells from oxidative stress damage. Catalase is a tetramer protein and each monomer contains a heme group. Cimetidine is a histamine H2 receptor blocker which inhibits acid release from stomach and is used for gasterointestinal diseases. In this research, effect of cimetidine on the activity of liver catalase was studied and the kinetic parameters of this enzyme and its conformational changes were investigated. Cell free extract of mouse liver was used for the catalase assay. The activity of the catalase was detected in the absence and presence of cimetidine by monitoring hydrogen peroxide reduction absorbance at 240 nm. The purified enzyme was used for conformational studies by Fluorescence spectrophotometry. The data showed that cimetidine could inhibit the enzyme in a non-competitive manner. Ki and IC50 values of the drug were determined to be about 0.75 and 0.85 uM, respectively. The Arrhenius plot showed that activation energy was 6.68 and 4.77 kJ/mol in the presence and absence of the drug, respectively. Fluorescence spectrophotometry revealed that the binding of cimetidine to the purified enzyme induced hyperchromicity and red shift which determined the conformational change on the enzyme. Cimetidine could non-competitively inhibit the liver catalase with high affinity. Binding of cimetidine to the enzyme induced conformational alteration in the enzyme.

Microvesicles (MVs) are submicron intact particles released from the cellular membrane of eukaryotic cells. MVs can be sub-categorised into microparticles (MPs), which are between 100nm- 1micron in size, and exosomes, measuring less than 100nm. Once thought to be cellular debris, MPs are now known to play important biological effector functions. Their biogenesis and release are as a result highly regulated processes in response to cellular activation or stress, and apoptosis. MPs are now known to play a crucial role in maintaining physiological homeostasis and have been demonstrated to be involved in numerous biological processes, including inflammation, cardiovascular disease, immune response, cancer dissemination, coagulation and angiogenesis. Consequently, there is active interest in studying MPs, and their ‘cause and effect’ in the initiation and potentiation of various pathologies. Circulating levels, both quantitative and qualitative, of MPs is thought to be a reflective index of cardiovascular competence. Therefore, studies to understand the biological relevance of the various permutations and combinations of circulating MPs, their cellular origin and bioactive cargo may lead to increased understanding of the sequelae of CVD and associated diseases. This review synopsizes our current understanding of the role of MPs in cardiovascular disease, their biogenesis and effector function, and their future use as both diagnostic and prognostic indices of cardiovascular disease.

Background: Previous studies have suggested that niacin may have antiplatelet properties, however the effects of niacin on the platelet activity are not well defined. Objective: The purpose of this trial was to investigate whether the oral administration of niacin inhibits platelet aggregation. Method: This study was run in three segments measuring the inhibitory effect of niacin: 1) 3 mmol/L niacin in vitro, 2) one hour after 1-gram sustained-release (SR) niacin administration, 3) twelve hours after 2-gram SR niacin administration. Platelet aggregation was measured using the VerifyNow-Aspirin and whole blood impedance aggregometry. Results: Preincubation with niacin resulted in a significant inhibition of platelet aggregation. Significant inhibition of platelet aggregation was found one hour following the oral administration of 1 gram of SR niacin while the oral administration of a 2 gram dose of SR niacin did not produce significant platelet inhibition when platelet aggregation was measured 12 hours after the dose. Conclusion: Niacin has a small, direct effect on platelet aggregation. Niacin platelet inhibition is transient and may dissipate as it is converted into metabolites. The clinical significance is unknown.

Organ clearance, which has been derived from the organ blood flow and extraction ratio (E), has been extensively used by clinical pharmacologists to explain the pharmacokinetics of many drugs in health and disease. For example, the extent of hepatic clearance or E (Eh) of drugs would determine their response to changes in the liver blood flow and/or activities of the metabolizing enzymes. Although Eh may be obtained directly by cannulating internal blood vessels, the method is invasive. Therefore, indirect methods have been used to estimate Eh from the peripheral blood concentration-time data after intravascular administration of drugs. Additionally, these indirect methods require an estimate of the liver blood flow in the patients or animals. However, some investigators use plasma concentrations and/or liver plasma flow for the estimation of Eh, which could potentially result in significant errors. It is shown here that when plasma concentrations are used along with liver blood flow, an overestimation or underestimation of the true value will result if the blood: plasma concentration (B:P) ratio is >1 or < 1, respectively, with the estimated Eh being different from the true value by a factor equal to the B:P ratio. On the other hand, the use of plasma concentrations and plasma liver flow will always result in an overestimation of the true Eh unless the drug does not penetrate the red blood cells. It is concluded that for the accurate estimation of Eh from the in vivo data, the blood concentration and blood flow should be used.

