In vivo and in vitro investigations of the effects of the antimalarial drug dihydroartemisinin (DHA) on rat embryos

Nanoscale dihydroartemisinin@zeolitic imidazolate frameworks for enhanced antigiardial activity and mechanism analysis

An artificial semisynthetic material can be derived from artemisinin (ART) called dihydroartemisinin (DHA). Although DHA has enhanced antigiardial potential, its clinical application is limited because of its poor selectivity and low solubility. The drug's absorption has a direct impact on the cell, and mechanism research is limited to its destruction of the cytoskeleton. In this study, we used the zeolitic imidazolate framework-8 and loaded it with DHA (DHA@Zif-8) to improve its antigiardial potential. DHA@Zif-8 can enhance cellular uptake, increase antigiardial proliferation and encystation, and expand the endoplasmic reticulum compared with the DHA-treated group. We used RNA sequencing (RNA-seq) to investigate the antigiardial mechanism. We found that 126 genes were downregulated and 123 genes were upregulated. According to the KEGG and GO pathway analysis, the metabolic functions in G. lamblia are affected by DHA@Zif-8 NPs. We used real-time quantitative reverse transcription polymerase chain reaction to verify our results using the RNA-seq data. DHA@Zif-8 NPs significantly enhanced the eradication of the parasite from the stool in vivo. In addition, the intestinal mucosal injury caused by G. lamblia trophozoites markedly improved in the intestine. This research provided the potential of utilizing DHA@Zif-8 to develop an antiprotozoan drug for clinical applications.

A rapid spectrophotometric method to identify inhibitors of human erythropoiesis

Erythropoiesis is a complex physiological process by which erythroid progenitors proliferate and differentiate into nonnucleated red blood cells. Several methods can be used to monitor in vitro the differentiation of erythroid precursors, and hence the toxic effects of drugs, chemicals, or pollutants. One of the most commonly available assay of erythropoiesis is the microscopic observation of differentiated cells after benzidine staining, which forms a blue complex with hemoglobin. However, this method is laborious and does not provide accurate results since it heavily relies on the reader's interpretation. Moreover, benzidine is a carcinogen and a highly reactive molecule which forces the reader to microscopically count differentiated and non-differentiated cells within a short time frame (5 min). Here we have developed a simple, inexpensive, in-vitro spectrophotometric assay to measure erythroid differentiation using K562 cell line as a model. Materials needed included 96-well round-bottomed microplates and a microplate reader. Remarkably, carcinogenic benzidine was replaced by its isomeric tetramethyl derivative, the 3,3', 5,5'- tetramethylbenzidine (TMB), which presents several advantages: it is cheap, not mutagenic and a ready-to-use chromogenic substrate. A small volume (50 μl) of TMB added to the samples forms a blue complex in 15 min, and the reaction can be easily stopped and stabilized by the addition of H₂SO₄. The yellow precipitate is then solubilized, and the absorbance is measured at 450 nm. In addition, the suitability of the assay to determine the effects of compounds on erythroid differentiation was further tested with known inhibitors (artemisinin derivatives) of K562 differentiation. Overall, the reported methodology permits to measure in an accurate and reproducible manner the K562 differentiation and can be used for medium throughput screenings (MTS) of compounds or environmental toxics with potential erythro-toxicity and ability to inhibit erythroid differentiation.

A tablet derived from Andrographis paniculata complements dihydroartemisinin-piperaquine treatment of malaria in pregnant mice

OBJECTIVES

The use of standard antimalarial drugs, such as dihydroartemisinin-piperaquine (DHP) for the treatment of malaria during pregnancy is limited due to the risk of teratogenicity. The alternative is therefore required although few exist. Here we show a phytopharmaceutical drug derived from Andrographis paniculata (AS201-01), which is effective as herbal antimalarial both in vitro and in vivo and may be a suitable alternative when used in complementary treatment with DHP.

METHODS

Plasmodium berghei infected pregnant BALB/c mice were divided into four groups: G1 (negative control), G2 (AS201-01), G3 (DHP), and G4 (combination of DHP and AS201-01). Pheripheral blood was collected during therapy for counting parasitemia. Placental samples were analyzed for the expression of IFN-γ, TNF- α, IL-10, placental parasite counts and foetal morphology.

RESULTS

Groups G4 and G3 both showed a 100% inhibition of peripheral parasitemia. However, the treatment in G4 was found to be less effective than that in G2 and G3 in preventing placental parasitemia. The G4 treatment was able to reduce the expression of IFN-γ and IL-10, whereas TNF-α was not significantly different from the control group. Foetal morphologic abnormalities were observed in all groups except G2; G4 showed lower percentage of abnormalities compared to G3 and G1.

CONCLUSIONS

A combination of A. paniculata tablet (AS201-01) with DHP has the potential to reduce the toxicity of DHP in malaria treatment.

Different effects of an N-phenylimide herbicide on heme biosynthesis between human and rat erythroid cells

Rat developmental toxicity including embryolethality and teratogenicity (mainly ventricular septal defects and wavy ribs) were produced by S-53482, an N-phenylimide herbicide that inhibits protoporphyrinogen oxidase (PPO) common to chlorophyll and heme biosynthesis. The sequence of key biological events in the mode of action has been elucidated as follows: inhibition of PPO interferes with normal heme synthesis, which causes loss of blood cells leading to fetal anemia, embryolethality and the development of malformations. In this study we investigated whether the rat is a relevant model for the assessment of the human hazard of the herbicide. To study effects on heme biosynthesis, human erythroleukemia, human cord blood, and rat erythroleukemia cells were treated with the herbicide during red cell differentiation. Protoporphyrin IX, a marker of PPO inhibition, and heme were determined. We investigated whether synchronous maturation of primitive erythropoiesis, which can contribute to massive losses of embryonic blood, occurs in rats. The population of primitive erythroblasts was observed on gestational days 11 through 14. Heme production was suppressed in rat erythroid cells. In contrast, heme reduction was not seen in both human erythroid cells when PPO was inhibited. Rats underwent synchronous maturation in primitive erythropoiesis. Our results combined with epidemiological findings that patients with deficient PPO are not anemic led us to conclude that human erythroblasts are resistant to the herbicide. It is suggested that the rat would be an inappropriate model for assessing the developmental toxicity of S-53482 in humans as rats are specifically sensitive to PPO inhibition by the herbicide.

