Dioxide - Explore the Science & Experts | ideXlab

Scan Science and Technology

Contact Leading Edge Experts & Companies

Dioxide

The Experts below are selected from a list of 477393 Experts worldwide ranked by ideXlab platform

Dioxide – Free Register to Access Experts & Abstracts

Pascal De Tullio – One of the best experts on this subject based on the ideXlab platform.

Bernard Pirotte – One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and Pharmacology of Mono‑, Di‑, and Trialkyl-Substituted 7‑Chloro-3,4-dihydro‑2H‑1,2,4-benzothiadiazine 1,1-Dioxides Combined with X‑ray Structure Analysis to Understand the Unexpected Structure–Activity Relationship at AMPA Receptors
    , 2016
    Co-Authors: Anja Probst Larsen, Pierre Fraikin, Eric Goffin, Pierre Francotte, Danielhenri Caignard, Pierre Lestage, L. Danober, Karla Frydenvang, Daniel Tapken, Bernard Pirotte
    Abstract:

    Positive allosteric modulators of 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)­propionic acid (AMPA)-type ionotropic glutamate receptors are promising compounds for treatment of neurological disorders, for example, Alzheimer’s disease. Here, we report synthesis and pharmacological evaluation of a series of mono-, di-, or trialkyl-substituted 7-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides, comprising in total 16 new modulators. The trisubstituted compounds 7b, 7d, and 7e revealed potent activity (EC2× = 2.7–4.3 μM; concentration of compound responsible for a 2-fold increase of the AMPA mediated response) as AMPA receptor potentiators in an in vitro cellular fluorescence assay (FLIPR). The 4-cyclopropyl compound 7f was found to be considerably less potent (EC2× = 60 μM), in contrast to previously described 4-monoalkyl-substituted benzothiadiazine Dioxides for which the cyclopropyl group constitutes the best choice of substituent. 7b was subjected to X-ray structural analysis in complex with the GluA2 ligand-binding domain. We propose an explanation of the unexpected structure–activity relationship of this new series of mono-, di-, and trialkyl-substituted 1,2,4-benzothiadiazine 1,1-Dioxide compounds. The methyl substituent in the 3-position directs the binding mode of the 1,2,4-benzothiadiazine 1,1-Dioxide (BTD) scaffold. When a methyl substituent is present in the 3-position of the BTD, additional methyl substituents in both the 2- and 4-positions increase potency, whereas introduction of a 4-cyclopropyl group does not enhance potency of 2,3,4-alkyl-substituted BTDs. A hydrogen bond donor in the 2-position of the BTD is not necessary for modulator potency

  • Hydroxylated Analogues of ATP-Sensitive Potassium Channel Openers Belonging to the Group of 6- and/or 7-Substituted 3-Isopropylamino-4H-1,2,4-benzothiadiazine 1,1-Dioxides: Toward an Improvement in Sulfonylurea Receptor 1 Selectivity and Metabolism S
    , 2016
    Co-Authors: Pascal De Tullio, Fabian Somers, Philippe Lebrun, Annecatherine Servais, Marianne Fillet, Florian Gillotin, Patrice Chiap, Bernard Pirotte
    Abstract:

    Diversely substituted 3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-Dioxides are known to be potent KATP channel openers, with several drugs being selective for the SUR1/Kir6.2 channel subtype. This work examined the biological activity, tissue selectivity, and in vitro metabolic stability of hydroxylated analogues of 3-isopropylaminobenzothiadiazine Dioxides. Because of the presence of a chiral center, the R and S isomers were prepared separately and characterized. R isomers were systematically found to be more potent and more selective than S isomers on pancreatic tissue (compared to vascular smooth muscle tissue), leading to compounds with an improved sulfonylurea receptor 1 (SUR1) selectivity. An in vitro metabolic study revealed that 7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-Dioxide (1a) was rapidly biotransformed and led in part to a mixture of the corresponding (R)- and (S)-3-(1-hydroxy-2-propyl)­amino-substituted derivatives. Radioisotopic experiments characterized one of the most potent and SUR1-selective enantiomers, (R)-7-chloro-3-(1-hydroxy-2-propyl)­amino-4H-1,2,4-benzothiadiazine 1,1-Dioxide 13a, as being a KATP channel opener. Moreover, 13a exhibited an enhanced metabolic stability. Such a compound can be considered as a new lead candidate displaying improved physicochemical (hydrosolubility) and pharmacological (tissue selectivity) properties as well as improved metabolic stability compared to its nonhydroxylated counterpart, 1a

