Neonatal hypoglycemia after beta-sympathomimetic tocolytic therapy

Drug-induced hyperinsulinemic hypoglycemia: An update on pathophysiology and treatment

The initial step for the differential diagnosis of hypoglycemia is to determine whether it is hyperinsulinemic or non hyperinsulinemic. Existing literature discusses drug-related hypoglycemia, but it misses a focus on drug-induced hyperinsulinemic hypoglycemia (DHH). Here we reviewed the association existing between drugs and hyperinsulinemic hypoglycemia. We primarily selected on the main electronic databases (MEDLINE, EMBASE, Web of Science, and SCOPUS) the reviews on drug-induced hypoglycemia. Among the drugs listed in the reviews, we selected the ones linked to an increase in insulin secretion. For the drugs missing a clear association with insulin secretion, we investigated the putative mechanism underlying hypoglycemia referring to the original papers. Our review provides a list of the most common agents associated with hyperinsulinemic hypoglycemia (HH), in order to facilitate both the recognition and the prevention of DHH. We also collected data about the responsiveness of DHH to diazoxide or octreotide.

Drug-Induced Hypoglycemia in Neonates Born to Nondiabetic Women Treated with Medications during the Pregnancy or the Labor: A Systematic Review of the Literature

The prompt identification of at-risk newborns for drug-induced hypoglycemia can minimize the risk for adverse side effects, inappropriate investigations, and considerable unnecessary costs. Existing literature discusses drug-induced hypoglycemia, but a systematic description of neonatal hypoglycemia induced or exacerbated by maternal medications is missing. We reviewed the association between neonatal hypoglycemia and maternal medications. We systematically searched the literature according to the PICOS model on drug-induced hypoglycemia in neonates born to nondiabetic women treated with medications during the pregnancy or the labor. The main outcomes of the review were: (1) prevalence of hypoglycemia, (2) risk factors and potential confounders, (3) time at onset and severity of hypoglycemia, (4) dose-response gradient, (5) metabolic features of hypoglycemia, (6) modalities to treat hypoglycemia, and (7) quality of the studies. We included 69 studies in this review and we identified 11 groups of maternal drugs related to neonatal hypoglycemia. Results were classified for each outcome. Our review aims at supporting clinicians in the identification of the newborn at risk for hypoglycemia and in the differential diagnosis of neonatal hypoglycemia. Further studies are necessary to assess the risk of neonatal hypoglycemia associated with common maternal medications. KEY POINTS: · A systematic description of neonatal hypoglycemia induced or exacerbated by maternal medications is missing.. · In our review we identified 11 groups of maternal drugs related to neonatal hypoglycemia.. · Our review aims at supporting clinicians in the identification of the newborn at risk for hypoglycemia..

Nursing Intervention and Summary of Evidence Pertaining to Neonatal Recurrent Hypoglycemia Induced by Terbutaline

Background

Neonatal hypoglycemia (NH) is a common clinical symptom that can occur in both normal and critically ill neonates. The placenta is the site of material exchange between the mother and the fetus, a special organ shared by the mother and the fetus during pregnancy, and one of its important functions is to transfer nutrients from the mother to the fetus. Terbutaline is used to relax frequent uterine contractions before delivery, and it can penetrate the placental barrier and affect the normal decomposition of neonatal glycogen. The situation is neonatal hypoglycemia if not timely detection and interventions in time, the neonate may have recurrent hypoglycemia, leading to irreversible nervous system damage, such as neonatal hypoglycemic encephalopathy, and visual and cognitive impairment.

Case Report

The male neonate was a single fetus, with a birth weight of 3660 g and a length of 50 cm. The blood glucose at birth was 5 mmol/L, Apgar score was 9-10, and body temperature was normal. The mother was healthy, was not diabetic, and had no other risk factors for neonatal hypoglycemia. She was injected with 0.25 mg of terbutaline 6 hours before delivery due to frequent uterine contractions. However, it was found that recurrent hypoglycemia occurred in the neonate even after adequate oral feeding.

Conclusion

We included evidence-based use of terbutaline 48 hours before delivery as a high-risk factor for hypoglycemia in the rooming-in neonatal hypoglycemia care program, and formulate the corresponding nursing process, with good effect.

