毒理性
大白鼠口服LD50为9100毫克/千克。来自饮食来源的过量镁在健康人中不会构成健康风险，因为肾脏会将过量的镁通过尿液排出体外。另一方面，从膳食补充剂或药物中摄入的高剂量镁通常会导致腹泻，这种情况可能会伴随恶心和腹部绞痛。最常导致腹泻的镁形式包括碳酸镁、氯化镁、葡萄糖酸镁和氧化镁。镁盐的腹泻和泻药效果是由于未吸收的盐分在小肠和结肠中的渗透活性和对胃动力的刺激。口服摄入后出现高镁血症的情况在肾功能障碍的患者中不常见。高镁血症的症状和体征可能包括呼吸抑制、由于神经肌肉阻滞导致的深部肌腱反射消失、恶心、呕吐、面部潮红、低血压、嗜睡、心动过缓和肌肉无力。
含有镁的泻药和抗酸剂（通常每天提供超过5000毫克的镁）的非常高的剂量与镁中毒的发生有关，包括一名28个月大的男孩以及一位老年人因高镁血症而死亡。镁中毒的症状，通常在浓度为1.74–2.61毫摩尔/升时出现，可能包括低血压、恶心、呕吐、面部潮红、尿潴留、肠梗阻、抑郁和乏力，然后进展为肌肉无力、呼吸困难、极度低血压、心跳不规则和心脏骤停。镁中毒的风险随着肾功能受损或肾衰竭而增加，因为去除过量镁的能力降低或丧失。
治疗：对于肾功能正常的患者，可以给予静脉输液或呋塞米以促进镁的排泄。对于有症状的高镁血症患者，可以缓慢静脉注射葡萄糖酸钙以对抗镁对心脏和神经肌肉的影响。
Oral LD50 is 9100 mg/kg in the rat. Excess magnesium from dietary sources does not pose a health risk in healthy individuals because the kidneys eliminate excess amounts of magnesium in the urine. On the other hand, high doses of magnesium from dietary supplements or medications often result in diarrhea that can be combined with nausea and abdominal cramping. Forms of magnesium most commonly reported to cause diarrhea include magnesium carbonate, chloride, gluconate, and oxide. Diarrheal and laxative effects of magnesium salts are due to the osmotic activity of unabsorbed salts in the intestine and colon and the stimulation of gastric motility. Hypermagnesaemia after oral ingestion is uncommon except in patients with renal impairment. Signs and symptoms of hypermagnesemia may include respiratory depression, loss of deep tendon reflexes due to neuromuscular blockade, nausea, vomiting, flushing, hypotension, drowsiness, bradycardia and muscle weakness. Very high doses of magnesium-containing laxatives and antacids (normally providing more than 5,000 mg/day magnesium) have been associated with the occurrence of magnesium toxicity, including fatal hypermagnesemia in a 28-month-old boy as well as an elderly man. Symptoms of magnesium toxicity, normally presenting at concentrations of 1.74–2.61 mmol/L, may include hypotension, nausea, vomiting, facial flushing, retention of urine, ileus, depression, and lethargy before progressing to muscle weakness, difficulty breathing, extreme hypotension, irregular heartbeat, and cardiac arrest. The risk of magnesium toxicity increases with compromised renal function or kidney failure because the ability to remove excess magnesium is reduced or lost. Treatment: In patients with normal renal function, IV fluids or furosemide may be administered to promote the excretion of magnesium. In patients with symptomatic hypermagnesaemia, slow IV injection of calcium gluconate can be administered to antagonize the cardiac and neuromuscular effects of magnesium.
来源:DrugBank
