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A rapid and sensitive microbore high-performance liquid chromatographic (HPLC) assay is reported for the quantitation of labetalol, an anti-hypertensive agent, in small volumes (250 microliters) of biological fluids (viz., maternal plasma, fetal plasma, amniotic fluid and fetal tracheal fluid) obtained from the chronically instrumented pregnant sheep. Labetalol was extracted from the samples using ethyl acetate and then partitioned into dilute phosphoric acid. Chromatography was performed on a microbore HPLC system using a 2.1 mm I.D. C18 column and detection was accomplished by a low-dispersion fluorescence detector designed for trace analysis. The drug was well separated from endogenous substances in all biological fluids sampled. The calibration curves were linear for all fluids over the range of study with mean coefficients of variation consistently below 5%. Quantitation was possible down to approximately 30 pg of labetalol injected (approximately 1.6 ng/ml in plasma using 250 microliters).

A sensitive and selective gas chromatographic assay method employing splitless injection, fused-silica capillary columns and electron-capture detection is reported for the quantitation of the tocolytic drug, ritodrine, in a variety of biological fluids obtained from the pregnant ewe and fetus. This method has improved sensitivity and selectivity over previously published assay procedures. A 25 m x 0.31 mm I.D., cross-linked 5% phenylmethylsilicone, fused-silica capillary column was employed for all analyses. Linearity of response was observed over the range 2.5-75 ng of ritodrine base per 0.05-0.5 ml of biological fluid, representing approximately 1-75 pg at the detector. The coefficient of variation was less than 10% over the range 2.5-75 ng of added ritodrine. The minimum quantifiable amount is approximately 2.5 ng from a 0.5-ml biological fluid sample. Applicability of this method to biological fluids, obtained from ovine subjects, is demonstrated by the analysis of samples obtained during the course of ritodrine placental transfer studies.

Surveys of drug use in pregnancy demonstrate that a significant proportion of human fetuses are exposed to prescription and non-prescription drugs antenatally or during labor, although recently a decrease in licit drug consumption during pregnancy may have occurred. However, legitimate medical reasons for drug therapy of the mother or fetus remain and there is an increasing problem with illicit drugs. Several approaches are used to examine placental transfer of and fetal exposure to drugs, including studies on pregnant women, the use of chronically catheterized pregnant animals (particularly sheep), acute studies on small animals (e.g. guinea pig and rabbit) and the use of the perfused placenta. Fetal drug exposure is affected by large number of maternal, placental and fetal factors. For long term maternal drug administration, drug binding in maternal and fetal plasma, and fetal drug elimination seem particularly important. Thus, the rate of non-placental clearance of morphine, methadone, acetamionophen, metoclopramide, ritodrine and diphenhydramine in the fetal lamb is comparable to that in the ewe, although the routes of fetal elimination are not fully elucidated. The fetal liver may be of lesser importance in overall drug elimination than in the adult, but conjugated drug metabolites in the fetus may persist because of limited placental transfer. Hence, we have observed that the glucuronide conjugate of ritodrine accumulates in amniotic fluid after intravenous ritodrine administration. Accumulation of intact drugs in amniotic fluid also occurs via fetal renal excretion and perhaps via the fetal membranes. Also, a number of basic amine drugs are also concentrated in fetal tracheal fluid, probably as a consequence of pulmonary uptake, which also takes place in the adult. However, this could result in high fetal lung levels of agents, such as beta 2-adrenergic agonists, that have potent effects on pulmonary function and maturation. When digoxin, metoclopramide and diphenhydramine are injected into amniotic fluid, they are preferentially distributed to the fetus and, for the latter 2 drugs, uptake by the chorioallantoic membranes appears to be important. Thus, there is the possibility of recycling of drugs from amniotic fluid to the fetal circulation and their persistence in the fetus. Many of the therapeutic agents given to pregnant women in late pregnancy have effects on fetal CNS, cardiovascular or metabolic functions. Alterations in fetal behaviour are elicited by prescription sedatives and anesthetics and illicit drugs, and also by the antihistamine, diphenhydramine, present in various nonprescription medications.

The placental and nonplacental clearances of metoclopramide were studied in nine chronically instrumented, near-term pregnant sheep using a two-compartment open model. Metoclopramide was administered to the ewe and fetus on separate occasions as an initial iv bolus loading dose followed by a constant-rate infusion, with steady-state maternal and fetal plasma concentrations being obtained by 45 min. Following the maternal infusions, metoclopramide reached average steady-state concentrations of 50.0 +/- 20.2 ng/mL in the ewe and 27.1 +/- 8.6 ng/mL in the fetus, with a mean fetal-to-maternal concentration ratio of 0.57 +/- 0.14. The ability of the fetus to eliminate metoclopramide by nonplacental routes appears to be responsible for this ratio being less than unity, rather than differential protein binding and ion-trapping effects. Mean steady-state concentrations were 13.8 +/- 4.5 and 253.7 +/- 92.1 ng/mL in the ewe and fetus, respectively, after fetal drug administration. Metoclopramide was bound significantly less to fetal (39.5 +/- 8.9%) than to maternal (49.5 +/- 7.9%) plasma proteins, with values similar to that reported for humans (approximately 40%). Clearance of metoclopramide across the placenta from the fetus to the ewe (6.2 +/- 2.4 L/h/kg) was significantly greater than that in the reverse direction (4.3 +/- 1.3 L/h/kg) and accounted for approximately 80% of total fetal drug elimination. This may be explained by the higher percentage of fetal cardiac output to the placenta and the flow-limited transfer of this compound.(ABSTRACT TRUNCATED AT 250 WORDS)