Beta-blocker-associated hypoglycaemia: New insights from a real-world pharmacovigilance study

AIMS

To investigate the statistical association between hypoglycaemia and β-blocker use and to define what patient and drug characteristics could potentially increase the risk for its occurrence.

METHODS

We investigated the relationship between pharmacological parameters of β-blockers and the occurrence of hypoglycaemia by conducting a case/non case analysis using the Food and Drug Administration Adverse Event Reporting System database. Pharmacological properties that could represent a predictive factor for hypoglycaemia were analysed through a multilinear binary logistic regression (null hypothesis rejected for values of P < .05). We also performed a systematic review of clinical studies on this association.

RESULTS

Of 83 954 selected reports, 1465 cases (1.75%) of hypoglycaemia were identified. The association was found statistically significant for nadolol (reporting odds ratio [95% confidence interval]: 6.98 [5.40-9.03]), celiprolol (2.35 [1.35-4.10]), propranolol (2.14 [1.87-2.46]) and bisoprolol (1.42 [1.25-1.61]). Paediatric cases (n = 310) showed a positive association with hypoglycaemia for long half-life drugs (odds ratio [95% confidence interval]: 2.232 [1.398-3.563]) and a negative association for β1-selectivity (0.644 [0.414-0.999]). Seven papers were included in the systematic review. Because of great heterogeneity in study design and demographics, hypoglycaemia incidence rates varied greatly among studies, occurring in 1.73% of the cases for propranolol treatment (n total participants = 575), 6.6% for atenolol (n = 30) and 10% for carvedilol (n = 20).

CONCLUSION

Nadolol appears to be the β-blocker significantly most associated with hypoglycaemia and children represent the most susceptible sample. Furthermore, long half-life and nonselective β-blockers seem to increase the risk for its occurrence.

Incidence and risk factors of neonatal hypoglycemia after ritodrine therapy in premature labor: a retrospective cohort study

Background

Ritodrine hydrochloride (RD), a β2-adrenergic agonist, is widely used as a tocolytic medication to suppress premature labor, but can cause neonatal hypoglycemia, a potentially severe side effect. We examined the incidence and risk factors of neonatal hypoglycemia following maternal intravenous administration of RD.

Methods

This was a retrospective study of neonates, who had birth weight of ≥2000 g and were delivered at 36 weeks gestation or later in Kanazawa University Hospital from August 2013 to July 2016. We defined neonatal hypoglycemia as blood glucose level < 50 mg/dL. Neonates who were delivered without maternal intravenous RD or who were delivered 8 days or more after stopping maternal RD or who received oral RD were defined as the RD non-administration group, while those delivered within 7 days after stopping maternal RD were defined as the RD intravenous administration group. We examined the incidence and risk factors of RD-induced neonatal hypoglycemia by comparing these two groups.

Results

We enrolled 603 neonates in this study; 504 (83.6%) showed no neonatal hypoglycemia, while 99 (16.4%) exhibited neonatal hypoglycemia. The incidence of neonatal hypoglycemia was significantly higher (61.7%; 58/94) in the RD intravenous administration group than in the RD non-administration group (8.1%; 41/509) (p < 0.001). Binomial logistic regression analysis in the RD intravenous administration group showed that maternal age over 35 years (AOR: 3.385; 95% CI, 1.082–10.588, p = 0.036) and the interval to delivery from stopping intravenous administration of RD (AOR: 0.974; 95% CI, 0.953–0.996, p = 0.020) were independent factors associated with neonatal hypoglycemia. The cut-off value of the interval to predict the incidence of neonatal hypoglycemia was about 6 h (sensitivity 82.8%, specificity 63.9%).

Conclusions

The incidence of neonatal hypoglycemia was significantly increased by maternal intravenous administration of RD. We newly identified maternal age (over 35 years) and the interval to delivery from stopping intravenous administration of RD (within 6 h) as independent risk factors for neonatal hypoglycemia following maternal intravenous administration of RD. In cases with these risk factors, careful blood glucose monitoring is recommended for early detection and treatment of neonatal hypoglycemia.