  • 1,4,2-Benzo/pyridodithiazine 1,1-Dioxides Structurally Related to the ATP-Sensitive Potassium Channel Openers 1,2,4-Benzo/pyridothiadiazine 1,1-Dioxides Exert a Myorelaxant Activity Linked to a Distinct Mechanism of Action
    , 2013
    Co-Authors: Bernard Pirotte, Pascal De Tullio, Fabian Somers, Xavier Florence, Eric Goffin, Stéphane Boverie, Philippe Lebrun
    Abstract:

    The synthesis of diversely substituted 3-alkyl/aralkyl/arylamino-1,4,2-benzodithiazine 1,1-Dioxides and 3-alkylaminopyrido­[4,3-e]-1,4,2-dithiazine 1,1-Dioxides is described. Their biological activities on pancreatic β-cells and on smooth muscle cells were compared to those of the reference ATP-sensitive potapotassiumnnel (KATP channel) openers diazoxide and 7-chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-Dioxide. The aim was to assess the impact on biological activities of the replacement of the 1,2,4-thiadiazine ring by an isosteric 1,4,2-dithiazine ring. Most of the dithiazine analogues were found to be inactive on the pancreatic tissue, although some compounds bearing a 1-phenylethylamino side chain at the 3-position exerted a marked myorelaxant activity. Such an effect did not appear to be related to the opening of KATP channels but rather reflected a mechanism of action similar to that of calcium channel blockers. Tightly related 3-(1-phenylethyl)­sulfanyl4H-1,2,4-benzothiadiazine 1,1-Dioxides were also found to exert a pronounced myorelaxant activity, resulting from both a KATP channel activation and a calcium channel blocker mechanism. The present work highlights the critical importance of an intracyclic NH group at the 4-position, as well as an exocyclic NH group linked to the 3-position of the benzo- and pyridothiadiazine Dioxides, for activity on KATP channels

Eric Goffin – One of the best experts on this subject based on the ideXlab platform.

  • 7-Phenoxy-Substituted 3,4-Dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides as Positive Allosteric Modulators of α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors with Nanomolar Potency
    Journal of Medicinal Chemistry, 2017
    Co-Authors: Eric Goffin, Pascal De Tullio, Thomas Drapier, Anja Probst Larsen, Pierre Geubelle, Christopher P. Ptak, Saara Laulumaa, Karoline Rovinskaja, Julie Gilissen, Lars Olsen
    Abstract:

    We report here the synthesis of 7-phenoxy-substituted 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides and their evaluation as AMPA receptor positive allosteric modulators (AMPApams). The impact of substitution on the phenoxy ring and on the nitrogen atom at the 4-position was examined. At GluA2(Q) expressed in HEK293 cells (calcium flux experiment), the most potent compound was 11m (4-cyclopropyl-7-(3-methoxyphenoxy)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxide, EC50 = 2.0 nM). The Hill coefficient in the screening and the shape of the dimerization curve in small-angle X-ray scattering (SAXS) experiments using isolated GluA2 ligand-binding domain (GluA2-LBD) are consistent with binding of one molecule of 11m per dimer interface, contrary to most benzothiadiazine Dioxides developed to date. This observation was confirmed by the X-ray structure of 11m bound to GluA2-LBD and by NMR. This is the first benzothiadiazine Dioxide AMPApam to reach the nanomolar range.