Tocainide carbamoyl-O-beta-D-glucuronide, a major urinary metabolite of the antiarrhythmic drug tocainide [2-amino-N-(2',6'-xylyl)propanoxylidide], was isolated by preparative-TLC and preparative-HPLC. The isolated glucuronide was hydrolyzed in sodium hydroxide (pH greater than 12) to 3-(2',6'-xylyl)-5-methylhydantoin. This hydantoin product was also identified when tocainide was reacted with urea in urine. Structural characterization of the isolated tocainide glucuronide was carried out using GC-MS of the permethylated derivative. The molecular ion of the permethylated glucuronide was not observed, but ion fragments at m/z 232(244), 277(288), and 334(349) were found to correspond to the postulated novel carbamoyl ester structure of the permethylated (perdeuteromethylated) glucuronide. Structural evidence for the underivatized tocainide glucuronide was obtained using fast atom bombardment-MS. The [M + H]+ ion at m/z 413 was observed. Characteristic sodium ion adducts [M + Na]+ and [M-H + 2Na]+ were also observed at m/z 435 and 457, respectively.

Abstract Oxytocin (OT) plays a role in reproduction at the level of the pituitary and mammary glands and uterus. This OT is synthesized in the hypothalamo-neurohypophyseal system (HNS). A number of observations have suggested that estrogens regulate the production of OT in the HNS. In this study the effect of 17beta-estradiol on the activity of the OT gene promoter was examined as well as the effect of 17beta-estradiol in vivo on OT messenger ribonucleic acid (mRNA) and peptide revels in the rat HNS. Vasopressin (VP) and its mRNA were also determined in the in vivo studies. The direct transcriptional stimulation of OT gene expression by 17beta-estradiol was studied in two different heterologous expression systems. When a plasmid having nucleotides -363 to +16 of the rat OT gene fused to the firefly luciferase reporter gene was co-transfected with an estrogen receptor expression vector in P19 embryonal carcinoma cells, luciferase activity was stimulated 80-fold by 17beta-estradiol. In estrogen receptor containing MCF-7 cells transfected with a plasmid having nucleotides -188 to +16 of the rat OT gene fused to the chloramphenicol acetyl transferase gene, 17beta-estradiol induced the expression of the chloramphenicol acetyl transferase gene through the cloned promoter element. After in vivo treatment of ovariectomized rats with 17beta-estradiol, levels of OT mRNA and VP mRNA were measured in microdissected supraoptic and paraventricular nuclei as well as VP and OT levels in these nuclei and the pituitary gland. As compared to non-treated ovariectomized rats there was no difference in contents of OT mRNA and VP mRNA in these hypothalamic nuclei and in levels of the peptides in paraventricular nuclei and the pituitary gland. A 30% reduction of the OT content of the supraoptic nuclei only was found, while the VP content did not change. To explain the results immunocytochemical analyses of the hypothalamus were performed, showing that the estrogen receptor was absent in the magnocellular neurons of the supraoptic and paraventricular nuclei. The results demonstrate that the 5'flanking region of the OT gene confers estrogen-sensitivity to transcription of the OT gene. This potential to respond to estrogens is not used in the OT-producing neurons of supraoptic and paraventricular nuclei probably due to the absence of the estrogen receptor.

Abstract It is well established that flank marking behavior in the Golden hamster is controlled by vasopressin-sensitive neurons localized to the anterior hypothalamus; however, the source(s) of vasopressinergic innervation to this area is unknown. Previous analysis by immunocytochemistry showed distinct populations of vasopressinergic magnocellular neurons localized to the supraoptic nucleus, paraventricular nucleus and the nucleus circularis that did not project to the neurohypophysis. In the present study, these same hypothalamic nuclei were lesioned by microinjection of kainic acid to determine which, if any, of these populations of vasopressin neurons are involved in the control of flank marking. Unilateral lesions in the areas of the nucleus circularis and supraoptic nucleus at the rostro-caudal plane of the anterior hypothalamus abolished odor-induced flank marking behavior. Lesions in the paraventricular nucleus at the level of the anterior hypothalamus did not consistently inhibit flank marking, while lesions of magnocellular neurons rostral or caudal to the anterior hypothalamus were ineffective. The microinjection of vasopressin into the anterior hypothalamus following lesion of the paraventricular and supraoptic nuclei stimulated flank marking, evidence that treatment with kainic acid did not damage the efferent component of this behavior. However, animals with lesions in the nucleus circularis did not respond to the microinjection of vasopressin; hence, it is uncertain whether lesions in this area disrupt vasopressinergic innervation to the anterior hypothalamus or simply destroy the motor neurons controlling flank marking. In summary, the data clearly demonstrate that vasopressin neurons localized primarily to the medial aspect of the supraoptic nucleus are necessary for sensory integration of odor-induced flank marking, and as such, may be one possible source of neurotransmitter controlling this behavior.

Abstract Vasopressin (VP) cells in the bed nucleus of the stria terminalis, medial amygdaloid nucleus and supraoptic and paraventricular nuclei are influenced by gonadal steroids. The present paper examined whether VP cells in the bed nucleus of the stria terminalis, medial amygdaloid nucleus, and supraoptic and paraventricular nuclei contain estrogen receptors. Brains from adult short-term castrated, colchicine-treated male rats were fixed with 4% paraformaldehyde and 0.5% glutaraldehyde. In the immunocytochemical double-staining procedure Vibratome sections were first incubated with an estrogen receptor antibody (#H222) and stained with diaminobenzidine-Ni(+). Following methanol-hydrogen peroxide washes, sections were incubated with anti-neurophysin and stained with diaminobenzidine. Parvocellular cells in the bed nucleus of the stria terminalis and medial amygdaloid nucleus were double-stained with a blue-black nucleus (indicating the estrogen receptors) surrounded by brown cytoplasm (resulting from VP-neurophysin-immunoreactivity). Our results provide the first direct anatomical evidence supporting the hypothesis that gonadal steroids' influence of parvocellular VP cells in the bed nucleus of the stria terminalis and medial amygdaloid nucleus is mediated directly via estrogen receptors localized in nuclei of VP neurons. We were unable to co-localize any estrogen receptors in VP and oxytocin cells of magnocellular size in the supraoptic, paraventricular and anterior commissural nuclei, suggesting that estrogen indirectly affects these magnocellular hypothalamic cells.

