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1. The objective was to determine the ontogeny of stereoselective fluoxetine (FX) disposition in postnatal sheep from newborn to adulthood.2. Catheters were implanted in a carotid artery an...

Approximately 1/3 of newborns exposed antenatally to selective serotonin reuptake inhibitors (SSRIs) exhibit poor neonatal adaptation. Although several potential mechanisms have been proposed, the actual mechanism has not been elucidated. We investigated outcomes in neonatal lambs exposed prenatally or postnatally to fluoxetine (FX). Daily FX injections (50 mg) were given intravenously (i.v.) to five pregnant ewes via implanted catheters beginning at 131–132 days gestation (term = 147 days) for 2 weeks. In another group, lambs with implanted vascular catheters had sterile water (n = 9) or FX (1 mg/kg, n = 12) injected i.v. on ~postnatal day (PND) 4. Prenatal FX-exposed lambs (n = 7) were hyperactive during PND 4 to 14 and their heart rate variability (HRV) was significantly lower than in control lambs (n = 7) on PND 2. In contrast, arterial pressure, heart rate, electrocardiogram, arterial blood gases, pH, glucose, lactate, cortisol, and sleep–activity cycles were not altered following postnatal FX injection. This abnormal postnatal hyperactivity with antenatal FX exposure may reflect increased maturity in terms of locomotory activity. The results suggest that altered brain development may be involved in the poor neonatal adaptation in human infants exposed to FX in utero.

1. The objective was to determine the ontogeny of stereoselective fluoxetine (FX) disposition in postnatal sheep from newborn to adulthood. 2. Catheters were implanted in a carotid artery and jugular vein. FX was administered intravenously, followed by serial arterial blood and cumulative urine collection. The concentrations of

To determine whether there are changes in blood gas and acid-base status with advancing gestation in the fetal lamb, similar to that reported in the human fetus, blood gas, acid-base, and blood metabolite values were measured in 447 control, arterial blood samples from 108 chronically instrumented fetal lambs between 103 and 146 days gestation. With advancing gestation, Po2, pH, O2saturation, and O2content fell significantly, while Pco2and hemoglobin concentration increased. Blood glucose and lactate concentrations were unchanged, although the lactate level increased with decreasing Po2, particularly when below ∼13 mmHg. Multiple linear regression indicated that increasing fetal number was associated with decreased Po2and glucose level and increased pH, HCO3−, base excess, and lactate concentration. Hemoglobin concentration was higher in female than male lambs. Overall, there was a linear relationship between glucose concentration and birth weight. It is concluded that in fetal lambs as in the human fetus, there are changes in blood gas and acid-base status with advancing gestation. This may be due to the decrease in fetal weight-normalized uterine and umbilical blood flows than occurs in these and other species as gestation proceeds. In addition, the reduced birth weight in twin and triplet lambs may be due to hypoglycemia rather than hypoxemia.

We used real-time ultrasound to measure motility and abdominal diameter in fetal lambs at weekly intervals for 30 minutes from 55 days to term (n = 8). Fetal body movement counts/min were relatively constant between 55 and ~90 days and declined progressively thereafter, a relationship best described by piecewise linear regression with 2 elements. The break point in the regression curves averaged 91.9 ± 5.2 days. The relationship between gestational age and abdominal diameter was also best described by piecewise linear regression. The break point of 113.1 ± 3.9 days was significantly greater than the movement break point. There was a significant linear relationship between the movement and abdominal break points, with the latter occurring 21.6 ± 6.6 days later. These results suggest that both fetal motility and growth may decrease in order to lower fetal O2 demands to match the progressive decline in fetal O2 delivery with advancing gestation.

In utero serotonin reuptake inhibitor (SRI) exposure is relatively common and neonatal behavioral outcomes vary greatly. Such exposure has led to questions about whether these effects reflect an acute short-lived pharmacological phenomenon that results in a “withdrawal” condition, or sustained neurological changes associated with altered serotonin (5-HT) signaling that begins long before birth. Emerging reports now suggest that certain effects associated with in utero SRI exposure become evident during gestation. For instance, in utero SRI exposure appears to influence fetal brain blood flow and neurobehavior. In this chapter, we summarize current research evidence reporting the fetal effects of in utero SRI exposure. Given the paucity of empiric fetal data in humans, we draw from what we know about three postnatal findings that may reflect fetal developmental sequelae associated with in utero SRI exposure.

Prenatal serotonin reuptake inhibitor exposure is common and neonatal outcomes vary greatly, often leading to confusion about whether to use or even continue antenatal use of these antidepressants. Importantly, some but not all infants are affected, which raises questions about how maternal drug metabolism contributes to fetal drug exposure. To address this key question, our paper reviews the role of key maternal, fetal, and placental pharmacokinetic, metabolic, and genetic factors that affect the extent of fetal drug exposure. Considering the role of these factors may further our understanding of variables that may assist in optimizing maternal psychopharmacotherapy during pregnancy and neonatal outcomes.

Sildenafil citrate therapy for severe early-onset intrauterine growth restriction. BJOG 2011;118:624-628. Currently, there is no effective therapy for severe early-onset intrauterine growth restriction (IUGR). Sildenafil citrate vasodilates the myometrial arteries isolated from women with IUGR-complicated pregnancies. Women were offered Sildenafil (25 mg three times daily until delivery) if their pregnancy was complicated by early-onset IUGR [abdominal circumference (AC)< 5th percentile] and either the gestational age was

A liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the quantitation of (R)-, (S)-fluoxetine, and (R)-, (S)-norfluoxetine in ovine plasma. The analytes were extracted from ovine plasma at a basic pH using a single-step liquid-liquid extraction with methyl-tert-butyl ether. Chromatographic separation of all enantiomers was achieved using an AGP-chiral column with a run time of 10 min. (R)-, (S)-fluoxetine, and (R)-, (S)-norfluoxetine were quantitated at the total ion current (TIC) of multiple reaction monitoring (MRM) transitions of m/z 310.2→44.1, m/z 310.2→147.7 for (R)-, (S)-fluoxetine, and m/z 296.2→30.3, m/z 296.2→133.9 for (R)-, (S)-norfluoxetine. This method was validated for accuracy, precision, linearity, range, limit of quantitation (LOQ), selectivity, recovery, dilution integrity, matrix effect, and evaluation of carry-over. Observed accuracy ranges were as follows: (R)-fluoxetine -8.82 to 3.75%; (S)-fluoxetine -10.8 to 1.46%; (R)-norfluoxetine -7.50 to 0.37% and (S)-norfluoxetine -8.77% to -1.33%. Observed precision ranges were as follows: (R)-fluoxetine 5.29-11.5%; (S)-fluoxetine 3.91-11.1%; (R)-norfluoxetine 4.32-7.67% and (S)-norfluoxetine -8.77% to -1.33%. The calibration curves were weighted (1/X(2), n=4) and observed to be linear for all analytes with the following r(2) values: (R)-fluoxetine ≥ 0.997; (S)-fluoxetine ≥ 0.996; (R)-norfluoxetine ≥ 0.989 and (S)-norfluoxetine ≥ 0.994. The analytical range of the method was 1-500 ng/ml with an LOQ of 1 ng/ml for all analytes, using a sample volume of 300 μL.

