Determination of sodium artesunate in plasma using ion-pairing high-performance liquid chromatography.

A chromatographic method is described for the determination of sodium artesunate in plasma. This includes cetyltrimethylammonium bromide as a cationic pairing ion in a reversed-phase system using an octadecylsilica 100 x 4.6 mm I.D. 3 microm analytical column with a mobile phase of acetonitrile/acetate buffer at pH7. Column switching incorporating a 5 microm octadecylsilica 100 x 4.6 mm I.D. precolumn is used in addition to off-line solid-phase extraction for pretreatment of plasma samples in order to eliminate interference from endogenous components. Detection is by post-column derivatisation with 1.0 M methanolic KOH followed by UV detection at 289 nm. Calibration is linear over the range 100-1600 ng ml(-1) and the limit of detection is estimated as 20 ng ml(-1). Illustrative results are shown of the artesunate plasma levels determined by the proposed method following the administration of artesunate as tablets and as suppositories to healthy volunteers.

Comparisons of the separations of some neutral analytes by LC, MEKC, and CEC.

The relative utility of high-performance liquid chromatography, micellar electrokinetic chromatography (MEKC), and capillary electrochromatography (CEC) is examined for the separation of essentially uncharged solute mixtures. Three model systems are used for which separations by reversed-phase liquid chromatography had been established. These consisted of a set of three substituted hydroxybenzoates; a mixture of six structurally closely related steroids; and the multicomponent aminoglycoside antibiotic, teicoplanin. These sets represented a range of difficulty in achieving separations by reversed-phase LC. It was found that equivalent or better separations for all systems could be established by MEKC and CEC. Both electrophoretic techniques offer much higher peak efficiencies than LC, and MEKC is found to be superior to CEC in terms of peak efficiencies and ruggedness of operation.

Determination of proguanil and metabolites in small sample volumes of whole blood stored on filter paper by high-performance liquid chromatography.

A method is reported for the determination of proguanil and its two metabolites cycloguanil and 4-chlorophenylbiguanide in whole blood and plasma samples obtained by thumbprick and stored dry on filter paper. The sample preparation involves liquid extraction from the filter paper and subsequent solid-phase extraction using C8 Bond-Elut cartridges. Separation and quantification is by a previously reported ion-pairing high-performance liquid chromatographic system with ODS Hypersil as stationary phase and an 50:50 acetonitrile-pH 2 phosphate buffer mobile phase containing 200 mM sodium dodecylsulphate as ion-pairing agent. The analytical characteristics of the method are reported. Representative concentrations are shown as a function of time from a human subject after ingestion of a single 200-mg dose of proguanil hydrochloride. Typical ranges of concentration detected by the proposed method in human subjects were proguanil 12-900 ng/ml, cycloguanil 16-44 ng/ml and 4-chlorophenylbiguanide 1.5-10 ng/ml in whole blood.

High-frequency jet ventilation in children with the adult respiratory distress syndrome complicated by pulmonary barotrauma.

High-frequency jet ventilation (HFJV) was used in 29 children with severe ARDS complicated by pulmonary barotrauma (PBT). Treatment with HFJV was begun when PBT was progressing over a 24-h period while receiving conventional ventilation (CV). The mean (+/- SD) age was 0.95 +/- 1.21 years (range, 0.03-4 years). The most common diagnosis was viral pneumonia (n = 17); other diagnoses included aspiration pneumonitis (n = 4), bacterial pneumonia (n = 3), multiple trauma (n = 2), and near-drowning (n = 3). The Bunnell Life-Pulse ventilator was used at a rate of 240/min or 300/min, with inspiratory time of 0.02 sec. Twenty children survived (69%). Survivors and nonsurvivors had equal disease severity prior to HFJV as assessed by ventilator settings, alveolar-to-arterial oxygen tension gradient, oxygenation index, and blood gas values. Survivors had spent significantly less time on conventional ventilation prior to HFJV than nonsurvivors, with a mean (+/- SD) of 3.7 +/- 2.1 days vs 9.6 +/- 4.5 days, respectively (P < 0.05). Survivors underwent an average of 4.4 +/- 3.9 days of HFJV, which supported adequate gas exchange with lower airway pressures, and produced resolution or significant improvement in airleak on chest radiograph. In conclusion, we speculate that the application of HFJV early in the course of severe hypoxemic respiratory failure complicated by airleak, allows the reduction of airway pressures, thereby minimizing pulmonary barotrauma and allowing the lung to recover from the underlying insult. Further controlled evaluation of HFJV in this high risk group of patients is warranted.