An acute challenge with gastrin-17 enhanced the uptake of 45Ca into sternum and several long bones in rats by about 10-30%; gastrectomy prevented this effect. Long-term treatment with (Leu15)-gastrin-17 (continuous infusion via osmotic minipumps for 4 weeks) enhanced the uptake of 45Ca into bone (examplified by radius and sternum) by 18-26% (tested on the last day of the infusion). Surgical removal of the acid-producing part of the stomach (fundectomy) or treatment with the anti-ulcer drugs, ranitidine (a histamine H2-receptor antagonist administered by continuous infusion) or omeprazole (an H+/K(+)-ATPase inhibitor administered daily by gastric tube for 4 weeks), induced sustained hypergastrinemia (through loss of acid feedback inhibition of gastrin release). The ranitidine- and omeprazole-evoked hypergastrinemia was associated with 32-62% enhancement of bone 45Ca uptake but the hypergastrinemia of fundectomized rats was not. Gastrectomy abolished the effect of omeprazole. We suggest that exogenous and endogenous gastrin influences calcium uptake into bone indirectly by releasing a calciotropic hormone (gastrocalcin) from the acid-producing part of the stomach. The bone ash weight was reduced by gastrectomy or fundectomy (4 weeks), but neither ranitidine nor omeprazole-evoked hypergastrinemia (4 weeks) raised the bone ash weight. The stimulated calcium uptake into bone of hypergastrinemic rats treated with ranitidine or omeprazole was associated with a 22-32% increase in the density of osteoclasts in the tibia. This finding is in line with the hypothesis that long-lasting hypergastrocalcinemia produces accelerated turn-over of bone rather than increased bone calcium content.

The influence of antrectomy and antrum exclusion on the enterochromaffin like cell kinetics in the gastric mucosa of the rat was studied using a combination of histamine immunocytochemistry and autoradiography after in vivo labelling with tritiated thymidine. In all experimental groups, the enterochromaffin like cells were found to incorporate the DNA precursor, thus indicating an ability to divide. The serum gastrin concentration was raised by antrum exclusion and reduced by antrectomy. After antrum exclusion, the enterochromaffin like cell proliferation rate increased as indicated by a doubling of the labelling index and by the resulting enterochromaffin like cell hyperplasia (after six weeks). After antrectomy, the enterochromaffin like cell labelling index decreased to reach 25% of the control value; at this time the enterochromaffin like cell density had not decreased significantly. The observed correlation between the enterochromaffin like cell labelling indices and the serum gastrin concentration supports the hypothesis that enterochromaffin like cell proliferation is influenced by serum gastrin.

Quantitation of tocainide carbamoyl-O-B-D-glucuronide, a major metabolite of the antiarrhythmic agent, tocainide, was previously reported using sodium hydroxide hydrolysis (pH greater than 12) of the glucuronide followed by gas chromatographic analysis of the hydrolyzed product, 3-(2',6'-xylyl)-5-methylhydantoin. In this investigation, the hydantoin was found to undergo rapid degradation during base hydrolysis of the tocainide glucuronide. The hydantoin was synthesized and its hydrolysis in sodium hydroxide (pH greater than 12) was found to follow first-order kinetics with an estimated half-life of 24.6 minutes. This spontaneous and rapid degradation of the hydantoin during hydrolysis of the tocainide glucuronide may result in underestimation of the hydantoin. To correct for the degradation of the hydantoin, a gas chromatographic assay with a timed, base-hydrolysis calibration protocol was designed. To demonstrate the applicability of this assay, the elimination kinetics of tocainide and the tocainide carbamoyl glucuronide were studied in three healthy male volunteers after a single 200 mg oral dose of tocainide hydrochloride. From urine data, the elimination half-life of tocainide was approximately 15.5 hours. The urinary excretion half-life of the tocainide carbamoyl glucuronide was approximately 13.8 hours.

Studies were conducted to characterize the pharmacokinetics of diphenhydramine in nonpregnant ewes after iv administration of 25-, 50-, 100-, and 200-mg doses of diphenhydramine hydrochloride on a crossover basis. Plasma drug concentration versus time data exhibited multiexponential characteristics. The initial distribution half-life increased from 5 to 9 min and the elimination half-life from 34 to 68 min as the dose was increased. There was also an increase in the volume of distribution (from 3 to 6 L/kg) with increasing dose. The elimination half-life and the volume of distribution after a 200-mg dose were significantly greater than after a 25-mg dose. There was, however, a linear increase in AUC0 infinity as dose was increased. The average total body clearance (approximately 5 L/h/kg) remained unchanged regardless of dose. The free fraction of diphenhydramine determined by equilibrium dialysis averaged 0.229 +/- 0.080, and the extent of drug binding to plasma protein was independent of the drug concentrations encountered (30-780 ng/mL) in the nonpregnant sheep in vivo. Concentration-independent binding of the drug was also confirmed by in vitro binding studies over the drug concentration range 10-2000 ng/mL. Therefore, it appears that changes in the volume of distribution are likely to be a result of changes in tissue uptake or binding of the drug as a function of dose.

