Cocaine selectively inhibits beta-adrenergic receptor binding in pregnant human myometrium

Crack cocaine smoke on pregnant rats: Maternal evaluation and teratogenic effect

This study aimed to evaluate maternal toxicity, teratogenic, and placental oxidative effects resulting from the exposure of rats to crack cocaine smoke during pregnancy. Pregnant rats were exposed either to the smoke of crack and ashes (Crack) or to the smoke of ashes alone, nonexposed or pair-fed with the Crack group. Crack group was exposed to the smoke resulting from the burning of 250 mg of crack for 10 min, twice a day, from 7 days prior to mating until cesarian on gestational day 20. Placental oxidative stress and classical parameters of maternal and fetal evaluation were studied, in addition to the morphometric analysis of the fetal metamers. Even in the absence of changes in body weight gain and feed intake, crack altered the reproductive performance of dams. Exposure to the drug promoted late closure of the fetal fontanel. Furthermore, the morphometric study of the brain mass (BM)/skull cap ratio revealed a decrease in the BM of the fetuses exposed to the drug. Exposure to crack has an oxidative potential in fetal development, since exposure to the drug promoted placental lipid peroxidation. Our study showed that daily exposure to crack, even in lower frequency than that performed by users, has a teratogenic potential.

Reduced duration of intrathecal sufentanil analgesia in laboring cocaine users

On the basis of our previous clinical experience, we hypothesized in this study that the duration and/or quality of labor analgesia produced by intrathecal sufentanil was less in cocaine-abusing parturients compared with nonabusing parturients. Ten micro g of sufentanil was given intrathecally as part of a combined spinal-epidural (CSE) technique to two groups of laboring parturients: 1). those whose urine tested positive for cocaine (cocaine group), and 2). those whose urine tested negative for cocaine (control group). The epidural catheter was not injected with local anesthetic until the patient requested additional pain relief. The time from injection of intrathecal sufentanil until patient request for additional pain relief was defined as duration of analgesia. Baseline visual analog pain score (VAPS) and cervical dilation were measured before the CSE was performed. After injection of intrathecal sufentanil, VAPS was recorded at specific intervals. Cervical dilation was again documented when the patient requested additional analgesia. We found that both groups reported high baseline VAPS and a marked decrease in VAPS after injection of sufentanil that did not differ between groups. Geometric mean duration of pain relief with adjustment for cervical dilation was 87 min in the cocaine group compared with 139 min in the control group (P = 0.019). All patients experienced itching. We conclude that intrathecal sufentanil produces a similar quality but shorter duration of analgesia in cocaine-abusing parturients compared with nonabusing parturients.

IMPLICATIONS

Intrathecal sufentanil administered as part of a combined spinal-epidural technique produces similar quality but reduced duration of labor analgesia in cocaine-abusing parturients compared with nonabusing parturients.

Fetal effects of cocaine: an updated meta-analysis

BACKGROUND

A very large number of women in the reproductive age group consume cocaine, leading to grave concerns regarding the long term health of millions of children after in utero exposure. The results of controlled studies have been contradictory, leading to confusion, and, possible, misinformation and misperception of teratogenic risk.

OBJECTIVE

To systematically review available data on pregnancy outcome when the mother consumed cocaine.

METHODS

A meta-analysis of all epidemiologic studies based on a priori criteria was conducted. Comparisons of adverse events in subgroups of exposed vs. unexposed children were performed. Analyses were based on several exposure groups: mainly cocaine, cocaine plus polydrug, polydrug but no cocaine, and drug free.

RESULTS

Thirty three studies met our inclusion criteria. For all end points of interest (rates of major malformations, low birth weight, prematurity, placental abruption, premature rupture of membrane [PROM], and mean birth weight, length and head circumference), cocaine-exposed infants had higher risks than children of women not exposed to any drug. However, most of these adverse effects were nullified when cocaine exposed children were compared to children exposed to polydrug but no cocaine. Only the risk of placental abruption and premature rupture of membranes were statistically associated with cocaine use itself.

CONCLUSIONS

Many of the perinatal adverse effects commonly attributed to cocaine may be caused by the multiple confounders that can occur in a cocaine using mother. Only the risk for placental abruption and PROM could be statistically related to cocaine. For other adverse effects, additional studies will be needed to ensure adequate statistical power.

Cocaine augments contractility of the pregnant human uterus by both adrenergic and nonadrenergic mechanisms

OBJECTIVE

Our purpose was to evaluate the mechanisms of cocaine's effect on both spontaneous and agonist-induced contractility of pregnant human myometrium.

STUDY DESIGN

Myometrium was obtained from 42 women at term who were undergoing cesarean section. Myometrial strips were suspended in contraction baths and isometric contractions were measured. Tissue was exposed to various combinations of cocaine, prazosin, desipramine, benzoylecgonine, and procaine. Spontaneous contractility and the contractile responses to increasing concentrations of methoxamine and oxytocin were measured and compared.

RESULTS

Cocaine increased spontaneous myometrial contractility by more than threefold. Prazosin, an alpha-adrenergic antagonist, blocked this effect only for the first 35 minutes of exposure. The cumulative concentration-response to the alpha-adrenergic agonist methoxamine was increased by cocaine in terms of both sensitivity and maximal response. The maximal response to oxytocin, but not the sensitivity, was increased by cocaine by an effect that could not be blocked by prazosin.

CONCLUSION

Cocaine augments spontaneous and agonist-induced contractility of pregnant human myometrium by mechanisms that appear to be both alpha-adrenergic and nonadrenergic in nature.

