Details About Overdose or Poisoning Generic Salt :: Magnesium
Magnesium
Drug Pharmacology ::
I. Pharmacology./b>
Magnesiumis the fourth most common cation in the body and is the second mostabundant intracellular cation after potassium. Magnesium plays anessential role as an enzymatic cofactor in a number of biochemicalpathways, including energy production from adenosine triphosphate (ATP).
Magnesium has a direct effect on the Na+,K+-ATPasepump in both cardiac and nerve tissues. Further, magnesium has somecalcium-blocking activity and may indirectly antagonize digoxin at themyocardial Na+,K+-ATPase pump.
Magnesiummodifies skeletal and smooth-muscle contractility. Infusions can causevasodilation, hypotension, and bronchodilation. It can reduce orabolish seizures of toxemia.
Magnesiumis primarily an intracellular ion, and only 1% is in the extracellularfluid. A low serum Mg level under 1.2 mg/dL may indicate a net bodydeficit of 5000 mg or more.
E. Hypomagnesemiacan be associated with a number of acute or chronic disease processes(malabsorption, pancreatitis, diabetic ketoacidosis). It may resultfrom chronic diuretic use or alcoholism. It is a potentially serious,life-threatening consequence of hydrofluoric acid poisoning.
Drug Indications ::
Indications
Replacement therapy for patients with hypomagnesemia.
Torsade de pointes ventricular tachycardia (see Ventricular arrhythmias).
C. Otherarrhythmias suspected to be related to hypomagnesemia. Magnesium may behelpful in selected patients with cardiac glycoside toxicity but is nota substitute for digoxin-specific Fab fragments.
Bariumingestions (see Barium). Magnesium sulfate can be used orally toconvert soluble barium to insoluble, nonabsorbable barium sulfate ifgiven early.
Drug Contra-Indications ::
III. Contraindications./b>
Magnesiumshould be administered cautiously in patients with renal impairment toavoid the potential for serious hypermagnesemia.
Heart block and bradycardia.
Drug Adverse Effects ::
IV. Adverse effects
Flushing, sweating, hypothermia.
Depression of deep tendon reflexes, flaccid paralysis, respiratory paralysis.
Depressionof cardiac function, hypotension, bradycardia, general circulatorycollapse (in particular with rapid administration).
D. Gastrointestinal upset and diarrhea with oral administration.
E. Use in pregnancy. FDA category A. Magnesium sulfate is used commonly used as a agent for premature labor (see Table III–1).
Drug Lab Interactions ::
Drug or laboratory interactions
General CNS depressants. Additive effects may occur when CNS depressants are combined with magnesium infusions.
Neuromuscularblocking agents. Concomitant administration of magnesium withneuromuscular blocking agents may enhance and prolong their effect.Dose adjustment may be needed to avoid prolonged respiratory depression.
Drug Dose Management ::
Dosage and method of administration (adults and children)
Magnesium can be given orally, IV, or by IM injection. When it is givenparenterally, the IV route is preferred and the sulfate salt generallyis used.
Magnesiumdosing is highly empiric and is guided by both clinical response andthe estimated total body deficit of Mg based on serum levels.
Adults: Give1 g (8.12 mEq) every 6 hours IV for four doses. For severehypomagnesemia, doses as high as 1 mEq/kg/24 h or 8–12 g/day in divideddoses have been used. Magnesium sulfate can be diluted in D5W or NS 50–100 mL and infused over 5–60 minutes. Children:Give 25–50 mg/kg/dose IV for three to four doses. Maximum single doseshould not exceed 2000 mg (16 mEq). Higher dosages of 100 mg/kg/dose IVhave also been employed.
Fortreatment of life-threatening arrhythmias (ventricular tachycardia orfibrillation associated with hypomagnesemia) in adults, give 1–2 g(8–16 mEq) IV, which can be given over 1–2 minutes. It should bediluted to 20% or less and infused no faster than 1 g/min (see IV,above). It can also be administered as a loading dose of 1–2 g (8–16mEq) IV diluted in 50–100 mL of D5W or NS and infused over 5 to 60 minutes. A common regimen for adults is 2 g IV over 20 minutes.
E.For soluble barium ingestions, magnesium sulfate can be given to forminsoluble, poorly absorbed barium sulfate. Adults should receive 30 gorally or by lavage, and children 250 mg/kg. Magnesium sulfate shouldnot be given IV in these cases.
Drug Chemical Formulations ::
Formulations.
A. Parenteral.Magnesium sulfate vials, 50% (4.06 mEq/mL, 500 mg/mL) in volumes of 2mL, 10 mL, 20 mL, and 50 mL where 2 mL is equivalent to 1 g or 8.12 mEqAlso available in 10% (0.8 mEq/mL) and 12.5% (1 mEq/mL) in 20- and50-mL ampules and vials as well as large-volume premix bags. Magnesiumchloride injection is also available but is used less commonly.
B. Oral. A large number of oral dosage forms are available, formulated in both immediate and sustained-release formulations.
C. The suggested minimum stocking level to treat a 70-kg adult for the first 24 hours is at least 12 g of parenteral magnesium sulfate.
