Plasmodium

Rat C6 glioma cell growth is inhibited by artemeether (0-200 μg/mL, 24-72 h) in a dose- and time-dependent manner[2]. Artemether (0-10 μM, 72 h) suppresses the expression of genes related to osteoclast formation (osteoclast precursor cells, BMMs) caused by RANKL (TRAP, NFATc1, V-ATPase-d2, CTSK, DC-STAMP, MMP-9)[2].
Artemether (48 or 96 h) inhibits the proliferation of BALB/c splenocytes induced by ConA or alloantigen (IC50: 6.3 and 3.5 μM)[4]. In BALB/c splenocytes, artemeether (0-50 μM, 16–36 h) suppresses IL-2 and IFN-γ production[4]. Artemether (0-50 μM, 72 h) inhibits cell cycle progression through G1/S transition, as well as ConA-induced splenocyte, CD4+T, and CD8+ T-cell divisions[4].

In SD rats containing C6 glioma cells, artemeether (0-66 mg/kg, p.o.) inhibits tumor growth and angiogenesis[2].
Mice treated with esters (10 mg/kg, i.p., for 8 days) are shielded from LPS-induced osteolytic bone loss[3].
In the DNFB-induced DTH model in BALB/c mice, artemeether (50 and 100 mg/kg, p.o.) inhibits T-cell-mediated immune responses (ear swelling)[4].

Cell Line: ConA-stimulated T lymphocytes
Concentration: 1, 10 and 50 μM
Incubation Time: 72 h
Result: Arrested 47, 56 and 91% (at 1, 10 and 50 μM) of the cells at G0/G1 phases, respectively.

Animal Model: LPS (5 mg/kg) treated mice[3]
Dosage: 10 mg/kg
Administration: i.p., 8 days
Result: prevented the loss of osteolytic bone and the decrease in bone volume caused by LPS. reduced osteoclast surface/bone surface (Oc.S/BS), increased bone volume/total volume (BV/TV), and number of TRAP-positive cells.

Absorption, Distribution and Excretion
Food increases absorption.
Little or none of the administered drugs or dihydroartemisinin is recovered in urine. /Dihydroartemisinin/
After intramuscular administration pharmacokinetics indicated peak plasma levels of artemether (AM) at 2 to 4 hours post-dose, slow elimination and a tendency to accumulate after repeated administration. Only low levels of the major metabolite, dihydroartemisinin (DHA), were found. AM levels in the cerebrospinal fluid (CSF) were < 10% of plasma levels. After oral administration AM concentrations were considerably lower than after i.m. administration. The concentration of DHA was high on day 1 but almost nil on day 7 indicating its fast inactivation in dogs. Two hours after the 8th oral administration neither AM nor DHA was detected in CSF which may explain the absence of neurotoxicity in dogs after oral administration of AM.
The pharmacokinetics of intramuscular artemether and its major plasma metabolite-dihydroartemisinin, were investigated in patients with severe manifestations of falciparum malaria. Six severe falciparum malaria patients with acute renal failure (ARF) and 11 without ARF were recruited into the study. They were treated with intramuscular artemether at a loading dose of 160 mg, followed by daily doses of 80 mg for another 6 days (total dose 640 mg). Patients with and without ARF showed a good initial response to treatment; the parasite and fever clearance times were 66 (30 to 164) and 76 (36 to 140) hr (median (range)), respectively. None had reappearance of parasitaemia in their peripheral blood smear within 7 days of initiation of treatment. In comatose patients, the time to recovery of consciousness was 51.6 (22 to 144) hr. Artemether was detected in plasma as early as 1hr after a 160 mg dose, and declined to undetectable levels within 24 hr in most cases. Patients with ARF had significantly higher Cmax (2.38 (1.89 to 3.95) vs 1.56 (1.05 to 3.38) ng/mL/mg dose), and lower Vz/F (5.45 (3.2 to 6.9) vs 8.6 (4.2 to 12.3) L/kg) and CL/F (7.4 (5.4 to 13.8) vs 19.1 (8.5 to 25.1) mL/min/kg) when compared to those without ARF. In addition, t1/2z, was significantly longer in ARF patients (7.0 (5.5 to 10.0) vs 5.7 (4.2 to 6.6) hr). The parmacokinetics of dihydroartemisinin in the two groups were comparable. ARF significantly modified the pharmacokinetics of intramuscular artemether. The changes could be contributed to either improved absorption/bioavailability, a reduction of systemic clearance, or a change in plasma protein binding of the drug.
Dihydroartemisinin is rapidly absorbed following oral administration, reaching peak levels after around 2.5 hr. Absorption via the rectal route is somewhat slower, with peak levels occurring around 4 hr after administration. Plasma protein binding is around 55%. Elimination half-life is approximately 45 min via intestinal and hepatic glucuronidation. /Dihydroartemisinin/
For more Absorption, Distribution and Excretion (Complete) data for ARTEMETHER (6 total), please visit the HSDB record page.

