Pharmacokinetics and metabolism of MZPES, a novel lipophilic antifolate

m-Azidopyrimethamine ethanesulphonate salt (MZPES) is a new potent dihydrofolate reductase inhibitor designed to be both lipophilic and rapidly biodegradable. The drug is active against some methotrexate-refractory cell lines and against a broad spectrum of malignant cells in murine models. The pharmacokinetics of the drug were evaluated in the mouse, rat and man. A specific analytical method was developed to allow determination of MZP (the free base of MZPES) and its putative metabolite m-amino-pyrimethamine (MAP) in plasma, urine, faeces and tissues. Analytical methodology involved solvent extraction followed by reversed-phase ion-pair high pressure liquid chromatography. Mice were dosed at 10 and 20 mg/kg IP and 10 mg/kg PO. Absorption was rapid from both sites with a mean plasma elimination half-life of 4 hours. Oral bio-availability, relative to intraperitoneal injection, exceeded 95% in the mouse. MZP attained concentrations in mouse tissues 4 to 14 fold greater than those found in plasma and penetrated the blood-brain barrier effectively. Following intraperitoneal administration of MZP to the rat, the recovery of MZP and MAP in urine and faeces was 14% during 72 hours. MZPES was formulated for a phase I clinical evaluation as a 1% w/v aqueous solution and was administered by IV infusion in 5% dextrose over 1 hour. The drug obeyed 2-compartment kinetics with a central compartment volume of 27 litres and a volume of distribution of 118 litres. Plasma distribution and elimination half-lives were 0.27 and 34 hours respectively and plasma clearance was 7.5 L/hr. MZP was removed from plasma more rapidly than the prototypic lipophilic dihydrofolate reductase inhibitor metoprine (half-life 216 hours). The pharmacokinetics of MZPES showed no dose-dependency over the dose-range studied (27 to 460 mg/m2). The dose-limiting toxicity was nausea and vomiting. The short half-life of the drug should allow easy assessment of the optimum dose and schedule of administration.

Cytotoxic activity of Fagonia cretica against human breast cancer cells

In many parts of the world, plants are directly utilised for their medicinal properties. Traditional medicine from Pakistan, India and the Far East is well documented and its history is embedded in folklore. It has been documented that an aqueous extract of the desert shrub, Fagonia cretica, is a popular treatment for breast cancer in Pakistan. The administration of an aqueous extract of Fagonia cretica is reported effective at reducing tumour size and improving the quality of life of breast cancer patients, is well tolerated and does not exhibit adverse effects like vomiting, diarrhoea or alopecia which are common side effects of standard cytotoxic therapy. In the past, many pharmacologically active and chemotherapeutic compounds have been isolated from plants which subsequently have proven to be successful in clinical trials and been used as primary compounds in therapeutic regimes. Fagonia cretica has historical use as a treatment for breast cancer, yet there is little scientific evidence which shows chemotherapeutic potential towards breast tumours. Preparation and analysis of an aqueous extract of Fagonia cretica may reveal novel chemotherapeutic agents that can be used to effectively target cancer cells. An understanding of the mechanism of any activity may improve our understanding of cancer cell biology and reveal novel therapeutic targets. This thesis describes for the first time that an aqueous extract of Fagonia cretica shows potent in vitro cytotoxic activity towards breast cancer epithelial cell lines which was not seen towards normal mammary epithelial cells. Elucidation and characterisation of the cytotoxic mechanism was undertaken by analysing DNA damage, cell cycle status, apoptosis, metabolic state and expression of transcription factors and their targets. Finally, methods for the isolation and identification of active compound(s) were developed using various chromatographic techniques. An aqueous extract of Fagonia cretica was able to reduce cell viability significantly in two phenotypically different breast cancer cell lines (MCF-7 and MDA-MB-231). This activity was markedly reduced in normal mammary epithelial cells (HMEpC). Further investigation into the mode of action revealed that extract treatment induced cell cycle arrest and apoptosis in both MCF-7 and MDA-MB-231 cell lines. This coincided with the formation of DNA double stranded breaks and the DNA repair marker ?-H2AX. In MCF-7 cells, ATM/ATR activation resulted in increased p53 expression and of its transcriptional targets p21 and bax, suggesting a role for a p53-mediated response. Furthermore, inhibition of extract-induced p53 expression with siRNA reduced the cytotoxic effect against MCF-7 cells. Extract treatment was also associated with increased FOXO3a expression in MCF-7 and MDA-MB-231 cells. In the absence of functional p53, siRNA knockdown of extract-induced FOXO3a expression was completely abrogated, suggesting that FOXO3a plays a vital role in extract-induced cytotoxicity. Isolation and characterisation of the active compound(s) within the extract was attempted using liquid chromatography and mass spectrometry in conjunction with a cell viability assay. Multiple fractionations generated an active fraction that contained four major compounds as detected by mass spectrometry. However, none of these compounds were identified structurally or chemically due to constraints within the methodology.

