Absorption, Distribution and Excretion
Magnesium is excreted solely by the kidney at a rate proportional to the serum concentration and glomerular filtration.
Magnesium sulfate is excreted by the kidneys at a rate that varies from one patient to another but that is directly proportional to the serum concn and glomerular filtration.
PLASMA CONCN OF MAGNESIUM INCR IN FETUS & APPROACH MATERNAL BLOOD VALUES AFTER MAGNESIUM SULFATE ADMIN IN ECLAMPSIA & PREECLAMPSIA.

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Metabolism / Metabolites
None
Magnesium is almost exclusively excreted in the urine, with 90% of the dose excreted during the first 24 hours after an intravenous infusion of MgSO4. The pharmacokinetic profile of MgSO4 after intravenous administration can be described by a 2-compartment model with a rapid distribution (a) phase, followed by a relative slow beta phase of elimination.
Route of Elimination: Magnesium is excreted solely by the kidney at a rate proportional to the serum concentration and glomerular filtration.
Half Life: 43.2 hours (for newborns)

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Biological Half-Life
43.2 hours (for newborns)

Toxicity Summary
Magnesium is the second most plentiful cation of the intracellular fluids. It is essential for the activity of many enzyme systems and plays an important role with regard to neurochemical transmission and muscular excitability. Magnesium sulfate reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholine release at the myoneural junction. Additionally, Magnesium inhibits Ca²⁺ influx through dihydropyridine-sensitive, voltage-dependent channels. This accounts for much of its relaxant action on vascular smooth muscle.

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Intravenous magnesium increases milk magnesium concentrations only slightly and oral absorption of magnesium by the infant is poor, so maternal magnesium therapy is not expected to affect the breastfed infant's serum magnesium. Although intravenous magnesium sulfate given prior to delivery might affect the infant's ability to breastfeed, intention to breastfeed may be a more important determinant of breastfeeding initiation. Postpartum use of intravenous magnesium sulfate for longer than 6 hours appears to delay the onset of lactation. One group of experts recommends reserving postpartum magnesium sulfate prophylaxis for those women with persistent neurologic symptoms within 7 days of birth.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
One mother who received intravenous magnesium sulfate for 3 days for pregnancy-induced hypertension had lactogenesis II delayed until day 10 postpartum. No other specific cause was found for the delay, although a complete work-up was not done. A subsequent controlled clinical trial found no evidence of delayed lactation in mothers who received intravenous magnesium sulfate therapy. Some, but not all, studies have found a trend toward increased time to the first feeding or decreased sucking in infants of mothers treated with intravenous magnesium sulfate during labor because of placental transfer of magnesium to the fetus. Another study found that among women with severe pre-eclampsia who received intravenous magnesium sulfate for up to one day postpartum and who intended to breastfeed, 85% of infants receiving routine well-baby care and 69% of those admitted to the NICU, breastfeeding was successfully initiated.
A study randomized women with preeclampsia to receive intravenous magnesium sulfate for either 6 or 24 hours postpartum. There was no difference in the rate of eclampsia between the two groups. However, those who received the infusion for 24 hours had a delayed onset of lactation, 36.5 hours compared with 25.7 hours in the 6-hour group.
A prospective, multicenter, randomized, controlled trial in 9 Latin American maternity hospitals compared patients with severe pre-eclampsia who had received at least 8 grams of magnesium sulfate prior to placebo. Patients were randomized to continue magnesium sulfate for 24 hours postpartum (n = 555) or stopping the infusion (n = 558). The time to lactation was significantly delayed in those who received magnesium sulfate postpartum (24.1 vs. 17.1 hours).
A study randomized pregnant women with moderate to severe pre-eclampsia to receive magnesium sulfate intravenously infused at the same dose (not specified) for 8 or 24 hours. In patients who received the 8-hour infusion, the mean time to initiate breastfeeding was 14.6 hours compared to 24.3 hours in the patients who received the 24-hour infusion, which was a statistically significant difference.
A retrospective chart review of mothers who delivered at the University of Chicago found that intravenous magnesium sulfate during delivery was associated with over 60% reduced odds of breastfeeding initiation compared to mothers who received no magnesium.

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Protein Binding
25-30%

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Toxicity Data
LD50: 1200 mg/kg (rat, parenteral-subcutaneous).
The first warning of impending toxicity is loss of the patellar reflex at plasma concentrations between 3.5 and 5 mmol/L. Respiratory paralysis occurs at 5 to 6.5 mmol/L. Cardiac conduction is altered at greater than 7.5 mmol/L, and cardiac arrest can be expected when concentrations of magnesium exceed 12.5 mmol/L.