Single dose pharmacokinetics of proguanil and its metabolites in pregnancy.

Plasma and whole blood concentrations of proguanil, its active metabolite cycloguanil, and the inactive metabolite 4-chlorophenyl-biguanide, were measured by HPLC in 10 healthy Karen women in the last trimester of pregnancy, following a 200 mg single oral dose of proguanil. Four of these women were restudied 2 months after delivery. The pharmacokinetic properties of proguanil were similar during and after pregnancy. Median peak plasma concentrations of proguanil during pregnancy and following delivery were 212 and 215 ng.ml-1, and occurred at 4.5 and 5 h, respectively. Mean plasma AUC values for proguanil during and following pregnancy were 94 and 98 ng.h.ml-1.kg-1, respectively. Corresponding whole blood AUC values were 361 and 396 ng.h.ml-1.kg-1. The mean elimination half lives and mean residence times of proguanil in plasma and whole blood were 12.3 and 19.6 h and 13.8 and 20.7 h respectively during pregnancy. Following pregnancy these values were 17.1 and 19.7 h for plasma and 19.7 h and 20.2 h for whole blood respectively. Mean peak plasma and whole blood concentrations of cycloguanil following pregnancy were 25 and 22 ng.ml-1 respectively. During pregnancy peak cycloguanil concentrations in both plasma and whole blood were markedly lower, 13 and 12 ng ml-1, respectively. Two pregnant women (neither of whom were restudied) were probably poor metabolisers of proguanil. The mean ratio of proguanil to cycloguanil plasma AUC was 16.7 in the third trimester of pregnancy and 7.8 following pregnancy, compared with less than 5 in previously reported studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Single dose pharmacokinetics of proguanil and its metabolites in healthy subjects.

1. Plasma and whole blood concentrations of proguanil and its two major metabolites cycloguanil (CG) and 4-chlorophenylbiguanide (CPB) were measured by a sensitive h.p.l.c. technique in nine healthy adult male volunteers after a single oral dose of proguanil 200 mg. 2. Proguanil was absorbed with a median time to peak plasma concentration of 3 h (range 2-4 h). 3. Peak plasma concentrations of proguanil ranged between 150 and 220 (median 170) ng ml-1 compared with 12 to 69 (median 41) ng ml-1 for the active antimalarial metabolite CG, and 3 to 16 (median 11) ng ml-1 for CPB. Peak (mean +/- s.d.) plasma CG concentrations occurred 5.3 +/- 0.9 h and peak CPB concentrations occurred 6.3 +/- 1.4 h after oral administration of proguanil. 4. Whole blood concentrations of proguanil were approximately five times higher, and whole blood CPB concentrations were four times higher than corresponding plasma values, whereas plasma and whole blood concentrations of CG were similar. 5. A triexponential function was fitted to these data; mean (+/- s.d.) values for the AUC were 3046 +/- 313 ng ml-1 h for proguanil, 679 +/- 372 ng ml-1 h for CG and 257 +/- 155 ng ml-1 h for CPB. 6. Plasma and whole blood concentrations of proguanil and its metabolites declined in parallel with terminal elimination half-lives estimated as 16.1 +/- 2.9 h and 15.7 +/- 2.4 h, respectively. Mean residence times in plasma and whole blood were estimated as 21.2 +/- 4.9 and 19.3 +/- 2.4 h.

Amatoxin poisoning in northern California, 1982-1983.

Twenty-two patients who ate mushrooms containing hepatotoxic amatoxins were treated during the fall and winter seasons of 1982 and 1983. All patients were treated with intensive supportive care and repeated oral doses of activated charcoal. In two patients fulminant hepatic failure developed and they died. One patient in whom encephalopathy developed had an orthotopic liver transplant and survived. Liver biopsy specimens obtained from five patients during the acute illness showed centrilobular hemorrhagic necrosis. The hepatic histopathology in a biopsy specimen from a 5-year-old boy eight weeks after mushrooms were eaten showed bands of fibrosis and islands of hepatocytes suggestive of early cirrhosis. Radioimmunoassay for amanitins, done on the serum from all patients, detected the toxins in only three, probably because most of the specimens were obtained 24 hours or more after the ingestion. This series, with a mortality rate of 9%, illustrates the outcome in patients who receive intensive supportive care and provides a background on which success of specific treatments should be judged.

