High-performance liquid chromatographic determination of floctafenine and its major metabolite, floctafenic acid in plasma.

A simple, rapid and selective high-performance liquid chromatographic method for the determination of floctafenine and its major metabolite, floctafenic acid, in plasma is reported. Plasma samples were purified using the mobile phase as a protein precipitant. The supernatant containing parent compounds and diazepam (internal standard) were eluted from a 5 micron C 18 reversed-phase column at ambient temperature. The mobile phase consisted of 0.05 M sodium acetate:acetonitrile: methanol (200:100:100 v/v/v) adjusted to pH 5 and pumped isocratically at a flow rate of 1.5 ml/min. The effluent was monitored at 350 nm. Quantification was achieved by the measurement of the peak-height ratio of each drug to the internal standard. The mean percentage recoveries from plasma samples spiked with floctafenine and floctafenic acid ranged from 88.13 to 101.93%. Detection limits were 100 ng/ml for floctafenine and 50 ng/ml for floctafenic acid. The coefficients of variation (RSD, %) for within-day and day-to-day analysis were less than 8%.

Simultaneous plasma determination of floctafenin and its major metabolites by high-performance liquid chromatography: preliminary observations in children.

An isocratic reversed-phase ion-pair liquid chromatography with UV detection at 350 nm for the determination in human plasma of floctafenin (F) and its three main metabolites--floctafenic acid (FA), hydroxyfloctafenin (HOF), and hydroxyfloctafenic acid (HOFA)--is reported. Analytes and internal standard were extracted from acid plasma into ethyl acetate, and this organic phase was evaporated to dryness. This extraction yielded plasma drug recoveries of greater than 72%. Using 1 ml of plasma, the lower quantification limit was 0.05 microgram ml-1 with excellent linearity up to 0.8 microgram ml-1 for HOF and HOFA and up to 4.0 micrograms ml-1 for F and FA. The reproducibility and the selectivity of the method for several drugs thought likely to be administered in conjunction with F, were demonstrated. This method has been successfully applied to a pharmacokinetic study with a single 10 mg kg-1 oral dose in ten children.

Binding of two anthranilic acid derivatives to human albumin, erythrocytes, and lipoproteins: evidence for glafenic acid high affinity binding.

The binding of two anthranilic acid derivatives, glafenic and floctafenic acids, to human erythrocytes and plasma proteins has been investigated in vitro by equilibrium dialysis. Despite their close chemical structures it was shown that the binding of the two compounds to serum albumin, lipoproteins, and erythrocytes was dramatically different both in quality and quantity. Using various techniques including fluorometry and circular dichroism, it was shown that glafenic acid binds to the human serum albumin (HSA) warfarin/azapropazone site and that floctafenic acid binds to both warfarin/azapropazone and benzodiazepine sites. Glafenic acid is strongly bound to HSA with n = 1, k = 2.4 X 10(6) liters/mol and to erythrocytes with N = 12.4 mumol/liter, K = 1.7 X 10(6) liters/mol. Floctafenic acid is bound with a weaker affinity to HSA, n = 2, k = 0.3 X 10(6) liters/mol and to erythrocytes, N = 2900 mumol/liter and K = 0.007 X 10(6) liters/mol.

Uterine prostaglandin E secretion and uterine blood flow in the pregnant rabbit.

Studies were performed in pregnant rabbits to assess the effect of inhibition of prostaglandin synthesis on uterine blood flow. Cardiac output and uteroplacental blood flow (UPBF) were measured using radiolabeled microspheres. Prostaglandin E (PGE) concentration was measured by radioimmunoassay in the uterine vein and peripheral artery of the pregnant nephrectomized rabbit. Either meclofenamate or indomethacin 2 mg/kg were utilized to inhibit prostaglandin synthesis. Systemic arterial pressure increased from 86 mm Hg to 98 mm Hg (P less than0.0001) after prostaglandin inhibition. Cardiac output was unchanged after the inhibition of prostaglandin synthesis, 326 ml/min to 7.8 ml/min. Uterine vein PGE concentration was extremely high, 172.4 ng/ml, with concomitant peripheral arterial PGE 2.1 NG/ML. Intravenous administration of either meclofenamate or indomethacin reduced uterine vein PGE to 23 ng/ml (P less than 0.01) and arterial PGE to 1.0 ng/ml (P less than 0.05). Male and nonpregnant female rabbits had lower arterial PGE, 0.37 ng/ml (P less 0.05). Studies in non-nephrectomized pregnant animals demonstrated that uteroplacental secretion of PGE was greater than five times renal secretion. These studies demonstrate that the rabbit uteroplacental unit is a rich source of PGE and suggest that production of the vasoactive lipid may have a key role in regulating UPBF during pregnancy.

Prophylaxis and treatment of experimental anaphylaxis in cattle by sodium meclofenamate.

Sodium meclofenamate was compared to saline for efficacy in preventing and treating experimentally induced, acute, systemic anaphylaxis in cattle. Respiratroy changes were shown to be reduced to the greatest extent. Lacrimation and collapse were not affected. The timing and routes of administration giving maximum efficacy were those which gave maximum plasma levels of the drug closest to the time of exposure of the animal to the specific antigen.