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Metabolism / Metabolites
Rapidly metablized to its active metabolite, dihydroartemisinin.
Artemether ... /is/ converted to dihydroartemisinin ... The antimalarial effect of artemisinin compounds results primarily from dihydroartemisinin ...
Artemisinin is completely and rapidly absorbed after oral administration in rats. However, a very low plasma level was obtained even after a dose of 300 mg/kg. Liver was found to be the chief site of inactivation. When artemisinin was given i.m., significant and more persistent plasma levels were detected. Artemisinin was shown to pass the blood-brain and blood-placenta barriers after i.v. injection. Very little unchanged artemisinin was found in the urine or feces in 48 hours regardless of the route of administration. Metabolites identified after administration to humans include deoxyartemisinin, deoxydihydroartemisinin, and 9,10-dihydroxydeoxyartemisinin. /Artemisinin/

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Biological Half-Life
Artemether, 1.6 +/- 0.7 and 2.2 +/- 1.9 hr; Dihydroartemisinin, 1.6 +/- 0.6 and 2.2 +/- 1.5 hr
Artemether ... /is/ converted to dihydroartemisinin ... which rapidly disappears from plasma with a half-life of about 45 min.

Protein Binding
Artemether and lumefantrine are both highly bound to human serum proteins in vitro (95.4% and 99.7%, respectively). Dihydroartemisinin is also bound to human serum proteins (47% to 76%).

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Interactions
The aim of this study was to evaluate the effect of grapefruit juice on the decreasing bioavailability over time of artemether. In a randomized, two-phase crossover study, eight healthy male subjects took 100 mg oral artemether with 350 mL water or with 350 mL double-strength fresh frozen grapefruit juice once daily for 5 days. On day 1 and day 5, 17 blood samples were collected over a period of 8 hours. The mean peak artemether plasma concentration (Cmax) and the mean area under the concentration-time curve (AUC) after the last dose at day 5 were about one third compared with day 1, without a change in the elimination half-life after intake with water (P = .006 for Cmax; P = .005 for AUC) and with grapefruit juice (P < .001 for Cmax and AUC). Grapefruit juice increased Cmax (P = .021) and AUC (P < .001) twofold on day 1 (P = .021) and day 5 (P = .05 for Cmax; P = .004 for AUC). Dihydroartemisinin, the active metabolite, showed a twofold increase in Cmax (P = .006) and AUC (P = .001) with grapefruit juice, without time-dependent changes of pharmacokinetic parameters. Grapefruit juice significantly increased the oral bioavailability of artemether but did not prevent the time-dependent reduction in bioavailability. It suggests that CYP3A4 in the gut wall is one of the metabolizing enzymes of artemether but seems to not be involved in the autoinduction process.
There has been some concern that antipyretics might attenuate the host defense against malaria, as their use is associated with delayed parasite clearance. However, this appears to result from delaying cytoadherence, which is likely to be beneficial. There is no reason to withhold antipyretics in malaria. ...Paracetamol (acetaminophen) and ibuprofen are the preferred options for reducing fever.

[1]. Recent investigations of artemether, a novel agent for the prevention of schistosomiasis japonica, mansoni and haematobia. Acta Trop, 2002. 82(2): p. 175-81.

[2]. Inhibitive effect of artemether on tumor growth and angiogenesis in the rat C6 orthotopic brain gliomas model. Integr Cancer Ther, 2009. 8(1): p. 88-92.

[3]. Artemether attenuates LPS-induced inflammatory bone loss by inhibiting osteoclastogenesis and bone resorption via suppression of MAPK signaling pathway. Cell Death Dis. 2018 May 1;9(5):498.