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of premature human infants, which may persist through adulthood. Airway inflammation has been firmly established in the pathogenesis of BPD. Previous studies to reduce airway inflammation with high-dose dexamethasone demonstrated adverse neurological outcomes, despite lower incidences of BPD. Instillation of budesonide and surfactant can facilitate early extubation and reduce the incidence of BPD and death among very low birth weight infants. However, the pharmacokinetics of budesonide and its distribution into the lung and brain are unknown. Therefore, 5 premature lambs were administered 0.25 mg/kg budesonide, with surfactant as the vehicle. Plasma and tissue samples were taken from the lambs for measurement of budesonide, 16α- hydroxy prednisolone, and budesonide palmitate using LC/MS/MS. Peak plasma budesonide concentrations were inversely correlated with the oxygenation index (correlation coefficient of -0.75). Plasma budesonide concentrations were extremely low (~10% of expected) for two lambs that had high oxygenation indices and were excluded from further analyses. For the remaining 5 premature lambs, a non-compartmental analysis demonstrated an AUCinf of 148.77 ± 28.16 h*μg/L, half-life of 4.76 ± 1.79 h, and Cmax of 46.17 ± 17.71 μg/L. Using population pharmacokinetic methods, a onecompartment model with exponential residual error and first-order absorption adequately described the data. The apparent clearance and apparent volume of distribution of budesonide were estimated at 6.29 L/h (1.99 L/h/kg) and 29.1 L (9.2 L/kg), respectively. Budesonide and budesonide palmitate, but not 16α-hydroxy prednisolone, were detected in lung tissue. In this study, budesonide and its metabolites were not detected in the brain, which suggests that intratracheal instillation suggests that after local pulmonary deposition, there is no evidence of budesonide accumulation in the central nervous system. Overall, these results show that peak plasma budesonide concentrations are inversely correlated with the oxygenation index and that lung-specific delivery of budesonide avoids accumulation of budesonide in the brain.

Introduction: Various factors have been shown to increase the risk of bleeding with warfarin. This study aimed to assess the association of CYP2C9 and VKORC1 with the development of bleeding following warfarin. Study Methods: A case control study was initiated after obtaining institutional ethics committee clearance and written informed consent from patients. Cases were defined as those who bled within three months of warfarin initiation and controls as those who did not have any episode of bleeding within three months. Genotyping for CYP2C9 (*1, *2, *3) and VKORC1 1639 (GG, GA and AA) was performed by PCRRFLP. Chi square test was used to find out the association and trend of CYP2C9 and VKORC1 genotypes with odds ratio (95% CI) for strength of association. A binary logistic regression model was developed associating age, body weight, sex, CYP2C9 and VKORC1 status with risk of bleeding. Results: A total of 100 controls and 38 cases were studied from Oct 2009 to July 2011. A significant association (P < 0.0001) and trend (P = 0.027) of mutant alleles of CYP2C9 and VKORC1 were noted with bleeding with odds ratios of 7.8 [3.4, 17.9] and 2.7 [1.3, 5.7] respectively. Weekly dose requirement was significantly lower with the presence of *3 allele relative to *1 in CYP2C9 (P < 0.001). The regression model showed an accuracy of 80% and could explain 35.3% of the variability. Conclusion: A significant association between CYP2C9 (*1,*2,*3) genotype and VKORC1 (1639 G>A) haplotype status has been found with increased bleeding tendency to warfarin. This may help to individualize therapy.

The treatment with antiepileptic drugs (AEDs), in particular conventional drugs, induces an increased risk of fractures in women and in epileptic patients in treatment with AEDs for more than 12 years. A supplementation with calcium and vitamin D is suggested in patients chronically treated with some AEDs and there are recommendations to do so. The lack of significant conclusive evidence about the effects of conventional and newer AEDs on bone metabolism needs for more clinical studies in order to perform an appropriate use of calcium and vitamin D supplementation in young and ederly epileptic patients.