  • 7‑Phenoxy-Substituted 3,4-Dihydro‑2H‑1,2,4-benzothiadiazine 1,1-Dioxides as Positive Allosteric Modulators of α‑Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors with Nanomolar Potency
    , 2017
    Co-Authors: Eric Goffin, Pascal De Tullio, Thomas Drapier, Anja Probst Larsen, Pierre Geubelle, Christopher P. Ptak, Saara Laulumaa, Karoline Rovinskaja, Julie Gilissen, Lars Olsen
    Abstract:

    We report here the synthesis of 7-phenoxy-substituted 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides and their evaluation as AMPA receptor positive allosteric modulators (AMPApams). The impact of substitution on the phenoxy ring and on the nitrogen atom at the 4-position was examined. At GluA2­(Q) expressed in HEK293 cells (calcium flux experiment), the most potent compound was 11m (4-cyclopropyl-7-(3-methoxyphenoxy)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxide, EC50 = 2.0 nM). The Hill coefficient in the screening and the shape of the dimerization curve in small-angle X-ray scattering (SAXS) experiments using isolated GluA2 ligand-binding domain (GluA2-LBD) are consistent with binding of one molecule of 11m per dimer interface, contrary to most benzothiadiazine Dioxides developed to date. This observation was confirmed by the X-ray structure of 11m bound to GluA2-LBD and by NMR. This is the first benzothiadiazine Dioxide AMPApam to reach the nanomolar range

  • Synthesis and Pharmacology of Mono‑, Di‑, and Trialkyl-Substituted 7‑Chloro-3,4-dihydro‑2H‑1,2,4-benzothiadiazine 1,1-Dioxides Combined with X‑ray Structure Analysis to Understand the Unexpected Structure–Activity Relationship at AMPA Receptors
    , 2016
    Co-Authors: Anja Probst Larsen, Pierre Fraikin, Eric Goffin, Pierre Francotte, Danielhenri Caignard, Pierre Lestage, L. Danober, Karla Frydenvang, Daniel Tapken, Bernard Pirotte
    Abstract:

    Positive allosteric modulators of 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)­propionic acid (AMPA)-type ionotropic glutamate receptors are promising compounds for treatment of neurological disorders, for example, Alzheimer’s disease. Here, we report synthesis and pharmacological evaluation of a series of mono-, di-, or trialkyl-substituted 7-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides, comprising in total 16 new modulators. The trisubstituted compounds 7b, 7d, and 7e revealed potent activity (EC2× = 2.7–4.3 μM; concentration of compound responsible for a 2-fold increase of the AMPA mediated response) as AMPA receptor potentiators in an in vitro cellular fluorescence assay (FLIPR). The 4-cyclopropyl compound 7f was found to be considerably less potent (EC2× = 60 μM), in contrast to previously described 4-monoalkyl-substituted benzothiadiazine Dioxides for which the cyclopropyl group constitutes the best choice of substituent. 7b was subjected to X-ray structural analysis in complex with the GluA2 ligand-binding domain. We propose an explanation of the unexpected structure–activity relationship of this new series of mono-, di-, and trialkyl-substituted 1,2,4-benzothiadiazine 1,1-Dioxide compounds. The methyl substituent in the 3-position directs the binding mode of the 1,2,4-benzothiadiazine 1,1-Dioxide (BTD) scaffold. When a methyl substituent is present in the 3-position of the BTD, additional methyl substituents in both the 2- and 4-positions increase potency, whereas introduction of a 4-cyclopropyl group does not enhance potency of 2,3,4-alkyl-substituted BTDs. A hydrogen bond donor in the 2-position of the BTD is not necessary for modulator potency