Prenatal exposure to stress and selective serotonin reuptake inhibitors (SSRIs) alter hypothalamic-pituitary-adrenal (HPA) stress reactivity in offspring, however, the effects of combined exposure to HPA activity in human infants is unknown.To examine HPA basal levels and stress responsiveness in 3-month olds with prenatal exposure to SSRIs.Salivary cortisol levels in infants of SSRI treated mothers (n=31, mean exposure 230.2+/-72.2 days) were compared with non-SSRI exposed (n=45) infants in response to a challenge (infant-controlled habituation task) and under basal conditions in the late afternoon/early evening. Mode of feeding, to account for possible postnatal drug exposure via breast milk, as well as measures of pre and postnatal maternal mood, were included as covariates.Lower post-stress cortisol levels were observed in non-SSRI exposed/non-breastfed infants compared with non-SSRI exposed infants who were breastfed at 3 months of age. Stress reactivity patterns among SSRI exposed infants did not differ with mode of feeding. The cortisol reactivity slope (CRS) was significantly lower among non-SSRI exposed non-breastfed infants compared with non-SSRI exposed breastfed infants. Early evening basal cortisol levels were lower in SSRI exposed infants than in non-SSRI exposed infants, controlling for maternal mood and mode of feeding. Postnatal SSRI exposure (infant SSRI drug levels) via breast milk was not associated with stress or basal cortisol levels. Total cortisol, reflected by the AUC measure, did not differ significantly between exposure groups.Prenatal SSRI exposure altered HPA stress response patterns and reduced early evening basal cortisol levels. Stress challenge HPA response differences only became apparent when the moderating effect of method of feeding was accounted for. These findings suggest an early "programming" effect of antenatal maternal mood, prenatal SSRI exposure and postnatal maternal care giving on the HPA system.

Meloxicam (MEL), a cyclooxygenase (COX)-2 inhibitor, decreases prostaglandin production and blocks preterm labor in sheep. The objective of this study is to investigate MEL dosage regimens on COX-1, COX-2, and prostaglandin dehydrogenase (PGDH) expression in ovine intrauterine and fetal tissues. Animals in preterm labor received maternal infusions of saline or MEL at maintained high or graded doses (study 1) or acute graded doses (study 2). MEL blocked preterm labor. In study 1, MEL decreased COX-2 expression in the endometrium, myometrium, and amnion but not placenta or fetal tissues. In study 2, COX-2 expression was unchanged. COX-1/PGDH expression was unaffected. While MEL is an effective tocolytic, reductions in COX-2 protein occurred only with maintained MEL exposure. MEL effects are tissue specific and do not affect COX-1 or PGDH expression. Maternal MEL does not affect fetal COX expression in the sheep, possibly contributing to its lack of fetal side effects.

Sigmoidal or autoactivation kinetics has been observed in vitro for both cytochrome P450- and UDP-glucuronosyltransferase-catalyzed enzymatic reactions. However, the in vivo relevance of sigmoidal kinetics has never been clearly demonstrated. In the current study we investigate the kinetics of valproic acid glucuronide (VPAG) formation both in vivo in adult sheep and in vitro in sheep liver microsomes (pool of 10). After a 100 mg/kg i.v. bolus dose of valproic acid (VPA) to adult sheep (n = 5), the majority of the dose was recovered in urine as VPAG (approximately 79%). Eadie-Hofstee plots of the VPAG formation rate (calculated from urinary excretion rate data for VPAG) were characteristic of autoactivation kinetics and provided estimates of the apparent maximum velocity of an enzymatic reaction (V(max)(app)), the substrate concentration resulting in 50% of V(max)(app) (S(50)(app)), and Hill coefficient (n) of 2.10 +/- 0.75 micromol/min/kg, 117 +/- 56 microM, and 1.34 +/- 0.14, respectively. Comparable estimates of V(max)(app) (2.63 +/- 0.33 micromol/min/kg), S(50)(app) (118 +/- 53 microM), and n (2.06 +/- 0.47) describing overall VPA elimination from plasma were obtained by fitting VPA unbound plasma concentration-time data to a two-compartment model with elimination described by the Hill equation. Consistent with our in vivo observations, Eadie-Hofstee plots of VPAG formation in sheep liver microsomes were characteristic of autoactivation kinetics. To our knowledge, these data provide the first clear demonstration that autoactivation kinetics observed in vitro in liver preparations can translate to the in vivo situation at least under certain experimental conditions and confirm its relevance.

The purpose of this study was to examine the disposition of diphenhydramine (DPHM) across the ovine blood-brain barrier (BBB). In six adult sheep, we characterized the central nervous system (CNS) pharmacokinetics of DPHM in brain extracellular fluid (ECF) and cerebrospinal fluid (CSF) using microdialysis in two experiments. In the first experiment, DPHM was administered via a five-step i.v. infusion (1.5, 5.5, 9.5, 13.5, and 17.5 microg/kg/min; 7 h per step). Average steady-state CNS/total plasma concentration ratios (i.e., [CNS]/[total plasma]) for steps 1 to 5 ranged from 0.4 to 0.5. However, average steady-state [CNS]/[free plasma] ratios ranged from 2 to 3, suggesting active transport of DPHM into the CNS. Plasma protein binding averaged 86.1 +/- 2.3% (mean +/- S.D.) and was not altered with increasing drug dose. Plasma, CSF, and ECF demonstrated biexponential pharmacokinetics with terminal elimination half-lives (t1/2beta) of 10.8 +/- 5.4, 3.6 +/- 1.0, and 5.3 +/- 4.2 h, respectively. The bulk flow of CSF and transport-mediated efflux of DPHM may explain the observed higher CNS clearances. In the second experiment, DPHM was coadministered with propranolol (PRN) to examine its effect on blood-brain CSF and blood-brain ECF DPHM relationships. Plasma total DPHM concentration decreased by 12.8 +/- 6.3% during PRN, whereas ECF and CSF concentrations increased (88.1 +/- 45.4 and 91.6 +/- 34.3%, respectively). This increase may be due to the inhibitory effect of PRN on a transporter-mediated efflux mechanism for DPHM brain elimination.

Aims To compare the disposition of fluoxetine and norfluoxetine enanantiomers in the mother, foetus and infant. Methods Blood from pregnant women taking fluoxetine (n = 9), during pregnancy was sampled in the third trimester and at delivery (maternal and cord venous blood), and from the infants 48 h after delivery. The subset of these women who were breastfeeding, plus additional subjects recruited in the postpartum period, were studied further, and maternal and infant blood, and breast milk was sampled between 6 days and 11 months (n = 23). Drug and metabolite concentrations were measured using gas chromatography/mass spectrometry or liquid chromatography, tandem mass spectrometry. Results There was a high correlation between maternal and foetal (cord blood) fluoxetine and norfluoxetine enantiomers (r2−0.9), the mean foetal/maternal ratios (95% confidence intervals) being 0.91 (0.61, 1.02) and 1.04 (0.93, 1.05), for fluoxetine and norfluoxetine, respectively. In 2 day old infants exposed to the drug in utero, the fluoxetine and norfluoxetine plasma concentrations were the same as in cord blood at delivery. Over the next 2 months, the plasma concentrations in the infants fell progressively. Stereoselective disposition of both the drug and metabolite in the mother, foetus, infant and breast milk was observed. The S : R ratios in the foetus and newborn (∼3) were significantly higher than in the serum (∼2) or breast milk (∼1.9) of the mothers, resulting in greater exposure of the foetus and infants to the biologically active enantiomers, particularly S-norfluoxetine. Conclusions Foetal and infant exposure to fluoxetine and norfluoxetine is enhanced by their stereoselective disposition in the mother, foetus, breast milk and infant. Increased exposure may also result from decreased metabolism of the drug in the foetus and neonate.

