Ingredients | Not Present |
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(Mg Bisglycinate Chelate)
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Magnesium L-Threonate
(Mg L-Threonate)
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Gelatin
Below is general information about the effectiveness of the known ingredients contained in the product Restful Brain Magnesium Supplement 450 mg. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
Below is general information about the safety of the known ingredients contained in the product Restful Brain Magnesium Supplement 450 mg. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
LIKELY SAFE ...when used orally and appropriately (13161,14306,14307,14308,15655,15752,17187,92271,92274,103247)(103250,108898). However, cocoa naturally contains caffeine, and caffeine may be unsafe when used orally in doses of more than 400 mg daily (11733,98806). While most cocoa products contain only small amounts of caffeine (about 2-35 mg per serving) (2708,3900), one cup of unsweetened, dry cocoa powder can contain up to 198 mg of caffeine (100515). To be on the safe side, cocoa should be used in amounts that provide less than 400 mg of caffeine daily. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine naturally found in ingredients such as cocoa does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. Cocoa and dark chocolate products worldwide also contain heavy metals such as lead and cadmium. In the US, one ounce (approximately 28 grams) of most commercially available dark chocolate products tested contained levels of lead and/or cadmium above the maximum allowable dose level for California, with cadmium levels generally increasing with the percentage of cocoa (109847,109848,109849). Advise patients to consume cocoa in moderation. ...when used topically. Cocoa butter is used extensively as a base for ointments and suppositories and is generally considered safe (11).
CHILDREN: POSSIBLY UNSAFE
when dark chocolate is used orally.
Cocoa and dark chocolate products worldwide contain heavy metals such as lead and cadmium. In the US, one ounce (approximately 28 grams) of most commercially available dark chocolate products tested contained levels of lead and/or cadmium above the maximum allowable dose level for California, with cadmium levels generally increasing with the percentage of cocoa (109847,109848,109849). Children are at increased risk of adverse effects from intake of lead and/or cadmium. There is insufficient reliable information available about the safety of other chocolate-based products that typically contain smaller quantities of cocoa.
PREGNANCY: POSSIBLY SAFE
when used orally in moderate amounts.
However, due to the caffeine content of cocoa preparations, intake should be closely monitored during pregnancy to ensure moderate consumption. Fetal blood concentrations of caffeine approximate maternal concentrations (4260). Some research has found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years (109846). While many cocoa products contain only small amounts of caffeine (about 2-35 mg per serving) (2708,3900), unsweetened, dry cocoa powder can contain up to 198 mg of caffeine per cup (100515). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, doses of up to 300 mg daily can be consumed during pregnancy without an increased risk of spontaneous abortion, still birth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). To be on the safe side, cocoa should be used in amounts that provide less than 300 mg of caffeine daily. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cocoa, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.
PREGNANCY: POSSIBLY UNSAFE
when used orally in large amounts.
Caffeine found in cocoa crosses the placenta producing fetal blood concentrations similar to maternal levels (4260). Consumption of caffeine in amounts over 300 mg daily is associated with a significantly increased risk of miscarriage in some studies (16014,98806). Additionally, high intake of caffeine during pregnancy have been associated with premature delivery, low birth weight, and loss of the fetus (6). While many cocoa products contain only small amounts of caffeine (about 2-35 mg per serving) (2708,3900), unsweetened, dry cocoa powder can contain up to 198 mg of caffeine per cup (100515). To be on the safe side, cocoa should be used in amounts that provide less than 300 mg of caffeine daily (2708). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cocoa, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. Cocoa and dark chocolate products worldwide also contain heavy metals such as lead and cadmium. In the US, one ounce (approximately 28 grams) of most commercially available dark chocolate products tested contained levels of lead and/or cadmium above the maximum allowable dose level for California, with cadmium levels generally increasing with the percentage of cocoa (109847,109848,109849). Large doses or excessive intake of cocoa should be avoided during pregnancy.
LACTATION: POSSIBLY SAFE
when used in moderate amounts or in amounts commonly found in foods.
Due to the caffeine content of cocoa preparations, intake should be closely monitored while breastfeeding. During lactation, breast milk concentrations of caffeine are thought to be approximately 50% of serum concentrations. Moderate consumption of cocoa would likely result in very small amounts of caffeine exposure to a nursing infant (6). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as cocoa, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.
LACTATION: POSSIBLY UNSAFE
when used orally in large amounts.