Phytochemistry and pharmacological activity of the genus artemisia

Artemisia and its allied species have been employed for conventional medicine in the Northern temperate regions of North America, Europe, and Asia for the treatments of digestive problems, morning sickness, irregular menstrual cycle, typhoid, epilepsy, renal problems, bronchitis malaria, etc. The multidisciplinary use of artemisia species has various other health benefits that are related to its traditional and modern pharmaceutical perspectives. The main objective of this review is to evaluate the traditional, modern, biological as well as pharmacological use of the essential oil and herbal extracts of Artemisia nilagirica, Artemisia parviflora, and other allied species of Artemisia. It also discusses the botanical circulation and its phytochemical constituents viz disaccharides, polysaccharides, glycosides, saponins, terpenoids, flavonoids, and carotenoids. The plants have different biological importance like antiparasitic, antimalarial, antihyperlipidemic, antiasthmatic, antiepileptic, antitubercular, antihypertensive, antidiabetic, anxiolytic, antiemetic, antidepressant, anticancer, hepatoprotective, gastroprotective, insecticidal, antiviral activities, and also against COVID-19. Toxicological studies showed that the plants at a low dose and short duration are non or low-toxic. In contrast, a high dose at 3 g/kg and for a longer duration can cause toxicity like rapid respiration, neurotoxicity, reproductive toxicity, etc. However, further in-depth studies are needed to determine the medicinal uses, clinical efficacy and safety are crucial next steps.

Teratogen update: Malaria in pregnancy and the use of antimalarial drugs in the first trimester

Malaria is a particular problem in pregnancy because of enhanced sensitivity, the possibility of placental malaria, and adverse effects on pregnancy outcome. Artemisinin-containing combination therapies (ACTs) are the most effective antimalarials known. WHO recommends 7-day quinine therapy for uncomplicated Plasmodium falciparum malaria in the first trimester despite the superior tolerability and efficacy of 3-day ACT regimens because artemisinins caused embryolethality and/or cardiovascular malformations at relatively low doses in rats, rabbits, and monkeys. The developmental toxicity of artesunate, artemether, and DHA were similar in rats but artesunate was embryotoxic at lower doses in rabbits (5 mg/kg/day) than artemether (no effect level = 25 mg/kg/day). In clinical studies in Africa, treatment with artemether-lumefantrine in the first trimester was observed to be highly efficacious and the miscarriage rate (≤3.1%) was similar to no antimalarial treatment (2.6%). When data from the first-trimester use of largely artesunate-based therapies in Thailand were pooled together, there was no difference in miscarriage rate compared to quinine. However, individually, artesunate-mefloquine was associated with a higher miscarriage rate (15/71 = 21%) compared to other artemisinin-based therapies including 7-day artesunate + clindamycin (2/50 = 4%) and quinine (92/842 = 11%). Thus, appropriate statistical comparisons of individual ACT groups are needed prior to assuming that they all have the same risk for developmental toxicity. Current limitations in the assessment of the safety of ACTs in the first trimester are a lack of exposures early in gestation (gestational weeks 6-7), limited postnatal evaluation for cardiovascular malformations, and the pooling of all ACTs for the assessment of risk.

Safety of Artemisinin Derivatives in the First Trimester of Pregnancy: A Controversial Story

Artemisinin combination therapy (ACT) is recommended by the World Health Organization (WHO) as first line treatment for uncomplicated malaria both in adults and children. During pregnancy, ACT is considered safe only in the second and third trimester, since animal studies have demonstrated that artemisinin derivatives can cause foetal death and congenital malformation within a narrow time window in early embryogenesis. During this period, artemisinin derivatives induce defective embryonic erythropoiesis and vasculogenesis/angiogenesis in experimental models. However, clinical data on the safety profile of ACT in pregnant women have not shown an increased risk of miscarriage, stillbirth, or congenital malformation, nor low birth weight, associated with exposure to artemisinins in the first trimester. Although further studies are needed, the evidence collected up to now is prompting the WHO towards a change in the guidelines for the treatment of uncomplicated malaria, allowing the use of ACT also in the first trimester of pregnancy.

Dihydroartemisinin exposure impairs porcine ovarian granulosa cells by activating PERK-eIF2α-ATF4 through endoplasmic reticulum stress

Dihydroartemisinin (DHA) is an artemisinin derivative commonly used in malaria therapy, and a growing number of studies have focused on the potent anticancer activity of DHA. However, the reproductive toxicity of anticancer drugs is a major concern for young female cancer patients. Previous studies have suggested that DHA can cause embryonic damage and affect oocyte maturation. Here, we explored the side effects of DHA exposure on ovarian somatic cells. We exposed porcine granulosa cells to 5 μM and 40 μM DHA for 24 h or 48 h in vitro. DHA inhibited granulosa cell viability in a dose-dependent manner and, in the 48 h treatment group, DHA enhanced the apoptotic rate. We observed that the levels of intracellular calcium, mitochondrial calcium, and ATP concentration were elevated with DHA treatment. In granulosa cells exposed to DHA, the mRNA levels of endoplasmic reticulum stress-related genes GRP78 and ATF4 were increased. Furthermore, analysis of the unfolded protein response signaling pathway showed that the protein levels of P-PERK, P-eIF2α, and ATF4 were upregulated by DHA exposure. These results demonstrate that in granulosa cells, DHA exposure induces endoplasmic reticulum stress that then activates the PERK/eIF2α/ATF4 signaling pathway, thus providing insight into the mechanism underlying DHA-induced reproductive toxicity, and giving reference to DHA use in females.

Systematic review of artemisinin embryotoxicity in animals: Implications for malaria control in human pregnancy

Pregnant women are one of the most susceptible and vulnerable groups to malaria, the most important parasitic disease worldwide. Artemisinin-based combination therapies (ACTs) are recommended for the treatment of uncomplicated malaria in all population groups including pregnant women. However, due to the embryotoxicity observed in animal studies, ACTs have long been contraindicated during the first trimester in pregnant women. Despite the safety concerns raised in pre-clinical studies, recent findings on ACTs's use in pregnant women appear to be reassuring regarding safety and have prompted a revision of malaria treatment guidelines for first trimester of pregnancy. To contribute to the risk-benefit assessment of ACTs, we conducted a systematic literature review of animal studies published between 2007 and 2019, which evaluated the embryotoxic effects of artemisinin and its derivatives among pregnant mammals. Eighteen experimental studies fitted the inclusion criteria. These studies confirmed and further characterized the severe embryolethal and embryotoxic dose-dependent effects of artemisinin and its derivatives when administered during the organogenesis period in rats, rabbits and monkeys. Timing of administration and dosage of the drug were found to be key factors in the appearance of embryo damage. Overall, the translation of the findings of artemisinin derivatives use in animal studies to pregnant women remains disturbing. Thus, a policy change in the use of ACTs during the first trimester in pregnant women for the treatment of uncomplicated malaria does not seem pertinent and if implemented, it should be accompanied by solid pharmacovigilance systems, which are challenging to establish in malaria endemic countries.

