Captopril: determination in blood and pharmacokinetics after single oral dose

The study describes a specific, precise, sensitive and accurate method for determination of unchanged captopril, an angiotensin-converting enzyme inhibitor, in human plasma. Captopril was stabilized by forming an adduct with p-bromophenacyl bromide and this adduct was measured by high-performance liquid chromatography with UV detection. The standard curve was linear over a range of 30-800 ng ml-1. The average yield of derivatization of the unchanged captopril was 73.6% and the recovery of captopril-adduct reached 93.1%. The limit of detection was 15 ng ml-1, while the quantitative limit was 30 ng ml-1. Inter- and intra-assay RSD was below 9%, but inter- and intra-assay accuracy was below 8%. On the basis of elaborated method, a single-dose pharmacokinetics in 12 men, in two doses (25 and 50 mg of captopril) has been investigated. The comparison of the pharmacokinetic parameters obtained from both doses of the drug have been made.     

Determination of alprazolam and alpha-hydroxyalprazolam in human plasma by gas chromatography/negative-ion chemical ionization mass spectrometry

A sensitive and specific method was developed for the determination of alprazolam and its major metabolite alpha-hydroxyalprazolam in plasma. After the addition of deuterium-labeled internal standards, plasma samples were buffered to pH 9 with 1 ml of saturated sodium borate buffer, extracted with toluene-methylene chloride (7:3) and evaporated to dryness. The residues were treated with N,O-bis(trimethylsilyl)trifluoroacetamide containing 1% of trimethylchlorosilane and analyzed on a Finnigan-MAT mass spectrometer operated in the negative-ion chemical ionization mode with methane as the reagent gas. Chromatographic separation was achieved on a Restek-200 capillary column using hydrogen as the carrier gas. The assay was linear from 0.25 to 50 ng ml-1 for both compounds. The intra-assay precision for alprazolam was 16.1% at 0.5 ng ml-1 and 4.6% at 50 ng ml-1 and that for alpha-hydroxyalprazolam was 15.8% at 0.5 ng ml-1 and 4.2% at 50 ng ml-1. The method was used to determine alprazolam and alpha-hydroxyalprazolam in human plasma samples collected after a single 2 mg oral does of alprazolam. A peak concentration of 32.9 ng ml-1 of alprazolam was detected at 1 h following the dose.     

High-performance liquid chromatography-mass spectrometry-mass spectrometry analysis of morphine and morphine metabolites and its application to a pharmacokinetic study in male Sprague-Dawley rats

A high-performance liquid chromatography tandem mass spectrometry-mass spectrometry (LC-MS-MS) assay was developed for the analyses of morphine, morphine glucuronides and normorphine in plasma samples from rats. The analytes were extracted by using C2 solid-phase extraction cartridges. The extraction recoveries were 100% for morphine, 84% for morphine-3-glucuronide, 64% for morphine-6-glucuronide and 88% for normorphine. Both intra- and inter-assay variabilities were below 11%. Using a plasma sample size of 100 microliters, the limits of detection were 13 nmol l-1 (3.8 ng ml-1) for morphine, 12 nmol l-1 (5.5 ng ml-1) for morphine-3-glucuronide, 26 nmol l-1 (12 ng ml-1) for morphine-6-glucuronide and 18 nmol l-1 (5.0 ng ml-1) for normorphine, at a signal-to-noise ratio of 3. The present assay was applied to a pharmacokinetic study in rats after intraperitoneal administration of morphine.     