Pierre Francotte – One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and Pharmacology of Mono‑, Di‑, and Trialkyl-Substituted 7‑Chloro-3,4-dihydro‑2H‑1,2,4-benzothiadiazine 1,1-Dioxides Combined with X‑ray Structure Analysis to Understand the Unexpected Structure–Activity Relationship at AMPA Receptors
    , 2016
    Co-Authors: Anja Probst Larsen, Pierre Fraikin, Eric Goffin, Pierre Francotte, Danielhenri Caignard, Pierre Lestage, L. Danober, Karla Frydenvang, Daniel Tapken, Bernard Pirotte
    Abstract:

    Positive allosteric modulators of 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)­propionic acid (AMPA)-type ionotropic glutamate receptors are promising compounds for treatment of neurological disorders, for example, Alzheimer’s disease. Here, we report synthesis and pharmacological evaluation of a series of mono-, di-, or trialkyl-substituted 7-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides, comprising in total 16 new modulators. The trisubstituted compounds 7b, 7d, and 7e revealed potent activity (EC2× = 2.7–4.3 μM; concentration of compound responsible for a 2-fold increase of the AMPA mediated response) as AMPA receptor potentiators in an in vitro cellular fluorescence assay (FLIPR). The 4-cyclopropyl compound 7f was found to be considerably less potent (EC2× = 60 μM), in contrast to previously described 4-monoalkyl-substituted benzothiadiazine Dioxides for which the cyclopropyl group constitutes the best choice of substituent. 7b was subjected to X-ray structural analysis in complex with the GluA2 ligand-binding domain. We propose an explanation of the unexpected structure–activity relationship of this new series of mono-, di-, and trialkyl-substituted 1,2,4-benzothiadiazine 1,1-Dioxide compounds. The methyl substituent in the 3-position directs the binding mode of the 1,2,4-benzothiadiazine 1,1-Dioxide (BTD) scaffold. When a methyl substituent is present in the 3-position of the BTD, additional methyl substituents in both the 2- and 4-positions increase potency, whereas introduction of a 4-cyclopropyl group does not enhance potency of 2,3,4-alkyl-substituted BTDs. A hydrogen bond donor in the 2-position of the BTD is not necessary for modulator potency

  • positive allosteric modulators of 2 amino 3 3 hydroxy 5 methylisoxazol 4 yl propionic acid receptors belonging to 4 cyclopropyl 3 4 dihydro 2h 1 2 4 pyridothiadiazine Dioxides and diversely chloro substituted 4 cyclopropyl 3 4 dihydro 2h 1 2 4 benzot
    Journal of Medicinal Chemistry, 2014
    Co-Authors: Pierre Francotte, Pascal De Tullio, Pierre Fraikin, Eric Goffin, Lars Olsen, Karla Frydenvang, Annbeth Norholm, Taru Deva, Sylvie Challal, Jeanyves Thomas
    Abstract:

    Two 4-ethyl-substituted pyridothiadiazine Dioxides belonging to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor positive allosteric modulators were cocrystallized with the GluA2 ligand binding domain in order to decipher the impact of the position of the nitrogen atom on their binding mode at the AMPA receptors. The latter was found to be very similar to that of previously described benzothiadiazine-type AMPA receptor modulators. The affinity of the two compounds for the receptor was determined by isothermal titration calorimetry. Accordingly, the synthesis and biological evaluation of novel 4-cyclopropyl-substituted pyridothiadiazine Dioxides was performed and completed with the synthesis of the corresponding chloro-substituted 4-cyclopropyl-3,4-dihydro-2H-benzothiadiazine 1,1-Dioxides. The “8-aza” compound 32 was found to be the most potent pyridothiadiazine-type AMPA receptor potentiator in vitro, whereas the 7-chloro-substituted compound 36c emerged as the most promising benzothiadiazine Dioxide. Due to proper drug-likeness and low in vivo acute toxicity in mice, 36c was chosen for a more complete preclinical evaluation. The compound was able to easily cross the blood-brain barrier. In an in vivo object recognition test with CD1 mice, oral administration of 36c was found to significantly improve cognition performance at doses as low as 1 mg/kg.