First trimester use of artemisinin-based combination therapy and the risk of low birth weight and small for gestational age

Background

While there is increasing evidence on the safety of artemisinin-based combination therapy (ACT) for the case management of malaria in early pregnancy, little is known about the association between exposure to ACT during the first trimester and the effect on fetal growth.

Methods

Data were analysed from prospective studies of pregnant women enrolled in Mozambique, Burkina Faso and Kenya designed to determine the association between anti-malarial drug exposure in the first trimester and pregnancy outcomes, including low birth weight (LBW) and small for gestational age (SGA). Exposure to anti-malarial drugs was ascertained retrospectively by record linkage using a combination of data collected from antenatal and adult outpatient clinic registries, prescription records and self-reported medication usage by the women. Site-level data synthesis (fixed effects and random effects) was conducted as well as individual-level analysis (fixed effects by site).

Results

Overall, 1915 newborns were included with 92 and 26 exposed to ACT (artemether–lumefantrine) and quinine, respectively. In Burkina Faso, Mozambique and Kenya at recruitment, the mean age (standard deviation) was 27.1 (6.6), 24.2 (6.2) and 25.7 (6.5) years, and the mean gestational age was 24.0 (6.2), 21.2 (5.7) and 17.9 (10.2) weeks, respectively. The LBW prevalence among newborns born to women exposed to ACT and quinine (QNN) during the first trimester was 10/92 (10.9%) and 7/26 (26.9%), respectively, compared to 9.5% (171/1797) among women unexposed to any anti-malarials during pregnancy. Compared to those unexposed to anti-malarials, ACT and QNN exposed women had the pooled LBW prevalence ratio (PR) of 1.13 (95% confidence interval (CI) 0.62–2.05, p-value 0.700) and 2.03 (95% CI 1.09–3.78, p-value 0.027), respectively. Compared to those unexposed to anti-malarials ACT and QNN-exposed women had the pooled SGA PR of 0.85 (95% CI 0.50–1.44, p-value 0.543) and 1.41 (95% CI 0.71–2.77, p-value 0.322), respectively. Whereas compared to ACT-exposed, the QNN-exposed had a PR of 2.14 (95% CI 0.78–5.89, p-value 0.142) for LBW and 8.60 (95% CI 1.29–57.6, p-value 0.027) for SGA. The level of between sites heterogeneity was moderate to high.

Conclusion

ACT exposure during the first trimester was not associated with an increased occurrence of LBW or SGA. However, the data suggest a higher prevalence of LBW and SGA for children born to QNN-exposed pregnancies. The findings support the use of ACT (artemether–lumefantrine) for the treatment of uncomplicated malaria during the first trimester of pregnancy.

Maternal and fetal outcome of pregnancy in Swiss mice infected with Plasmodium berghei ANKAGFP

Malaria in pregnant women is associated with risk of maternal and perinatal morbidity and mortality, and there are few antimalarial drugs considered safe to treat them, so it is necessary to develop safer antimalarial medicines. The goal of this study was to develop an animal model for human malaria during pregnancy by characterizing the maternal and fetal outcomes in malaria infected Swiss mice. For that, in the present study, we evaluated the outcome of pregnancy in Swiss mice infected with Plasmodium berghei ANKA^GFP. We observed a reduction of fetal body weight and signs of skeletal ossification retardation in the offspring of mice infected on GD 12. The group of mice infected with malaria presented premature deliveries and histopathology changes consistent with placental malaria. Our study suggests that Swiss Webster mice infected with P. berghei ANKA^GFP on GD 12 might be a valuable model to investigate the safety and the efficacy of new antimalarial drugs indicated to pregnant women.

Dihydroartemisinin enhances VEGFR1 expression through up-regulation of ETS-1 transcription factor

Angiogenesis is required for tumor growth. Dihydroartemisinin (DHA), a the effective anti-malarial derivative of artemisinin, demonstrated potent anti-angiogenic activities that closely related to the regulation of vascular endothelial growth factor (VEGF) signaling cascade. VEGF receptor 1 (VEGFR1), a receptor in endothelial cells (ECs), coordinately regulate angiogenic activity triggered by ligand-receptor binding. Here we aimed to explore the effects of DHA on VEGFR1 expression in ECs. We found that DHA significantly increases VEGFR1 expression in human umbilical vein endothelial cells (HUVECs). In addition, DHA significantly upregulates the level of V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 1 (ETS-1), a transcriptional factor which binds to the human VEGFR1 promoter. ChIP assay showed that DHA increases ETS-1 binding to the -52 ETS motif on the VEGFR1 promoter. Knockdown of ETS-1 by RNA interference abolished DHA-induced increase of VEGFR1 expression. Taken together, we demonstrated that DHA elevates VEGFR1 expression via up-regulation of ETS-1 transcription in HUVECs.

Developmental toxicity studies of lumefantrine and artemether in rats and rabbits

The combination of artemether plus lumefantrine is a type of artemisinin-based combination therapy (ACT) recommended by the World Health Organization for uncomplicated falciparum malaria except in the first trimester of pregnancy. The first trimester restriction was based on the marked embryotoxicity in animals (including embryo death and cardiac and skeletal malformations) of artemisinins such as artesunate, dihydroartemisinin, and artemether. Before recommending ACTs for use in the first trimester, the World Health Organization has requested that all information relevant to the assessment of risk of ACTs to the embryo be made available to the public. This report describes the results of embryo-fetal development studies of artemether alone, lumefantrine alone, and the combination in rats and rabbits as well as toxicokinetic studies of lumefantrine in pregnant rabbits. The developmental no-effect levels for lumefantrine were 300 mg/kg/day in rats (based on a 25% decrease in litter size at 1000 mg/kg/day) and 1000 mg/kg/day in rabbits. The calculated safety margins based on human equivalent dose and plasma C_max and AUC values were in the range of 2.5- to 17-fold. The developmental no-effect levels for artemether were 3 mg/kg/day in rats and 25 mg/kg/day in rabbits. Lumefantrine caused no teratogenicity and was not a potent embryotoxin in rats and rabbits. Expected artemisinin-like findings were seen with artemether alone and with artemether/lumefantrine combined except that no malformations were observed. There were no findings in pregnant rats and rabbits that would cause increased concern for the use of artemether-lumefantrine in the first trimester compared to other ACTs.