Drug-induced hypoglycaemia: an update

Drugs are the most frequent cause of hypoglycaemia in adults. Although hypoglycaemia is a well known adverse effect of antidiabetic agents, it may occasionally develop in the course of treatment with drugs used in everyday clinical practice, including NSAIDs, analgesics, antibacterials, antimalarials, antiarrhythmics, antidepressants and other miscellaneous agents. They induce hypoglycaemia by stimulating insulin release, reducing insulin clearance or interfering with glucose metabolism. Several drugs may also potentiate the hypoglycaemic effect of antidiabetic agents. Administration of these agents to individuals with diabetes mellitus is of most concern. Many of these drugs, and depending on clinical setting, may also induce hyperglycaemia. Drug-induced hepatotoxicity and nephrotoxicity may lead in certain circumstances to hypoglycaemia. Some drugs may also induce hypoglycaemia by causing pancreatitis. Drug-induced hypoglycaemia is usually mild but may be severe. Effective clinical management can be handled through awareness of this drug-induced adverse effect on blood glucose levels. Herein, we review pertinent clinical information on the incidence of drug-induced hypoglycaemia and discuss the underlying pathophysiological mechanisms, and prevention and management.

Drug-Induced Endocrine and Metabolic Disorders

Complex interactions exist amongst the various components of the neuroendocrine system in order to maintain homeostasis, energy balance and reproductive function. These components include the hypothalamus-pituitary- adrenal and -gonadal axes, the renin-angiotensin-aldosterone system, the sympathetic nervous system and the pancreatic islets. These hormones, peptides and neurotransmitters act in concert to regulate the functions of many organs, notably the liver, muscles, kidneys, thyroid, bone, adrenal glands, adipocytes, vasculature, intestinal tract and gonads, through many intermediary pathways. Endocrine and metabolic disorders can arise from imbalance amongst numerous hormonal factors. These disturbances may be due to endogenous processes, such as increased secretion of hormones from a tumour, as well as exogenous drug administration. Drugs can cause endocrine abnormalities via different mechanisms, including direct alteration of hormone production, changes in the regulation of the hormonal axis, effects on hormonal transport, binding, and signalling, as well as similar changes to counter-regulatory hormone systems. Furthermore, drugs can affect the evaluation of endocrine parameters by causing interference with diagnostic tests. Common drug-induced endocrine and metabolic disorders include disorders of carbohydrate metabolism, electrolyte and calcium abnormalities, as well as drug-induced thyroid and gonadal disorders. An understanding of the proposed mechanisms of these drug effects and their evaluation and differential diagnosis may allow for more critical interpretation of the clinical observations associated with such disorders, better prediction of drug-induced adverse effects and better choices of and rationales for treatment.

Severe hyperinsulinaemic hypoglycaemia in a baby born to a mother taking oral ritodrine therapy for preterm labour

Hyperinsulinism of infancy is a major cause of persistent hypoglycaemia in the newborn period. Transient mild self-limiting hyperinsulinaemia and hypoglycaemia have been described in neonates born to mothers taking ritodrine therapy for premature labour. Ritodrine crosses the placental barrier and enters the fetal circulation readily but the mechanism of how it causes hyperinsulinaemia and hypoglycaemia is unclear. We report the case of severe prolonged hyperinsulinaemic hypoglycamia in a neonate born to a mother taking ritodrine therapy from 16 weeks' gestation for preterm labour. The hyperinsulinaemic hypoglycaemia was managed with oral nifedipine as diazoxide was contraindicated due to fluid overload. Possible mechanisms of ritodrine-induced hypoglycaemia and insulin secretion are discussed.

Drugs that affect the fetus and newborn infant via the placenta or breast milk

In general, drugs that are taken by a mother during pregnancy or after birth may be transferred to the fetus or the infant (through breast milk). Many factors are involved that determine the amount of drugs that are transferred and their potential effects on the fetus or infant. A careful assessment of the risk versus benefit is necessary and should be individualized. In the breastfed infant, many measures can be undertaken further so that the amount of drug transferred to the infant is minimized.