  • Positive Allosteric Modulators of 2‑Amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic Acid Receptors Belonging to 4‑Cyclopropyl-3,4-dihydro‑2H‑1,2,4-pyridothiadiazine Dioxides and Diversely Chloro-Substituted 4‑Cyclopropyl-3,4-dihydro‑2H‑1,2,4-benzo
    , 2014
    Co-Authors: Pierre Francotte, Pascal De Tullio, Pierre Fraikin, Eric Goffin, Lars Olsen, Karla Frydenvang, Annbeth Norholm, Taru Deva, Sylvie Challal, Jeanyves Thomas
    Abstract:

    Two 4-ethyl-substituted pyridothiadiazine Dioxides belonging to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor positive allosteric modulators were cocrystallized with the GluA2 ligand binding domain in order to decipher the impact of the position of the nitrogen atom on their binding mode at the AMPA receptors. The latter was found to be very similar to that of previously described benzothiadiazine-type AMPA receptor modulators. The affinity of the two compounds for the receptor was determined by isothermal titration calorimetry. Accordingly, the synthesis and biological evaluation of novel 4-cyclopropyl-substituted pyridothiadiazine Dioxides was performed and completed with the synthesis of the corresponding chloro-substituted 4-cyclopropyl-3,4-dihydro-2H-benzothiadiazine 1,1-Dioxides. The “8-aza” compound 32 was found to be the most potent pyridothiadiazine-type AMPA receptor potentiator in vitro, whereas the 7-chloro-substituted compound 36c emerged as the most promising benzothiadiazine Dioxide. Due to proper drug-likeness and low in vivo acute toxicity in mice, 36c was chosen for a more complete preclinical evaluation. The compound was able to easily cross the blood–brain barrier. In an in vivo object recognition test with CD1 mice, oral administration of 36c was found to significantly improve cognition performance at doses as low as 1 mg/kg

Pierre Fraikin – One of the best experts on this subject based on the ideXlab platform.

  • Synthesis and Pharmacology of Mono‑, Di‑, and Trialkyl-Substituted 7‑Chloro-3,4-dihydro‑2H‑1,2,4-benzothiadiazine 1,1-Dioxides Combined with X‑ray Structure Analysis to Understand the Unexpected Structure–Activity Relationship at AMPA Receptors
    , 2016
    Co-Authors: Anja Probst Larsen, Pierre Fraikin, Eric Goffin, Pierre Francotte, Danielhenri Caignard, Pierre Lestage, L. Danober, Karla Frydenvang, Daniel Tapken, Bernard Pirotte
    Abstract:

    Positive allosteric modulators of 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)­propionic acid (AMPA)-type ionotropic glutamate receptors are promising compounds for treatment of neurological disorders, for example, Alzheimer’s disease. Here, we report synthesis and pharmacological evaluation of a series of mono-, di-, or trialkyl-substituted 7-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-Dioxides, comprising in total 16 new modulators. The trisubstituted compounds 7b, 7d, and 7e revealed potent activity (EC2× = 2.7–4.3 μM; concentration of compound responsible for a 2-fold increase of the AMPA mediated response) as AMPA receptor potentiators in an in vitro cellular fluorescence assay (FLIPR). The 4-cyclopropyl compound 7f was found to be considerably less potent (EC2× = 60 μM), in contrast to previously described 4-monoalkyl-substituted benzothiadiazine Dioxides for which the cyclopropyl group constitutes the best choice of substituent. 7b was subjected to X-ray structural analysis in complex with the GluA2 ligand-binding domain. We propose an explanation of the unexpected structure–activity relationship of this new series of mono-, di-, and trialkyl-substituted 1,2,4-benzothiadiazine 1,1-Dioxide compounds. The methyl substituent in the 3-position directs the binding mode of the 1,2,4-benzothiadiazine 1,1-Dioxide (BTD) scaffold. When a methyl substituent is present in the 3-position of the BTD, additional methyl substituents in both the 2- and 4-positions increase potency, whereas introduction of a 4-cyclopropyl group does not enhance potency of 2,3,4-alkyl-substituted BTDs. A hydrogen bond donor in the 2-position of the BTD is not necessary for modulator potency