First-trimester artemisinin derivatives and quinine treatments and the risk of adverse pregnancy outcomes in Africa and Asia: A meta-analysis of observational studies

BACKGROUND

Animal embryotoxicity data, and the scarcity of safety data in human pregnancies, have prevented artemisinin derivatives from being recommended for malaria treatment in the first trimester except in lifesaving circumstances. We conducted a meta-analysis of prospective observational studies comparing the risk of miscarriage, stillbirth, and major congenital anomaly (primary outcomes) among first-trimester pregnancies treated with artemisinin derivatives versus quinine or no antimalarial treatment.

METHODS AND FINDINGS

Electronic databases including Medline, Embase, and Malaria in Pregnancy Library were searched, and investigators contacted. Five studies involving 30,618 pregnancies were included; four from sub-Saharan Africa (n = 6,666 pregnancies, six sites) and one from Thailand (n = 23,952). Antimalarial exposures were ascertained by self-report or active detection and confirmed by prescriptions, clinic cards, and outpatient registers. Cox proportional hazards models, accounting for time under observation and gestational age at enrollment, were used to calculate hazard ratios. Individual participant data (IPD) meta-analysis was used to combine the African studies, and the results were then combined with those from Thailand using aggregated data meta-analysis with a random effects model. There was no difference in the risk of miscarriage associated with the use of artemisinins anytime during the first trimester (n = 37/671) compared with quinine (n = 96/945; adjusted hazard ratio [aHR] = 0.73 [95% CI 0.44, 1.21], I2 = 0%, p = 0.228), in the risk of stillbirth (artemisinins, n = 10/654; quinine, n = 11/615; aHR = 0.29 [95% CI 0.08-1.02], p = 0.053), or in the risk of miscarriage and stillbirth combined (pregnancy loss) (aHR = 0.58 [95% CI 0.36-1.02], p = 0.099). The corresponding risks of miscarriage, stillbirth, and pregnancy loss in a sensitivity analysis restricted to artemisinin exposures during the embryo sensitive period (6-12 wk gestation) were as follows: aHR = 1.04 (95% CI 0.54-2.01), I2 = 0%, p = 0.910; aHR = 0.73 (95% CI 0.26-2.06), p = 0.551; and aHR = 0.98 (95% CI 0.52-2.04), p = 0.603. The prevalence of major congenital anomalies was similar for first-trimester artemisinin (1.5% [95% CI 0.6%-3.5%]) and quinine exposures (1.2% [95% CI 0.6%-2.4%]). Key limitations of the study include the inability to control for confounding by indication in the African studies, the paucity of data on potential confounders, the limited statistical power to detect differences in congenital anomalies, and the lack of assessment of cardiovascular defects in newborns.

CONCLUSIONS

Compared to quinine, artemisinin treatment in the first trimester was not associated with an increased risk of miscarriage or stillbirth. While the data are limited, they indicate no difference in the prevalence of major congenital anomalies between treatment groups. The benefits of 3-d artemisinin combination therapy regimens to treat malaria in early pregnancy are likely to outweigh the adverse outcomes of partially treated malaria, which can occur with oral quinine because of the known poor adherence to 7-d regimens.

REVIEW REGISTRATION

PROSPERO CRD42015032371.

Clinical and non-clinical safety of artemisinin derivatives in pregnancy

Malaria in pregnancy is a clinically wasting infectious disease, where drug therapy has to be promptly initiated. Currently, the treatment of this infection depends on the use of artemisinin derivatives. The World Health Organization does not recommend the use of these drugs in the first trimester of pregnancy due to non-clinical findings that have shown embryolethality and teratogenic effects. Nevertheless, until now, this toxicity has not been proved in humans. Artemisinin derivatives mechanisms of embryotoxicity are related to depletion of circulating embryonic primitive erythroblasts. Species differences in this sensitive period for toxicity and the presence of malaria infection, which could reduce drug distribution to the fetus, are significant to the risk assessment of artemisinin derivatives treatment to pregnant women. In this review we aimed to assess the results of non-clinical and clinical studies with artemisinin derivatives, their mechanisms of embryotoxicity and discuss the safety of their use during pregnancy.

Mechanism of Developmental Effects in Rats Caused by an N-Phenylimide Herbicide: Transient Fetal Anemia and Sequelae during Mid-to-Late Gestation

BACKGROUND

Rat developmental toxicity including embryolethality and teratogenicity (mainly ventricular septal defects [VSDs] and wavy ribs) was produced by an N-phenylimide herbicide that inhibits protoporphyrinogen oxidase (PPO) common to chlorophyll and heme biosynthesis. Major characteristics of the developmental toxicity included species difference between rats and rabbits, compound-specific difference among structurally similar herbicides, and sensitive period. Protoporphyrin accumulation in treated fetuses closely correlated with the major characteristics. Iron deposits in erythroblastic mitochondria and degeneration of erythroblasts were observed in treated rat fetuses. In this study we investigated fetal anemia and subsequent developmental effects in rats, and inhibition of PPO in rats, rabbits, and humans by the herbicides in vitro.

METHODS

Fetuses were treated on gestational day (GD) 12 and removed on GDs 13 through 20. All litters were examined externally. One half of litters were examined for blood and skeletal development, and the other half for interventricular foramen closure. Effects on PPO were determined in mitochondria from embryos and adult livers.

RESULTS

Fetal anemia in rats was evident on GDs 13 through 16. Subsequently, enlarged heart, delayed closure of the foramen, reduced serum protein, and retarded rib ossification were observed. In vitro PPO inhibition exhibited species- and compound-specific differences corresponding to the developmental toxicity.

CONCLUSION

We propose that developmental toxicity results from PPO inhibition in primitive erythroblasts, causing transient fetal anemia followed by death. Compensatory enlargement of the fetal heart results in failure of interventricular foramen closure and VSD. Reduced serum protein leads to delayed ossification and wavy ribs.