Economic consequences of teenage childbearing

Two methods are described for the determination of salbutamol in human plasma. The drug is extracted from the plasma as a salbutamol tetraphenylboron ion pair and determined by gas chromatography mass spectrometry. Trideuterio-salbutamol is used as an internal standard. In the first method an extensive purification procedure is used to separate salbutamol from plasma cholesterol which interferes in the assay. Salbutamol is then determined as its TMS-ether using a multiple ion recording technique to measure the intensity of the fragment ion m/e 369 and the ion m/e 372 from the TMS ether of trideuterio-salbutamol. The second method is based on the ion pair extraction of salbutamol into heptan-3-one and its determination by gas chromatography mass spectrometry as the t-butyldimethylsilyl ether. The base peak in the mass spectrum of the t-butyldimethylsilyl-salbutamol is an ion of m/e 495, which is of sufficiently high mass to distinguish it from any of the ions which arise from t butyldimethylsilyl-cholesterol. Six replicate analyses of plasma samples containing 1 ng salbutamol ml-1 were carried out using both methods. When the first method was used the mean value obtained was 1.3 ng ml-1 and the coefficient of variation was 17.7%. When the second method was used the mean value obtained was 0.95 ng ml-1 and the coefficient of variation was 10%. The second method is more rapid and therefore preferable for use in clinical pharmacological studies. This method has been used to determine the plasma salbutamol concentrations at varying times after either a 4 mg oral or a 200 mug intravenous dose of salbutamol to man.     

High-performance liquid chromatographic assay for diltiazem in small-volume blood specimens and application to pharmacokinetic studies in rats

A high-performance liquid chromatographic (HPLC) method was developed which involves the use of two 5-microns BDS silica gel columns (15 cm x 4.6 mm I.D.) in series for increased resolution and sensitivity, and an organic mobile phase for both extraction and elution of diltiazem. Plasma samples (400 microliters) were extracted using the organic mobile phase [n-hexane-methanol-dichloromethane-ammonia (370:35:30:0.3)] and the extracts were monitored at 240 nm. Desipramine (30 micrograms ml-1) was the internal standard. The limit of quantification in plasma was 20 ng ml-1 with a correlation coefficient of > or = 0.999 within the 20-800 ng ml-1 standard window. The inter- and intra-assay R.S.D.s were within 5%. The recovery of diltiazem varied from 101.1% at 20 ng ml-1 to 93.7% at 400 ng ml-1. The method was applied to the investigation of diltiazem absorption in a rat. Drug absorption was based on the intestinal single-pass perfusion model. The concentration of diltiazem in all test perfusion solutions was 1 mg ml-1 (2.4 mM) and the flow-rate through the system was 3.33.10(-3) ml s-1. A non-specific mucolytic absorption enhancer was also added to a diltiazem solution and studied in the in situ system. The pharmacokinetics of diltiazem hydrochloride were investigated in two study groups of Wistar rats (n = 4). A two-sample Student's t-test was employed to compare values of the area under the curve (AUC). The pharmacokinetic data indicated that the AUC in the group which received the enhancer [18.12 +/- 5.43 ng ml-1 h-1 (+/- S.D.)] was higher than that in the control group (11.49 +/- 3.67 ng h-1 ml-1), t-test; p = 0.0483. Hence it was shown that administration of an enhancer could increase the oral bioavailability of diltiazem.     

Sensitive determination of erythromycin in human plasma by LC-MS/MS

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of erythromycin in human plasma (EDTA as anticoagulant) was developed and validated. The concentration ranges were 0.5-50 and 50-5000 ng ml-1. The procedure involved alkalization of 0.5 ml of plasma, one step liquid-liquid extraction, dryness of the extract and reconstitution in 80:20 water:acetonitrile. An Inertsil ODS-2 5 microns, 3.0 x 50 mm column (Metachem) with a C8 guard column and isocratic mobile phase were used for liquid chromatography. The mobile phase consisted of 1:1 acetonitrile:water with 2 mM NH4OAc and 0.1% HOAc. A flow rate of 0.7 ml min-1 was used. The analysis time on LC-MS/MS for one sample was approximately 2 min. A Turbo-Ionspray source was interfaced between the HPLC and triple quadrupole mass spectrometer (Sciex API III Plus). MS/MS analysis used Multi-Reaction Monitoring (MRM) mode. The lowest limit of quantitation (LOQ) was 0.5 ng ml-1 with all Quality Control (QC) sample recoveries varying between 88 and 105%. Nine intraday and interday calibration curves were generated yielding correlation coefficients ranging from 0.995 to 1.000. Average recovery for erythromycin at 1 ng ml-1 was 105% (+/- 4.5%). Average recovery for the internal standard was 83-103%. Short-term and long-term stability in the freezer (-20 degrees C), bench stability, and stability after 3 freeze/thaw cycles at -20 and -80 degrees C were conducted. The samples were found to be stable under all conditions. The method developed and validated proved useful for clinical pharmacokinetic study sample analysis with high throughput due to its high sensitivity and very short analysis time.     