[4]. Investigation of the immunosuppressive activity of artemether on T-cell activation and proliferation. Br J Pharmacol. 2007 Mar;150(5):652-61.

Artemether is an artemisinin derivative that is artemisinin in which the lactone has been converted to the corresponding lactol methyl ether. It is used in combination with lumefantrine as an antimalarial for the treatment of multi-drug resistant strains of falciparum malaria. It has a role as an antimalarial. It is a sesquiterpenoid, a cyclic acetal, an organic peroxide, an artemisinin derivative and a semisynthetic derivative.
Artemether is an antimalarial agent used to treat acute uncomplicated malaria. It is administered in combination with lumefantrine for improved efficacy. This combination therapy exerts its effects against the erythrocytic stages of Plasmodium spp. and may be used to treat infections caused by P. falciparum and unidentified Plasmodium species, including infections acquired in chloroquine-resistant areas.
An artemisinin derivative that is used in the treatment of MALARIA.

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Drug Indication
Artemether and lumefantrine combination therapy is indicated for the treatment of acute uncomplicated malaria caused by Plasmodium falciparum, including malaria acquired in chloroquine-resistant areas. May also be used to treat uncomplicated malaria when the Plasmodium species has not been identified. Indicated for use in adults and children greater than 5 kg.
FDA Label

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Mechanism of Action
Involves an interaction with ferriprotoporphyrin IX (“heme”), or ferrous ions, in the acidic parasite food vacuole, which results in the generation of cytotoxic radical species. The generally accepted mechanism of action of peroxide antimalarials involves interaction of the peroxide-containing drug with heme, a hemoglobin degradation byproduct, derived from proteolysis of hemoglobin. This interaction is believed to result in the formation of a range of potentially toxic oxygen and carbon-centered radicals.
Artemether (AM) is an antimalarial drug derived from artemisinin (Qinghaosu), an extract of the herb Artemisia annua L., sweet wormwood. Its antiparasitic effect is that of a schizontocide and is explained by rapid uptake by parasitized erythrocytes and interaction with a component of hemoglobin degradation resulting in formation of free radicals. It has been shown to exhibit a high clinical cure rate.
Two theories have been put forward for the mode of antimalarial action of the artemisinin antimalarials, in accodance with the known properties of peroxides with medicinal activity. The first assumes that the artemisinins must be activated by contact with either reduced haem (ferrous haem, Fe(ll)PPIX) or non-haem ferrous iron (exogenous iron), causing cleavage of the peroxide to generate oxygen-centered radicals (alkoxy radicals') which are then presumed to be converted into carbon-centered radicals by transfer of proximate hydrogen atoms from the periphery of the peroxide molecule. These carbon-centered radicals are then thought to alkylate sensitive, yet unspecified, biomolecules in the parasite. A second theory argues for a process in which the intact artemisinin binds to a site within a vital protein in the parasite. The act of binding causes the peroxide to be converted to hydroperoxide or similar open peroxide, which in accordance with known properties of such compounds, generates one or more active chemical entities, either oxidizing agents or oxygen transfer agents per se, or oxygen-centered free radicals. This would be associated with the binding process. In such a way, the artemisinins might act as (irreversibile) inhibitors. Iron may, or may not, be associated with the activation process. No specific biological target in the parasite has yet been identified in support of this theory, but it may be membrane-bound proteins.

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Therapeutic Uses
MESH Heading: Antimalarial, antifungal, antiprotozoal, coccidiostats, schistosomicides
Therap Cat: Antimalarial
To counter the threat of resistance of P. falciparum to monotherapies, and to improve treatment outcome, combinations of antimalarials are now recommended by WHO for the treatment of falciparum malaria. ...The following ACTs are currently recommended: artemether-lumefantrine.
Artemether-lumefantrine: This is currently available as co-formulated tablets .... The total recommended treatment is a 6-dose regimen of artemether-lumefantrine twice a day for 3 days. An advantage of this combination is that lumefantrine is not available as a monotherapy and has never been used by itself for the treatment of malaria. Recent evidence indicates that the therapeutic response and safety profile in young children of less than 10 kg is similar to that in older children, and artemether-lumefantrine is now recommended for patients 5 kg. Lumefantrine absorption is enhanced by co-administration with fat. Low blood levels, with resultant treatment failure, could potentially result from inadequate fat intake, and so it is essential that patients or carers are informed of the need to take this ACT /antimalarial combination therapy/ with milk or fat-containing food -- particularly on the second and third days of treatment.
For more Therapeutic Uses (Complete) data for ARTEMETHER (11 total), please visit the HSDB record page.