Cocaine in pregnancy. Recent data on maternal and fetal risks

Cocaine continues to be abused during pregnancy, creating increased demands on the health care system. Epidemiology and basic science research have identified and confirmed risks of adverse maternal and fetal effects when cocaine is used during pregnancy. These effects of cocaine in pregnant women often are influenced by a number of confounding variables. This article reviews those cocaine effects as well as recent data, which examine in greater detail the risks of adverse outcomes of prenatal cocaine exposure during pregnancy.

[Consequences of cocaine addiction during pregnancy on the development in the child]

Cocaine facilitates neurotransmitter release from the central nervous system, decreases their re-uptake at the synapse junction level and increases their blood level due to receptors blockade. During pregnancy cocaine inhibits uterine adrenergic beta receptors and easily crosses the placenta, the main obstetrical consequences of overstimulation of the noradrenergic system being miscarriage, retroplacental haematoma, ruptured uterus, short and premature labour. Fetal and neonatal consequences resulting from both a decreased uterine blood flow and a direct effect of cocaine on fetal development can be severe. Decreased uterine blood flow lowers oxygen and nutriment transport which in turn can induce intra-uterine growth retardation. The direct effect of cocaine on the fetus is responsible for an increased catecholamine plasma concentration leading to vasoconstriction episodes, increased heart rate and blood pressure, and subsequent oxygen requirement. Several malformations have been reported, sometimes severe (involving central nervous system, heart, digestive tract, urinary tract and bone) that are mainly due to fetal circulation failure. Cocaine can also directly alter brain development because of neuronal mistargeting within the cerebral cortex.

Cocaine and beta-adrenergic receptor function in pregnant myometrium

OBJECTIVE

Our purpose was to evaluate the in vitro effect of cocaine on beta-adrenergic receptor function in pregnant human myometrium.

STUDY DESIGN

Myometrium was obtained from 25 pregnant women at term who were undergoing cesarean section but who were not in labor. Membrane preparations were assayed for cyclic adenosine monophosphate production after exposure to isoproterenol, sodium fluoride, or forskolin in the presence and absence of either cocaine or benzoylecgonine, a major metabolite of cocaine.

RESULTS

Cocaine inhibited isoproterenol-induced cyclic adenosine monophosphate production in concentrations as low as 10(-8) mol/L but had no effect on cyclic adenosine monophosphate production induced by sodium fluoride or forskolin. Benzoylecgonine (10(-4) mol/L) had no effect on isoproterenol-induced cyclic adenosine monophosphate production.

CONCLUSION

Cocaine is a beta-adrenergic receptor antagonist in human myometrium at concentrations as low as 10(-8) mol/L. This acute effect of cocaine may result in increased uterine contractility with adrenergic stimulation, potentially leading to increased uterine activity associated with acute cocaine use.

The effect of cocaine on myometrial contractile activity: basic mechanisms

Several clinical studies have reported an association between cocaine use in pregnancy and preterm labor. The mechanism by which cocaine exerts this effect is unclear. Although cocaine stimulates isolated myometrial contractile activity, results using whole animal models are conflicting. Although cocaine inhibits uterine neuronal and extraneuronal uptake of catecholamines and increases circulating levels of catecholamines in experimental animals, it is unlikely that facilitation of the alpha-adrenergic pathway is the sole mechanism of cocaine's action. Further investigation of possible indirect mechanisms of action including altered prostaglandin production, inhibition of beta-adrenergic response, and direct effects on intracellular calcium mobilization may lead to enhanced understanding of the clinical ramifications of cocaine use during pregnancy.

Cocaine downregulates beta-adrenergic receptors in pregnant sheep myometrium

Cocaine abuse is associated with premature labor. Although cocaine is known to competitively inhibit beta-adrenergic receptor binding, cocaine's effect on receptor downregulation is uncertain. This study was designed to determine the in vitro effect of cocaine on downregulation of beta-adrenergic receptors in pregnant myometrium. Pregnant sheep myometrium was incubated with either cocaine, isoproterenol, or a cocaine metabolite, benzoylecgonine. Membrane fractions were assayed for beta-adrenergic receptors using (125I)-cyanopindolol and the beta 2-adrenergic antagonist ICI 118,551. We found that cocaine (10(-6) to 10(-4) mol/L), but not benzoylecgonine, downregulated both beta 1- and beta 2-adrenergic receptors, but did not further augment receptor downregulation by isoproterenol. The 46% decrease in beta-adrenergic receptors seen after exposure to cocaine was similar to the 53% decrease seen after isoproterenol. We hypothesize downregulation of beta-adrenergic receptors by cocaine may play a role in the association of cocaine abuse with premature labor.

Preterm rupture of the membranes associated with recent cocaine use

OBJECTIVE

We postulated that recent cocaine use is common among patients with preterm (< 37 weeks) rupture of the membranes and that cocaine users have shorter latency periods before the onset of labor and delivery compared with those without recent cocaine use.

STUDY DESIGN

A urine toxicologic screen was performed on all patients admitted with preterm rupture of the membranes. Patients were managed expectantly, without tocolytics, antibiotics, or steroids.

RESULTS

One hundred three patients were enrolled; 71 had negative screens and 19 were positive for cocaine alone. Cocaine-positive women were significantly older and had more advanced cervical dilatation at admission and a significantly shorter latency period from rupture of membranes to labor and delivery.

CONCLUSION

Preterm rupture of the membranes associated with recent cocaine use is characterized by advanced cervical dilatation at admission and a shorter latency period to labor and delivery.