Dihydroartemisinin targets VEGFR2 via the NF-κB pathway in endothelial cells to inhibit angiogenesis

The anti-malarial agent dihydroartemisinin (DHA) has strong anti-angiogenic activity. This study aimed to investigate the molecular mechanism underlying this effect of DHA on angiogenesis. We found that DHA shows a dose-dependent inhibition of proliferation and migration of in HUVECs. DHA specifically down-regulates the mRNA and protein expression of VEGFR2 in endothelial cells. Treatment with DHA increases IκB-α protein and blocks nuclear translocation of NF-κB p65. In addition, DHA directly regulates VEGFR2 promoter activity through p65 binding motif, and decreases the binding activity of p65 and VEGFR2 promoter, suggesting defective NF-κB signaling may underlie the observed effects of DHA on VEGFR2 expression. In the presence of the NF-κB inhibitor PDTC, DHA could not further repress VEGFR2. Co-treatment with PDTC and DHA produced minimal changes compared to the effects of either drug alone in in vitro angiogenesis assays. Similar findings were found in vivo through a mouse retinal neovascularization model examining the effects of PDTC and DHA. Our data suggested that DHA inhibits angiogenesis largely through repression of the NF-κB pathway. DHA is well tolerated, and therefore may be an ideal candidate to use clinically as an angiogenesis inhibitor for cancer treatment.

Imported malaria in pregnant women: A retrospective pooled analysis

BACKGROUND

Data on imported malaria in pregnant women are scarce.

METHOD

A retrospective, descriptive study of pooled data on imported malaria in pregnancy was done using data from 1991 to 2014 from 8 different collaborators in Europe, the United States and Japan. National malaria reference centres as well as specialists on this topic were asked to search their archives for cases of imported malaria in pregnancy. A total of 631 cases were collated, providing information on Plasmodium species, region of acquisition, nationality, country of residence, reason for travel, age, gestational age, prophylactic measures and treatment used, as well as on complications and outcomes in mother and child.

RESULTS

Datasets from some sources were incomplete. The predominant Plasmodium species was P. falciparum (78.5% of cases). Among the 542 cases where information on the use of chemoprophylaxis was known, 464 (85.6%) did not use chemoprophylaxis. The main reason for travelling was "visiting friends and relatives" VFR (57.8%) and overall, most cases of malaria were imported from West Africa (57.4%). Severe anaemia was the most frequent complication in the mother. Data on offspring outcome were limited, but spontaneous abortion was a frequently reported foetal outcome (n = 14). A total of 50 different variants of malaria treatment regimens were reported.

CONCLUSIONS

Imported cases of malaria in pregnancy are mainly P. falciparum acquired in sub-Saharan Africa. Malaria prevention and treatment in pregnant travellers is a challenge for travel medicine due to few data on medication safety and maternal and foetal outcomes. International, collaborative efforts are needed to capture standardized data on imported malaria cases in pregnant women.

A bibliometric analysis of research productivity of Malaysian publications in leading toxicology journals during a 10-year period (2003-2012)

BACKGROUND

Toxicology in Malaysia has experienced rapid development and made great progress in education and research in conjunction with economic development in Malaysia over the past two decades.

OBJECTIVES

The main objectives of this study were to analyse the research originating from Malaysia and published in toxicology journals and to examine the authorship pattern and the citations retrieved from the Scopus database.

METHODS

Data from 1 January 2003 till 31 December 2012 were searched for documents with specific words in the toxicology field as a 'source title' and Malaysia as an affiliation country. Research productivity was evaluated based on a methodology we developed and used in other bibliometric studies by analysing: (a) total and trends of contributions in toxicology fields between 2003 and 2012; (b) Malaysian authorship pattern and productivity; (c) collaboration patterns; (d) journals in which Malaysian researchers publish; (e) the classification of journals to Institute for Scientific Information (ISI) or non-ISI; (f) impact factors (IFs) of all publications; and (g) citations received by the publications.

RESULTS

In total, 290 documents were retrieved from 55 international peer-reviewed toxicology journals. The quantity of publication increased by around 10-fold from 2003 to 2012. The h-index of the retrieved documents was 20. Of the 55 journal titles, 42 (76.4%) have their IF listed in the journal citation reports 2012. Forty-two documents (14.5%) were published in journals that had no official IF. The total number of citations, at the time of manuscript writing (5 August 2013), was 1707, with a median (interquartile range) of 3 (0-7). Malaysia collaborated mostly with countries in the Asia-Pacific regions (18.3%), especially India and Japan, followed by the Middle East and Africa (10.0%), especially Palestine and Yemen.

CONCLUSION

The present data show a promising rise and a good start for toxicology research activity in Malaysia. The sharing of relevant research questions by developed and developing countries can lead to research opportunities in the field of toxicology.

Malaria: an update on current chemotherapy

INTRODUCTION

Chemotherapy of malaria has become a rapidly changing field. Less than two decades ago, treatment regimens were increasingly bound to fail due to emerging drug resistance against 4-aminoquinolines and sulfa compounds. By now, artemisinin-based combination therapies (ACTs) constitute the standard of care for uncomplicated falciparum malaria and are increasingly also taken into consideration for the treatment of non-falciparum malaria.

AREAS COVERED

This narrative review provides an overview of the state-of-art antimalarial drug therapy, highlights the global portfolio of current Phase III/IV clinical trials and summarizes current developments.

EXPERT OPINION

Malaria chemotherapy remains a dynamic field, with novel drugs and drug combinations continuing to emerge in order to outpace the development of large-scale drug resistance against the currently most important drug class, the artemisinin derivatives. More randomized controlled studies are urgently needed especially for the treatment of malaria in first trimester pregnant women. ACTs should be used for the treatment of imported malaria more consequently. Gaining sufficient efficacy and safety information on ACT use for non-falciparum species including Plasmodium ovale and malariae should be a research priority. Continuous investment into malaria drug development is a vital factor to combat artemisinin resistance and successfully improve malaria control toward the ultimate goal of elimination.

Artemisinin induces hormonal imbalance and oxidative damage in the erythrocytes and uterus but not in the ovary of rats

Artemisinin is an antimalarial drug previously reported to induce neurotoxicity and embryotoxicity in animal models. This study investigated the erythrocytes and reproductive toxicity potentials of artemisinin in female rats. Animals were randomly divided into four study groups of eight rats each. The control group (group I) received corn oil, the vehicle, while groups II-IV were orally exposed to 7, 35 and 70 mg kg(-1) day(-1) of artemisinin, respectively, by gastric intubation for 7 consecutive days. Subsequently, we evaluated the impact of artemisinin on the endocrine environment and selected markers of oxidative damage and antioxidant status of the erythrocytes, ovary and uterus. Artemisinin significantly increased hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels and decreased catalase, glutathione peroxidase and superoxide dismutase activities in erythrocytes and uterus of rats compared with control group (p < 0.05). However, artemisinin did not alter ovarian MDA, H2O2, glutathione levels and catalase activity, while ovarian and uterine histological assessment revealed absence of visible lesions. Moreover, artemisinin significantly decreased follicle-stimulating hormone and increased progesterone levels compared with control (p < 0.05). Thus, these data suggest that in the absence of malarial parasite infection, artemisinin induced hormonal imbalance and oxidative damage in the erythrocytes and uterus but spared the ovary of rats.