Depression during pregnancy is frequently treated with the selective serotonin reuptake inhibitor (SSRI), fluoxetine (FX), commonly known as Prozac (Eli Lilly & Co, Indianapolis, IN). FX potentiates serotoninergic neurotransmission and serotonin has been implicated in the regulation of circadian rhythms. We have therefore investigated the effect of chronic administration of FX on maternal and fetal circadian rhythms in sheep. Following an initial bolus dose of 70 mg FX, an 8-day continuous infusion of FX (n = 11, 98.5 μg/kg • d) was performed. Controls (n = 13) were treated with sterile water vehicle only. Maternal and fetal plasma melatonin and prolactin concentrations were determined every 3 hours for 24 hours and then every 6 hours for 24 hours beginning on the fourth day of infusion. FX treatment did not alter either the basal or circadian rhythms of either maternal or fetal plasma melatonin and prolactin concentrations. Fetal cardiovascular and behavioral state parameters were measured continuously. While the incidence of low-voltage (LV) electrocortical (ECOG) activity was significantly reduced in fetuses in the FX group, there was no effect of FX on the diurnal rhythms in fetal arterial pressure, heart rate, breathing movements, or behavioral state. These results show that maternal FX treatment does not result in significant alterations in maternal and fetal hormonal and behavioral circadian rhythms.

Objective. In this prospective study, we examined biobehavioral responses to acute procedural pain at 2 months of age in infants with prenatal and postnatal selective serotonin reuptake inhibitor (SSRI) medication exposure. Based on previous findings showing reduced pain responses in newborns after prenatal exposure, we hypothesized that altered pain reactivity would also be found at 2 months of age.Methods. Facial action (Neonatal Facial Coding System) and cardiac autonomic reactivity derived from the respiratory activity and heart rate variability (HRV) responses to a painful event (heel-lance) were compared between 3 groups of infants: (1) infants with prenatal SSRI exposure alone (n = 11; fluoxetine, n = 2; paroxetine, n = 9); (2) infants with prenatal and postnatal SSRI (via breast milk) exposure (total n = 30; fluoxetine, n = 6; paroxetine, n = 20; sertraline, n = 4); and (3) control infants (n = 22; nonexposed) during baseline, lance, and recovery periods. Measures of maternal mood and drug levels were also obtained, and Bayley Scales of Infant Development-II were administered at ages 2 and 8 months.Results. Facial action increased in all groups immediately after the lance but was significantly lower in the pSE group during the lance period. HR among infants in the pSE and ppSE groups was significantly lower during recovery. Using measures of HRV and the transfer relationship between heart rate and respiration, exposed infants had a greater return of parasympathetic cardiac modulation in the recovery period, whereas a sustained sympathetic response continued in control infants. Although postnatal exposure via breast milk was extremely low when infant drug levels could be detected in ppSE infants, changes in HR and HRV from lance to recovery were greater compared among infants with levels too low to be quantified. Neither maternal mood nor the presence of clonazepam influenced pain responses.Conclusions. Blunted facial-action responses were observed among infants with prenatal SSRI exposure alone, whereas both prenatal and postnatal exposure was associated with reduced parasympathetic withdrawal and increased parasympathetic cardiac modulation during recovery after an acute noxious event. These findings are consistent with patterns of pain reactivity observed in the newborn period in the same cohort. Given that postnatal exposure via breast milk was extremely low and altered biobehavioral pain reactivity was not associated with levels of maternal reports of depression, these data suggest possible sustained neurobehavioral outcomes beyond the newborn period. This is the first study of pain reactivity in infants with prenatal and postnatal SSRI exposure, and our findings were limited by the lack of a depressed nonmedicated control group, small sample size, and understanding of infant behaviors associated with pain reactivity that could have also have been influenced by prenatal SSRI exposure. The developmental and clinical implications of our findings remain unclear, and the mechanisms that may have altered 5-hydroxytryptamine-mediated pain modulation in infants after SSRI exposure remain to be studied. Treating maternal depression with antidepressants during and after pregnancy and promoting breastfeeding in this setting should remain a key goal for all clinicians. Additional study is needed to understand the long-term effects of prenatal and early postnatal SSRI exposure.

Depression during pregnancy is frequently treated with the selective serotonin reuptake inhibitor, fluoxetine (FX). FX increases serotonergic neurotransmission and serotonin plays a role in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis. We have therefore investigated the effect of chronic administration of FX to the pregnant ewe on the maternal and fetal HPA axes. Nineteen late-gestation sheep were surgically prepared for chronic study of the fetus. FX (n = 7, 98.5 microg/kg/d) or sterile water (control, n = 8) was administered to the ewe for 8 d by constant rate i.v. infusion with an initial FX bolus dose of 70 mg. Maternal and fetal plasma ACTH and cortisol concentrations were determined at 0700 h each day. Maternal plasma ACTH concentrations fell on infusion d 2, but no changes were observed in maternal plasma cortisol concentrations. Fetal plasma ACTH concentrations increased on infusion d 7, and fetal plasma cortisol concentrations increased on infusion d 6, 7, and 8 in the FX group. In addition, the regression coefficient for the relationship between fetal ACTH and cortisol levels was significantly greater in the FX group compared with the control group. Thus, maternal FX treatment increased fetal plasma cortisol concentration. These results are of particular interest in the context that exposure of the fetus to excess glucocorticoids at critical windows during development has been shown to increase the risk of poor health outcomes in later life.

Background: Selective serotonin reuptake inhibitor antidepressants (SSRIs) and benzodiazepines are frequently used to treat maternal depression and anxiety disorders during pregnancy. Recent reports suggest that prenatal SSRI exposure is associated with a neonatal discontinuation syndrome. It remains unclear whether these symptoms are directly related to SSRI exposure alone or are due to concurrent pharmacologic factors. Also, this study explores relationships between neonatal outcomes and medication levels during pregnancy, at delivery, and in the newborn period. Method: This study sought to compare newborn behavior following second and third trimester exposure to either single-agent SSRIs (group 1) or SSRIs combined with clonazepam (group 2). A prospective cohort of mothers and their infants (N = 46) who had received SSRI medication alone or in combination with clonazepam were studied from June 1996 through June 2000 and compared with a nonexposed control group (N = 23). Infants were assessed in the newborn period for signs suggestive of a discontinuation syndrome. Maternal drug levels were measured during the pregnancy and at delivery. Infant drug levels from cord blood and at day 2 of life were also obtained. Results: Overall, 30% of the exposed infants (groups 1 and 2, N = 14) showed symptoms of transient poor neonatal adaptation compared with 9% (N = 2) of control infants. In group 1, 25% had symptoms (fluoxetine N = 3; paroxetine N = 3; sertraline N = 1) and in group 2. 39% of infants had symptoms (paroxetine with clonazepam, N = 7). Symptoms were typically mild respiratory distress and, less commonly, hypotonia. Symptoms were self limited and not associated with other neonatal conditions. When paroxetine was combined with clonazepam, infants with symptoms had significantly elevated paroxetine levels when compared with similarly exposed infants without symptoms (p