Neonatal glucose metabolism: differential diagnoses, evaluation, and treatment of hypoglycemia

Hypoglycemia is one of the most common clinical care issues facing the neonatal practitioner. Increasing evidence indicates that neonatal hypoglycemia may have long-term neurologic effects. Care is complicated by the lack of a clearly defined threshold for hypoglycemia in term and preterm infants, however, and by highly variable clinical signs and symptoms. Furthermore, many infants with low blood glucose measurements do not exhibit obvious signs of impairment. The complexity of neonatal glucose metabolism is illustrated by the variety of conditions producing or associated with both neonatal hypo- and hyperglycemia. Maintenance of euglycemia is especially challenging in the sick or low birth weight neonate. This article defines euglycemia by its range and reviews the differential diagnoses and etiology of hypoglycemia--as well as the principles of its management--in the neonatal period.

Neonatal hypoglycaemia and withdrawal symptoms after exposure in utero to valproate

AIMS

To define, in a prospective study, the risk of hypoglycaemia-defined as blood glucose concentration < 1.8 mmol/l-in term infants exposed in utero to valproate and to describe the withdrawal symptoms.

METHODS

Twenty epileptic women were treated with valproate only during pregnancy and two were treated with valproate and carbamazepine. In the first trimester, the daily median dose of valproate was 1.0 g (range 0.3-4.2) and in the third trimester 1.2 g (range 0.3-4.8).

RESULTS

Thirteen of the 22 infants became hypoglycaemic. One infant had eight episodes of hypoglycaemia, one had three episodes, two had two episodes, and nine had one episode each. The lowest blood glucose concentration was 1.0 mmol/l. All episodes were asymptomatic. The maternal mean plasma concentration of total valproate during the third trimester correlated negatively with blood glucose concentration one hour after delivery (p < 0.0003) and with the development of hypoglycaemia (p < 0.0001). There was no evidence for hyperinsulinaemia as the cause of hypoglycaemia. Ten infants developed withdrawal symptoms, which correlated positively with the mean dose of valproate in the third trimester and the concentration of the free fraction of valproate in maternal plasma at delivery (p < 0.02).

CONCLUSIONS

Infants exposed to valproate in utero had a significantly elevated risk of hypoglycaemia, and withdrawal symptoms were often observed.

Hypoglycemia following albuterol overdose in a child

Acute overdose with beta-sympathomimetics results in transient elevation of blood glucose levels. Hypoglycemia has previously been reported in newborns of mothers following prolonged use of sympathomimetics used as tocolytic therapy. The authors report the first case of symptomatic hypoglycemia in a child, occurring 16 hours after acute albuterol overdose. Hypoglycemia may occur as a complication of acute beta-sympathomimetic overdose, probably as a reaction to acute elevation of blood sugar and resultant hyperinsulinemia. The authors suggest that in children with a large overdose of beta-sympathomimetics, blood glucose levels should be monitored for several hours. In those with marked hyperglycemia, monitoring should be extended until normalization of blood glucose levels.

Risk-benefit assessment of tocolytic drugs

beta 2-Mimetics are the principal agents used for myometrial relaxation. As all the available drugs also have beta 1-stimulant effects, the various side effects (cardiovascular, pulmonary and metabolic) require a critical consideration of the clinical indications, thorough supervision and combined therapeutic concepts. With regard to clinical indications, 'prophylactic tocolysis' frequently turns out to be unnecessary, as does the treatment of physiological uterine contractions during pregnacy which have no effect on the cervix. The benefit of tocolysis must be seen not so much in a reduction of preterm labour but in enabling the obstetrician and neonatologist to optimise the handling of the premature baby, e.g. by allowing lung maturation or by enabling the patient to reach a centre for perinatal medicine before the birth. Labour-dependent fetal distress situations during birth at term can also be managed successfully. Supervision involves thorough control of both mother (especially of cardiovascular and metabolic parameters, electrolyte and water balance) and fetus (cardiotocography, fetometry) in order to decide individually when possible benefits are outweighed by maternal or fetal risks. Combination of beta 2-mimetic treatment with magnesium therapy reduces the beta-mimetic dosage required, has a cardioprotective action, and reduces the development of drug tolerance and the risk of lung oedema. This combination, therefore, should become routine in tocolytic therapy. If further protection against cardiovascular and risk of lung oedema is required, administration of beta 1-blockers is advisable.