Dihydroartemisinin promotes angiogenesis during the early embryonic development of zebrafish

AIM

To investigate the embryotoxicity of dihydroartemisinin (DHA), the main active metabolite of artemisinin, in zebrafish, and explore the corresponding mechanisms.

METHODS

The embryos of wild type and TG (flk1:GFP) transgenic zebrafish were exposed to DHA. Developmental phenotypes of the embryos were observed. Development of blood vessels was directly observed in living embryos of TG (flk1:GFP) transgenic zebrafish under fluorescence microscope. The expression of angiogenesis marker genes vegfa, flk1, and flt1 in the embryos was detected using real-time PCR and RNA in situ hybridization assays.

RESULTS

Exposure to DHA (1-10 mg/L) dose-dependently caused abnormal zebrafish embryonic phenotypes in the early developmental stage. Furthermore, exposure to DHA (10 mg/L) resulted in more pronounced embryonic angiogenesis in TG (flk1:GFP) zebrafish line. Exposure to DHA (10 mg/L) significantly increased the mRNA expression of vegfa, flk1, and flt1 in the embryos. Knockdown of the flk1 protein partially blocked the effects of DHA on embryogenesis.

CONCLUSION

DHA causes abnormal embryonic phenotypes and promotes angiogenesis in zebrafish early embryonic development, demonstrating the potential embryotoxicity of DHA.

Effects of the combined artesunate and mefloquine antimalarial drugs on rat embryos

Artemisinins combination therapy (ACT) is the first choice therapy for falciparum malaria. Data on the safety of ACTs in pregnancy are limited and controversial and the use is not recommended on the first trimester. To evaluate the effects of isolated and combined artesunate (AS)/mefloquine (MQ) on embryo rats, pregnant rats were treated orally with AS (15 and 40 mg/kg body weight (bwt)/day), MQ (30 and 80 mg/kg bwt/day) and AS/MQ (15/30 and 40/80 mg/kg bwt/day) on days 9–11 post coitum (pc). The dams were euthanized on day 12 pc and gestational and embryos histological parameters were evaluated. Embryolethality and histopathological anomalies were significant when AS was given alone or combined with MQ. Combination of AS and MQ did not enhance their toxicity compared to their separate administrations; on the other side, there was a reduction in the toxic effects of the AS when combined with MQ. Isolated MQ did not induce developmental toxicity.

Study on the developmental toxicity of combined artesunate and mefloquine antimalarial drugs on rats

Antimalarial drug combinations containing artemisinins (ACTs) have become first choice therapies for Plasmodium falciparum malaria. Data on safety of ACTs in pregnancy are limited and no previous study has been conducted on the developmental toxicity of artesunate-mefloquine combinations on the first trimester of gestation. To evaluate the developmental toxicity of an artesunate/mefloquine combination, pregnant rats were treated orally with artesunate (15 and 40 mg/kg bwt/day), mefloquine (30 and 80 mg/kg bwt/day) and artesunate/mefloquine (15/30 and 40/80 mg/kg bwt/day) on gestation days 9-11. Dams were C-sectioned on day 20, and their uteri and fetuses removed and examined for soft tissue and skeleton abnormalities. Artesunate increased embryolethality and the incidence of limb long bone malformations on the absence of overt maternal toxicity. Mefloquine (80 mg/kg bwt/day) was maternally toxic and enhanced fetal variations. Combination of artesunate and mefloquine did not enhance their toxicity compared to the toxicity observed after its separate administration. Embryotoxicity of artesunate was apparently attenuated when it is co-administered with mefloquine.

Review of current and "omics" methods for assessing the toxicity (genotoxicity, teratogenicity and nephrotoxicity) of herbal medicines and mushrooms

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing use of traditional herbal medicines around the world requires more scientific evidence for their putative harmlessness. To this end, a plethora of methods exist, more or less satisfying. In this post-genome era, recent reviews are however scarce, not only on the use of new "omics" methods (transcriptomics, proteomics, metabonomics) for genotoxicity, teratogenicity, and nephrotoxicity assessment, but also on conventional ones.

METHODS

The present work aims (i) to review conventional methods used to assess genotoxicity, teratogenicity and nephrotoxicity of medicinal plants and mushrooms; (ii) to report recent progress in the use of "omics" technologies in this field; (iii) to underline advantages and limitations of promising methods; and lastly (iv) to suggest ways whereby the genotoxicity, teratogenicity, and nephrotoxicity assessment of traditional herbal medicines could be more predictive.

RESULTS

Literature and safety reports show that structural alerts, in silico and classical in vitro and in vivo predictive methods are often used. The current trend to develop "omics" technologies to assess genotoxicity, teratogenicity and nephrotoxicity is promising but most often relies on methods that are still not standardized and validated.

CONCLUSION

Hence, it is critical that toxicologists in industry, regulatory agencies and academic institutions develop a consensus, based on rigorous methods, about the reliability and interpretation of endpoints. It will also be important to regulate the integration of conventional methods for toxicity assessments with new "omics" technologies.

Adverse effects of falciparum and vivax malaria and the safety of antimalarial treatment in early pregnancy: a population-based study

Background

The effects of malaria and its treatment in the first trimester of pregnancy remain an area of concern. We aimed to assess the outcome of malaria-exposed and malaria-unexposed first-trimester pregnancies of women from the Thai–Burmese border and compare outcomes after chloroquine-based, quinine-based, or artemisinin-based treatments.

Methods

We analysed all antenatal records of women in the first trimester of pregnancy attending Shoklo Malaria Research Unit antenatal clinics from May 12, 1986, to Oct 31, 2010. Women without malaria in pregnancy were compared with those who had a single episode of malaria in the first trimester. The association between malaria and miscarriage was estimated using multivariable logistic regression.