Consumption of excess chocolate (16 oz per day) may cause irritability and increased bowel activity in the infant (6026). Cocoa and dark chocolate products worldwide also contain heavy metals such as lead and cadmium. In the US, one ounce (approximately 28 grams) of most commercially available dark chocolate products tested contained levels of lead and/or cadmium above the maximum allowable dose level for California, with cadmium levels generally increasing with the percentage of cocoa (109847,109848,109849). Large doses or excessive intake of cocoa should be avoided during lactation.
LIKELY SAFE ...when used orally and appropriately. Oral magnesium is safe when used in doses below the tolerable upper intake level (UL) of 350 mg daily (7555). ...when used parenterally and appropriately. Parenteral magnesium sulfate is an FDA-approved prescription product (96484).
POSSIBLY UNSAFE ...when used orally in excessive doses. Doses greater than the tolerable upper intake level (UL) of 350 mg daily frequently cause loose stools and diarrhea (7555).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Magnesium is safe when used in doses below the tolerable upper intake level (UL) of 65 mg daily for children 1 to 3 years, 110 mg daily for children 4 to 8 years, and 350 mg daily for children older than 8 years (7555,89396). ...when used parenterally and appropriately (96483).
CHILDREN: LIKELY UNSAFE
when used orally in excessive doses.
Tell patients not to use doses above the tolerable upper intake level (UL). Higher doses can cause diarrhea and symptomatic hypermagnesemia including hypotension, nausea, vomiting, and bradycardia (7555,8095).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately.
Magnesium is safe for those pregnant and breast-feeding when used in doses below the tolerable upper intake level (UL) of 350 mg daily (7555).
PREGNANCY AND LACTATION: POSSIBLY SAFE
when prescription magnesium sulfate is given intramuscularly and intravenously prior to delivery for up to 5 days (12592,89397,99354,99355).
However, due to potential adverse effects associated with intravenous and intramuscular magnesium, use during pregnancy is limited to patients with specific conditions such as severe pre-eclampsia or eclampsia. There is some evidence that intravenous magnesium can increase fetal mortality and adversely affect neurological and skeletal development (12590,12593,60818,99354,99355). However, a more recent analysis of clinical research shows that increased risk of fetal mortality seems to occur only in the studies where antenatal magnesium is used for tocolysis and not for fetal neuroprotection or pre-eclampsia/eclampsia (102457). Furthermore, antenatal magnesium does not seem to be associated with increased risk of necrotizing enterocolitis in preterm infants (104396). There is also concern that magnesium increases the risk of maternal adverse events. A meta-analysis of clinical research shows that magnesium sulfate might increase the risk of maternal adverse events, especially in Hispanic mothers compared to other racial and ethnic groups (60971,99319).
PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses.
Tell patients to avoid exceeding the tolerable upper intake level (UL) of 350 mg daily. Taking magnesium orally in higher doses can cause diarrhea (7555). ...when prescription magnesium sulfate is given intramuscularly and intravenously prior to delivery for longer than 5 days (12592,89397,99354,99355). Maternal exposure to magnesium for longer than 5-7 days is associated with an increase in neonatal bone abnormalities such as osteopenia and fractures. The U.S. Food and Drug Administration (FDA) recommends that magnesium injection not be given for longer than 5-7 days (12590,12593,60818,99354,99355).
Below is general information about the interactions of the known ingredients contained in the product Restful Brain Magnesium Supplement 450 mg. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
Theoretically, taking cocoa with ACEIs might increase the risk of adverse effects.
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Theoretically, cocoa might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
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Cocoa contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine. It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests. However, methylxanthines appear more likely to interfere with dipyridamole than adenosine-induced stress testing (11771).
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Theoretically, concomitant use might increase levels and adverse effects of caffeine.
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Cocoa contains caffeine. Alcohol reduces caffeine metabolism. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects (6370).
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Theoretically, cocoa may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
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Clinical research shows that intake of cocoa can inhibit platelet adhesion, aggregation, and activity (6085,17076,41928,41948,41957,41958,41995,42014,42070,42145)(111526) and increase aspirin-induced bleeding time (23800). For patients on dual antiplatelet therapy, cocoa may enhance the inhibitory effect of clopidogrel, but not aspirin, on platelet aggregation (111526).
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Theoretically, taking cocoa with antihypertensive drugs might increase the risk of hypotension.
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Theoretically, large amounts of cocoa might increase the cardiac inotropic effects of beta-agonists.