Outcome of very-low-birth-weight infants exposed to beta-sympathomimetics in utero

In this study we examined neonatal and early childhood outcomes after intrauterine exposure to beta-sympathomimetic agents on infants with birth weights less than or equal to 1500 gm. The hospital courses and anthropomorphic, developmental, and neurologic development of 201 infants exposed to one or more beta-sympathomimetic agents (isoxsuprine, 33; ritodrine, 70; terbutaline, 43; combination, 55) were analyzed and compared with those of 130 control infants of similar birth weight. One hundred and seventy-seven infants had follow-up to 1 year of age, 101 to age 3, and 58 to age 4. When treatments consisting of a single beta-sympathomimetic or no treatment were compared, there were no statistically significant overall differences found in growth and development or in most of the short-term measures of infant well-being. However, significant overall differences with no evidence of confounding by time-related effects were found for the following; mortality, none greater than terbutaline; maximum positive inspiratory pressure when respiratory distress syndrome was present, none greater than terbutaline; neonatal trauma, terbutaline greater than ritodrine. Other differences were found in conjunction with evidence of time-related confounding, or within specific time intervals. It should be noted that these differences are not necessarily due to effects of the different treatments, as the data are observational.

Gestational diabetes-perinatal outcome with a policy of liberal and intensive insulin therapy

During 3 years of continuous screening for gestational diabetes mellitus in the county of Uppsala, 133 pregnant women (1.2%) were given this diagnosis. Maternal characteristics and the perinatal outcome of the pregnancies were examined retrospectively. Maternal overweight [body mass index greater than 23.9 kg/(m)2] was noted in 54.9% of the 133 women. Insulin therapy, with a mean daily dose of 42 U, was given to 62.4% of the patients, whereas the others were given dietary instructions alone. The frequency of infants with a birth weight greater than 2 SD was 24.1% and was significantly (p less than 0.025) related to pre-pregnancy overweight and also to pregnancy weight gain 18kg (p less than 0.01). Caesarean section was performed in 27% of the pregnancies complicated by diabetes, compared with the overall figure of 11% in Uppsala during the study period. Neonatal hypoglycaemia (blood glucose greater than or equal to 1.6 mM) was noted in 17.3% of the infants and was significantly (p less than 0.01) related to maternal sympathomimetic therapy. Despite liberal and intensive insulin therapy, there was a considerable rate of perinatal complications. Although not severe, they indicate a need for further improvement in the care of women with gestational diabetes.

Changes in thyroid status in newborn infants utero-exposed to ritodrine

A clinical study to assess whether utero exposure to ritodrine influences thyroid status was performed in 21 healthy term newborn infants, 10 exposed in utero to ritodrine (treated group) and 11 non-exposed in utero to drugs (control group). The treated group had a T3/T4 ratio significantly higher than the control group (mean +/- SD: 124.10 +/- 23.70 vs. 96.09 +/- 18.11, p less than 0.005) and T3 slightly increased (mean +/- SD nmol/l 2.48 +/- 0.69 vs. 1.95 +/- 0.56). The mean serum values of the other parameters studied, TSH, T4, fT4, fT3, were not significantly different in either groups. Since beta-mimetics induces deiodinating activity of the liver and propranolol reduces extrathyroidal conversion of T4 to T3, it was suggested that ritodrine enhances deiondinating activity of fetal and neonatal liver.

Beta-adrenoceptor agonists and hypoxia in sheep fetuses

Sheep fetuses, near term, were studied to test the influence of a tocolytic beta agonist, terbutaline, on fetal responses to hypoxia. After fetal exteriorization the drug was administered intravenously to the mother in three different doses: The max group comprised 11 ewes receiving 67-134 micrograms min-1. Seven ewes were given 30 micrograms min-1 and eight ewes were infused with 10 micrograms min-1. Seventeen fetuses served as controls. Hypoxia was induced by intermittent complete occlusions of the maternal abdominal aorta. Maternal terbutaline levels were high (range 50-748 nmol l-1) in the max group and the 30-micrograms group, whereas those in the 10-micrograms group were in the clinical range (range 11-58 nmol l-1). Fetuses in the max and 30-micrograms groups reacted to moderate hypoxia with excessive responses of heart rate, blood pressure myocardial contractility and ST waveform changes and a 50% mortality rate during severe hypoxia as compared with 12% in the control animals. Ten micrograms min-1 did not decrease the survival but caused an increase in myocardial workload and a negative energy balance during severe hypoxia.