Findings

Of 48 426 pregnant women, 17 613 (36%) met the inclusion criteria: 16 668 (95%) had no malaria during the pregnancy and 945 (5%) had a single episode in the first trimester. The odds of miscarriage increased in women with asymptomatic malaria (adjusted odds ratio 2·70, 95% CI 2·04–3·59) and symptomatic malaria (3·99, 3·10–5·13), and were similar for Plasmodium falciparum and Plasmodium vivax. Other risk factors for miscarriage included smoking, maternal age, previous miscarriage, and non-malaria febrile illness. In women with malaria, additional risk factors for miscarriage included severe or hyperparasitaemic malaria (adjusted odds ratio 3·63, 95% CI 1·15–11·46) and parasitaemia (1·49, 1·25–1·78 for each ten-fold increase in parasitaemia). Higher gestational age at the time of infection was protective (adjusted odds ratio 0·86, 95% CI 0·81–0·91). The risk of miscarriage was similar for women treated with chloroquine (92 [26%] of 354), quinine (95 [27%) of 355), or artesunate (20 [31%] of 64; p=0·71). Adverse effects related to antimalarial treatment were not observed.

Interpretation

A single episode of falciparum or vivax malaria in the first trimester of pregnancy can cause miscarriage. No additional toxic effects associated with artesunate treatment occurred in early pregnancy. Prospective studies should now be done to assess the safety and efficacy of artemisinin combination treatments in early pregnancy.

Funding

Wellcome Trust and Bill & Melinda Gates Foundation.

Effects of artemisinins on reticulocyte count and relationship to possible embryotoxicity in confirmed and unconfirmed malarial patients

Rat studies suggest that artemisinin-induced decreases in reticulocyte count are a marker for embryotoxicity (in one study, r = 0.82; p < 0.05). In clinical studies, therapeutic doses of artemisinins induced decreases in reticulocyte count that were larger in five of six groups of healthy volunteers (mean decreases of 47-75%) than in 12 groups of patients with malaria (mean decreases of 0-34% and incidences of low reticulocyte count of 0.6-18%). Malaria causes hypoferremia and drug concentrates in infected red cells so, among the explanations for the lesser decreases in patients, is that malaria protects against artemisinin-induced decreases in reticulocyte count by reducing the target tissue levels of active drug and/or ferrous iron which activates the drug to toxic free radicals. The disease could also protect against embryotoxicity in which case pregnant women without malaria would be at greater risk of artemisinin-induced embryotoxicity. Malaria protection against artesunate toxicity has been observed in rats. No artemisinin-induced embryotoxicity has been identified in limited numbers of women with confirmed malaria in the first trimester. However, in large parts of tropical Africa, malaria treatment is based on fever rather than confirmation of parasitemia and many pregnant women without malaria are exposed to antimalarials. No clinical studies have been conducted on uninfected women for whom pregnancy was identified and then an artemisinin was administered subsequently. Testing in rats and/or humans is needed to determine if malaria protects against reticulocytopenia and embryotoxicity and whether the parasite is a more or less sensitive target than the embryo and reticulocyte.

Artesunate and artelinic acid: association of embryotoxicity, reticulocytopenia, and delayed stimulation of hematopoiesis in pregnant rats

The artemisinin antimalarials cause embryo death and malformations in animals by killing embryonic erythroblasts. Groups of pregnant rats (N = 4) were administered 35 and 48 µmol/kg artesunate and 17.2, 28.7, 48, 96, and 191 µmol/kg artelinic acid as a single oral dose on gestational day (GD) 12. Litters were examined on GD21. The ED(50) for embryo death with artelinic acid (23.4 µmol/kg) was just slightly lower than that for decreased reticulocyte count at 24 hr postdose (33.5 µmol/kg) and both had similarly steep dose responses (maximal effects of total litter loss and ∼60% decreases in reticulocyte count at 48 µmol/kg). Results with artesunate were similar. The correlation coefficient between embryo death and decreased reticulocyte count was 0.82 (p<0.01). The close relationship between embryotoxicity and reticulocytopenia is suggestive of a common mechanism-artemisinin-induced mitochondrial damage leading to cell death. At 9 days postdose, treatment with artesunate and artelinic acid also caused increases in counts of reticulocytes, lymphocytes, basophils, and monocytes (up to 3.7 ×, 1.7 ×, 4.7 ×, and 1.7 × control, respectively). This stimulation of hematopoiesis may have been mediated by the direct oxidative conversion of artesunate or artelinic acid to the artemisininyl hydroperoxide within the bone marrow cells or by an indirect increase in reactive oxygen species. The high correlation between embryotoxicity and reticulocytopenia further supports the assertion that therapeutic dosage regimens of artemisinins that cause decreases in reticulocyte count in pregnant women during the putative critical period (approximately postconception wk 3 to 9) are at risk of also causing adverse effects on the embryo.

WITHDRAWN. Neurological assessments after treatment with the antimalarial β-arteether in neonatal and adult rats

The World Health Organization currently recommends combinatorial treatment including artemisinins as first-line therapy against drug-resistant Plasmodium falciparum malaria. Although highly efficacious, artemisinin and its derivatives, including β-arteether (βAE), are associated with ototoxicity, tremors, and other autonomic and motor impairments in the clinic. Similar neurological symptoms, as well as brainstem lesions, have been observed in adult laboratory species (mice, rats, dogs, and non human primates) following acute treatment with βAE; however, few long-term, nonclinical studies have been conducted. Furthermore, the majority of deaths attributed to malarial infection occur in children under age five, yet no laboratory studies have been initiated in neonatal or juvenile animals. In the current study, neonatal 7-day-old rats were administered intramuscular doses of 1-90mg/kg βAE in sesame oil for up to eight treatment cycles (one cycle=7days treatment+7days without treatment). Neonates were tested for changes in sensorimotor function, and the same animals were tested as adults in the Functional Observational Battery, for motor activity, and in the 8-arm radial maze. Pups receiving a single cycle of 60 or 90mg/kg died within a week of treatment but had few behavioral changes and no brainstem pathology. In the long-term study, behavioral and motor changes and brainstem lesions were observed in a dose- and time-related manner. Rats given repeated cycles of 1 or 5mg/kg βAE showed subtle motor abnormalities (e.g., slight loss of righting reflex) while repeated cycles of 10mg/kg βAE treatment resulted in obvious motor and behavioral changes. Rats receiving 1mg/kg βAE had no brainstem lesions whereas some rats treated with 5mg/kg βAE and all rats treated with 10mg/kg βAE had brainstem lesions. Brainstem lesions were observed after as few as five cycles and were characterized by gliosis, satellitosis and progressive necrosis in motor neurons of the trapezoid, vestibular, and olivary nuclei. This study shows that repeated treatment with clinically relevant doses of βAE causes motor deficits associated with brainstem damage in rodents and suggests that repeated treatment with βAE in children may elicit neurological damage.

