Pharmacokinetics of a novel surface-active agent, purified poloxamer 188, in rat, rabbit, dog and man.

Purified poloxamer 188 (PP188) is a non-ionic, block copolymer surfactant that is currently being evaluated clinically in sickle cell disease vaso-occlusive crisis and acute chest syndrome and preclinically in spinal cord injury and muscular dystrophy. This paper describes the pharmacokinetics of PP188 in rats, pregnant rats, pregnant rabbits, dogs and humans. Plasma protein binding interaction studies demonstrated no clinically significant effects on narcotic analgesics, hydroxyurea, warfarin, diazepam or digitoxin, but an increase in free fraction for propranolol.

Determination of steroid hormones in a human-serum reference material by isotope dilution--mass spectrometry: a candidate definitive method for cortisol.

We report a method, based on isotope dilution--mass spectrometry, for determining cortisol in a pooled specimen of human serum. Isotopically labeled cortisol is added to 5.0 mL of serum so that the molar concentrations of labeled cortisol and unlabeled cortisol are approximately equal.

Multivariate and univariate optimization studies of liquid-chromatographic separation of steroid mixtures.

We developed a high-performance liquid-chromatographic separation of five steroids (estriol, estradiol, cortisol, progesterone, and testosterone), eluting with a water-acetonitrile gradient from a reversed-phase (C18) column. By applying a simplex search algorithm to maximize a chromatographic-response function, we sought to optimize the original conditions of the chromatographic analysis, which did not separate two pairs of overlapping peaks. Our chromatographic-response function incorporated both peak separation and total time of analysis.

Separation of protoporphyrins and related compounds by reversed-phase liquid chromatography.

We describe the separation of protoporphyrin and related porphyrins by reversed-phase "high-performance" liquid chromatography, with fluorometric detection. We used the method to demonstrate that acid hydrolysis of the dimethyl ester of protoporphyrin IX is complete in 2 to 3 h and is followed by the acid-catalyzed conversion of protoporphyrin IX to a chemical species that chromatographic evidence indicates to be hematoporphyrin IX. In addition, the method was used to evaluate the purity of a commercial preparation of protoporphyrin IX and was also demonstrated to have the sensitivity and specificity needed for measuring the protoporphyrin IX content of whole-blood.

Determination of free, total, and esterified cholesterol by high-performance liquid chromatography.

A method is described for measuring free, total, and esterified cholesterol in blood serum in which reversed-phase liquid chromatography is used and the eluate is monitored at 200 nm. The sample for total cholesterol is prepared according to the Abell-Kendall procedure, and for free cholesterol an extract of serum--isopropanol (1:5, v/v) is used. The column is a muBondapak C18, 10 micrometers, and the mobile phase for total cholesterol is isopropanol--acetonitrile (50:50, v/v); for free cholesterol, it is isopropanol--acetonitrile--water (60:30:10).

4-Nitrophenol in 4-nitrophenyl phosphate, a substrate for alkaline phosphatase, as measured by paired-ion high-performance liquid chromatography.

We used paired-ion high-performance liquid chromatography to determine the 4-nitrophenol content of 4-nitrophenyl phosphate, a substrate for alkaline phosphatase analysis. This was done on a reversed-phase column with a mobile phase of methanol/water, 45/55 by vol, containing 3 ml of tetrabutylammonium phosphate reagent per 200 ml of solvent. At a flow rate of 1 ml/min, 4-nitrophenol was eluted at 9 min and monitored at 404 nm; 4-nitrophenyl phosphate was eluted at 5 min and could be monitored at 311 nm.