We examined the stereoselective disposition of fluoxetine (FX) and its metabolite norfluoxetine (NFX) in five pregnant sheep. Racemic FX was administered i.v. to the ewe (50 mg) and the fetus (10 mg) on separate occasions. Maternal and fetal blood, maternal urine, and fetal amniotic and tracheal fluid samples were collected for 72 h. FX and NFX isomers were quantified by gas chromatography-mass spectrometry. They rapidly crossed the placenta [maternal to fetal area under the plasma concentration versus time curve (AUC) ratios 0.59 and 0.65, respectively]. There was significant FX stereoselectivity with S/R FX AUC ratios averaging 1.65 +/- 0.33 and 1.73 +/- 0.29 in ewe and fetus, respectively, after maternal dosing. The maternal clearance and volume of distribution were also higher for (R)-fluoxetine than for (S)-fluoxetine. FX, NFX, and their glucuronides were present in maternal urine but accounted for only 3.4% of maternal drug elimination. In contrast, NFX was not detected in the fetus after fetal FX administration, which is consistent with the absence of measurable fetal nonplacental clearance of the drug and the lack of NFX formation in fetal hepatic microsomal incubations. There was also no fetal production of FX and NFX glucuronides in vivo. Both FX and NFX were extensively and stereoselectively bound in maternal and fetal plasma, with the free fraction S/R FX ratio averaging 0.46 +/- 0.06 and 0.58 +/- 0.10 in ewe and fetus, respectively. Thus, FX exhibits extensive stereoselective disposition, which is likely due to differential plasma protein binding of the FX isomers, and there is no detectable fetal formation of NFX, FX, and NFX glucuronides.

Indometacin is used in pregnancy for the treatment of premature labour, but there are limited data on the disposition of the drug in the fetus. In order to elucidate fetal indometacin pharmacokinetics at plasma levels and duration comparable with those occurring with use of the drug for tocolysis in humans, indometacin was administered at doses of 1.9 (low dose, LD; n = 5) or 7.5 (high dose, HD; n = 9) μg min−1 to steady state over a 3-day period in chronically instrumented fetal lambs. Indometacin concentrations in biological fluid samples were analysed by a sensitive capillary gas chromatography-electron capture detection method. The mean steady-state fetal arterial plasma indometacin concentrations were 68.6 ± 16.5 ng mL−1 in the LD infusion and 230.3 ± 28.8 ng mL−1 in the HD infusion. Indometacin concentrations in amniotic fluid were ∼10% of those in fetal plasma, and below assay detection limits in tracheal fluid. Total body clearance (TBC) in the LD and HD infusions were not different and the overall mean was 11.3 ± 1.2 mL min−1 kg−1. In the 11 experiments where paired fetal arterial and umbilical venous samples were collected, the extraction of indometacin across the placenta averaged only 5.2 ± 1.1%, indicating low placental permeability to the drug in sheep. However, fetal placental clearance (CLpl) of indometacin (10.0 ± 2.5 mL min−1 kg−1, n = 10) averaged 115.1± 41.2% of TBC in these animals and the calculated value for fetal non-placental clearance (0.6 ± 2.8 mL min−1 kg−1) was not significantly different from zero. Fetal renal clearance of intact indometacin (3.8 ± 1.1 μL min−1 kg−1; n = 12) was also very low. However, treatment of fetal urine with glucuronidase indicated the presence of glucuronide conjugates and these comprised 69.9 ± 8.2% of the total drug concentration (i.e. intact + conjugated) in urine. Thus, the fetal lamb appears to be able to glucuronidate indometacin, but the contribution of this and other non-placental routes to overall fetal elimination of the drug appear minimal. CLpl of the drug is also low owing to the physicochemical properties of indometacin (high polarity) and the permeability characteristics of the sheep placenta.

Selective serotonin reuptake inhibitors (SSRIs) and benzodiazepines are frequently used to treat maternal depression during pregnancy, however the effect of increased serotonin (5HT) and gamma-amino-butyric acid (GABA) agonists in the fetal human brain remains unknown. 5HT and GABA are active during fetal neurologic growth and play early roles in pain modulation, therefore, if prolonged prenatal exposure alters neurodevelopment this may become evident in altered neonatal pain responses. To examine biologic and behavioral effects of prenatal exposure, neonatal responses to acute pain (phenylketonuria heel lance) in infants with prolonged prenatal exposure were examined. Facial action (Neonatal Facial Coding System) and cardiac autonomic reactivity derived from the relationship between respiratory activity and short term variations of heart rate (HRV) were compared between 22 infants with SSRI exposure (SE) [fluoxetine (n = 7), paroxetine (n = 11), sertraline (n = 4)]; 16 infants exposed to SSRIs and clonazepam (SE+) [paroxetine (n = 14), fluoxetine (n = 2)]; and 23 nonexposed infants during baseline, lance, and recovery periods of a heel lance. Length of maternal SSRI use did not vary significantly between exposure groups-[mean (range)] SE:SE+ 183 (31-281):141 (54-282) d (p > 0.05). Infants exposed to SE and SE+ displayed significantly less facial activity to heel lance than control infants. Mean HR increased with lance, but was significantly lower in SE infants during recovery. Using measures of HRV and the transfer relationship between heart rate and respiration, SSRI infants had a greater return of parasympathetic cardiac modulation in the recovery period, whereas a sustained sympathetic response continued in the control group. Prolonged prenatal SSRI exposure appears to be associated with reduced behavioral pain responses and increased parasympathetic cardiac modulation in recovery following an acute neonatal noxious event. Possible 5HT-mediated pain inhibition, pharmacologic factors and the developmental course remain to be studied.

Prenatal serotonin reuptake inhibitor (SRI) exposure is common and neonatal outcomes vary greatly, often leading to confusion about whether to use or even continue antenatal use of these antidepressants. Importantly, some but not all infants are affected, which raises questions about how maternal drug metabolism contributes to fetal drug exposure. To address this question, this chapter reviews the role of key maternal, fetal, and placental pharmacokinetic, metabolic, and genetic factors that affect the extent of fetal drug exposure. Considering the role of these factors may further our understanding of variables that might assist in optimizing maternal psychopharmacotherapy during pregnancy and neonatal outcomes.