The development of a sensitive and specific enzyme immunoassay for FK480, a novel cholecystokinin type-A receptor antagonist, in human plasma

A sensitive and specific enzyme immunoassay for FK480, a novel cholecystokinin type-A (CCK-A) receptor antagonist, was developed to study the pharmacokinetics of the drug at low-dose administration using a specific monoclonal antibody. The high performance liquid chromatography (HPLC) method had been used for studying toxicokinetics, but its determination limit (2.5 ng ml-1) was too high for use in clinical studies. Subsequently we developed an enzyme immunoassay (EIA) using rabbit anti-FK480 serum (polyclonal antibody). It had higher sensitivity (0.1 ng ml-1) when 0.5 ml of plasma was used but its specificity was low because of the cross-reactivity of the metabolites of FK480. Therefore we produced several monoclonal antibodies for FK480 by cell fusion, and selected the antibody which was least cross-reactive for the isolated metabolites of FK480. Finally we developed a sensitive and specific EIA using this monoclonal antibody. The lower limit of quantification of this method was 0.2 ng ml-1 when 0.2 ml of human plasma was used. The coefficient of variation over the calibration range (0.2-10 ng ml-1) was less than 15%. We used this method for clinical studies, and it showed a good correlation to the HPLC method when plasma concentration was 2.5 ng ml-1 or more.     

The urinary ratio of 5-hydroxytryptophol to 5-hydroxyindole-3-acetic acid in surgical patients with chronic alcohol misuse

Interactions among growth factors are important in a variety of physiological and pathological processes. The regulation of IGF-I mRNA expression by bFGF was investigated in cultured rat Müller cells and the mechanism of regulation studied. Müller cells from 1- to 3-day-old Sprague-Dawley rats were isolated and cultured with Eagle MEM+10% FCS. Cultured cells were identified by immunocytochemistry using antibodies against vimentin, carbonic anhydrase C, and glutamine synthetase. Cells of passage 1-4 were treated with bFGF, the PKC inhibitor H-7, calphostin C, the PKC activator PMA or the PKA inhibitor H-89, as well as the adenylate cyclase activator forskolin, or adenylate cyclase inhibitor SQ22536. IGF-I and bFGF expression levels were assessed by Northern blot analysis. The addition of bFGF to culture medium down-regulated IGF-I expression in a dose- and time-dependent manner. Decrease of IGF-I expression started at a bFGF concentration of 1 ng ml-1. IGF-I mRNA level declined to 44% of baseline level at 10 ng ml-1 of bFGF, and reached a trough of 40% at 50 ng ml-1. At 10 ng ml-1 of bFGF, down-regulation of IGF-I expression was observed as early as 4 hr (60%) after treatment, and reached a trough of 42% by 8 hr. The temporal and concentration dependence of IGF-I expression by addition of the PKC activator PMA, to culture medium was similar to that due to the addition of bFGF. The down-regulation of IGF-I expression by bFGF (10 ng ml-1) and PMA (0.1 microM) was blocked by the PKC inhibitors H-7 (30 microM) and calphostin C (1 microM). Forskolin (5 microM), an adenylate cyclase activator, had activator, had no effect on IGF-I expression. SQ22536 (100 microM), an adenylate cyclase inhibitor, and H-89, a PKA inhibitor, had no inhibitory effect on bFGF-induced down-regulation of IGF-I expression. These results indicate that bFGF down-regulates IGF-I expression in cultured rat M uller cells through PKC activation.     