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Cocoa contains caffeine. Theoretically, large amounts of caffeine might increase cardiac inotropic effects of beta-agonists (15). A case of atrial fibrillation associated with consumption of large quantities of chocolate in a patient with chronic albuterol inhalation abuse has also been reported (42075).
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Theoretically, concomitant use might increase the effects and adverse effects of caffeine in cocoa.
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Theoretically, concomitant use might increase the effects and adverse effects of caffeine found in cocoa.
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Theoretically, concomitant use might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Caffeine is metabolized by cytochrome P450 1A2 (CYP1A2) (3941,5051,11741,23557,23573,23580,24958,24959,24960,24962), (24964,24965,24967,24968,24969,24971,38081,48603). Theoretically, drugs that inhibit CYP1A2 may decrease the clearance rate of caffeine from cocoa and increase caffeine levels.
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Theoretically, cocoa might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Details
Cocoa contains caffeine. Caffeine may inhibit dipyridamole-induced vasodilation (11770,11772). It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests (11770). Methylxanthines appear more likely to interfere with dipyridamole than adenosine-induced stress testing (11771).
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Theoretically, disulfiram might increase the risk of adverse effects from caffeine.
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Cocoa contains caffeine. In human research, disulfiram decreases the rate of caffeine clearance (11840).
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Theoretically, using cocoa with diuretic drugs might increase the risk of hypokalemia.
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Theoretically, concomitant use might increase the risk for stimulant adverse effects.
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Theoretically, estrogens might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Estrogen inhibits caffeine metabolism (2714).
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Theoretically, fluconazole might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022).
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Theoretically, cocoa might increase the levels and adverse effects of flutamide.
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Cocoa contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide (23553).
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Theoretically, fluvoxamine might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Fluvoxamine reduces caffeine metabolism (6370).
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Theoretically, abrupt cocoa withdrawal might increase the levels and adverse effects of lithium.
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Theoretically, methoxsalen might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Methoxsalen can reduce caffeine metabolism (23572).
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Theoretically, metformin might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Animal research suggests that metformin can reduce caffeine metabolism (23571).
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Theoretically, mexiletine might increase the levels and adverse effects of caffeine.
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Theoretically, concomitant use might increase the risk of a hypertensive crisis.
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Cocoa contains caffeine. Large amounts of caffeine with MAOIs might precipitate a hypertensive crisis (15).
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Theoretically, concomitant use might increase the risk of hypertension.
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Cocoa contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (36549).
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Theoretically, cocoa might decrease the effects of pentobarbital.
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Cocoa contains caffeine. Caffeine might negate the hypnotic effects of pentobarbital (13742).
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Theoretically, cocoa might reduce the effects of phenobarbital and increase the risk for convulsions.
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Theoretically, phenothiazines might increase the levels and adverse effects of caffeine.
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Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.
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Theoretically, cocoa might reduce the effects of phenytoin and increase the risk for convulsions.
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Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.
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Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.
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Cocoa contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2, and concomitant use might reduce metabolism of one or both agents (11739).
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Theoretically, concomitant use might increase stimulant adverse effects.
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Cocoa contains caffeine. Concomitant use might increase the risk of stimulant adverse effects (11832).
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Theoretically, terbinafine might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Terbinafine decreases the rate of caffeine clearance (11740).
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Theoretically, cocoa might increase the levels and adverse effects of theophylline.
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Theoretically, cocoa tea might increase the levels and adverse effects of tiagabine.
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Cocoa contains caffeine. Animal research suggests that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine (23561).
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Theoretically, ticlopidine might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. In vitro evidence suggests that ticlopidine can inhibit caffeine metabolism (23557). However, this effect has not been reported in humans.
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Theoretically, cocoa might reduce the effects of valproate and increase the risk for convulsions.
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Theoretically, verapamil might increase the levels and adverse effects of caffeine.
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Cocoa contains caffeine. Verapamil increases plasma caffeine concentrations by 25% (11741).
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Concomitant use of aminoglycoside antibiotics and magnesium can increase the risk for neuromuscular weakness.
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Both aminoglycosides and magnesium reduce presynaptic acetylcholine release, which can lead to neuromuscular blockade and possible paralysis. This is most likely to occur with high doses of magnesium given intravenously (13362).
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Use of acid reducers may reduce the laxative effect of magnesium oxide.