Term and preterm labor are associated with increased fetal hypothalamic-pituitary-adrenal (HPA) activation and synthesis of prostaglandins (PGs) generated through the increased expression of prostaglandin H synthase-II (PGHS-II) in the placenta. Inhibition of PGHS-II has been advocated as a means of producing uterine tocolysis, but the effects of such treatment on fetal endocrine functions have not been thoroughly examined. Because PGE 2 is known to activate the fetal HPA axis, we hypothesized that administration of meloxicam, a PGHS-II inhibitor, to sheep in induced labor would suppress fetal HPA function. Chronically catheterized pregnant ewes were treated with RU486, a progesterone receptor antagonist, to produce active labor, and then treated with either high-maintenance-dose meloxicam, graded-maintenance-dose meloxicam, or a saline infusion. Maternal uterine contraction frequency increased 24 h after the RU486 injection and the animals were in active labor by 48 6 4 h. RU486 injection led to increased concentrations of PGE 2, ACTH, and cortisol in the fetal circulation, and increased concentrations of 13,14 dihydro 15-ketoprostaglandin F2a (PGFM) in the maternal circulation. Uterine activity was inhibited within 12 h of beginning meloxicam infusion at both infusion regimes. During meloxicam infusion there were significant decreases in fetal plasma PGE 2, ACTH, and cortisol concentrations, and PGFM concentrations in maternal plasma. In control animals, frequency of uterine contractions, maternal plasma PGFM, fetal plasma PGE 2, ACTH, and cortisol concentrations increased after RU486 administration, and continued to rise during saline infusion until delivery occurred. We conclude that RU486-provoked labor in sheep is associated with activation of fetal HPA function, and that this is attenuated during meloxicam treatment to a level considered compatible with pregnancy maintenance. ACTH, cortisol, parturition

The developmental disposition of diphenhydramine (DPHM) and its metabolites, diphenylmethoxyacetic acid (DPMA) and DPHM-N-oxide (DPHMNO), was investigated in postnatal lambs. Lambs received a DPHM intravenous (iv) bolus 15 days (Group A; n = 5) or 2 months (Group B; n = 6) after birth. Total body clearance of DPHM in postnatal lambs (Group A = 138.7 +/- 80.5 mL/min/kg; Group B = 165.7 +/- 51.3 mL/min/kg) was similar to the nonplacental clearance values (i.e., the component of fetal total body clearance that is not due to elimination via the placenta) estimated for fetal lamb (116.3 +/- 49. 6 mL/min/kg), and significantly greater than estimates in adult sheep (38.5 +/- 12.3 mL/min/kg). In addition, Group A DPHM renal clearance (CL(r), >1.80 +/- 1.24 mL/min/kg) was similar to that of the fetus (2.06 +/- 0.24 mL/min/kg), and significantly greater than that for Group B (0.26 +/- 0.17 mL/min/kg) and the adult (0.012 +/- 0.005 mL/min/kg). In contrast, similar to the fetal situation, postnatal DPMA CL(r) (Group A = 0.02 +/- 0.02 mL/min/kg; Group B = 0.05 +/- 0.01 mL/min/kg) was significantly less than adult values (0. 53 +/- 0.19 mL/min/kg). Because DPMA is not sequentially metabolized in sheep, the lower CL(r) in postnatal lambs results in longer apparent elimination half-lives of this metabolite (Group A = 90.4 +/- 32.2 h; Group B = 13.13 +/- 11.0 h) compared with that in the adult (2.9 +/- 1.6 h). No age-related difference in DPHMNO CL(R) was observed. Alterations in the CL(r) of DPHM and DPMA are likely related to differences in the rate of development of mechanisms (i.e. , tubular secretion and reabsorption and glomerular filtration rate) involved in the urinary drug excretion of organic acids and bases.

The objective of this study was to identify the important factors that determine plasma concentrations of diphenhydramine (DPHM) in the mother and the fetus after maternal as well as fetal steady-state drug administration. Inter-relationships were evaluated between maternal and fetal placental and nonplacental clearances, plasma protein binding, and steady-state plasma concentrations of DPHM among data obtained from 18 pregnant sheep during late gestation. The major determinant of plasma DPHM concentrations in the mother after maternal as well as fetal administration appears to be maternal plasma protein binding and maternal nonplacental clearance. In contrast, the major determinant of fetal plasma DPHM concentrations after maternal drug administration was the extent of fetal first-pass hepatic drug uptake from the umbilical vein. However, after fetal drug administration, the fetal plasma concentrations were related to the extent of fetal plasma protein binding and fetal placental and nonplacental clearances. The index of fetal-to-maternal placental drug transfer after fetal drug administration (steady-state maternal-to-fetal plasma concentration ratio) was related to steady-state fetal plasma unbound fraction and fetal placental and nonplacental clearance. However, this index was not related to the magnitude of the factors operating on the maternal side of the placenta such as maternal plasma protein binding and maternal nonplacental clearance. This might indicate a lack of complete equilibration of the unbound drug concentrations on the two sides of the placenta at the exchange site.

Our studies on drug disposition in chronically instrumented pregnant sheep involve simultaneous administration of the antihistamine diphenhydramine (DPHM), its deuterated analogue ([2H10]DPHM) and their metabolites to the mother or the fetus via various routes. Such studies require sensitive and selective mass spectrometric methods for quantitation of these labeled and unlabeled compounds in order to assess comparative maternal and fetal drug metabolism. The objective of this study was to develop and validate a liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method for the simultaneous quantitation of DPHM, its N-oxide metabolite and their deuterium-labeled analogues in ovine plasma and urine. Samples spiked with the analytes and the internal standard, orphenadrine, were processed using liquid-liquid extraction. The extract was chromatographed on a propylamino LC column and MS/MS detection was performed in the positive ion electrospray mode using multiple reaction monitoring. The linear concentration ranges of the calibration curves for the N-oxides and the parent amines were 0.4-100.0 and 0.2-250.0 ng ml-1, respectively. In validation tests, the assay exhibited acceptable variability (< or = 15% at analyte concentrations below 2.0 ng ml-1 and < 10% at all other concentrations) and bias (< 15% at all concentrations), and the analytes were stable under a variety of sample handling conditions. Using this method, the labeled and unlabeled N-oxide metabolite was identified in fetal plasma after DPHM and [2H10]DPHM administration. This method will be used further to examine the comparative metabolism of diphenhydramine to its N-oxide metabolite in the mother and the fetus.

An ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS) method was developed and validated for the quantification of serotonin (5-HT) in lamb plasma using [(2)d(4)]-serotonin ([(2)d(4)]-5-HT) as an internal standard. Charcoal-stripped human plasma was used as the blank matrix during validation, and 5-HT was quantitated using selected reaction monitoring. The UHPLC/MS/MS system consisted of an Agilent 1290 Infinity ultrahigh-performance liquid chromatograph coupled with an AB SCIEX QTRAP(®) 5500 hybrid linear ion trap triple quadrupole mass spectrometer. The method was validated for accuracy, precision, linearity, lower limit of quantification (LLOQ), selectivity, and other parameters. The LLOQ was 1.0 ng/mL, requiring 100 μL of sample. The method was applied to monitor the 5-HT levels in lamb plasma after the administration of fluoxetine. Tandem mass spectrometry cubed (MS(3)) experiments were also performed to investigate the fragmentation pattern of 5-HT and [(2)d(4)]-5-HT. A liquid chromatography-MS(3) (LC/MS(3)) method was developed, and the UHPLC/MS/MS and the LC/MS(3) methods were compared for performance.