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Interactions
ADMIN OF MAGNESIUM SULFATE IN PREECLAMPSIA & ECLAMPSIA POTENTIATES NEUROMUSCULAR BLOCKADE PRODUCED BY D-TUBOCURARINE, DECAMETHONIUM, & SUCCINYLCHOLINE.
When barbiturates, opiates, general anesthetics, or other CNS depressants are administered concomitantly with magnesium sulfate, dosage of these agents must be carefully adjusted because of the additive central depressant effects.
...Magnesium inhibited extracellular calcium entry, intracellular calcium release, cytosolic calcium oscillations, and phasic contractions of myometrial smooth muscle /induced by oxytocin and other uterotonic agonists/.
...The present in vivo rat study examined the effect of magnesium sulfate to alter the pressor response to norepinephrine (NE) and angiotensin II (A II). Magnesium doses were chosen to approximate those used in treating preeclampsia. NE resulted in a significant rise in mean arterial pressure (delta MAP, 46 +/- 3.7 mmHg; p<0.001). A II also resulted in a significant rise in MAP (delta MAP, 23 +/- 3.6 mmHg, p<0.02). Magnesium sulfate alone had no significant effect on MAP but attenuated the pressor response to both NE (delta MAP, 16 +/- 1.5 mmHg) and A II (delta MAP, 12 +/- 2.5 mmHg). After discontinuation of the magnesium sulfate infusion, the control pressor responses to NE and A II were again seen (delta MAP, 39 +/- 3.5 mmHg and delta MAP, 28 +/- 4.2 mmHg, respectively). Although magnesium sulfate is not a primary antihypertensive agent, it may have effects on blood pressure by attenuating the actions of circulating vasoconstrictors.
For more Interactions (Complete) data for MAGNESIUM SULFATE (6 total), please visit the HSDB record page.

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Non-Human Toxicity Values
LD50 Mouse subcutaneous 645 mg/kg
LD50 Rat subcutaneous 1200 mg/kg

[1]. Clinical pharmacokinetic properties of magnesium sulphate in women with pre-eclampsia and eclampsia. BJOG. 2016;123(3):356-366.

[2]. Magnesium sulfate as a tocolytic agent. Semin Perinatol. 2001;25(4):236-247.

Therapeutic Uses
Analgesics; Anesthetics; Anti-Arrhythmia Agents; Anticonvulsants; Calcium Channel Blockers; Cathartics; Tocolytic Agents
AN EFFECTIVE & WIDELY EMPLOYED SALINE CATHARTIC. /HEPTAHYDRATE, USP/
FULL DOSES OF SALINE CATHARTICS (15 G MAGNESIUM SULFATE OR ITS EQUIVALENT) PRODUCE A SEMIFLUID OR WATERY EVACUATION IN 3 HR OR LESS. LOW DOSES PRODUCE A LAXATIVE EFFECT WITH GREATER LATENCY.
A COLD, WET COMPRESS OF MAGNESIUM SULFATE SOLN IN WATER HAS BEEN EMPLOYED IN TREATMENT OF SUCH SKIN DISORDERS AS ERYSIPELAS. HOT CONCN AQ SOLN...(ABOUT 1 LB/PINT OF WATER) ARE SOMETIMES USED IN TREATMENT OF DEEP-SEATED INFECTIONS, CLOTHS BEING SATURATED & APPLIED WHILE HOT. ACTION MUCH LIKE THAT OF POULTICE. /HEPTAHYDRATE/
For more Therapeutic Uses (Complete) data for MAGNESIUM SULFATE (32 total), please visit the HSDB record page.

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Drug Warnings
SOME ABSORPTION OF COMPONENT IONS OF SALINE CATHARTICS DOES OCCUR, & IN CERTAIN INSTANCES THEY MAY PRODUCE SYSTEMIC TOXICITY. IN AN INDIVIDUAL WITH IMPAIRED RENAL FUNCTION, ACCUM OF MAGNESIUM IONS IN BODY FLUIDS MAY BE SUFFICIENT TO CAUSE INTOXICATION. MAGNESIUM CATHARTICS SHOULD BE ADMIN ONLY IF RENAL FUNCTION IS ADEQUATE.
THE DRUG IS GENERALLY SAFE BUT CAN CAUSE TEMPORARY LOSS OF DEEP TENDON REFLEXES IN MOTHER & MAY SUPPRESS SKELETAL MUSCLE ACTIVITY IN NEONATE. IT SHOULD NOT BE USED IN PT WITH HEART DISEASE...
NEONATE MAY BE DROWSY & EXHIBIT RESP DIFFICULTIES & DIMINISHED MUSCLE TONE. HOWEVER...NO RELATIONSHIP BETWEEN PLASMA MAGNESIUM CONCN OF BLOOD COLLECTED FROM UMBILICAL CORD & THE APGAR SCORE /HAS BEEN FOUND/.
Patients receiving parenteral magnesium sulfate shold be observed carefully, and serum magnesium concn should be monitored to avoid overdosage. ... An IV preparation of a calcium salt (e.g., calcium gluconate) should be readily available for use when magnesium sulfate is given IV. /Magnesium sulfate injection/
For more Drug Warnings (Complete) data for MAGNESIUM SULFATE (14 total), please visit the HSDB record page.