  • positive allosteric modulators of 2 amino 3 3 hydroxy 5 methylisoxazol 4 yl propionic acid receptors belonging to 4 cyclopropyl 3 4 dihydro 2h 1 2 4 pyridothiadiazine Dioxides and diversely chloro substituted 4 cyclopropyl 3 4 dihydro 2h 1 2 4 benzot
    Journal of Medicinal Chemistry, 2014
    Co-Authors: Pierre Francotte, Pascal De Tullio, Pierre Fraikin, Eric Goffin, Lars Olsen, Karla Frydenvang, Annbeth Norholm, Taru Deva, Sylvie Challal, Jeanyves Thomas
    Abstract:

    Two 4-ethyl-substituted pyridothiadiazine Dioxides belonging to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor positive allosteric modulators were cocrystallized with the GluA2 ligand binding domain in order to decipher the impact of the position of the nitrogen atom on their binding mode at the AMPA receptors. The latter was found to be very similar to that of previously described benzothiadiazine-type AMPA receptor modulators. The affinity of the two compounds for the receptor was determined by isothermal titration calorimetry. Accordingly, the synthesis and biological evaluation of novel 4-cyclopropyl-substituted pyridothiadiazine Dioxides was performed and completed with the synthesis of the corresponding chloro-substituted 4-cyclopropyl-3,4-dihydro-2H-benzothiadiazine 1,1-Dioxides. The “8-aza” compound 32 was found to be the most potent pyridothiadiazine-type AMPA receptor potentiator in vitro, whereas the 7-chloro-substituted compound 36c emerged as the most promising benzothiadiazine Dioxide. Due to proper drug-likeness and low in vivo acute toxicity in mice, 36c was chosen for a more complete preclinical evaluation. The compound was able to easily cross the blood-brain barrier. In an in vivo object recognition test with CD1 mice, oral administration of 36c was found to significantly improve cognition performance at doses as low as 1 mg/kg.

  • Positive Allosteric Modulators of 2‑Amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic Acid Receptors Belonging to 4‑Cyclopropyl-3,4-dihydro‑2H‑1,2,4-pyridothiadiazine Dioxides and Diversely Chloro-Substituted 4‑Cyclopropyl-3,4-dihydro‑2H‑1,2,4-benzo
    , 2014
    Co-Authors: Pierre Francotte, Pascal De Tullio, Pierre Fraikin, Eric Goffin, Lars Olsen, Karla Frydenvang, Annbeth Norholm, Taru Deva, Sylvie Challal, Jeanyves Thomas
    Abstract:

    Two 4-ethyl-substituted pyridothiadiazine Dioxides belonging to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor positive allosteric modulators were cocrystallized with the GluA2 ligand binding domain in order to decipher the impact of the position of the nitrogen atom on their binding mode at the AMPA receptors. The latter was found to be very similar to that of previously described benzothiadiazine-type AMPA receptor modulators. The affinity of the two compounds for the receptor was determined by isothermal titration calorimetry. Accordingly, the synthesis and biological evaluation of novel 4-cyclopropyl-substituted pyridothiadiazine Dioxides was performed and completed with the synthesis of the corresponding chloro-substituted 4-cyclopropyl-3,4-dihydro-2H-benzothiadiazine 1,1-Dioxides. The “8-aza” compound 32 was found to be the most potent pyridothiadiazine-type AMPA receptor potentiator in vitro, whereas the 7-chloro-substituted compound 36c emerged as the most promising benzothiadiazine Dioxide. Due to proper drug-likeness and low in vivo acute toxicity in mice, 36c was chosen for a more complete preclinical evaluation. The compound was able to easily cross the blood–brain barrier. In an in vivo object recognition test with CD1 mice, oral administration of 36c was found to significantly improve cognition performance at doses as low as 1 mg/kg