The disposition of tocainide enantiomers were examined in healthy human subjects and uraemic patients following a single i.v. dose (200 mg) of racemic tocainide hydrochloride. In the healthy subjects, the total body clearance of R(-)-tocainide was significantly greater than that of S(+)-tocainide (2.62 vs 1.70 ml.min-1.kg-1). Renal clearance also favoured R(-)-tocainide and appeared to contribute significantly to the stereoselective total body clearance. The volume of distribution of the enantiomers did not differ significantly. Uraemia produced a marked decrease in the total body clearance with no apparent effect on the volume of distribution of both enantiomers. The S/R ratio for total body clearance decreased significantly from 0.66 in healthy subjects to 0.54 in the uraemics, while the ratio for terminal elimination half-life significantly increased from 1.43 to 1.59. These results indicate that uraemia alters the degree of stereoselectivity in the pharmacokinetic parameters of tocainide enantiomers.

An electron-capture gas-liquid chromatographic assay for metoclopramide using cross-linked fused silica capillary columns which provides improved selectivity and sensitivity is reported. A 25 m X 0.31 mm fused silica capillary column was used for all analyses. Linearity was observed in the range of 4--40 ng of metoclopramide base per 0.25--0.5 ml of plasma. This represents from ca. 0.9--9.0 pg at the detector employing a split ratio of 30:1 and an injection volume of 2 microliters. Applicability of the method is demonstrated by the analysis of human and sheep plasma (maternal, fetal and neonatal) from metoclopramide placental transfer studies.

In vitro and in vivo studies utilizing a combination of leukocyte interferon-alpha (IFN) and chlorambucil (CLB) were done to investigate possible synergism between a biological response modifier and a chemotherapy drug. In vitro studies utilized a human myeloid leukemia cell line (K-562) pretreated with IFN and then exposed to CLB. The combination resulted in significant depression of cell growth compared with use of IFN or CLB alone. In vivo studies involved eight heavily pretreated patients given 6 million units IFN for 5 days followed by oral CLB (16 mg/m2) for 5 days repeated every 4 weeks. Three myeloma patients had reduction in immunoglobulins and experienced clinical responses. Three of four patients with Hodgkin's disease responded after relatively short periods of treatment. One patient with a diffuse lymphocytic lymphoma had a complete unmaintained remission lasting 6 months. Toxicity was minimal, with mild fever, nausea, and vomiting. These preliminary studies suggest that IFN may be a biological response modifier when used in combination with a cytotoxic agent.

The pharmacokinetics of metoclopramide was studied in chronically instrumented pregnant and nonpregnant sheep. Metoclopramide was administered to the ewe by intravenous bolus injections (on a crossover basis) of 10, 20, and 40 mg, with an additional 80-mg dose to the nonpregnant animals. Transfer of the drug to the fetus was rapid with significant concentrations in fetal plasma 1 min after maternal dosing. The ratio of fetal-to-maternal area under the plasma concentration-time curves averaged 0.74, indicating significant fetal exposure to the drug. Maternal metoclopramide administration resulted in minimal fetal effects, with no change in arterial pressure, heart rate, or arterial pH or PCO2, and only a small (approximately 1.8 mmHg) transient decline in PO2. Plasma concentrations in maternal and fetal plasma in most animals were best described by a biexponential equation with rapid distribution and elimination phases. The terminal elimination half-lives in maternal and fetal plasma averaged 71.3 and 86.8 min, respectively, with fetal half-life being significantly longer. The number of fetuses present had no consistent effects on either maternal or fetal pharmacokinetic parameters. Total body clearance and volume of distribution averaged 3.5 L/h/kg and 5.8 L/kg, respectively, in the pregnant ewe, and 4.5 L/h/kg and 6.9 L/kg, respectively, in the nonpregnant animals. The terminal elimination half-life in the nonpregnant ewes averaged 67.5 min. Pharmacokinetic parameters were compared in the pregnant and nonpregnant ewes at the 10-, 20-, and 40-mg doses, and no significant differences were observed in the distribution or elimination rate constants, elimination half-life, or volume of distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

The protein binding of propafenone, a Class I antiarrhythmic agent, was studied in vitro using a selective and sensitive electron-capture detection gas-liquid capillary chromatographic assay method developed in our laboratory. The concentration-dependency of the serum protein binding of propafenone was confirmed in vitro by equilibrium dialysis, using serum obtained from healthy human subjects and patients with chronic renal failure. In normal serum the unbound fraction of propafenone was 0.027 at a propafenone concentration of 0.25 microgram.ml-1, 0.041 within the therapeutic concentration range (0.5-2 micrograms.ml-1), 0.138 at a propafenone concentration of 25 micrograms.ml-1, and 0.187 when the propafenone concentration was increased to 100 micrograms.ml-1. There was no evidence of significant concentration-dependent changes in unbound fraction within the propafenone concentration range of 0.5-1.5 micrograms.ml-1. However, concentration-dependent binding was demonstrated at concentrations greater than 1.5 micrograms.ml-1. A high-affinity, low-capacity binding site (K1 = 6.53 x 10(5) l.mol-1; n1P1 = 1.73 x 10(-4) mol.l-1) and a low-affinity, high-capacity binding site (K2 = 8.77 x 10(3) l.mol-1; n2P2 = 8.57 x 10(-3) mol. x l-1) were identified. In pooled uraemic serum the unbound fraction of propafenone was approximately 50% of that of normal serum throughout the concentration range studied (1-5 micrograms.ml-1). In sera from patients with chronic renal failure the increase in propafenone binding ratio or the decrease in unbound fraction was associated with the increase in alpha 1-acid glycoprotein concentrations, and there was a correlation (r = 0.8302) between alpha 1-acid glycoprotein concentration and the propafenone binding ratio.

Long-term exposure to constant dim illumination dissociated the circadian activity rhythms of female rats. Evaluation of this phenomenon by visual and spectral analysis indicated that ultradian rhythms survive the breakdown of circadian organization.

