Magnesium plasma concentrations were measured in healthy probands before and after administration of trimagnesium dicitrate by the oral and intravenous routes. There was a notable circadian fluctuation of the plasma concentration with a peak in the evening hours. After oral administration of 12 and 24 mmol magnesium, a long-lasting, statistically significant increase in plasma magnesium concentration measured as the increase in area under the curve (AUC) between 0 and 12 h, of 3.1% and 4.6%, respectively, was found. After intravenous administration of 4 and 8 mmol magnesium, AUCs increased by 9.5% and 16.1%, respectively. The decline in the plasma magnesium concentration after i.v. administration was compatible with a three-compartment model with a terminal half-time of about 8 h. Although no absolute value of the oral bioavailability of trimagnesium dicitrate could be determined from the data, our results may be important in helping to elucidate the influence of magnesium preparations on the plasma magnesium concentration. By comparing the effects of different preparations, it should be possible to estimate the relative oral bioavailability and the bioequivalence of these preparations.

The fibrinolytic system in 18 healthy women treated with an oral contraceptive hormone (Eugynon®: 50 µg ethinyl estrenol, 500 µg norgestrel) was studied repeatedly over 3 months. An increased level of immunoreactive plasminogen, as well as Fibrinogen degradation products an increased plasmin and activator activity, could be demonstrated. Venous occlusion experiments were suggestive for an enhancement of local activator release during the treatment. The level of fibrinogen degradation products, however, remained unchanged. It is concluded that thrombophilia under contraceptive hormone treatment cannot be explained by disturbances of the fibrinolytic system.