Orthotopic liver transplantation in a patient with Amanita poisoning.

Orthotopic liver transplantation in patients with acute toxic hepatitis has not, to our knowledge, been reported. Our recent experience with orthotopic liver transplantation in a 3-year-old girl with acute hepatic failure secondary to Amanita poisoning is described. Aspects of Amanita toxin-induced pathophysiology pertinent to orthotopic liver transplantation are discussed. The results in this case provide important implications for patients with fulminant hepatic failure secondary to other hepatotoxic agents in whom liver transplantation is considered.

Use of intravenous isoproterenol for status asthmaticus in children.

The use of continuous drip iv isoproterenol was studied to determine its efficacy and indications in lower doses in severe asthma. Thirty-seven patients (6 months to 16 yr) received iv isoproterenol with asthma score of 6 (mean 6.8) or greater indicating PCO2 of 60 torr or higher or a PCO2 of 55 (mean 58.4) torr or greater without response to therapeutic levels of aminophylline, corticosteroids, and aerosolized isoetharine as well as appropriate oxygen. The initial dose of isoproterenol was 0.05 microgram/kg X min; if there was no response in PCO2, the continuous drip was increased by increments of not more than 0.05 microgram/kg X min every 15-20 min; iv aminophylline was continued by continuous infusion at therapeutic levels. The isoproterenol was infused until the PCO2 less than or equal to 40 torr and maintained at that dose for an equal time, then decreased over an interval equal to the response and maintenance time. There was complete response in 34 patients (mean dose 0.2 microgram/kg X min; mean response time 1.3 h, range 0.2-3.2 h). One patient had a partial response but the isoproterenol was discontinued with reversal of an arrhythmia; a 2nd patient had initial resolution but had rebound bronchospasm when the isoproterenol was abruptly discontinued. Thus, iv isoproterenol at lower initial and responding dose is effective for reversing increased PCO2 and impending respiratory failure in status asthmaticus in children, but the limitations and complications must be closely monitored.

High-performance liquid chromatography of proguanil, cycloguanil and 4-chlorophenylbiguanide using hydrophobic pairing ion and its application to serum assay.

A high-performance liquid chromatographic separation of proguanil, cycloguanil and 4-chlorophenylbiguanide is reported using a hydrophobic stationary phase and lauryl sulphate as pairing ion. It is suggested, on the basis of the behaviour of phenylbenzoate as an undissociated solute and the variation of retention with lauryl sulphate and sodium ion concentrations that the mechanism of separation is one of ion exchange. The biguanides can be detected in serum at concentrations in the region of 60 ng ml-1 and preliminary results are presented to show the variation of proguanil in serum over a 24-h peroid following ingestion of 200 mg orally.

Foxglove (Digitalis purpurea) poisoning in farmed red deer (Cervus elaphus).

A series of unexpected deaths and unthriftiness was encountered in red deer at Glensaugh Deer Farm, Kincardineshire, Scotland, in the autumn and winter of 1975--76. Occurrence and gross post mortem findings suggested a common etiology but microbiological, helminthological and histological examinations indicated that the syndrome was not of infectious or parasitic origin. Some of the lesions suggested an irritant poison. Foxglove plants were found in the pasture and their poisonous potential seemed to fit the post mortem findings and clinical signs. The diagnosis was confirmed by chemical analysis of tissues and botanical examination of rumen contents, and a similar fatality was produced in a penned red deer by test dosing with powdered foxglove leaves. Possible control and treatment are discussed. It is concluded that foxglove poisoning may be an occasional hazard in the husbanding of red deer. The history, clinical syndrome and gross post mortem findings may be sufficiently characteristic to allow a provisional diagnosis to be made in the field.

Mescaline: its effects on learning rate and dopamine metabolism in goldfish (Carassius auratus).

The pharmacological action of mescaline on goldfish was studied with the Bitterman-Agranoff shock-avoidance test. In short term experiments with high mescaline doses an increase in learning rates was observed. Similar results were obtained with apomorphine and L-dopa. However, when the fish were exposed to smaller mescaline doses (or to fluphenazine) for 3 days, their ability to avoid electric shock was reduced. Apparently, mescaline induced a release of dopamine which stimulated central dopaminergic systems. Subsequently, MAO destroys the liberated dopamine. Thus, the ensuing dopamine deficit appears to be responsible for the marked changes in behavior in the chronic experiment.