Twenty-three patients undergoing general anaesthesia for Caesarian section for healthy term pregnancies were entered into a double blind study using metoclopramide (MCP) and a normal saline placebo. Of these patients, eight received intravenous metoclopramide, 12 a normal saline placebo and three were lost to clinical follow-up. The maternal gastric volumes were measured and maternal and foetal MCP plasma concentrations were determined by gas-liquid chromatography. The Neurological and Adaptive Capacity Score tests of Amiel, Barrier and Schnider (NACS) were used to attempt evaluation of neonatal responses to MCP. Maternal gastric volume was significantly lower (p less than 0.05) in the treated patients. There were no marked differences in Apgar scores, cardiovascular parameters or neurobehavioural scores between the treated and untreated groups of neonates. At no time were the foetal metoclopramide plasma concentrations observed to exceed maternal values.

The free (unbound) concentration of drug in plasma is often an important determinant of pharmacological and toxicological effects. Unfortunately, studies examining the factors influencing the free fraction of quinidine in plasma have yielded inconsistent results. It is probable that differences in the type of blood collection tubes utilized and the analytical procedure employed biased some of these estimates of quinidine binding. The present study was executed in a manner free of factors now known to introduce artifacts into estimates of the free fraction of quinidine. In healthy volunteers, the free fraction of quinidine (1.0 microgram/mL) was 0.129 +/- 0.019 (mean +/- SD) and was constant throughout the therapeutic range. A high-affinity, low-capacity binding site (K = 1.17 X 10(5) M-1; nP = 3.49 X 10(-5) M) and a low-affinity, high-capacity binding site (K = 1.33 X 10(3) M-1; nP = 3.14 X 10(-3) M) were identified. The characteristics of quinidine binding in a 4.5-g/dL solution of human serum albumin (K = 3.05 X 10(3) M-1; nP = 1.36 X 10(-3) M) suggested that the low-affinity, high-capacity binding site was on this quinidine free fraction increased from 0.114 to 0.231. A lidocaine concentration of 250 micrograms/mL caused a similar increase. Patients suffering traumatic injury had a significant increase in alpha 1-acid glycoprotein concentration (197 mg/dL) and a decreased quinidine free fraction (0.075 +/- 0.019). Patients with hyperlipidemia had free fractions similar to those observed in healthy individuals (0.118 +/- 0.019).(ABSTRACT TRUNCATED AT 250 WORDS)

The reported interaction of griseofulvin with phenobarbital was studied in the rat following oral administration of different dosage forms. A single oral dose of 15 mg of phenobarbital/kg 24 hr prior to the oral administration of a suspension of 100 mg og griseofulvin/kg in 0.5% polysorbate 80 significantly reduced plasma griseofulvin levels. An increase in the concentration of polysorbate 80 to 2% reduced the extent of the interaction from 50 to 32%. Phenobarbital did not influence plasma griseofulvin levels when griseofulvin was given in either 70% polyethylene glycol 300 (suspensions of 20 or 100 mg/kg) or 100% polyethylene glycol 600 (solution of 50 mg/kg). It is concluded that the observed interaction is formulation dependent and is a result of diminished dissolution and, consequently, reduced absorption of griseofulvin.

1. The disposition of orally administered disopyramide was studied in a population of smokers (n = 6) and non-smokers (n = 8) before and during phenobarbitone treatment (100 mg daily for 21 days; Cp 21st day = 13.9 +/- 2.0 micrograms ml-1). The comparative inducibility of these populations by phenobarbitone was assessed as was the inductive effect of cigarette smoking, per se. Furthermore, the determinants of the intensity of the inductive effect were examined, as well as the effect of the barbiturate on the binding of disopyramide to alpha 1-acid glycoprotein (AGP). 2. Smokers and non-smokers exhibited similar half-lives (6.48 +/- 1.49 vs 6.66 +/- 1.02 h), apparent total body clearances (0.100 +/- 0.020 vs 0.117 +/- 0.034 l h-1 kg-1), mean renal clearances (0.043 +/- 0.0093 vs 0.057 +/- 0.013 l h-1 kg-1) and apparent intrinsic metabolic clearances (0.057 +/- 0.015 vs 0.060 +/- 0.024 l h-1 kg-1) before phenobarbitone treatment. 3. Both populations responded comparably to barbiturate exposure in that apparent intrinsic metabolic clearance more than doubled. Interestingly, the magnitude of this increase was highly dependent on the observed baseline apparent intrinsic metabolic clearance, (r' = 0.81; P less than 0.001). 4. Phenobarbitone treatment of non-smokers resulted in an increase in the AUC of the active metabolite N-despropyl disopyramide (MND), but not significantly (3.8 +/- 1.6 vs 4.1 +/- 2.3 micrograms ml-1 h). Similar results were observed in smokers (3.5 +/- 1.4 vs 3.9 +/- 2.0 micrograms ml-1 h, respectively). 5. The percent of administered dose recovered in urine as disopyramide in non-smokers was significantly decreased upon phenobarbitone treatment (43 +/- 6% vs 25 +/- 5%), whereas the percent of dose recovered as MND increased significantly in this group (25 +/- 6% vs 31 +/- 5%). The population of smokers responded similarly. 6. At doses typically used to achieve hepatic microsomal enzyme induction in man, phenobarbitone treatment caused no significant change or trend towards a change in serum AGP concentrations as measured using the radial immunodiffusion method in nonsmokers (67.4 +/- 19.9 mg dl-1 vs 68.0 +/- 40.7 mg dl-1) or smokers (64.5 +/- 15.7 vs 67.9 +/- 14.9). Similarly, when AGP concentration was estimated in serum from non-smokers using a nephelometric method no effect attributable to phenobarbitone was observed (47.9 +/- 1.3 vs 47.9 +/- 16.8 mg dl-1). Consistent with this observation, disopyramide free fraction was not affected by barbiturate treatment.