Umbilical artery catheterization: a potential cause of refractory hypoglycemia

Two infants with persistent, symptomatic hypoglycemia are reported. Both were thought to have iatrogenic hyperinsulinism due to a malpositioned umbilical artery catheter. Repositioning of the catheter to avoid direct infusion into the arterial blood supply to the pancreas resulted in prompt cessation of hypoglycemia.

Ventricular septal thickness and cardiac function in neonates after in utero ritodrine exposure

Cardiac septal hypertrophy occurs after in utero ritodrine exposure. To assess the effect of septal hypertrophy on cardiac function we obtained M-mode echocardiograms on day 1 of life in 41 infants exposed to ritodrine and 22 control infants matched for gestational age. Mean duration of ritodrine exposure was 16.2 +/- 13.2 days (range 1 to 49 days). Disproportionate septal hypertrophy (DSH) was defined as an interventricular septal thickness/posterior wall thickness ratio (ST/PW) of greater than 1.3. Infants exposed to ritodrine in utero had DSH and increased right systolic time intervals compared with control values (P less than 0.05). A subgroup, those infants exposed for 2 weeks or longer, had not only DSH but also an absolute increase in septal thickness compared with control infants and infants exposed to ritodrine for less than 2 weeks. ST/PW correlated well with the duration of ritodrine exposure (r = 0.96); the longer the exposure the thicker the septum. Although all echocardiographic changes lasted for less than 3 months, we have no information regarding the effect on the fetus of maternal ritodrine exposure for longer than 7 weeks. Until such information is available, cardiac evaluation is recommended in neonates exposed to ritodrine in utero for longer than 7 weeks.

Carbohydrate metabolism in the fetus and neonate and altered neonatal glucoregulation

Altered glucose homeostasis in the neonate often results from antecedent events during fetal life. This article describes the normal and altered development of glucoregulatory capabilities during perinatal life and relates it to problems of hypo- and hyperglycemia in the neonate.

Mechanisms of beta sympathomimetic action on neonatal glucose homeostasis in the lamb

Beta sympathomimetic drugs are used clinically to inhibit premature labor. Significant alterations in glucose homeostasis have been documented in both mother and offspring. To determine the mechanism(s) of beta sympathomimetic drugs on neonatal glucose homeostasis, ritodrine hydrochloride was infused in a newborn term lamb model of glucose kinetics by a crossover design. There was a progressive rise in plasma glucose concentration and plasma insulin concentration during ritodrine hydrochloride infusion compared with the control (saline) infusion. The rise in plasma glucose concentration was associated with a progressive rise in Ra (rate of appearance, production) and Rd (rate of disappearance, utilization). The ritodrine hydrochloride-infused animals had a progressive rise in [insulin/glucose] compared with our prior studies in the newborn lamb, suggesting direct stimulation of pancreatic beta cell secretion. In the neonatal lamb, beta sympathomimetic drugs directly stimulate both hepatic glucose production and pancreatic beta cell secretion. These effects explain, in part, why infants of mothers infused with ritodrine hydrochloride may evidence alterations in neonatal glucose homeostasis.

Complications of beta-mimetic therapy in preterm labour

Selective beta-mimetic drugs are the most frequently used agents for arresting preterm labour. For this purpose these drugs have to be given in high doses for several hours and since they act on several organ systems, side-effects, some of which are potentially dangerous, appear. These hazards, which involve chiefly the cardiovascular and metabolic areas, have been examined in the light of available experience with these drugs. This review considers the possible mechanisms for the side-effects and offers suggestions on how the dangers in the use of beta-mimetic drugs in preterm labour might be avoided.