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Drug Warnings
Transient first-degree heart block, dose-related reversible decreases in reticulocyte and neutrophil counts, and temporary elevations of serum aspartate aminotransferase activity have been reported ... Brief episodes of drug-induced fever in human volunteers were noted in some studies ... /Artemisinin drugs/
Because high doses of artemisinin drugs can produce neurotoxicity, prolongation of the QT interval, bone marrow depression, and fetal reabsorption in experimental animals, the possibility of long-term toxicity in human beings exists. /Artemisinin drugs/
Some patients cannot tolerate oral treatment, and will require parenteral or rectal administration for 1-2 days until they can swallow and retain oral medication reliably. Although such patients may not show signs of severity, they should receive the same antimalarial dose regimens as for severe malaria.
Some patients may have no signs of severity but on examination of the blood film are found to have very high parasitaemia. The risks associated with high parasitaemia vary depending on the age of the patient and on transmission intensity. Thus cut-off values and definitions of hyperparasitaemia also vary. Patients with high parasitaemias are at an increased risk of treatment failure and of developing severe malaria, and therefore have an increased risk of dying. These patients can be treated with the oral Antimalarial Combination Therapies (ACTs) recommended for uncomplicated malaria. However, they require close monitoring to ensure that the drugs are retained and that signs of severity do not develop, and they may require a longer course of treatment to ensure cure.
For more Drug Warnings (Complete) data for ARTEMETHER (18 total), please visit the HSDB record page.

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Pharmacodynamics
In the body, artemether is metabolized into the active metabolite metabolite dihydroartemisinin. The drug works against the erythrocytic stages of P. falciparum by inhibiting nucleic acid and protein synthesis. Artemether is administered in combination with lumefantrine for improved efficacy. Artemether has a rapid onset of action and is rapidly cleared from the body. It is thought that artemether provides rapid symptomatic relief by reducing the number of malarial parasites. Lumefantrine has a much longer half life and is believed to clear residual parasites.

C16H26O5

298.3746

298.178

C, 64.41; H, 8.78; O, 26.81

71963-77-4

Artemether-d3;93787-85-0

68911

Crystals

1.2±0.1 g/cm3

357.5±42.0 °C at 760 mmHg

86-89ºC

140.5±27.8 °C

0.0±0.8 mmHg at 25°C

1.518

3.07

0

5

1

21

429

8

O1C23[C@]4([H])O[C@@]([H])([C@]([H])(C([H])([H])[H])[C@]2([H])C([H])([H])C([H])([H])[C@@]([H])(C([H])([H])[H])C3([H])C([H])([H])C([H])([H])C(C([H])([H])[H])(O1)O4)OC([H])([H])[H]

SXYIRMFQILZOAM-HVNFFKDJSA-N

InChI=1S/C16H26O5/c1-9-5-6-12-10(2)13(17-4)18-14-16(12)11(9)7-8-15(3,19-14)20-21-16/h9-14H,5-8H2,1-4H3/t9-,10-,11+,12+,13+,14-,15-,16-/m1/s1

(3R,5aS,6R,8aS,9R,10S,12R,12aR)-decahydro-10-methoxy-3,6,9-trimethyl-3,12-epoxy-12H-pyrano[4,3-j]-1,2-benzodioxepin

Dihydroqinghaosu methyl ether; Dihydroartemisinin methyl ether; SM224; SM-224; Artemos; Artenam; Artesaph; Artesian; Dihydroartemisinin Methyl Ether; Falcidol; Gvither; Larither; Malartem; SM 224; β-Artemether; β-Dihydroartemisinin Methyl Ether

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : 60~100 mg/mL ( 201.09~335.15 mM )
Ethanol : ~60 mg/mL
H2O : ~0.1 mg/mL (~0.34 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 3% DMSO + 97% Corn oil: 6mg/ml (20.11mM)

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 (Please use freshly prepared in vivo formulations for optimal results.)