The role of heme and the mitochondrion in the chemical and molecular mechanisms of mammalian cell death induced by the artemisinin antimalarials

The artemisinin compounds are the frontline drugs for the treatment of drug-resistant malaria. They are selectively cytotoxic to mammalian cancer cell lines and have been implicated as neurotoxic and embryotoxic in animal studies. The endoperoxide functional group is both the pharmacophore and toxicophore, but the proposed chemical mechanisms and targets of cytotoxicity remain unclear. In this study we have used cell models and quantitative drug metabolite analysis to define the role of the mitochondrion and cellular heme in the chemical and molecular mechanisms of cell death induced by artemisinin compounds. HeLa ρ(0) cells, which are devoid of a functioning electron transport chain, were used to demonstrate that actively respiring mitochondria play an essential role in endoperoxide-induced cytotoxicity (artesunate IC(50) values, 48 h: HeLa cells, 6 ± 3 μM; and HeLa ρ(0) cells, 34 ± 5 μM) via the generation of reactive oxygen species and the induction of mitochondrial dysfunction and apoptosis but do not have any role in the reductive activation of the endoperoxide to cytotoxic carbon-centered radicals. However, using chemical modulators of heme synthesis (succinylacetone and protoporphyrin IX) and cellular iron content (holotransferrin), we have demonstrated definitively that free or protein-bound heme is responsible for intracellular activation of the endoperoxide group and that this is the chemical basis of cytotoxicity (IC(50) value and biomarker of bioactivation levels, respectively: 10β-(p-fluorophenoxy)dihydroartemisinin alone, 0.36 ± 0.20 μM and 11 ± 5%; and with succinylacetone, >100 μM and 2 ± 5%).

Severe embryotoxicity of artemisinin derivatives in experimental animals, but possibly safe in pregnant women

Preclinical studies in rodents have demonstrated that artemisinins, especially injectable artesunate, can induce fetal death and congenital malformations at a low dose range. The embryotoxicity can be induced in those animals only within a narrow window in early embryogenesis. Evidence was presented that the mechanism by which embryotoxicity of artemisinins occurs seems to be limited to fetal erythropoiesis and vasculogenesis/ angiogenesis on the very earliest developing red blood cells, causing severe anemia in the embryos with higher drug peak concentrations. However, this embryotoxicity has not been convincingly observed in clinical trials from 1,837 pregnant women, including 176 patients in the first trimester exposed to an artemisinin agent or artemisinin-based combination therapy (ACT) from 1989 to 2009. In the rodent, the sensitive early red cells are produced synchronously over one day with single or multiple exposures to the drug can result in a high proportion of cell deaths. In contrast, primates required a longer period of treatment of 12 days to induce such embryonic loss. In humans only limited information is available about this stage of red cell development; however, it is known to take place over a longer time period, and it may well be that a limited period of treatment of 2 to 3 days for malaria would not produce serious toxic effects. In addition, current oral intake, the most commonly used route of administration in pregnant women with an ACT, results in lower peak concentration and shorter exposure time of artemisinins that demonstrated that such a concentration–course profile is unlikely to induce the embryotoxicity. When relating the animal and human toxicity of artemisinins, the different drug sensitive period and pharmacokinetic profiles as reviewed in the present report may provide a great margin of safety in the pregnant women.

Sensitive periods for developmental toxicity of orally administered artesunate in the rat

BACKGROUND

Artesunate has been reported to cause embryolethality and malformations when administered orally to rats during organogenesis. The purpose of this study was to determine the most sensitive period(s) for the induction of these effects in order to provide clues about possible mechanisms and to identify a short treatment regimen for further studies.

METHODS

Pregnant rats were orally administered artesunate (10, 17 or 30 mg/kg/day) on single or multiple days of gestation. Cesarean sections and fetal evaluations were conducted on Day 21 postcoitum (pc).

RESULTS

Embryolethality, cardiovascular malformations and a syndrome of skeletal defects were observed after single doses on days 10 to 14 pc, while no developmental effects were observed before (day 9 pc) or after (days 16 or 17 pc) that period. The most sensitive day for embryo lethality was day 11 pc, where lethality occurred with a very steep dose response (postimplantation loss was approximately 15% at 10 mg/kg and 100% at 17 mg/kg/day). The most sensitive day for the induction of malformations was day 10 pc. Malformations tended to occur in partially resorbed litters and included cardiovascular defects and bent and misshapen long bones and scapulae.

CONCLUSIONS

The sensitive window for developmental toxicity of artesunate in the rat was identified as days 10 to 14 pc. Single oral doses produced embryolethality and similar cardiovascular and skeletal malformations as previously reported in longer term dosing experiments. These single dose treatment regimens could be useful to further investigate the mechanistic basis for artesunate-induced developmental toxicity.

Artesunate: developmental toxicity and toxicokinetics in monkeys

BACKGROUND

The developmental toxicity, toxicokinetics, and hematological effects of the antimalarial drug, artesunate, were previously studied in rats and rabbits and have now been studied in cynomolgus monkeys.

METHODS

Groups of up to 15 pregnant females were dosed on Gestation Days (GD) 20-50 or for 3-7-day intervals.

RESULTS

At 30 mg/kg/day, 6 embryos died between GD30 and GD40. Histologic examination of 3 live embryos (GD26-GD36) revealed a marked reduction in embryonic erythroblasts and cardiomyopathy. At 12 mg/kg/day, 6 embryos died between GD30 and GD45. Four surviving fetuses examined on GD100 had no malformations, but long bone lengths were slightly decreased. At the developmental no-adverse-effect-level (4 mg/kg/day), maternal plasma AUC was 3.68 ng.h/mL for artesunate and 6.93 ng.h/ml for its active metabolite, dihydroartemisinin (DHA). No developmental toxicity occurred with administration of 12 mg/kg/day for 3 or 7 days, GD29-31 or GD27-33 (maternal plasma AUC of 9.84 ng.h/mL artesunate and 16.4 ng.h/mL DHA). Exposures at embryotoxic doses were substantially lower than human therapeutic exposures. However, differences in monkey and human Vss for artesunate (0.5 L/kg vs. 0.18 L/kg) confound relying solely on AUC for assessing human risk. Decreases in reticulocyte count occur at therapeutic doses in humans. Changes to reticulocyte counts at embryotoxic doses in monkeys (> or =12 mg/kg/day) were variable and generally minor.

CONCLUSIONS

Artesunate was embryolethal at > or =12 mg/kg/day when dosed for at least 12 days at the beginning of organogenesis, but not when dosed for 3 or 7 days, indicating that developmental toxicity of artesunate is dependent upon duration of dosing in cynomologus monkeys.