Artemisinin induces omeprazole metabolism in human beings

OBJECTIVE

This study investigated whether time-dependent artemisinin pharmacokinetics correlated to CYP3A4 or CYP2C19 activity in vivo.

METHODS

Artemisinin (two oral doses per day of 250 mg) was given to nine healthy Vietnamese subjects for 7 days (day 1 to day 7). Single 20 mg doses of omeprazole were given orally on day -7, day 1, and day 7. Single doses of artemisinin and omeprazole were given in combination on day 14 after a 6-day washout period. The pharmacokinetics of artemisinin, omeprazole, hydroxyomeprazole, and omeprazole sulfone were evaluated on days -7, 1, 7, and 14. On the same days urine was collected for the determination of 6beta-hydroxycortisol and cortisol excretion.

RESULTS

Areas under plasma concentration-time curves (AUC) for artemisinin and omeprazole decreased on day 7 to 20% (95% confidence intervals, 13%, 28%) and 35% (25%, 46%), respectively, compared with values on day 1. AUC ratios for hydroxyomeprazole/omeprazole increased 2.2-fold (1.7, 2.7) on day 7 compared with values on day 1. All values were normalized at day 14. There were no significant changes in the omeprazole sulfone/omeprazole ratio or in the 6beta-hydroxycortisol/cortisol ratio between the study days. In one subject found to have poor CYP2C19 metabolization, the elimination of omeprazole increased after artemisinin exposure, with no change in the hydroxyomeprazole/omeprazole AUC ratio.

CONCLUSION

Artemisinin did not alter CYP3A4 activity, whereas an increase in CYP2C19 activity was observed. The increased elimination of omeprazole in both poor and extensive CYP2C19 metabolizers suggests artemisinin induces both CYP2C19 and another enzyme.

Artemisinin kinetics and dynamics during oral and rectal treatment of uncomplicated malaria

OBJECTIVE

To compare parasite clearance times after oral and rectal administration of artemisinin in adults with uncomplicated malaria and to relate pharmacodynamics with artemisinin kinetics and to disclose any pharmacokinetic changes during treatment.

METHODS

Thirty male Vietnamese patients with falciparum malaria were randomized to treatment with 500 mg artemisinin daily by either the oral or rectal route of administration. Parasite densities in capillary blood were determined by microscopy every 4 to 6 hours. Artemisinin plasma concentrations on the first and last day of treatment were determined by HPLC and unbound fractions in plasma were determined by ultrafiltration.

RESULTS

Mean parasite clearance times and 95% confidence intervals (95% CI) were 25 (95% CI, 16 to 33) and 29 (95% CI, 23 to 35) hours during oral and rectal treatment, respectively. The bioavailability after rectal relative to oral artemisinin was 30%. Artemisinin areas under the plasma concentration-time curve (AUC) on the fifth (last) day of oral or rectal treatment were 30% (95% CI, 4% to 56%) and 40% (95% CI, -6% to 91%), respectively, of those after the first dose. The fraction unbound in plasma was 15% (95% CI, 12% to 19%), increasing marginally during treatment. No relationship was found between main clinical end points and drug exposure, although indices for the rapidity of response onset were lower after oral treatment and correlated to unbound AUC values (rS = -0.7; p < 0.001).

CONCLUSIONS

The similarity in parasite clearance times despite lower drug levels during rectal treatment suggests that initial oral doses may be unnecessarily high. The singular time dependency of artemisinin pharmacokinetics, attributed to autoinduction of drug elimination, has possible implications for combination chemotherapy. Decreasing artemisinin concentrations during treatment may partly explain recrudescences and increase the risk for resistance development.

Psychosocial stressors and the prognosis of major depression: a test of Axis IV

BACKGROUND

Axis IV is for reporting 'psychosocial and environmental problems that may affect the diagnosis, treatment and prognosis of mental disorders'. No studies have examined the prognostic value of Axis IV in DSM-IV.

METHOD

We analyzed data from 2497 participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) with major depressive episode (MDE). We hypothesized that psychosocial stressors predict a poor prognosis of MDE. Secondarily, we hypothesized that psychosocial stressors predict a poor prognosis of anxiety and substance use disorders. Stressors were defined according to DSM-IV's taxonomy, and empirically using latent class analysis (LCA).

RESULTS

Primary support group problems, occupational problems and childhood adversity increased the risks of depressive episodes and suicidal ideation by 20-30%. Associations of the empirically derived classes of stressors with depression were larger in magnitude. Economic stressors conferred a 1.5-fold increase in risk for a depressive episode [95% confidence interval (CI) 1.2-1.9]; financial and interpersonal instability conferred a 1.3-fold increased risk of recurrent depression (95% CI 1.1-1.6). These two classes of stressors also predicted the recurrence of anxiety and substance use disorders. Stressors were not related to suicidal ideation independent from depression severity.

