Opposite malaria and pregnancy effect on oral bioavailability of artesunate – a population pharmacokinetic evaluation

Aim

The aim was to compare the pharmacokinetic properties of artesunate and dihydroartemisinin in the same women: i) pregnant with acute uncomplicated malaria on day 1 and 2, ii) pregnant with convalescent malaria on day 7 and iii) in a healthy state 3 months post-partum on day 1, 2 and 7.

Methods

Non-linear mixed-effects modelling was used to compare plasma concentration–time profiles of artesunate and dihydroartemisinin over 7 days of treatment following oral and intravenous artesunate administration to pregnant women with uncomplicated Plasmodium falciparum malaria during their second or third trimesters of pregnancy. The same women were restudied 3 months after delivery when fully recovered. Non-compartmental results of the same study have been published previously.

Results

Twenty pregnant patients on the Thailand-Myanmar border were studied and 15 volunteered to be restudied 3 months post-partum. Malaria and pregnancy had no effect on the pharmacokinetic properties of artesunate or dihydroartemisinin after intravenous artesunate administration. However, malaria and pregnancy had opposite effects on the absorption of orally administered artesunate. Malaria increased the absolute oral bioavailability of artesunate by 87%, presumably by inhibiting first pass effect, whereas pregnancy decreased oral bioavailability by 23%.

Conclusions

The population pharmacokinetic analysis demonstrated opposite effects of malaria and pregnancy on the bioavailability of orally administered artesunate. Lower drug exposures during the second and third trimesters of pregnancy may contribute to lower cure rates and thus the development of drug resistance. Dose optimization studies are required for artesunate containing artemisinin-based combination therapies (ACTs) in later pregnancy.     

Multidisciplinary diabetes team care: the experiences of young adults with Type 1 diabetes

Background

This research examined whether young adults with Type 1 diabetes engage with the multidisciplinary consultation process and if not, then why.

Methods

We designed a web‐based self‐reported survey, available online from February to May 2011, for Australian adults 18–35 years with Type 1 diabetes. Respondents were asked about which clinicians they consulted to assist with self‐management. To expand on the results of the survey, we interviewed 33 respondents.

Results

Survey: Respondents (n = 150) consulted with the following clinicians: endocrinologist and diabetes educators: 23.3%; endocrinologist only: 18.0%; endocrinologist, diabetes educators and dieticians: 14.6%; endocrinologist, diabetes educators, dietician and general practitioners (GP): 11.3%; endocrinologist and GP: 10.6%; GP only: 4.6%; all clinicians recommended to assist with self‐management: 1.3%; 2.7% did not consult any clinician. Interview: Participants (n = 33) reported eight key disincentives to consultation with multidisciplinary clinicians. These were time constraints; provision of conflicting advice; inaccessibility of health services; variation in service standards; cost constraints; failure of clinicians to refer to other clinicians; lack of opportunity to build a therapeutic relationship; and failure of clinicians to engage in shared decision making.

Conclusion

Our results indicate that high attrition rates of young adults with Type 1 diabetes from recommended diabetes health services is linked to the failure of those services to meet the needs and preferences of their patients. The identified needs and preferences included joint consultation with multi‐disciplinary team clinicians; flexible access to advice by email or telephone consultation; and shared decision making. Patient engagement in health‐service re‐design has implications for improved health‐service delivery and enhanced treatment outcomes.     

Pathogenesis of steatohepatitis

Understanding the pathogenesis of non-alcoholic steatohepatitis has recently assumed great importance with the recognition that it has the potential to progress to fibrosis and cirrhosis. The 'two-hit' model of pathogenesis was proposed in 1998, with the first 'hit' - steatosis - increasing the sensitivity of the liver to the second 'hits' mediating liver injury. The main aim of this chapter is to review this model in the light of studies that have been published over the subsequent 4 years. Particular attention will be focused on the role of insulin resistance and recent advances in our understanding of the basic cellular mechanisms linking obesity and insulin resistance. Based on this information I will propose a modification of the two-hit model that places more emphasis on the role of free fatty acids. This model will provide the basis for further research and enable the rational design of treatment strategies.     

Interleukin 10 promoter region polymorphisms and susceptibility to advanced alcoholic liver disease

BACKGROUND: The factors determining why less than 10% of heavy drinkers develop advanced alcoholic liver disease (ALD) remain elusive, although genetic factors may be important. Interleukin 10 (IL-10) is an important cytokine with anti-inflammatory, anti-immune, and antifibrotic functions. Several polymorphisms have been identified in the IL-10 promoter and recent evidence suggests that some of these may have functional effects on IL-10 secretion. AIMS: To test the hypothesis that IL-10 promoter region polymorphisms are associated with susceptibility to ALD. METHODS: The allele frequencies for the two single base pair substitutions at positions -627 (C-->A) and -1117 (A-->G) in the IL-10 promoter were determined in 287 heavy drinkers with biopsy proved advanced ALD, 107 heavy drinkers with no evidence of liver disease or steatosis only on biopsy, and 227 local healthy volunteers. RESULTS: At position -627, 50% of patients with advanced ALD had a least one A allele compared with 33% of controls (p<0.0001) and 34% of drinkers with no or mild disease (p=0.017). At position -1117, the slight excess of the A allele in drinkers with advanced disease was because of linkage disequilibrium between the A alleles at the two sites. CONCLUSIONS: Among heavy drinkers, possession of the A allele at position -627 in the IL-10 promoter is associated with an increased risk of advanced liver disease. This is consistent with recent functional data that the -627*A allele is associated with low IL-10 expression which will favour inflammatory, immune mediated, and profibrotic mechanisms of alcohol related liver injury.     

Late life metabolic syndrome, early growth, and common polymorphism in the growth hormone and placental lactogen gene cluster

Low rates of fetal and infant growth are associated with the metabolic syndrome and cardiovascular disease in later life. We investigated common genetic variation in the GH-CSH gene cluster on chromosome 17q23 encoding GH, placental lactogens [chorionic somatomammotropins (CSH)], and placental GH variant in relation to fetal and infant growth and phenotypic features of the metabolic syndrome in subjects aged 59-72 yr from Hertfordshire, UK. Allele groups T, D1, and D2 of a locus herein designated CSH1.01 were examined in relation to GH-CSH single nucleotide polymorphisms and to specific phenotypes. Average birth weights were similar for all genotype groups. Men with T alleles were significantly lighter at 1 yr of age, shorter as adults, and had higher blood pressures, fasting insulin (T/T 66% higher than D2/D2) and triglyceride concentrations, and insulin and glucose concentrations during a glucose tolerance test. Birth weight and 1-yr weight associations with metabolic syndrome traits were independent of the CSH1.01 effects. Common diversity in GH-CSH correlates with low 1-yr weight and with features of the metabolic syndrome in later life. GH-CSH genotype adds substantially to, but does not account for, the associations between low body weight, at birth and in infancy, and the metabolic syndrome.