Cholinesterase inhibitors for Parkinson's disease dementia

Background - The loss of cholinergic, dopaminergic and noradrenergic innervations seen in Parkinson's Disease Dementia (PDD) suggest a potential role for cholinesterase inhibitors. Concerns have been expressed about a theoretical worsening of Parkinson's disease related symptoms, particularly movement symptoms. Objectives - To assess the efficacy, safety, tolerability and health economic data relating to the use of cholinesterase inhibitors in PDD. Search methods - The trials were identified from the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 19 April 2005 using the search term parkinson*. This register contains records from major health care databases and many ongoing trial databases and is updated regularly. Comprehensive searches of abstracts from major scientific meetings were performed. Pharmaceutical companies were approached for information regarding additional and ongoing studies. Selection criteria - Randomized, double-blind, placebo-controlled studies assessing the effectiveness of cholinesterase inhibitors in PDD. Inclusion and exclusion criteria were stated to limit bias. Data collection and analysis - Two reviewers (IM, CF) independently reviewed the quality of the studies utilizing criteria from the Cochrane Collaboration Handbook. Medications were examined separately and as a group. The outcome measures assessed were in the following domains: neuropsychiatric features, cognition, global impression, daily living activities, quality of life, burden on caregiver, Parkinsonian related symptoms, treatment acceptability as determined by withdrawal from trials, safety as determined by the frequency of adverse events, institutionalisation, death and health economic factors. Main results - A detailed and systematic search of relevant databases identified one published randomized, double-blind, placebo-controlled study (Emre 2004) involving 541 patients that compared rivastigmine with placebo. Rivastigmine produced statistically significant improvements in several outcome measures. On the primary cognitive measure, the ADAS-Cog, rivastigmine was associated with a 2.80 point ADAS-Cog improvement [WMD -2.80, 95% Cl -4.26 to -1.34, P = 0.0002] and a 2.50 point ADCS-ADL improvement [95% Cl 0.43 to 4.57, P = 0.02] relative to placebo. Clinically meaningful (moderate or marked) improvement occurred in 5.3% more patients on rivastigmine, and meaningful worsening occurred in 10.1% more patients on placebo. Tolerability appeared to be a significant issue. Significantly more patients on rivastigmine dropped out of the study due to adverse events [62/362 versus 14/179, OR 2.44, 95% Cl 1.32 to 4.48, P = 0.004]. Nausea [20/179 versus 105/362, OR 3.25, 95% Cl 1.94 to 5.45, P < 0.00001], tremor [7/179 versus 37/362, OR 2.80, 95% Cl 1.22 to 6.41, P = 0.01] and in particular vomiting [3/179 versus 60/362, OR 11.66, 95% Cl 3.60 to 37.72, P < 0.0001] were significantly more common with rivastigmine. However, significantly fewer patients died on rivastigmine than placebo [4/362 versus 7/179, OR 0.27, 95% CI 0.08 to 0.95, P = 0.04] Authors' conclusions - Rivastigmine appears to improve cognition and activities of daily living in patients with PDD. This results in clinically meaningful benefit in about 15% of cases. There is a need for more studies utilising pragmatic measures such as time to residential care facility and both patient and carer quality of life assessments. Future trials should involve other cholinesterase inhibitors, utilise tools to analyse the data that limit any bias and measure health economic factors. It is unlikely that relying solely on the last observation carried forward (LOCF) is sufficient. Publication of the observed case data in the largest trial would assist (Emre 2004). Adverse events were associated with the cholinergic activity of rivastigmine, but may limit patient acceptability as evidenced by the high drop out rate in the active arm.

Pregnancy complications in hyperemesis-affected pregnancy:a large hospital database study

Objective: Vomiting in pregnancy is a common condition affecting 80% of pregnant women. Hyperemesis is at one end of the spectrum, seen in 0.5–2% of the pregnant population. Known factors such as nulliparity, younger age and high body mass indexare associated with an increased risk of this condition in the first trimester. Late pregnancy complications attributable to hyperemesis, the pathogenesis of which is poorly understood, have not been studied in large population-based studies in the United Kingdom. The objective of this study was to determine a plausible association between hyperemesis and pregnancy complications,such as pregnancy-related hypertension, gestational diabetes and liver problems in pregnancy, and the rates of elective (ElCS) and emergency caesarean section (EmCS). Methods: Using a database based on ICD-10 classification, anonymised data of admissions to a large multi-ethnic hospital in Manchester, UK between 2000 and 2012 were examined.Notwithstanding the obvious limitations with hospital database-based research, this large volume of datasets allows powerful studies of disease trends and complications.Results Between 2000 and 2012, 156 507 women aged 45 or under were admitted to hospital. Of these, 1111 women were coded for hyperemesis (0.4%). A greater proportion of women with hyperemesis than without hyperemesis were coded forhypertensive disorders in pregnancy such as pregnancy-induced hypertension, pre-eclampsia and eclampsia (2.7% vs 1.5%;P=0.001). The proportion of gestational diabetes and liver disorders in pregnancy was similar for both groups (diabetes:0.5% vs. 0.4%; P=0.945, liver disorders: 0.2% vs. 0.1%;P=0.662). Hyperemesis patients had a higher proportion of elective and emergency caesarean sections compared with the non-hyperemesis group (ElCS: 3.3% vs. 2%; P=0.002, EmCS: 5% vs.3%; P=0.00). Conclusions: There was a higher rate of emergency and elective caesarean section in women with hyperemesis, which could reflect the higher prevalence of pregnancy-related hypertensive disorders(but not diabetes or liver disorders) in this group. The factors contributing to the higher prevalence of hypertensive disorders arenot known, but these findings lead us to question whether there is a similar pathogenesis in the development of both the conditions and hence whether further study in this area is warranted.