Pathophysiology, diagnosis, and management of glucose homeostasis in the neonate

The neonate appears to be in a transitional stage of glucose homeostasis. Maturation of neonatal glucose homeostasis requires coordination of opposing hormonal, neural, and enzymatic controls. The vulnerability of the neonate to carbohydrate disequilibrium has been described by tracing the maturation of carbohydrate homeostasis physiologically. The many examples of neonatal hypoglycemia and hyperglycemia have been enumerated. Much information in recent years has increased our understanding of the mechanism of these conditions in the newborn. Continued research of the biochemical and physiologic bases for alterations of carbohydrate metabolism should further enhance our ability to diagnose and treat the neonate effectively.

Betamimetic drugs in the prophylaxis of preterm labour: extent and rationale of their use

A questionnaire survey among 1004 specialist and trainee obstetricians in The Netherlands and northern Belgium (Flanders), revealed that 45% of the 521 (52%) respondents would use prophylactic betamimetics to prevent preterm labour. A further 33% would only use them as maintenance therapy after an acute episode of preterm labour. Only 22% would use neither form of prophylaxis, 23% would not prescribe oral betamimetics for out-patients, and a mere 12% would use neither prophylaxis nor out-patient treatment. Nevertheless, only 4% of those using betamimetics either prophylactically or as maintenance therapy said that they were very effective. The data indicate that a large body of obstetricians will resort to dubious treatments with poor effectiveness and unknown risks in an attempt to avoid the known risks of a condition for which aetiological insight and effective therapy are lacking.

Transplacental transfer of beta-adrenergic drugs studied by an in vitro perfusion method of an isolated human placental lobule

A study was made of the transfer across an in vitro perfused human placenta of four beta-mimetics commonly used in obstetric practice. Between 2% and 3% of fenoterol, ritodrine, and salbutamol appeared on the fetal side after bolus injection into the maternal circulation. For hexoprenaline, the transfer (1%) was significantly lower than that observed with other beta-mimetics studied. With constant infusion of fenoterol into the maternal circulation and recycling of a small volume of perfusate on the fetal side, a fairly rapid rise in the concentration was seen. Some sulfate conjugation of fenoterol during its diffusion from the maternal to the fetal side of the placenta could be seen. In the in vitro perfused human placental lobule there is no apparent effect of synthetic beta-mimetics on the transfer of antipyrine or glucose and no stimulation of the production of lactate and pyruvate.

L/S ratio, biochemical and clinical changes after ritodrine intravenous infusion

The effects of ritodrine hydrochloride on the L/S ratio, the clinical and biochemical status of the mother, and the amniotic fluid were studied in a total of 46 women between the 28th and 35th wk of their pregnancy. An increase in the L/S ratio and creatinine levels in the amniotic fluid, significant changes in the maternal serum levels of potassium, sodium, alpha 1-antitrypsin and glucose were found, whereas the urea levels remained unchanged. Maternal hyperglycemia and hypokalemia in both maternal serum and amniotic fluid, were more pronounced when the ritodrine was infused in 5% dextrose. The findings from monitoring the cardiovascular systems of both mother and fetus, agreed with previous reports. It was concluded that ritodrine hydrochloride has a positive effect on the fetal lung maturation, probably by accelerating the release of surfactant. Its administration, however, should be under laboratory control.

Pulmonary edema occurring after isoxsuprine and dexamethasone treatment for preterm labor: Case report

A case of maternal pulmonary edema occurring in a patient in the 32nd week of gestation is presented. This was our first case of pulmonary edema seen during a period of five years' usage of isoxsuprine in the treatment of premature labor. The patient presented was 28 years old, gravida 2, para 1, admitted to the maternity ward with premature uterine contractions. Her past history eliminate cardiac or pulmonary disease. Isoxsuprine therapy was begun with initial dose of 0.04 mg/min. and increased to 0.32 mg/min., the total dose administered was 560 mg during 48 hours. During this period she was given in dexamethasone 24 mg. Fluid balance on the first day of the treatment was +1.7 liters and on the second day +5.2 liters. Forty-eight hours from the commencement of the treatment, the patient experienced shortness of breath and chest pain. Physical examination disclosed wet rales over both lungs, sinus tachycardia and tachypnea. Laboratory examination disclosed hypopotassemia of 3 mEq/liter, hypoxemia (PO2 of 80 torr on 0.5 FiO2 face mask) with mild hyperventilation 28 torr PCO2 with normal ph 7.43. Recognition of the early signs of pulmonary edema enable swift clinical diagnosis and steps to be taken to prevent disasterous condition due to progressive hypoxemia. The prompt treatment in this complication includes discontinuation of isoxsuprine and fluid administration, placement of the patient in an erect position, intravenous furosemid 40 mg, oxygen supplement by face mask and 25 mg of meperidine. The patient's condition dramatically improved though the lung fields became completely clear from wet rales only eight hours from the start of dyspneic attack.(ABSTRACT TRUNCATED AT 250 WORDS)