The metabolic and behavioral effects of 40-45% hemorrhage (at approximately 1%/min) were studied in nine fetal lambs in utero (130-135 days of gestation) until 2 days posthemorrhage. Umbilical blood flow (Qum) fell from 192 +/- 14 to 100 +/- 9 ml.min-1.kg-1 at the end of blood loss, and on the day of hemorrhage it was linearly related to blood volume. However, on the posthemorrhage days, Qum was restored even though blood volume was still reduced. Fetal O2 delivery (DO2) fell with the decrease in Qum and later due to anemia (decrease in hematocrit from 33.4 +/- 1.2 to 23.6 +/- 1.2%), from 946 +/- 81 to 494 +/- 47 mumol.min-1.kg-1, but the decrease was lessened because of a rise in umbilical venous PO2 (31.7 +/- 2.6 to 45.9 +/- 2.8 mmHg). Fetal O2 consumption was reduced during and for 2 h after hemorrhage (262 +/- 17 to 190 +/- 16 mumol.min-1.kg-1), and this was associated with modest lactic acidemia (1.25 +/- 0.11 to 2.91 +/- 0.43 mM). There was also a temporary reduction in fetal breathing activity, low voltage electrocortical state, and rapid eye movements, but this was not associated with hypoxemia. It is concluded that reductions in fetal DO2 achieved via fetal blood loss are better tolerated than during hypoxemia and that the associated depression in fetal biophysical activities involves mechanisms other than systemic hypoxia.

The effects of 15-50% fetal hemorrhage (at approximately 1%/min) were studied in 13 pregnant ewes at 130-135 days of gestation for up to 5 days posthemorrhage. The upper limit of acute blood loss appears to be approximately 45%, and the rate of restoration of blood volume decreases with the severity of hemorrhage, particularly with hemorrhage > 30-40%. The restoration of fetal blood volume was due primarily to the restoration of plasma volume; in the animals subject to 40-45% blood loss (n = 9), red cell mass was still only 69.1 +/- 3.9% of the prehemorrhage value at day 5 posthemorrhage. There appear to be two phases in the restoration of plasma: 1) plasma volume was restored by 2 h posthemorrhage and 2) the restoration of plasma protein mass occurred primarily from 2 to 24 h. There was a significant correlation between blood volume and plasma protein mass. However, the regression line for the posthemorrhage days was shifted significantly upward in relation to that for the hemorrhage day because of a significant rise of plasma protein concentration. This may be important for the maintenance of blood volume after hemorrhage. Finally, fetal growth rate was determined by comparing fetal weight estimated in utero (from blood volume) with birth weight in 12 nonhemorrhaged control fetuses and in the 9 fetuses subject to 40-45% hemorrhage. The average rate of growth per day was 1.57 +/- 0.34% and -1.82 +/- 1.02%, respectively. The latter value is not significantly different from zero, suggesting that the acute blood loss impaired fetal growth.

An improved method for the quantitative determination of valproic acid (VPA) and sixteen of its metabolites has been developed using gas chromatography-mass spectrometry with selected-ion monitoring. The method is applicable to serum or urine and all metabolites are measured in a single chromatographic run of 29.5 min. Ions selected for quantitative purposes were the characteristic [M-57]+ ions of the tert.-butyldimethylsilyl (tBDMS) derivatives. The method utilizes heptadeuterated VPA as well as six heptadeuterated metabolites as internal standards [i.e. 2-[2H7]propyl-2-pentenoic acid (2-ene[2H7]VPA), 2-[2H7]propyl-4-pentenoic acid (4-ene[2H7]VPA), 2-[2H7]propyl-3-oxopentanoic acid (3-keto[2H7]VPA), 2-[2H7]propyl-4-oxopentanoic acid (4-keto[2H7]VPA), 2-[2H7]propyl-3-hydroxypentanoic acid (3-OH[2H7]VPA), 2-[2H7]propyl-5-hydroxypentanoic acid (5-OH[2H7]VPA)]. The method demonstrates very good accuracy and precision over a large range of concentrations for VPA and all metabolites measured in both human and sheep biological fluids. The assay was applied to the analysis of VPA and metabolites in serum and urine samples collected from three non-pregnant ewes following intravenous bolus administration of a mixture of VPA and [13C4]VPA. Sheep were observed to produce measurable quantities of the majority of metabolites found in humans, with the notable exception of the di-unsaturated compounds (i.e. 2,3'-diene VPA and 2,4-diene VPA). The pharmacokinetics and metabolism of VPA and [13C4]VPA appear to be equivalent in the sheep model. The elimination half-life of VPA and [13C4]VPA in the ewe were estimated to be approximately 3.5 +/- 0.4 and 3.2 +/- 0.4 h, respectively.

Background There have been contradictory reports on the risks of persistent pulmonary hypertension (PPHN) in infants exposed to SSRIs in utero. However, there has been no assessment of fetal pulmonary arterial dynamics in such pregnancies. Aims and subjects To measure fetal right pulmonary artery (RPA) variables using Doppler ultrasound at 36 weeks gestation in fetuses of mothers taking SSRI antidepressants (n = 23) and in a control, normal pregnancy group (n = 35). Outcome measures At 36 weeks gestation, Doppler ultrasound estimates of Pulsatility Index (PI), Resistance Index (RI), vessel diameter, peak systolic velocity, mean velocity and volume flow were obtained from the fetal right pulmonary artery in a morning session (~ 0830), before the SSRI mothers took their daily drug dose and in an afternoon session (~ 1300). Venous blood was drawn at 5 time points across the day (~ 08:30 AM, ~ 10:30 AM, ~ 13:00 PM, ~ 13:45 PM, and ~ 15:00 PM) from the SSRI treated mothers for measurement of plasma SSRI concentration using high performance liquid chromatography tandem mass spectrometry. Results There were no differences in the RPA Doppler measures between the control and SSRI-exposed fetuses. However 8 of the 23 latter fetuses experience transient respiratory difficulties at birth and, in these RPA flow was significantly higher than in the SSR-exposed fetuses without respiratory problems. There were, however, no differences in RPA PI and RI between the 2 groups. Conclusions In SSRI-exposed infants with transient postnatal respiratory difficulties, fetal RPA flow in increased, likely due to partial constriction of the ductus arteriosus. However, this was not associated with PPHN.

Prenatal selective serotonin reuptake inhibitor (SSRI) exposure increases the risk for adverse neonatal behavioral outcomes; although it is unknown whether altered brain function is present before birth. We investigated fetal vascular and heart rate changes at 36-wk gestation in SSRI-treated women with mood disorders (n = 29) [exposed (EXP)] and controls (n = 45) [non-EXP (NEXP)]. Fetal middle cerebral artery (MCA) flow parameters and heart rate characteristics were obtained during pre-SSRI dose morning and postdose afternoon sessions. Maternal mood and cord Hb and hematocrit were measured. Basal fetal heart rate (fHR) did not differ between groups or across the day. The fHR short- and long-term variations, accelerations, and duration of high variability episodes remained lower and did not change across the day in EXP, whereas all increased significantly in NEXP. In both groups, MCA flow velocity and volume flow increased significantly across the day. EXP MCA pulsatility index was significantly lower, as was MCA cross-sectional area. EXP cord Hb and hematocrit were significantly increased. Prenatal SSRI exposure reduced fetal MCA flow resistance and fHR variability, before and after an SSRI dose, controlling for maternal mood. These changes and the SSRI-related increased red cell indices suggest possible fetal hypoxia.