Quantitation of acetazolamide in rat plasma, brain tissue and cerebrospinal fluid by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method for the analysis of acetazolamide (AZ) in rat blood (plasma/serum, whole blood and serum ultrafiltrate), brain tissue and cerebrospinal fluid (CSF) was described. Quantitative extraction of AZ with ethyl acetate from both buffered plasma and brain tissue homogenate (pH 8.0) was achieved. Each extract was evaporated to dryness and the residue was chromatographed on a reversed-phase column. CSF was directly analysed without extraction step. The limits of detection were 0.05 microgram ml-1 for plasma, 0.02 microgram g-1 for brain tissue and 0.004 microgram ml-1 for CSF. Calibration curves were linear over the working ranges of 0.1-100 micrograms ml-1 for plasma, 0.05-50 micrograms g-1 for brain tissue and 0.025-50 micrograms ml-1 for CSF. The reproducibility of AZ assay in the rat biologic media indicated very low relative standard deviations (RSDs). The recoveries of AZ added to plasma and brain tissue were more than 96% with an RSD of less than 5%. The present method was applied to studies of plasma concentration profiles of the drug after administration and its distribution into central nervous system.     

Pharmacokinetics of orally administered estradiol valerate. Results of a single-dose cross-over bioequivalence study in postmenopausal women

A randomized, single-dose cross-over study in 32 postmenopausal women was performed to demonstrate bioequivalence of two estradiol valerate containing formulations (first sequence of Klimonorm as test preparation). The serum levels of estradiol, free and conjugated estrone were measured until 48 h after an oral dosage of 4 mg estradiol valerate (CAS 979-32-8). The mean AUC(0-48) of estradiol was calculated as 1006.6 +/- 479.4 h x pg x ml-1 (Test) and 1015.2 +/- 555.2 h x pg x ml-1 (Reference). The corresponding (AUC(0-48) of the active metabolite, free estrone, exceeded that of estradiol at 3578.3 h x pg x ml-1 (Test) and 3485.1 h x pg x ml-1 (Reference). Much higher was the AUC(0-48) for conjugated estrone at 132.4 h x ng x ml-1 (Test) and 133.6 h x ng x ml-1 (Reference). Mean estradiol Cmax values of 39.8 +/- 17.7 pg/ml (Test) and 42.9 +/- 21.0 pg/ml (Reference) were attained 8.2 +/- 4.5 h (Test) and 10.0 +/- 5.9 h (Reference) after the administration of 4 mg estradiol valerate. Maximal free estrone concentrations of 163 pg/ml (Test) and 174.3 pg/ml (Reference) were reached after 7.2 h (Test) and 7.5 h (Reference). Maximal conjugated estrone concentrations of 15.5 ng/ml (Test) and 16.2 ng/ml (Reference) were reached after 2.4 h (Test) and 2.0 h (Reference). The terminal elimination half-life of estradiol was calculated at 16.9 +/- 6.0 h (Test) and 15.0 +/- 4.8 h (Reference), that of free estrone at 16.3 h (Test) and 13.5 h (Reference), that of conjugated estrone at 11.8 h (Test) and 10.6 h (Reference). After logarithmic transformation, the 90% confidence intervals of the AUC(0-48) and Cmax ratios for estradiol and also for the metabolites (free and conjugated estrone) were within the acceptance ranges for bioequivalence. Therefore the test preparation and the reference preparation are bioequivalent.     

In vitro ammonia utilization and urea synthesis by rat liver after portacaval shunt