Single injection of terbutaline in term labor: placental transfer and effects on maternal and fetal carbohydrate metabolism

Maternal and fetal blood glucose and insulin levels were studied in 10 women in the second stage of labor after administration of terbutaline, 250 micrograms intravenously. The transport of the drug across the placenta was also studied. Saline solution was administered to four other women who served as controls. A rise in maternal plasma insulin levels occurred in all patients but was more pronounced in patients treated with terbutaline less than 25 minutes before delivery than in those treated more than 45 minutes prior to delivery. No difference was found in maternal blood glucose levels between terbutaline-treated patients and controls. Blood glucose increased in the fetuses during the second stage of labor and paralleled that of the mothers, but on a lower level. None of the newborn infants demonstrated hypoglycemia during the first 90 minutes after birth. Terbutaline crossed the placenta rapidly, and fetal plasma levels up to 55% of the maternal plasma levels were found. The conclusion is that this form of administration of terbutaline does not seem to have any negative short-term influences on the fetal carbohydrate metabolism.

Isoxsuprine in the perinatal period. II. Relationships between neonatal symptoms, drug exposure, and drug concentration at the time of birth

Forty preterm infants with maternal isoxsuprine exposure less than 24 hours delivery and 40 matched control infants were studied prospectively to determine the acute neonatal effects of maternal ISX exposure. The cord ISX concentration correlated inversely with the drug-free interval before delivery (P < 0.001). Cord ISX concentrations > 10 mg/ml were seen only with intravenous maternal therapy and a drug-discontinuance to delivery interval of two hours or less. The plasma half-life of ISX in neonates ranged from 1.7 to 8 hours; gestationally younger infants required a longer time for drug clearance. Ileus was 13 times more common in the ISX group and was not directly related to the cord ISX concentration. The incidence of hypotension and hypocalcemia rose directly with the cord ISX concentration, reaching 89% and 100%, respectively, when the cord ISX level exceeded 10 ng/ml. The incidence of respiratory distress syndrome was low in the ISX infants with low cord drug values, but increased to that of the control group when the cord ISX concentration reached > 10 ng/ml.

Isoxsuprine infusion in the rat: alterations in maternal, fetal and neonatal glucose homeostasis

To determine the mechanism of alteration in glucose homeostasis associated with maternal isoxsuprine administration, isoxsuprine or 0.04 M saline was administered intravenously for 3 hours to term pregnant and age-matched virgin rats. Isoxsuprine infusion significantly increased plasma glucose and insulin concentrations and decreased hepatic glycogen stores in both. Compared to rat pups of saline infused mothers, pups of isoxsuprine infused mothers had significantly elevated plasma glucose concentrations for the first 4 hours of life and plasma insulin concentrations for the first two. Plasma glucose concentrations for the offspring of isoxsuprine treated mothers then decreased significantly and remained so until 16 hours of age. Hepatic glycogen concentrations were significantly less in rat pups of isoxsuprine treated mothers at birth and for the first 4 hours of life. In a limited number of studies, isoxsuprine was present at birth in substantial quantities (80-85% of maternal levels) in the plasma of rat pups of isoxsuprine infused mothers. These data suggest that maternal isoxsuprine therapy mobilizes hepatic glycogen and results in maternal hyperlgycemia. Maternal isoxsuprine infusion may directly deplete fetal hepatic glycogen and result in transient fetal and neonatal hyperglycemia. the in utero depletion of glycogen and possibly, the early stimulation of insulin production may be responsible for the later significant decreases in plasma glucose in the offspring of isoxsuprine treated mothers.