UDP glucuronosyltransferases (UGTs) are important for the metabolism of many drugs. To understand the ontogeny of these enzymes in sheep ( Ovis aries ), knowledge of their expression levels at different developmental stages is important. cDNA sequences of six UGTs (UGT1A1, UGT1A3, UGT1A4, UGT1A6 and UGT1A9) were cloned in sheep liver by rapid amplification of cDNA ends. The mRNA and protein levels of the enzymes in sheep liver (adult n = 4; newborn n = 3; fetus n = 3) were determined using PCR and Western blots. mRNA levels in adult were very high followed by newborn and then fetus. However, no protein bands were detected on the Western blots of sheep hepatic microsomal proteins using several different antibodies against human UGTs. The effect of antenatal glucocorticoid administration was also studied by infusion of cortisol (0.45 mg/h; 80 h) to another group of fetuses (n = 5). This did not result in any significant changes in fetal mRNA levels. However, the correlation observed between the UGT enzymes and hepatocyte nuclear factor 4α (HNF4α) suggests a possible regulatory role for this transcription factor in sheep. We postulate that fetal and newborn lambs may have a reduced ability to metabolize drugs that are substrates of these enzymes.

The objective was to compare gestation length in chronically instrumented (laboratory) pregnant sheep (n = 131) and in the breeding flock (n = 476) that provided the experimental sheep. In the breeding flock, gestation length was normally distributed and varied between 141 and 151 days (mean = 147 ± 0.1 days). In the laboratory sheep, gestation length varied between 128 and 151 days (mean = 142 ± 1 day), and was bimodal, with 35.9% delivering preterm (

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)

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 central nervous system (CNS) pharmacokinetics of the H(1) receptor antagonist diphenhydramine (DPHM) were studied in 100- and 120-day-old fetuses, 10- and 30-day-old newborn lambs, and adult sheep using in vivo microdialysis. DPHM was administered i.v. at five infusion rates, with each step lasting 7 h. In all ages, cerebrospinal fluid (CSF) and extracellular fluid (ECF) concentrations were very similar to each other, which suggests that DPHM between these two compartments is transferred by passive diffusion. In addition, the brain-to-plasma concentration ratios were >or=3 in all age groups, suggesting the existence of a transport process for DPHM into the brain. Both brain and plasma DPHM concentrations increased in a linear fashion over the dose range studied. However, the ECF/unbound plasma and CSF/unbound plasma DPHM concentration ratios were significantly higher in the fetus and lambs (approximately 5 to 6) than in the adult (approximately 3). The factors f(CSF) and f(ECF), the ratios of DPHM areas under the curves (AUCs) in CSF and ECF to the plasma DPHM AUC, respectively, decreased with age, indicating that DPHM is more efficiently removed from the brain with increasing age. The extent of plasma protein binding of the drug increased with age. This study provides evidence for a transporter-mediated mechanism for the influx of DPHM into the brain and also for an efflux transporter for the drug, whose activity increases with age. Moreover, the higher brain DPHM levels in the fetus and lamb compared with the adult may explain the greater CNS effects of the drug at these ages.

Objective Preterm birth occurs in 5% to 10% of all pregnancies and is associated with considerable neonatal mortality and morbidity. Effective and safe drugs to prevent preterm labor are not currently available. We have hypothesized that the nonsteroidal anti-inflammatory drug meloxicam, a more selective cyclooxygenase-2 inhibitor will successfully inhibit labor but avoid the complications associated with inhibition of cyclooxygenase-1. Study design Preterm labor was induced in chronically catheterized sheep by RU486 administration. Animals were then randomized to receive maternal infusions of saline (n = 5) or meloxicam (n = 4) for 48 hours or until delivery when the animals were killed and tissues and blood samples collected. Results Maternal infusion of meloxicam inhibited uterine contractions, increasing contraction duration, and attenuating frequency and amplitude. Saline-treated animals progressed to delivery. Administration of meloxicam was not associated with any change in fetal or maternal blood gas status, osmolality, arterial pressure, heart rate, or fetal blood flows. Conclusion Meloxicam may represent a potentially safe and effective tocolytic agent.

Women are at greatest risk of suffering from depression during the childbearing years and thus may either become pregnant while taking an antidepressant or may require a prescription for one during pregnancy. The antidepressant fluoxetine (FX) is a selective serotonin reuptake inhibitor (SSRI), which increases serotonin neurotransmission. Serotonin is involved in the regulation of a variety of physiological systems, including the sleep–wake cycle, circadian rhythms and the hypothalamic–pituitary–adrenal axis. Each of these systems also plays an important role in fetal development. Compared with other antidepressant drugs, the SSRIs, such as FX, have fewer side effects. Because of this, they are now frequently prescribed, especially during pregnancy. Clinical studies suggest poor neonatal outcome after exposure to FX in utero. Recent studies in the sheep fetus describe the physiological effects of in utero exposure to FX with an 8 day infusion during late gestation in the sheep. This is a useful model for determining the effects of FX on fetal physiology. The fetus can be studied for weeks in its normal intrauterine environment with serial sampling of blood, thus permitting detailed studies of drug disposition in both mother and fetus combined with monitoring of fetal behavioural state and cardiovascular function. Fluoxetine causes an acute increase in plasma serotonin levels, leading to a transient reduction in uterine blood flow. This, in turn, reduces the delivery of oxygen and nutrients to the fetus, thereby presenting a mechanism for reducing growth and/or eliciting preterm delivery. Moreover, because FX crosses the placenta, the fetus is exposed directly to FX, as well as to the effects of the drug on the mother. Fluoxetine increases high-voltage/non-rapid eye movement behavioural state in the fetus after both acute and chronic exposure and, thus, may interfere with normal fetal neurodevelopment. Fluoxetine also alters hypothalamic function in the adult and increases the magnitude of the prepartum rise in fetal cortisol concentrations in sheep. Fetal FX exposure does not alter fetal circadian rhythms in melatonin or prolactin. Studies of the effects of FX exposure on fetal development in the sheep are important in defining possible physiological mechanisms that explain human clinical studies of birth outcomes after FX exposure. To date, there have been insufficient longer-term follow-up studies in any precocial species of offspring exposed to SSRIs in utero. Thus, further investigation of the long-term consequences of in utero exposure to FX and other SSRIs, as well as the mechanisms involved, are required for a complete understanding of the impact of these agents on development. This should involve studies in both humans and appropriate animal models.

To examine fetal (FHR) and neonatal heart rate patterns following use of common oral antihypertensives in pregnancy.A systematic review of randomized controlled trials (RCTs), observational studies (N/= 6 women), and animal studies. Data were abstracted (two reviewers) to determine relative risk (RR) (or risk difference (RD) for low event rates) and 95% CI.Eighteen RCTs (1858 women), one controlled observational study (N = 22), and seven case series (N = 117) were reviewed. Most hypertension was pregnancy-induced (N = 14 studies). The FHR was assessed by cardiotocogram (CTG) (N = 17 studies (visual interpretation); 1 study (computerized CTG), or umbilical artery velocimetry (N = 4). Four studies examined neonatal heart rate. In placebo-controlled RCTs (N = 192 women), adverse FHR effects did not differ between groups [9/101 (drugs) vs. 7/91 (placebo); RD 0.02, 95% CI (- 0.06, 0.11); chi2 = 1.02]. In six drug vs. drug RCTs (295 women), adverse FHR effects did not differ between groups [29/144 (methyldopa) vs. 42/151 (other drugs); RR 0.72, 95% CI (0.49, 1.07); chi2 = 0.69]. In one labetalol vs. placebo trial, neonatal bradycardia did not differ between groups [4/70 (labetalol) vs. 4/74 (placebo); OR 1.06, 95% CI (0.26, 4.39)], while in three drug vs. drug RCTs, neonatal bradycardia was not observed (0/24 vs. 0/26).Available data are inadequate to conclude whether oral methyldopa, labetalol, nifedipine, or hydralazine adversely affect fetal or neonatal heart rate and pattern. Until definitive data are available, FHR changes cannot be reliably attributed to drug effect, but may be due to progression of the underlying maternal or placental disease.