AIMS: To investigate the transplacental distribution of salbutamol enantiomers after administration of racemate to women prior to Caesarian section. METHODS: Five women about to undergo elective Caesarian section were administered a single 0.25 mg bolus intravenous dose of (R,S)-salbutamol. The time from drug administration to delivery was different for each woman (27-105 min). Maternal and foetal umbilical cord venous blood samples were collected immediately after delivery and the plasma fraction analysed for salbutamol enantiomer concentrations by enantioselective high pressure liquid chromatography. RESULTS: The concentrations (mean +/- s.d.) of the active (R) enantiomer of salbutamol in cord and maternal plasma were 0.46 +/- 0.35 and 0.89 +/- 0.50 ng ml-1, respectively, and the difference was statistically significant (95% confidence interval (CI) of the difference: 0.12-0.74 ng ml-1). The corresponding concentrations of the (S) enantiomer of 0.92 +/- 0.45 and 1.11 +/- 0.67 ng ml-1, respectively, were not significantly different (95% CI of the difference -0.08-0.48 ng ml-1). The ratio of (R):(S) in cord plasma was significantly less than that in maternal plasma (P=0.016). CONCLUSIONS: Transplacental distribution of salbutamol enantiomers at Caesarian section after prior administration of racemate to mothers leads to concentrations in cord plasma that are significantly less for the active (R) enantiomer and not significantly different for the (S) enantiomer than in maternal plasma presumably due to enantioselective placental-foetal metabolism.     

Coping strategies of enrolled nurses in nursing homes: shifting between organizational imperatives and residents'' needs

An in vitro perifusion system for bovine hypothalamic tissue was used to determine if growth hormone-releasing hormone (GHRH) and somatostatin (SRIF) modulate each other's release, and whether SRIF mediates D1-agonist-induced suppression of GHRH in cattle. Up to three sagittal slices (600 microns) of bovine hypothalamus, immediately parallel++ to the midline, were cut in an oxygenated balanced salt solution at 4 degrees C, placed in 5 cc syringe barrels, and perifused at 37 degrees C with oxygenated minimum essential medium-alpha at a flow rate of 0.15 ml/min. Three experiments were conducted, and medium effluent was collected every 20 min before (two samples), during (one or three samples), and after (six samples) treatment. Areas under GHRH and SRIF response curves (AUC), adjusted by covariance for pretreatment values, were calculated from samples collected during the treatment/post-treatment period. Perifusion of SRIF at 10(-6) M and 10(-4) M decreased AUC for GHRH from 86.3 (control) to 65.4 and 59.5 +/- 6.3 ng.ml-1 min, but 10(-8) M SRIF was ineffective. Relative to controls, 10(-8).10(-6), and 10(-4) M GHRH increased release of SRIF 190, 675, and 1,135%, respectively. Activation of D1 receptors with 10(-6) M SKF 38393 increased AUC for SRIF from 12.5 ng.ml-1 min (control) to 484.9 ng.ml-1 min and decreased AUC for GHRH from 36.4 ng.ml-1 min (control) to 18.2 ng.ml-1 min. Blockade of SRIF action with a SRIF antagonist, cyclo-[7-aminoheptanoyl-phe-D-trp-lys-thr(bzl)], increased release of GHRH 1.9-fold. In addition, the SRIF antagonist blocked SKF 38393-induced suppression of GHRH. We concluded that GHRH and SRIF interact within the bovine hypothalamus/pituitary stalk to modulate the release of the other. Moreover, SRIF mediates the inhibitory effects of activation of D1 receptors on release of GHRH in cattle.     

Some experiences with hospital-based psychiatric aftercare over ten years

Smooth muscle cells represent a significant percentage of the total cells in the airway but their contribution to the inflammatory response seen in airway disease has not been studied. Hence, we have looked at the release of the cytokine granulocyte-macrophage colony stimulating factor (GM-CSF) in response to bacterial lipopolysaccharide (LPS) and the pro-inflammatory cytokines interleukin-1 beta (IL-1 beta), tumour necrosis factor alpha (TNF alpha) and interferon gamma (IFN gamma). Human airway smooth muscle (HASM) cells released GM-CSF under basal conditions (45.4 +/- 13.1 pg ml-1) that was significantly enhanced by IL-1 beta and TNF alpha with a maximal effect seen at 10 ng ml-1 (1.31 +/- 0.07 ng ml-1 and 0.72 +/- 0.16 ng ml-1, respectively). In contrast, neither LPS nor IFN gamma produced a significant increase in GM-CSF release. However, HASM cells exposed to IL-1 beta, TNF alpha and IFN gamma generated more GM-CSF than that evoked by any cytokine alone (2.2 +/- 0.15 ng ml-1). The release of GM-CSF elicited by the cytokine mixture was inhibited by cycloheximide and dexamethasone. These data suggest that HASM cells might play an active part in initiating and/or perpetuating airway inflammation in addition to controlling airway calibre.     