CONCLUSIONS

Psychosocial and environmental problems are associated with the prognosis of MDE and other Axis I disorders. Although DSM-IV's taxonomy of stressors stands to be improved, these results provide empirical support for the prognostic value of Axis IV. Future work is needed to determine the reliability of Axis IV assessments in clinical practice, and the usefulness of this information to improving the clinical course of mental disorders.

Artemisinin pharmacokinetics in healthy adults after 250, 500 and 1000 mg single oral doses

Eight healthy male, Vietnamese subjects were administered 1 x 250, 2 x 250, and 4 x 250 mg artemisinin capsules in a cross-over design with randomized sequence with a 7-day washout period between administrations. The inter-individual variability in artemisinin pharmacokinetics was large with parameter coefficient of variation (CV) typically between 50-70%. The parameter with the smallest variability was the elimination half-life (CV approximately equal to 30-40%). Analysis of variance indicated also a large intra-subject variability. (CV, or = 24%) for the dose-normalized area under the plasma concentration-time curve (AUC/dose). The pharmacokinetic results suggested artemisinin to be subject to high pre-systemic extraction. Artemisinin half-life could not predict the extent of in vivo exposure to the drug, there being no correlation between half-life and oral clearance. Artemisinin oral plasma clearance was about 400 L h-1 exhibiting a slight decrease with dose, although the effect was weak. Thus results from studies using different artemisinin doses may, within the studied dose range, be compared without the complication of disproportionate changes in drug exposure with varying dose levels. Half-lives appeared to increase with dose. An observed period effect in the analysis of variance was tentatively associated with time-dependency in artemisinin pharmacokinetics. There was a high correlation between artemisinin plasma concentrations determined at various time-points after drug administration and the AUCs after the 500 and 1000 mg doses, but less so after the 250 mg dose. This may show a tentative approach to assess the systemic exposure of the patients to artemisinin from the determination of artemisinin plasma concentrations in one or two plasma samples only. Artemisinin was well tolerated with no apparent dose or time dependent effects on blood pressure, heart rate or body temperature.

Distribution of microtubule-associated proteins (MAPs) in adult and embryonic mouse retinal explants: presence of the embryonic map, MAP5/1B, in regenerating adult retinal axons

Microtubule-associated proteins (MAPs) are developmentally regulated proteins involved in microtubule polymerization and stabilization. We have asked whether MAPs in regenerating adult mouse retinal ganglion cell axons recapitulate the pattern of MAPs seen during development. Adult and Embryonic Day 15 (E15) mouse retinal segments were explanted onto laminin-coated coverslips and allowed to extend neurites in serum-free medium. Using a variety of monoclonal antibodies (Mabs), we stained adult and E15 explant cultures for early (MAP5) and late (MAP1, MAP2, MAP2a+b, tau) MAPs. Optic neurites growing from E15 explants were strongly immunoreactive for MAP5. Labeling was absent for MAP1 and MAP2a+b. Mabs to MAP2 and tau lightly stained axons and cell bodies, probably due to MAP2c and juvenile tau which are found in developing neurons. In adult explant cultures, both perikarya and axons were immunoreactive for MAP1. MAP2 and MAP2a+b labeled perikarya and fibers within the explant, and tau stained axons on the substrate. MAP5 immunoreactivity was intense in the adult explant cultures, labeling axons extending over the substrate and perikarya and dendrites in the explant in a pattern similar to that seen in E15 explants. In summary, adult retinal explants maintain their adult complement of MAPs, in showing high levels of MAP1, tau immunoreactivity restricted to neurites on the substrate, and MAP2 segregated into neurites and perikarya within the explant. The exception is MAP5 for which the pattern of immunoreactivity is similar in adult and E15 retinal explants.

Practice variations in the management of sinusitis

OBJECTIVE

It has been shown that controlling inappropriate practice variations decreases cost, increases efficiency, and improves quality of health care. The objective of this study was to identify practice variations in the management of acute sinusitis in primary care practice and to explore possible influential factors.

DESIGN

A cross-sectional study by mail survey was conducted.

SUBJECTS

Practicing primary care physicians in the province of Quebec were selected for the study.

METHODS

A questionnaire was sent to a random sample of 500 physician members of the Quebec College of Physicians.

RESULTS

Three hundred and twenty-seven questionnaires were returned (total response rate = 65.4%), of which 53 were excluded. Two hundred and seventy-four completed surveys were then analyzed. Practice variations in the management of acute sinusitis were observed with respect to diagnostic indicators, the use of diagnostic tools and imagery, prescription of therapeutic agents, factors influencing the choice of antimicrobial agents, and the indications for referral to a specialist. Factors affecting such variations included age, gender, practice region (urban vs. rural), volume of practice, and university affiliation.

CONCLUSIONS

This survey confirms that confusion exists among primary care physicians about the recommended management of acute sinusitis, despite the recent advent of a multitude of clinical practice guidelines. These variations highlight the need for further research to clarify these issues, as well as better methods and more specific objectives for continuing medical education.