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A retrospective analysis shows that, in the presence of H2 receptor antagonists (H2RAs) or proton pump inhibitors (PPIs), a higher dose of magnesium oxide is needed for a laxative effect (90033). This may also occur with antacids. Under acidic conditions, magnesium oxide is converted to magnesium chloride and then to magnesium bicarbonate, which has an osmotic laxative effect. By reducing acidity, antacids may reduce the conversion of magnesium oxide to the active bicarbonate salt.
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Theoretically, magnesium may have antiplatelet effects, but the evidence is conflicting.
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In vitro evidence shows that magnesium sulfate inhibits platelet aggregation, even at low concentrations (20304,20305). Some preliminary clinical evidence shows that infusion of magnesium sulfate increases bleeding time by 48% and reduces platelet activity (20306). However, other clinical research shows that magnesium does not affect platelet aggregation, although inhibition of platelet-dependent thrombosis can occur (60759).
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Magnesium can decrease absorption of bisphosphonates.
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Cations, including magnesium, can decrease bisphosphonate absorption. Advise patients to separate doses of magnesium and these drugs by at least 2 hours (13363).
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Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
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Magnesium inhibits calcium entry into smooth muscle cells and may therefore have additive effects with calcium channel blockers. Severe hypotension and neuromuscular blockades may occur when nifedipine is used with intravenous magnesium (3046,20264,20265,20266), although some contradictory evidence suggests that concurrent use of magnesium with nifedipine does not increase the risk of neuromuscular weakness (60831). High doses of magnesium could theoretically have additive effects with other calcium channel blockers.
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Magnesium salts may reduce absorption of digoxin.
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Gabapentin absorption can be decreased by magnesium.
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Clinical research shows that giving magnesium oxide orally along with gabapentin decreases the maximum plasma concentration of gabapentin by 33%, time to maximum concentration by 36%, and area under the curve by 43% (90032). Advise patients to take gabapentin at least 2 hours before, or 4 to 6 hours after, magnesium supplements.
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Magnesium might precipitate ketamine toxicity.
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In one case report, a 62-year-old hospice patient with terminal cancer who had been stabilized on sublingual ketamine 150 mg four times daily experienced severe ketamine toxicity lasting for 2 hours after taking a maintenance dose of ketamine following an infusion of magnesium sulfate 2 grams (105078). Since both magnesium and ketamine block the NMDA receptor, magnesium is thought to have potentiated the effects of ketamine.
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Magnesium can reduce the bioavailability of levodopa/carbidopa.
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Clinical research in healthy volunteers shows that taking magnesium oxide 1000 mg with levodopa 100 mg/carbidopa 10 mg reduces the area under the curve (AUC) of levodopa by 35% and of carbidopa by 81%. In vitro and animal research shows that magnesium produces an alkaline environment in the digestive tract, which might lead to degradation and reduced bioavailability of levodopa/carbidopa (100265).
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Potassium-sparing diuretics decrease excretion of magnesium, possibly increasing magnesium levels.
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Potassium-sparing diuretics also have magnesium-sparing properties, which can counteract the magnesium losses associated with loop and thiazide diuretics (9613,9614,9622). Theoretically, increased magnesium levels could result from concomitant use of potassium-sparing diuretics and magnesium supplements.
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Magnesium decreases absorption of quinolones.
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Magnesium can form insoluble complexes with quinolones and decrease their absorption (3046). Advise patients to take these drugs at least 2 hours before, or 4 to 6 hours after, magnesium supplements.
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Sevelamer may increase serum magnesium levels.
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In patients on hemodialysis, sevelamer use was associated with a 0.28 mg/dL increase in serum magnesium. The mechanism of this interaction remains unclear (96486).
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Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
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Parenteral magnesium shortens the time to onset of skeletal muscle relaxants by about 1 minute and prolongs the duration of action by about 2 minutes. Magnesium potentiates the effects of skeletal muscle relaxants by decreasing calcium-mediated release of acetylcholine from presynaptic nerve terminals, reducing postsynaptic sensitivity to acetylcholine, and having a direct effect on the membrane potential of myocytes (3046,97492,107364). Magnesium also has vasodilatory actions and increases cardiac output, allowing a greater amount of muscle relaxant to reach the motor end plate (107364). A clinical study found that low-dose rocuronium (0.45 mg/kg), when given after administration of magnesium 30 mg/kg over 10 minutes, has an accelerated onset of effect, which matches the onset of effect seen with a full-dose rocuronium regimen (0.6 mg/kg) (96485). In another clinical study, onset times for rocuronium doses of 0.3, 0.6, and 1.2 mg/kg were 86, 76, and 50 seconds, respectively, when given alone, but were reduced to 66, 44, and 38 seconds, respectively, when the doses were given after a 15-minute infusion of magnesium sulfate 60 mg/kg (107364). Giving intraoperative intravenous magnesium sulfate, 50 mg/kg loading dose followed by 15 mg/kg/hour, reduces the onset time of rocuronium, enhances its clinical effects, reduces the dose of intraoperative opiates, and prolongs the spontaneous recovery time (112781,112782). It does not affect the activity of subsequently administered neostigmine (112782).