Multivariate image analysis of magnetic resonance images with the direct exponential curve resolution algorithm (DECRA). Part 2: Application to human brain images

Seasonal levels of cortisol, growth hormone (GH), insulin like growth factor 1 (IGF-1), glucose, triiodothyronine (T3), free T3, thyroxine and free fatty acids (FFA) were measured every 3 weeks for 54 weeks in the plasma of five adult bulls, and four barren and five pregnant Alaskan reindeer (Rangifer tarandus) cows. Three consecutive samples were taken from each animal. Cortisol levels exhibited wide seasonal variation (9-45 ng/ml) [corrected] without any peak or difference in levels among groups. Rising levels were detected between the 3 consequent samples. Peak GH levels, detected during January and February, were higher in the non-pregnant group (54 ng/ml) than the pregnant (26 ng ml-1) and the male (27 ng ml-1) groups. Low GH levels (2-10 ng ml-1) were recorded between May and September. IGF-1 reached peak levels (715 ng ml-1) in males in August, in non-pregnant females in September (677 ng ml-1), and in the pregnant females in October (505 ng ml-1). Seasonal minima (404 in males, 172 and 93 in pregnant and non-pregnant groups) were detected in February. Glucose was fairly stable throughout the year (100-200 mg/100 ml). A rising levels were found between the three consecutive samples. Triiodothyronine (T3) (2.16-2.30 ng ml-1) peaked in all three groups during the spring and early summer, and minimal levels (0.61-0.97 ng ml-1) were detected from October to January. Conversely, thyroxine or free T3 did not exhibit seasonal variation. FFA fluctuated widely (97-1076 nmol l-1) throughout the year. Only in pregnant females were concentrations more stable (150-460 nmol l-1). Perhaps, because of ad libitum supply of food in captive reindeer, only T3 and GH exhibited pronounced seasonal fluctuations which could be related to the metabolic changes expected during the annual cycle.     

Quantitative analysis of non-steroidal anti-inflammatory drugs by capillary zone electrophoresis

The potential utility of capillary zone electrophoresis (CZE) for the separation and quantitative determination of some non-steroidal anti-inflammatory drugs (NSAIDs) was investigated. The influence of different parameters on migration times, peak symmetry, efficiency and resolution was studied; these parameters included the nature and concentration of the anionic and cationic components of the separation buffer. A buffer consisting of 75 mM glycine adjusted to pH 9.1 with triethanolamine was found to provide a very efficient and stable electrophoretic system for the CZE analysis of NSAIDs, giving RSD values of about 0.1 and 0.5% for the within-day reproducibility of migration times and peak areas, respectively at a concentration of 25 micrograms ml-1 (n = 5). Response was linear from 2-100 micrograms ml-1 for both sulindac and tiaprofenic acid, for which the LOQ values were 2.8 and 1.9 micrograms ml-1, respectively, using UV detection at 280 nm. Accuracy for each drug was 102-103%.     

Internal decompression with hippocampectomy for massive cerebral infarction

Salinomycin is a polyether antibiotic used to promote growth in cattle and poultry. Workers may be exposed to salinomycin through handling of animal feeds that contain the drug and it is necessary to monitor plasma samples from these workers for salinomycin to ensure safety. A method for analysis of salinomycin in plasma samples was therefore developed. Salinomycin and the internal standard narasin are extracted into iso-octane then subjected to silica gel solid-phase extraction in which the sample is washed with methylene chloride-methanol (98.5:15) then eluted with a 90:10 proportion of the same mixture. Both salinomycin and narasin are oxidized with pyridinium dichromate to form a chromophore absorbing at 225 nm. The concentrated product was injected onto a C18 pre-column and heart cut from 1.85 to 3.65 min onto a C18 analytical column. The method was shown to be selective for salinomycin and narasin in six blank plasma samples. The method was linear over a range of 15-300 ng ml-1 with a detection limit of approximately 5 ng ml-1. The mean absolute recovery was found to be 93.4 and 97.9% for salinomycin and narasin, respectively. The method was accurate to within 5% at all concentrations studied. Within-run and between-run precision were both less than 8% RSD at all concentrations studied and the method was suitable for the purpose of monitoring plasma from exposed agricultural workers.     