Sixteen patients with advanced non-small-cell lung cancer were treated with the combination of cis-platinum, 5-fluorouracil, and hydroxyurea. There were two complete responses (lasting 16 weeks each) and one partial response (lasting 12 weeks). Toxicity was manageable, but responders were unable to tolerate further therapy. Despite the obtaining of complete responses, the overall benefit of this particular combination requires further clinical investigation.

Previous studies have reported that elevation of the pH of local anaesthetics is associated with enhanced quality and duration of block. This study investigated the effect, on time to onset and duration of analgesia, of pH adjustment of 0.25 per cent bupivacaine immediately prior to injection into the epidural space in parturients. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.25 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.65 to 7.26 (mean values). Thirty parturients received an epidural injection of 8 ml of pH-adjusted 0.25 per cent bupivacaine and a control group of 30 parturients received 8 ml of the standard commercial preparation of 0.25 per cent bupivacaine. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of analgesia from 6.0 minutes to 3.2 minutes and the duration of analgesia was significantly lengthened from 79.4 minutes to 96.5 minutes. There was no significant influence on time to peak effect, nor on mean maternal plasma levels of bupivacaine.

Naturally acquired Brucella canis infection is believed to be uncommon, but is not readily diagnosed. A 55-year-old woman developed fever, abdominal pain, malaise, weakness, and anorexia eight weeks after her dog delivered stillborn pups. Blood cultures yielded B canis. Specific B canis agglutinins were negative initially and remained negative during convalescence. Therapy with tetracycline and streptomycin was successful but was associated with a probable Jarisch-Herxheimer reaction.

A sensitive and specific capillary gas liquid chromatographic nitrogen/phosphorus selective detection technique was used to measure unbound disopyramide in human plasma. The concentration dependent protein binding of disopyramide was examined. Various concentrations of disopyramide alone ranging from 0.5 to 10.0 micrograms/ml in 0.4 ml of isotonic phosphate buffer (pH 7.4) were dialyzed for 6 hours at 37 degrees C, against 0.4 ml blank plasma from five healthy volunteers. The concentration-dependent binding of disopyramide was confirmed. The average free fraction for disopyramide at concentrations of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 and 10.0 micrograms/ml were 0.14, 0.15, 0.20, 0.27, 0.30, 0.34 and 0.53, respectively.

Saliva and plasma samples collected from four healthy volunteers who had received racemic tocainide by intravenous infusion for 20 minutes were analysed by a stereospecific and sensitive gas chromatographic method. The enantiomeric composition of mixed saliva obtained for a period of 48 hrs have been determined and compared with the corresponding plasma profiles. The concentration of each enantiomer in saliva tended to be greater than those in the corresponding plasma sample, such that the mean saliva to plasma ratio for S(+) tocainide was 2.07 +/- 0.50 (SEM) and for the R(-) isomer 3.683 +/- 0.76 (SEM). Marked intersubject variability was found in the saliva/plasma ratio of both isomers, however, the correlation of saliva/plasma concentrations in each volunteer was good and ranged from r = 0.910 to 0.987 for S(+) tocainide and r = 0.884 to 0.986 for R(-) tocainide. There was a 6-fold difference between saliva and plasma concentration of R(-) isomer in one subject whose saliva pH ranged from 6.9 to 7.1. The difference was only 3.5 fold in another subject whose saliva pH was consistently higher (7.4 to 7.5). Therefore, the saliva/plasma ratio appeared to depend on pH, increasing with decreasing pH. However, the correlation between the saliva/plasma ratio observed and the ratio predicted was poor. Mechanisms other than passive diffusion are likely to be involved in the transfer of tocainide enantiomers from plasma to saliva and are more pronounced with the levo isomer.

Thirteen patients with advanced non-Hodgkin's lymphoma who previously failed conventional chemotherapy protocols were treated with a combination of alpha-interferon (IFN) 6,000,000 units i.m. days 1-5 and 8, plus chlorambucil (CLB) 16 mg/m2 days 5-9 repeated every 4 weeks. There were five complete responses (CRs) and one partial response (PR) (46% total responses) with mean duration of remission of 456+ days. Responses were obtained in low and intermediate grade lymphomas. Toxicity was acceptable and easily managed. It is unlikely that IFN alone using this low dose intermittent schedule is responsible for the remissions. The combination of the two agents appears to be an effective treatment modality. IFN may be functioning as a biological response modifier when used in combination with a cytotoxic agent.

We have previously shown that although Silastic implants of progesterone reduce the amount of running of animals living in activity wheels, progesterone-treated animals continue to show periodic fluctuations or peaks in activity. We hypothesized that although progesterone treatment inhibited estrous cycles, ovaries of animals treated with Silastic implants of progesterone continued to secrete estradiol in amounts adequate to stimulate moderate levels of running. In the present study we tested this hypothesis by removing ovaries from progesterone-treated animals and comparing their running behavior and steroid levels to progesterone-treated animals who received sham ovariectomies. Although progesterone treatment significantly inhibited running activity, removal of ovaries in progesterone-treated animals further suppressed running activity. In addition, both estradiol and progesterone levels were significantly reduced following removal of ovaries in progesterone-treated animals. We conclude that although Silastic progesterone implants inhibit normal ovarian and estrous activity cycles, ovaries produce sufficient estradiol to stimulate running behavior.