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Magnesium increases the systemic absorption of sulfonylureas, increasing their effects and side effects.
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Clinical research shows that administration of magnesium hydroxide with glyburide increases glyburide absorption, increases maximal insulin response by 35-fold, and increases the risk of hypoglycemia, when compared with glyburide alone (20307). A similar interaction occurs between magnesium hydroxide and glipizide (20308). The mechanism of this effect appears to be related to the elevation of gastrointestinal pH by magnesium-based antacids, increasing solubility and enhancing absorption of sulfonylureas (22364).
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Magnesium decreases absorption of tetracyclines.
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Magnesium can form insoluble complexes with tetracyclines in the gut and decrease their absorption and antibacterial activity (12586). Advise patients to take these drugs 1 hour before or 2 hours after magnesium supplements.
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Below is general information about the adverse effects of the known ingredients contained in the product Restful Brain Magnesium Supplement 450 mg. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
General
...Orally and topically, cocoa is generally well tolerated.
Most Common Adverse Effects:
Orally: Borborygmi, constipation, diuresis, gastrointestinal discomfort, headaches, and nausea.
Serious Adverse Effects (Rare):
Orally: Tachycardia.
Cardiovascular ...Some cases of increased heart rate have been reported with oral cocoa use (13161,42132).
Dermatologic ...In some cases, when taken orally, cocoa can cause allergic skin reactions (13161). Topically, cocoa butter has occasionally caused a rash. In animals, it has been shown to block pores and cause acne; however, this has not been found in humans (11).
Gastrointestinal ...In human trials, chocolate consumption was associated with a higher incidence of flatulence, irritable bowel syndrome, upset stomach, gastric upset, borborygmi (a gurgling noise made by fluid or gas in the intestines), bloating, nausea, vomiting, and constipation or obstipation (41986,42221,41921,1374,42220,1373,42099,42097,42156,42123,18229,42169,42111). Chocolate consumption has been implicated as a provoking factor in gastroesophageal reflux disease (GERD) (41974,42005,41946,1374). Unpalatability has been reported (42079,42169). Consumption of chocolate and other sweet foods may lead to increased dental caries (42129,42030).
Genitourinary ...In some cases, when taken orally, cocoa can cause increased urination (13161).
Neurologic/CNS ...In some cases, when taken orally, cocoa can cause shakiness and might trigger migraine and other headaches (13161,42169,92271).
Other ...Due to the high sugar and caloric content of chocolate, there is concern about weight gain in people who consume large amounts of chocolate (17187).
General
...Magnesium is generally well tolerated.
Some clinical research shows no differences in adverse effects between placebo and magnesium groups.
Most Common Adverse Effects:
Orally: Diarrhea, gastrointestinal irritation, nausea, and vomiting.
Intravenously: Bradycardia, dizziness, flushing sensation, hypotension, and localized pain and irritation. In pregnancy, may cause blurry vision, dizziness, lethargy, nausea, nystagmus, and perception of warmth.
Serious Adverse Effects (Rare):
All ROAs: With toxic doses, loss of reflexes and respiratory depression can occur. High doses in pregnancy can increase risk of neonatal mortality and neurological defects.
Cardiovascular
...Intravenously, magnesium can cause bradycardia, tachycardia, and hypotension (13356,60795,60838,60872,60960,60973,60982,61001,61031).
Magnesium sulfate may cause rapid heartbeat when administered antenatally (60915).
In one case report, a 99-year-old male who took oral magnesium oxide 3000 mg daily for chronic constipation was hospitalized with hypermagnesemia, hypotension, bradycardia, heart failure, cardiomegaly, second-degree sinoatrial block, and complete bundle branch block. The patient recovered after discontinuing the magnesium oxide (108966).
Dermatologic ...Intravenously, magnesium may cause flushing, sweating, and problems at the injection site (including burning pain) (60960,60982,111696). In a case study, two patients who received intravenous magnesium sulfate for suppression of preterm labor developed a rapid and sudden onset of an urticarial eruption (a skin eruption of itching welts). The eruption cleared when magnesium sulfate was discontinued (61045). Orally, magnesium oxide may cause allergic skin rash, but this is rare. In one case report, a patient developed a rash after taking 600 mg magnesium oxide (Maglax) (98291).