Determination of amphotericin B in cerebrospinal fluid by solid-phase extraction and liquid chromatography

A highly sensitive and reproducible liquid chromatography (LC) method for the determination of Amphotericin B in cerebrospinal fluid has been developed and validated. This LC-based method involves using nystatin as an internal standard and solid-phase extraction for sample preparation, followed by reversed-phase separation monitored by absorbance at 410 nm. The method has a limit of quantification of less than 1 ng ml-1 and excellent precision and accuracy, with both percentage relative standard deviation and percentage relative error less than 10%. The established linearity range was 1-10 ng ml-1 (r2 > 0.99). The extraction recovery of Amphotericin B from the cerebrospinal fluid is higher than 90% over the entire linear range. The method has been successfully employed for studying the penetration of Amphotericin B into the central nervous system in dogs and human.     

Noncanonical conformation of nucleic acids: structure with slipped-loops, occurring in DNA oligonucleotides

A HPLC method was developed and validated for the quantitation of 9-cis-retinoic acid (ALRT1057) and its major metabolite, 4-oxo-9-cis-retinoic acid (LG100182) in human plasma. Samples were buffered and extracted with methyl-tert-butyl-ether. The analytes and an I.S. were separated on a C18 HPLC column using a shallow gradient of 70-89% organic solvent. The analytes were quantitated by UV detection at 348 nm. Selectivity against endogenous compounds and potential metabolites (retinol, all trans-, 13-cis-, and 4-hydroxy-9-cis-retinoic acid) was demonstrated. The run time was 29 min. The standard curve was linear from 2.5 to 450 ng ml-1. Interassay precision for both analytes in quality control samples was less than 5.0% RSD. Accuracy was within 11.0% RE for both compounds. Analyte stability during sample storage, extraction processing, and chromatography was established. Method ruggedness was tested by two analysts and on two HPLC systems. This method has been applied to the quantitation of clinical samples.     

Ethoxycoumarin O-deethylation (ECOD) activity in rat liver slices exposed to beta-naphthoflavone (BNF) in vitro

1. To test whether cystic fibrosis (CF) altered the kinetics and dynamics of oral salbutamol, 11 patients with CF (19-33 years old; five females; FEV1: 37 +/- 12% of predicted value) and 10 healthy volunteers (20-41 years old; five females; FEV1: 99 +/- 14% of predicted value) received orally 4 mg salbutamol. 2. The estimated pharmacokinetic parameters of salbutamol in patients with CF were identical to those in healthy subjects. For instance, peak plasma concentrations of salbutamol were 10.5 +/- 2.6 (mean +/- s.d.) and 10.2 +/- 2.9 ng ml-1 (NS), and the area under salbutamol plasma concentrations as a function of time (AUC (0, 7 h)) was 43.0 +/- 9.3 ng ml-1 h and 43.3 +/- 12.7 ng ml-1 h (NS) in CF patients and in healthy subjects, respectively. Since on a mg kg-1 dose basis, CF patients received a dose 28% greater than healthy subjects, this lack of differences implies a decrease in the amount of salbutamol absorbed, or alternatively, an increase in both clearance and volume of distribution of salbutamol. 3. Salbutamol did not elicit bronchodilation in CF patients, but increased heart rate from 77 +/- 2 to 103 +/- 3 beats min-1 (P < 0.05). 4. Salbutamol decreased plasma potassium concentrations from 4.5 +/- 0.1 to 3.8 +/- 0.1 mmol l-1 in the CF group (P < 0.05) and from 4.1 +/- 0.2 to 3.4 +/- 0.1 mmol l-1 in the controls (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)