Magnesium serum levels

Hypomagnesemia - Magnesium sulfate is used as replacement therapy in magnesium deficiency especially in acute hypomagnesemia accompanied by signs of tetany similar to those observed in hypocalcemia. In such cases, the serum magnesium (Mg++) level is usually below the lower limit of normal (1.5 to 2.5 or 3 mEq/L) and the serum calcium (Ca++) level is normal (4.3 to 5.3 mEq/L) or elevated. 

Pharmacokinetics IM injection results in therapeutic plasma levels within 60 minutes and persists for 3 to 4 hours. IV doses provide immediate effects that last for 30 minutes. Effective anticonvulsant serum levels range from 2.5 to 7.5 mEq/L. Magnesium is excreted by the kidneys at a rate proportional to the plasma concentration and glomerular filtration. 

Monitoring Carefully monitor standard hypercalcemia-related metabolic parameters, such as serum levels of calcium, phosphate, magnesium, and potassium following pamidronate and zoledronic acid initiation. Also, closely monitor electrolytes, creatinine as well as CBC, differential and hematocrit/hemoglobin. Carefully monitor patients who have preexisting anemia, leukopenia or thrombocytopenia in the first 2 weeks following treatment. 

Willis (Wll), using a potassium hollow cathode tube instead of the commonly employed discharge lamp, determined potassium in blood serum. At the 1 50 dilution no interference was encountered from calcium, magnesium, and phosphate at serum levels, but sodium gave a small enhancement. The sodium interference was controlled by the addition in excess of sodium chloride or of the disodium salt of EDTA to samples and standards alike. 

Urinary potassium and magnesium losses are anticipated consequences of AmB therapy. Some of the losses can be compensated for with increased dietary intake, while others will require oral or intravenous replacement. It should be recognized that the serum levels of these ions do not necessarily correlate with the total deficit, as the plasma levels tend to be conserved while cellular stores are becoming depleted. In general, potassium and magnesium supplements should be given to all patients and the amounts increased if the... 

HCQ cimetidine increases serum levels absorption decreased when taken with kaolin and magnesium trisilicate MTX decreases effect of phenytoin concomitant use with other hepatotoxic drugs can increase risk of hepatotoxicity. NSAIDs can increase half-life and prolong excretion of MTX however, low doses of MTX with NSAIDs for RA are allowed with close monitoring. 

Hypomagnesemia is treated initially with oral, intramuscular, or intravenous administration of magnesium salts. Immediate control of the symptoms of acute hypermagnesemia is obtained with doses of intravenous calcium repeated hourly but extreme toxicity may require cardiac support or mechanical ventilation. Calcium gluconate and calcium chloride can also be administered as antidotes. Serum levels are lowered by reducing intake and by normal methods of excretion, with diuretics given to patients with normal renal function. Other accompanying electrolyte imbalances should be treated concurrently, followed by treatment of the condi-tion(s) that lead to the imbalances. 

In cases of severe magnesium depletion (serum levels < 1 mEq/L), or if signs and symptoms are present regardless of the... 

Magnesium deficiency is common in SBS patients with large ostomy or diarrheal losses. This deficiency should be corrected aggressively because of the correlation between low magnesium and potassium concentrations, and magnesium supplementation decreases the formation of calcium oxalate kidney stones. Serum concentrations are most commonly monitored, but urinary magnesium concentrations may decrease earlier with deficiency, and may be a better estimate of total body stores than serum levels. Oral supplementation may be difficult because it can contribute to increased diarrhea or ostomy output. However, repletion is necessary to correct potassium deficits in addition to magnesium losses. ... 

Edetate disodium, a heavy metal antagonist, is indicated in hypercalcemia (500 mg/kg daily by slow IV infusion) and in digitalis-induced cardiac arrhythmias (15 mg/kg/hour by IV infusion). Ethylenediaminetetraacetic acid (EDTA) will lower serum levels of calcium, magnesium, and zinc. It should not be used in anuria, and renal excretory functions (BUN and creatinine) should be monitored carefully. EDTA should be used cautiously in hypokalemia and in patients with limited cardiac reserve. 

B. Magnesium dosing is highly empiric and is guided by both clinical response and estimated body burden of Mg based on serum levels. 

Aspirin 1.3 to 3.6 g daily more than halved the serum levels of ibuprofen 800 mg to 2.4 g daily, without affecting salicylate levels. There was little additional clinical benefit from the combination. Similarly, aspirin reduced the AUC of flurbiprofen by about two-thirds, but without any clear changes in clinical effectiveness. The pharmacokinetics of the aspirin were unchanged by flurbiprofen. Aspirin 3.9 g daily also virtually halved the AUC of fenoprofen 2.4 g daily,and reduced the AUC of ke-toprofen 200 mg daily by about one-third. The AUC of naproxen was only minimally reduced (by 10 to 15%). Choline magnesium trisalicylate increased the clearance of naproxen by 56% and decreased its serum levels by 26% in one study. ... 

