Therapeutic availability of iron administered orally as the ferrous gluconate together with magnesium-L-aspartate hydrochloride.

Since in vitro experiments had excluded interactions between Fe-gluconate (Fe-gluc) and magnesium-L-aspartate hydrochloride (MAH) in aqueous solutions the present in vivo studies seemed to be justified. Animal studies: Rats were kept on magnesium-(Mg)- and iron-(Fe)- sufficient and deficient diets. The intragastral administration of Fe-gluc significantly increased plasma Fe after 3 h, either given alone, or in combination with MAH (inducing hypermagnesemia). Same results were obtained when fortified diets were offered to Fe/Mg-deficient animals. Human studies: The combination of Fe-gluc (2 x 50 mg Fe per day, per os) plus MAH (2 x 7.5 mmol Mg per day, p.o.) was well tolerated by healthy volunteers. Single dose experiments revealed that Fe-gluc alone and in combination with MAH increased plasma Fe levels during 3 h to the same extent. Two groups of pregnant women with moderately reduced hemoglobin levels either received Fe-gluc (out-patients) or its combination with MAH (at least temporarily hospitalised because of preterm labor). Treatments were well tolerated. Hemoglobin levels did not further decrease, as expected without Fe supplements, during the course of pregnancy, thus indicating the therapeutic availability of the electrolytes in both study groups. Progesterone-induced constipation is frequently observed during pregnancy; hence stool softening reported by 50% of the women receiving Fe-gluc plus MAH (versus 33% in the Fe-gluc group) can be regarded as desirable effect. It is concluded that MAH does not interfere with the enteral absorption of Fe-gluc when both electrolytes are orally administered together. Taking both electrolytes together instead of 2 to 3 h apart from each other, as actually recommended, means a less complicated dosage regimen and probably improves compliance.

Potentiation of magnesium-deficiency-induced foetotoxicity by concomitant iron deficiency and its prevention by adequate supply via drinking water.

Magnesium (Mg) and iron (Fe) deficiency frequently develop during pregnancy. Therefore these factors were studied alone (Mg-L, resp. Fe-L) or in combination (Mg-L/Fe-L) on 16 female and 8 male adult fertile Sprague-Dawley rats. The animals were offered a basal diet containing 30 per cent and 17 per cent of the rat's requirement for magnesium and iron, respectively, starting 21 days before mating (2:1) until 49 days after mating. Offspring were also kept on this regimen during a 3-week lactation period and 7 days post weaning. Drinking water was either enriched with 101 ppm Fe2+ (ferrous gluconate): Mg-L, or 365 ppm magnesium (magnesium-L-aspartate hydrochloride trihydrate, MAH): Fe-L, or with any: Mg-L/Fe-L or with both electrolytes: Controls. Fertility remained unaffected under these conditions. Clinically, Fe-L induced iron deficiency and growth retardation of offspring. Pronounced reproductive toxicity was elicited by Mg-L and was even potentiated by Mg-L/Fe-L. In the parental generation, too, adverse effects of Mg-L were aggravated by Mg-L/Fe-L despite the fact that no iron accumulation occurred. Bioavailability of iron was not impaired by magnesium as MAH. With respect to human pregnancy magnesium supplementation has higher priority over iron supplements. To improve tolerance and compliance both minerals are suggested to be taken simultaneously.

Interactions between magnesium and iron. In vitro studies.

In vitro experiments were performed to study the effects of magnesium (Mg) on the absorption of iron (Fe), which have been reported in the literature. Both poorly soluble Mg compounds (Mg oxide and Mg trisilicate) and a readily soluble Mg salt (Mg aspartate hydrochloride trihydrate) were studied along with ferrous gluconate. The influence of the addition of Mg aspartate hydrochloride, Mg oxide and Mg trisilicate on the pH of aqueous acidic solutions was examined initially. As expected, the Mg salts employed as antacids (Mg oxide and Mg trisilicate) were found to have a potent neutralising effect, while after the addition of Mg aspartate hydrochloride the pH value was only slightly shifted toward the alkaline side. These findings suggest that Mg aspartate hydrochloride--unlike Mg oxide and Mg trisilicate--has no appreciable influence on Fe absorption, as the availability of Fe salts in the intestinal tract is pH dependent. A procedure simulating the physiological variations of the pH value in the gastrointestinal tract was used to determine the Fe and Mg content in the supernatant after the addition of the above Fe and Mg salts to aqueous solutions. The addition of poorly water-soluble Mg compounds was shown to result in a drastic reduction in the amount of Fe contained in the supernatant. These data are in agreement with those reported in the literature. However, no decrease in the amount of dissolved Fe was noted in the presence of Mg aspartate hydrochloride. These findings confirm that poorly water-soluble Mg compounds have a high capacity to adsorb Fe and, thus, interfere with Fe absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnesium in pregnant women and the newborn.

In this article the importance of Mg for pregnant women and fetal outcome is reviewed. The physiological changes of Mg-containing body fluids and of tissues are discussed. Mg supplementation during pregnancy seems to be necessary and the efficacy on maternal health and on the newborn are reported. Serum Mg levels decrease during pregnancy and there is a 25% increase of renal Mg excretion. Mg supplementation has a positive effect, with reduced incidence of hospital admission and preterm labour, while the gestational age of the fetus is longer. Convulsions may occur in newborns with hypomagnesaemia. Hypermagnesaemia of the newborn following MgSO4 infusions to toxaemic mothers has been reported.