Hypoxemia is known to induce various physiological changes which can result in alteration in drug pharmacokinetics. To examine the effect of acute moderate hypoxemia on metoclopramide (MCP) pharmacokinetics, a continuous 14-hour infusion of MCP during a normoxemic, hypoxemic and subsequent normoxemic period was conducted in eight adult sheep. Arterial blood and urine samples were collected to examine the effects on the pharmacokinetics of MCP and its deethylated metabolites. MCP and its mono- and di-deethylated metabolites were quantitated using a GC/MS method. Steady-state concentrations of MCP were achieved in each of the three periods. During hypoxemia, MCP plasma steady-state concentration increased significantly from 50.72 +/- 1.06 to 63.62 +/- 1.79 ng/mL, and later decreased to 55.83 +/- 1.15 ng/mL during the post-hypoxemic recovery period. Total body clearance (CL(TB)) of MCP was significantly decreased from 274.2 +/- 48.0 L/h to 205.40 +/- 28.2 L/h during hypoxemia, and later restored to 245.8 +/- 44.2 L/h during the post-hypoxemic period. Plasma mono-deethylated MCP concentration (32.78 +/- 1.73 ng/mL) also increased, compared to the control group (21.20 +/- 1.39 ng/mL), during hypoxemia and subsequent normoxemic period. Renal excretion of MCP and its metabolites was also decreased during hypoxemia, while urine flow was increased with a concomitant decrease in urine osmolality. Thus, the results indicate that acute moderate hypoxemia affects MCP pharmacokinetics.

Clinical depression, diagnosed in 5–15% of women during pregnancy, increases the risk of negative pregnancy outcomes including an increased incidence of low birth weight newborns and preterm delivery. Fluoxetine, a selective serotonin reuptake inhibitor, is often prescribed to treat depression due to its efficacy, high margin of safety, and mild side effects. However, fluoxetine initially increases plasma serotonin concentration, and serotonin causes uterine vasoconstriction in sheep, which could result in fetal hypoxemia. To assess fetal fluoxetine effects, late-gestation pregnant sheep were surgically prepared for the measurement of blood gases, heart rate, blood pressure, and uterine artery blood flow (n = 29). Ewes received a 70-mg bolus i.v. infusion of fluoxetine over 2 min in 10 mL of sterile water followed by continuous infusion at a rate of 100 μg/min for 8 d (n = 14), or continuous infusion of sterile water (n = 15). Transient decreases in uterine artery blood flow, fetal Po2, and oxygen saturation were observed within the first 15 min after fluoxetine exposure, which did not return to normal values by 24 h. Fetal pH decreased and Pco2 increased over the first 4 h with a return to normal by 24 h. However, there were no differences in uterine artery blood flow, blood gas status, or cardiovascular measures between the control and fluoxetine group over the rest of the 8-d infusion period. Thus, fluoxetine exposure during pregnancy has transient effects on fetal status that may be of developmental consequence if they occur repetitively.

Clinical depression is diagnosed in 5-15% of women during pregnancy, increasing the risk of negative outcomes. Fluoxetine (FX), a selective serotonin reuptake inhibitor, is prescribed during pregnancy. In adults, FX alters sleep patterns with single doses decreasing total sleep time and rapid eye movement sleep. The effects of FX on sleep in the fetus are unknown. However, 5-hydroxytryptophan, the precursor of serotonin, has been reported to prolong high-voltage (HV) electrocortical (ECoG) activity and increase the incidence of fetal breathing movements (FBM) in the sheep fetus. We hypothesize that FX exposure will decrease the incidence of LV ECoG in the fetus. Twenty-one pregnant sheep were surgically prepared for chronic study of blood gases, ECoG activity, eye movements and FBM. After 3 days of recovery, ewes received a 70-mg bolus i.v. infusion of FX or sterile water followed by continuous infusion at a rate of 0.036 mg/min for 8 days. The incidence of low-voltage (LV) ECoG decreased from 54+/-4% on the preinfusion day to 45+/-5% on infusion day 1 in the FX group and remained decreased throughout the infusion period. In addition, the incidence of both eye movements and FBM was decreased on infusion day 1 compared to preinfusion day in the FX group. HV ECoG increased from 39+/-3% on preinfusion day to 68+/-14% on FX infusion day 1 and remained elevated throughout the infusion period. These data show that maternal FX administration alters fetal behavioural state.

Diphenylmethoxyacetic acid (DPMA) is a major metabolite of diphenhydramine in monkeys, dogs, and humans. The metabolic fate of diphenhydramine (DPHM) in sheep is not yet well understood; however, preliminary studies have demonstrated the presence of DPMA in the plasma and urine of sheep following an intravenous bolus of DPHM. Our current studies employ the simultaneous intravenous co-administration of DPHM and the stable isotope analog of DPHM to investigate the pharmacokinetics of DPHM in sheep. In these studies, in order to investigate the pharmacokinetics of the DPMA metabolite, measurement of both unlabeled and stable-isotope labeled DPMA is required. Thus, a stable isotope analog of DPMA ([2H10]DPMA) was synthesized, characterized, and purified for use as an analytical standard. The quantitative method for the gas chromatography-electron-impact mass spectrometry (GC-EI-MS) analysis of DPMA and [2H10]DPMA used a single step liquid-liquid extraction procedure using toluene for sample cleanup. The samples were derivatized with N-methyl-N-(tert.-butyldimethylsilyl) trifluoroacetamide. A 1.0-microliter aliquot of the prepared sample was injected into the GC-MS system and quantitated using selected-ion monitoring (SIM). One ion was monitored for each compound, namely, m/z 165 for the internal standard diphenylacetic acid, m/z 183 for DPMA, and m/z 177 for [2H10]DPMA. The ion chromatograms were free from chromatographic peaks co-eluting with the compound of interest. The calibration curve was linear from 2.5 ng/ml (limit of quantitation) to 250.0 ng/ml in both urine and plasma. The intra-day and inter-day variabilities of this assay method were within acceptable limits (below 20% at the limit of quantitation and below 10% at all other concentrations). This method was used to measure the concentration of DPMA and [2H10]DPMA in plasma and urine samples from a ewe in which equimolar amounts of DPHM and [2H10]DPHM were administered by an intravenous bolus dose via the femoral vein. DPMA appeared to persist longer in the plasma and the urine as compared to DPHM. This method is robust and reliable for the quantitation of DPMA and [2H10]DPMA in biological samples obtained from sheep (e.g. plasma and urine).