Gastrointestinal
...Orally, magnesium can cause gastrointestinal irritation, nausea, vomiting, and diarrhea (1194,4891,10661,10663,18111,60951,61016,98290).
In rare cases, taking magnesium orally might cause a bezoar, an indigestible mass of material which gets lodged in the gastrointestinal tract. In a case report, a 75-year-old female with advanced rectal cancer taking magnesium 1500 mg daily presented with nausea and anorexia from magnesium oxide bezoars in her stomach (99314). Magnesium can cause nausea, vomiting, or dry mouth when administered intravenously or by nebulization (60818,60960,60982,104400). Antenatal magnesium sulfate may also cause nausea and vomiting (60915). Two case reports suggest that giving magnesium 50 grams orally for bowel preparation for colonoscopy in patients with colorectal cancer may lead to intestinal perforation and possibly death (90006).
Delayed meconium passage and obstruction have been reported rarely in neonates after intravenous magnesium sulfate was given to the mother during pregnancy (60818). In a retrospective study of 200 neonates born prematurely before 32 weeks of gestation, administration of prenatal IV magnesium sulfate, as a 4-gram loading dose and then 1-2 grams hourly, was not associated with the rate of meconium bowel obstruction when compared with neonates whose mothers had not received magnesium sulfate (108728).
Genitourinary ...Intravenously, magnesium sulfate may cause renal toxicity or acute urinary retention, although these events are rare (60818,61012). A case of slowed cervical dilation at delivery has been reported for a patient administered intravenous magnesium sulfate for eclampsia (12592). Intravenous magnesium might also cause solute diuresis. In a case report, a pregnant patient experienced polyuria and diuresis after having received intravenous magnesium sulfate in Ringer's lactate solution for preterm uterine contractions (98284).
Hematologic ...Intravenously, magnesium may cause increased blood loss at delivery when administered for eclampsia or pre-eclampsia (12592). However, research on the effect of intravenous magnesium on postpartum hemorrhage is mixed. Some research shows that it does not affect risk of postpartum hemorrhage (60982), while other research shows that intrapartum magnesium administration is associated with increased odds of postpartum hemorrhage, increased odds of uterine atony (a condition that increases the risk for postpartum hemorrhage) and increased need for red blood cell transfusions (97489).
Musculoskeletal
...Intravenously, magnesium may cause decreased skeletal muscle tone, muscle weakness, or hypocalcemic tetany (60818,60960,60973).
Although magnesium is important for normal bone structure and maintenance (272), there is concern that very high doses of magnesium may be detrimental. In a case series of 9 patients receiving long-term tocolysis for 11-97 days, resulting in cumulative magnesium sulfate doses of 168-3756 grams, a lower bone mass was noted in 4 cases receiving doses above 1000 grams. There was one case of pregnancy- and lactation-associated osteoporosis and one fracture (108731). The validity and clinical significance of this data is unclear.
Neurologic/CNS
...Intravenously, magnesium may cause slurred speech, dizziness, drowsiness, confusion, or headaches (60818,60960).
With toxic doses, loss of reflexes, neurological defects, drowsiness, confusion, and coma can occur (8095,12589,12590).
A case report describes cerebral cortical and subcortical edema consistent with posterior reversible encephalopathy syndrome (PRES), eclampsia, somnolence, seizures, absent deep tendon reflexes, hard to control hypertension, acute renal failure and hypermagnesemia (serum level 11.5 mg/dL), after treatment with intravenous magnesium sulfate for preeclampsia in a 24-year-old primigravida at 39 weeks gestation with a previously uncomplicated pregnancy. The symptoms resolved after 4 days of symptomatic treatment in an intensive care unit, and emergency cesarian delivery of a healthy infant (112785).
Ocular/Otic ...Cases of visual impairment or nystagmus have been reported following magnesium supplementation, but these events are rare (18111,60818).
Psychiatric ...A case of delirium due to hypermagnesemia has been reported for a patient receiving intravenous magnesium sulfate for pre-eclampsia (60780).
Pulmonary/Respiratory ...Intravenously, magnesium may cause respiratory depression and tachypnea when used in toxic doses (12589,61028,61180).
Other ...Hypothermia from magnesium used as a tocolytic has been reported (60818).