The serum levels of many of the quinolone antibacterials can be reduced by aluminium and magnesium antacids. Calcium compounds interact to a lesser extent, and bismuth compounds onfy minimal. Separating administration by 2 to 6 hours where significant interactions occur reduces admixture in the gut and can minimise the effects. 

When 12 healthy subjeets were given ciprofloxacin 750 mg with two didanosine plaeebo tablets (i.e. all of the antacid additives but no didanosine), the ciprofloxacin AUC and maximum serum levels were reduced by 98% and 93%, respectively. The antacids in this formulation were dihy-droxyaluminium sodium carbonate and magnesium hydroxide. 

The absorption of ciprofloxacin is markedly reduced by iron and zinc compounds. Several studies have clearly demonstrated reductions in the AUC and maximum serum levels of 30 to 90% with ferrous fumarate, ferrous gluconate, ferrous sulfate, iron-glycine sulfate, Centrum Forte (a multi-mineral preparation containing iron, magnesium, zinc, calcium, copper and manganese) and with Stresstabs 600-with-zinc (a multi vitamin-with-zinc preparation). However iron-ovotransferrin has been found to have no significant effect on the absorption of ciprofloxacin. ... 

The serum levels and therefore the therapeutic effectiveness of the tetracyclines can be markedly reduced or even abolished by antacids containing aluminium, bismuth, calcium or magnesium. Other antacids, such as sodium bicarbonate, may also reduce the bioavailability of some tetracyclines. Even intravenous doxycy-cline levels can be reduced by antacids. 

Bismuth subsalicylate reduces the absorption of tetracycline by 34% and reduces the maximum serum levels of doxycycline by 50%. ° It has been suggested the excipient Veegum (magnesium aluminium silicate) in some bismuth subsalicylate formulations enhances this effect." Bismuth carbonate similarly interacts with the tetracyclines in vitro... 

Quinapril, formulated as Accupro also contains magnesium carbonate (250 mg in a 40 mg quinapril capsule, 47 mg in a 5 mg capsule). A pharmacokinetic study in 12 healthy subjects investigating the potential interaction between the magnesium carbonate in these capsules and tetracycline found that single doses of both of these formulations of quinapril markedly reduced the tetracycline absorption. The 5 mg and 40 mg quinapril capsules reduced the tetracycline AUC by 28% and 37%, respectively, and the maximum serum levels were reduced by 25% and 34%, respectively. ... 

Sodium bicarbonate 3 g significantly increased the absorption of glipizide 5 mg and enhanced its effects to some extent, but the total absorption was unaltered. The AUCs from 0 to 30 minutes, 1-hour, and 2-hours, were increased six-, four- and twofold, respectively, and the time to reach the peak serum level fell from 2.5 to 1 hour. Alnminium hydroxide 1 g did not appear to affect the absorption of glipizide 5 mg. Magnesium hydroxide 850 mg considerably increased the rate of absorption of glipizide 5 mg, the AUCs from 0 to 30 minutes and 1-hour being increased by 180 and 69%, respectively. ... 

Antacids containing aluminium/magnesium hydroxide or magnesium trisilicate can reduce the serum levels of chlorpromazine which would be expected to reduce the therapeutic response. Sucralfate and an aluminium/magnesium hydroxide antacid can reduce the absorption of sulpiride. In vitro studies suggest that this interaction may possibly also occur with other antacids and phe-nothiazines. There seem to be no clinical studies or reports confirming the anecdotal evidence of a possible reduction in the effects of haloperidol by antacids. 

Mylanta 11 (aluminium/magnesium hydroxide mixture) 30 mL reduced the AUC and peak serum levels of famotidine by about a third when taken simultaneously, but no significant interaction occurred when the antacid was taken 2 hours after famotidine.Another study found that the peak serum levels of famotidine were reduced by about 25% by Mylanta II in 17 healthy subjects. ... 

Mylanta II (aluminium/magnesium hydroxide mixture) 30 mL reduced the ranitidine peak serum levels and AUC after a single 150-mg dose by about one-third in 6 healthy subjects. Mylanta Double Strength (aluminium/magnesium hydroxide with simeticone) reduced the absorption of ranitidine by 26%, which was not thought to be clinically significant. ... 

Pantoprazole 40 mg daily was given to 24 healthy subjects with and without 10 mL of Maalox (aluminium/magnesium hydroxide). The AUC, maximum serum levels, and the half-life of the pantoprazole were unchanged by the antacid. No special precautions would seem to be necessary if pantoprazole is given with Maalox. 

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