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Pharmacodynamics
Magnesium sulfate is a small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. Magnesium sulfate is gaining popularity as an initial treatment in the management of various dysrhythmias, particularly torsades de pointes, and dyrhythmias secondary to TCA overdose or digitalis toxicity.

MGO4S

120.3676

119.936

7487-88-9

10034-99-8 (heptahydrate)

24083

White to off-white solid powder

1.07 g/mL at 20 °C

330ºC at 760 mmHg

1124 °C

<0.1 mm Hg ( 20 °C)

88.64

0

4

0

6

62.2

0

CSNNHWWHGAXBCP-UHFFFAOYSA-L

InChI=1S/Mg.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2

magnesium;sulfate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

注意： 请将本产品存放在密封且受保护的环境中，避免吸湿/受潮。

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

H2O: 25 mg/mL

注意: 如下所列的是一些常用的体内动物实验溶解配方，主要用于溶解难溶或不溶于水的产品（水溶度<1 mg/mL）。 建议您先取少量样品进行尝试，如该配方可行，再根据实验需求增加样品量。

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注射用配方1: DMSO : Tween 80： Saline = 10 : 5 : 85 (如： 100 μL DMSO → 50 μL Tween 80 → 850 μL Saline)
*生理盐水/Saline的制备：将0.9g氯化钠/NaCl溶解在100 mL ddH ₂ O中，得到澄清溶液。
注射用配方 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL DMSO → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)
注射用配方 3: DMSO : Corn oil = 10 : 90 (如： 100 μL DMSO → 900 μL Corn oil)
示例: 以注射用配方 3 (DMSO : Corn oil = 10 : 90) 为例说明, 如果要配制 1 mL 2.5 mg/mL的工作液, 您可以取 100 μL 25 mg/mL 澄清的 DMSO 储备液，加到 900 μL Corn oil/玉米油中, 混合均匀。

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注射用配方 4: DMSO : 20% SBE-β-CD in Saline = 10 : 90 [如：100 μL DMSO → 900 μL (20% SBE-β-CD in Saline)]
*20% SBE-β-CD in Saline的制备（4°C，储存1周）：将2g SBE-β-CD (磺丁基-β-环糊精) 溶解于10mL生理盐水中，得到澄清溶液。
注射用配方 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (如： 500 μL 2-Hydroxypropyl-β-cyclodextrin (羟丙基环胡精)→ 500 μL Saline)
注射用配方 6: DMSO : PEG300 : Castor oil : Saline = 5 : 10 : 20 : 65 (如： 50 μL DMSO → 100 μL PEG300 → 200 μL Castor oil → 650 μL Saline)
注射用配方 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (如： 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
注射用配方 8: 溶解于Cremophor/Ethanol (50 : 50), 然后用生理盐水稀释。
注射用配方 9: EtOH : Corn oil = 10 : 90 (如： 100 μL EtOH → 900 μL Corn oil)
注射用配方 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL EtOH → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)

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口服配方 1: 悬浮于0.5% CMC Na (羧甲基纤维素钠)
口服配方 2: 悬浮于0.5% Carboxymethyl cellulose (羧甲基纤维素)
示例: 以口服配方 1 (悬浮于 0.5% CMC Na)为例说明, 如果要配制 100 mL 2.5 mg/mL 的工作液, 您可以先取0.5g CMC Na并将其溶解于100mL ddH2O中，得到0.5%CMC-Na澄清溶液；然后将250 mg待测化合物加到100 mL前述 0.5%CMC Na溶液中，得到悬浮液。

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口服配方 3: 溶解于 PEG400 (聚乙二醇400)
口服配方 4: 悬浮于0.2% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 5: 溶解于0.25% Tween 80 and 0.5% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 6: 做成粉末与食物混合

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注意: 以上为较为常见方法，仅供参考， InvivoChem并未独立验证这些配方的准确性。具体溶剂的选择首先应参照文献已报道溶解方法、配方或剂型，对于某些尚未有文献报道溶解方法的化合物，需通过前期实验来确定（建议先取少量样品进行尝试），包括产品的溶解情况、梯度设置、动物的耐受性等。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。