Tocainide, a lidocaine congener with low hepatic clearance, is eliminated predominantly by formation of a novel glucuronide conjugate. This suggested the possibility of metabolic interactions with enzyme inducers or competitive substrates for glucuronyl transferase. The time course of tocainide blood concentration as well as the urinary excretion-time profiles of drug and principal metabolite (a glucuronide of tocainide carbaminic acid, TOCG) were examined in six subjects before and after 15 days on phenobarbital (100 mg/day). In another study, the effect of salicylamide and clofibrate on the time courses of tocainide and TOCG urinary excretion were examined in four of the same six subjects. After 600 mg tocainide HCl by mouth, the area under the tocainide blood concentration-time curve was 48.2 +/- 11.9 hr micrograms/ml for the control dose and 49.6 +/- 4.2 hr micrograms/ml (mean = SD) after phenobarbital. Percent of dose excreted unchanged in urine (46.0 +/- 4.9 and 43.4 +/- 5.6) and percent of dose excreted as TOCG (30.6 +/0 3.3 and 27.7 +/- 7.2) were not affected by phenobarbital (data presented as control and after phenobarbital). Because salicylamide has been reported to be a potent inhibitor of the glucuronidation of some drugs and because clofibrate yields metabolites that may be competitive inhibitors of tocainide conjugation, the two were given together with tocainide. Average percent of dose recovered in urine as unchanged tocainide in 24 hr was 26.8%, 28.3%, and 29.7% in the control, salicylamide, and clofibrate studies. The urinary excretion of TOCG was also not affected. It is concluded that under the conditions of our investigation, the principal urinary metabolite of tocainide, a glucuronide of tocainide carbaminic acid, is formed by a mechanism not subject to induction by phenobarbital or competitive inhibition by salicylamide or clofibrate.

The effect of food intake on the bioavailability of propafenone, a new antiarrhythmic agent, was evaluated by comparing its kinetics in 24 healthy volunteers in a fasted state and after a standard breakfast. With food, the maximum plasma drug concentration was reached earlier and was significantly increased. When data from 'slow' metabolizers were excluded, there was an average increase of 147% in the area under the concentration-time curve (AUCo) following the standard breakfast. There was a significant correlation (r = 0.946) between [(AUCo fed - AUCo fasted)/AUCo fasted] and propafenone intrinsic clearance in the fasted state. Food intake, however, does not appear to affect the bioavailability of propafenone in 'slow' metabolizers. Patients should be advised to take propafenone in a constant relationship to food to assure consistent bioavailability.

In vivo and in vitro experiments were conducted in rats to examine the possibility of either extrahepatic metabolism or saturable first-pass effect as an explanation for the unusual presystemic clearance of metoclopramide (I) previously reported. In vivo studies involved two-thirds hepatectomized rats and animals pretreated with carbon tetrachloride to induce hepatic necrosis, whereas in vitro studies involved incubation of equal amounts of I (5.0 mumol/mL) with various tissue homogenates (viz., liver, kidney, and lung) or their 9000 X g supernatant fractions. Results suggest that the metabolism of I principally occurs in the rat liver, and there was no evidence suggesting the involvement of kidney or lung tissue in the metabolism of I. Forty-eight-hour cumulative urinary excretion studies following oral and intravenous administration of less than or equal to 5.0 mg/kg of metoclopramide hydrochloride were conducted. The bioavailability (F) values of I at dosage levels 0.1, 0.5, 1.0, and 5.0 mg/kg were 0.49, 0.75, 0.77, and 0.83, respectively. It is concluded that the liver is the primary organ for the metabolism of I in the rat and that the drug exhibits dose-dependent hepatic first-pass metabolism.

Immune hemolytic anemia is an acquired anemia resulting from the premature destruction of red cells caused by the presence of antibody and/or complement on the red cell surface. The Coombs test, modified and improved, remains the mainstay of diagnosis.

We measured sexual behavior (lordosis) in ovariectomized, steroid-treated, exercising female rats. When estradiol-treated animals exercised voluntarily, lordosis was directly related to the amount of exercise. Forced exercise (swimming) following treatment with estradiol 17 beta and progesterone significantly increased lordosis scores but only after animals swam for 2.5 hr per day. Lordosis behavior returned to baseline levels 7 weeks after forced exercise was stopped. Circulating levels of estrogen and progesterone measured immediately after behavioral testing did not differ between animals forced to exercise and their controls. The mechanisms responsible for the increase in lordosis behavior following exercise are unclear. It is possible that a change in body composition, a change in neural sensitivity to gonadal steroids, and/or changes in pituitary or adrenal function contribute to the increased lordosis behavior in exercised animals.

A sensitive and specific electron-capture detector GLC method capable of detecting picogram quantities of tocainide, a lidocaine analog, in biological fluids was developed. This method consists of extracting the compound into methylene chloride and derivatizing with heptafluorobutyric anhydride to form the monoheptafluorobutyryl derivative. The derivative formation was confirmed by GLC-mass spectrometry. Quantitative estimation was performed using 1-bromonaphthalene as an internal standard. The minimum detectable level by the electron-capture method was approximately 30 pg/injection as opposed to approximately 3 ng/injection with a flame-ionization detector Linear response was observed in the range from 50 pg to 3 ng using an electron-capture detector. No interference from endogenous substances was observed.

To study the placental transfer and pharmacokinetics of the H1 receptor blocker, diphenhydramine [2-(diphenylmethoxy)-N,N-dimethylethylamine], 100 mg of the drug was administered to four pregnant sheep (122-129 d gestation) by intravenous injection through catheters chronically implanted in the ewe and fetus. Rapid placental transfer occurred, with peak fetal plasma concentrations occurring within 5 min after injection. The fetal-maternal ratio of the area under the plasma concentration versus time curves averaged 0.85, indicating significant fetal exposure to the drug. The average apparent terminal elimination half-life in the ewe (52 min) was not significantly different from that obtained in the fetus (46 min). The maternal total body clearance was 3.6 L X h-1 X kg-1, and the volume of distribution at steady state was 3.2 L/kg. In summary, this study demonstrates rapid and extensive placental transfer of diphenhydramine after maternal drug administration. Since placental permeability to lipid-soluble compounds does not differ greatly in different species, it is likely that a similar situation exists in humans.

Data from the household portion of the 1977-78 USDA Nationwide Food Consumption Survey were used to determine expenditures for convenience and nonconvenience foods and nutrients from those foods. Households with male food preparers accounted for approximately 15% of the survey population, frequently included only one person, and had a larger proportion of young and elderly heads of household than households with a female food preparer. As a group, the foods most frequently reported in households with male food preparers were quite similar to those used by households with female food preparers. Male food preparers spent less of the food dollar on nonconvenience items than did other food preparers, and conversely they spent more on complex and manufactured convenience foods. Total food energy and nutrient levels per nutrition unit of the foods used by households with male food preparers were significantly higher than those in households with female food preparers for all nutrients except thiamin and riboflavin. However, the values were more than 100% of the Recommended Dietary Allowance values except for vitamin B-6 for both sample groups.

A nitrogen-specific detector gas-liquid chromatographic assay method is reported which provides improved selectivity and sensitivity for disopyramide and its mono-N-dealkylated metabolite using a crosslinked fused-silica capillary column. The quantitation of disopyramide and mono-N-dealkylated disopyramide was accomplished by injecting trifluoroacetic anhydride-treated samples containing derivatized internal standard p- chlorodisopyramide , into a gas chromatograph equipped with a nitrogen--phosphorus detector and an automatic liquid sampler. A 25 m X 0.31 mm crosslinked, 5% phenylmethyl silicone-coated fused-silica column was utilized and samples were injected using the splitless injection mode. Linearity was observed in the range 0.05-5.00 micrograms/ml for disopyramide and 0.02-3.00 micrograms/ml for the mono-N-dealkylated metabolite. The coefficient of variation was found to be within 10% for both compounds in the concentration range studied.

Gastrin is a trophic hormone for the stomach, and permanent reduction of circulating gastrin by antrectomy leads to atrophy of the oxyntic mucosa, including a reduced density of histamine-storing endocrine cells (so-called ECL cells). Recently, it was proposed that also the vagal nerve has a trophic influence on the stomach. The two vagal trunks innervate the anterior and posterior side of the gastric wall, respectively. This arrangement makes it possible to denervate one side of the stomach selectively. The objective of the present study was to examine the consequences of combined antrectomy and vagotomy (unilateral or bilateral). Male Sprague-Dawley rats were subjected to unilateral or bilateral subdiaphragmatic truncal vagotomy with or without antrectomy. Control rats were sham-operated. The rats were killed 8 weeks after the operation. Bilateral vagotomy raised the basal serum gastrin concentration (fasting level). The thickness of the oxyntic mucosa and the density of ECL cells were not significantly different from age-matched vagally intact controls. Unilateral vagotomy induced no change in the basal serum gastrin concentration, nor did it affect the mucosa on the intact side. On the denervated side, however, there was reduced mucosal thickness and a greatly reduced ECL cell density. With a combination of antrectomy and vagal denervation the decrease in ECL cell density was exaggerated compared to the effect of antrectomy or unilateral vagotomy alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous studies have reported that elevation of the pH of local anaesthetics results in more rapid onset of action, with enhanced quality and duration of block. This study investigated the effect of pH adjustment of 0.5 per cent bupivacaine immediately prior to epidural anaesthesia for Caesarean section. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.5 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.49 to 7.04 (mean values). One hundred patients, presenting for elective Caesarean section under epidural anaesthesia participated in the study. Forty patients received epidural anaesthesia, using pH-adjusted 0.5 per cent bupivacaine, in a dosage adequate to produce block to the T4 level. A control group of 40 patients received the standard commercial preparation of 0.5 per cent bupivacaine. A further ten patients in each group received epidural anaesthesia using 0.5 per cent bupivacaine with the addition of 1:400,000 epinephrine, to study the effect of epinephrine on pH adjustment of the local anaesthetic. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of action from 6.4 minutes to 3.2 minutes and the time to peak effect from 24.8 minutes to 18.1 minutes, while the duration of anaesthesia was increased from 124.8 minutes to 147.3 minutes. The time to S2 segment blockade was also shortened from 13.5 to 8.6 minutes. Addition of 1:400,000 epinephrine to the local anaesthetic did not influence the effect of pH adjustment. Maternal and umbilical cord plasma levels of bupivacaine were not affected by pH adjustment of the local anaesthetic, while MV/UV and UA/UV ratios were unaltered.

The metabolism of the antiarrhythmic drug tocainide (I) has been shown previously to occur via a novel pathway involving the addition of carbon dioxide to the primary amine nitrogen of I followed by conjugation with glucuronic acid. The product of this reaction, tocainide carbamoyl O-beta-D-glucuronide (II), the principal metabolite of I in humans, has been found to cyclize under strongly basic conditions to form 3-(2,6-xylyl)-5-methylhydantoin (III). Thus, evidence for the existence of II can be obtained by two different procedures: conversion of II to III in the presence of strong base and by hydrolysis of II with beta-glucuronidase. The principal purpose of the present investigation was to identify suitable species for studies of the mechanism involved in the formation of II, as well as to find an animal model suitable for toxicological evaluation of tocainide and structurally related compounds. Eight animal species were examined to identify those capable of metabolizing I into II. The fraction of an intraperitoneal dose excreted in urine as II was estimated by measurement of tocainide released by beta-glucuronidase mediated hydrolysis of urine and by the quantitation of III formed after alkalinization of urine samples. Urinary recovery of unchanged drug ranged from 9.5% of the dose in the gerbil to 48.7% in the cat. The percent of the dose excreted in urine as acid hydrolyzable conjugates ranged from less than 1% in the gerbil to a mean of 13% in the rabbit. Guinea pigs, dogs, cats, rabbits, and pigtail monkeys excreted amounts of II ranging from 0.2 to 2.4% of the dose. Thus, none of the species appeared to be a suitable model for the study of the mechanism of formation of II because of the quantitative insignificance of this pathway.