Gabapentin use in hyperemesis gravidarum: a pilot study

Inpatient Management of Hyperemesis Gravidarum

Hyperemesis gravidarum has a reported incidence of approximately 0.3-3% of pregnancies. Without treatment, refractory hyperemesis gravidarum can result in dehydration, electrolyte deficiencies, and severe nutritional deficiencies, resulting in significant maternal morbidity. The overall goals of inpatient management of refractory hyperemesis gravidarum are the resumption of oral intake to an adequate level to maintain hydration and nutrition, including the ability to tolerate oral pharmacotherapy. Patients initially are stabilized with rehydration and electrolyte repletion. There are numerous pharmacotherapeutics available that can be administered intravenously to control symptoms when oral intake is not an option. However, despite maximizing typical antiemetics, there will be cases refractory to these medications, and alternative pharmacotherapeutics and nutrition-support modalities must be considered. Mirtazapine, olanzapine, corticosteroids, and gabapentin are examples of alternative pharmacotherapeutics, and enteral and parenteral nutrition are alternative therapies that can be used when oral intake is not tolerated for prolonged time periods with ongoing weight loss. In refractory cases of hyperemesis gravidarum, the risks and benefits of these alternative forms of management must be considered, along with the risks of undertreated hyperemesis gravidarum and the overall effect of hyperemesis gravidarum on patients' quality of life.

Systematic evidence map of evidence addressing the top 10 priority research questions for hyperemesis gravidarum

OBJECTIVE

Knowledge gaps regarding hyperemesis gravidarum (HG) are substantial. We aimed to systematically identify and map recent evidence addressing the top 10 priority questions for HG, as published in 2021 in a James Lind Alliance Priority Setting Partnership.

DESIGN

Systematic evidence map.

METHODS

We searched MEDLINE and EMBASE on 12 January 2021 and CINAHL on 22 February 2021 with search terms hyperemesis gravidarum, pernicious vomiting in pregnancy and their synonyms. Results were limited to 2009 onwards. Two reviewers independently screened titles and abstracts to assess whether the studies addressed a top 10 priority questions for HG. Differences were discussed until consensus was reached. Publications were allocated to one or more top 10 research questions. Study design was noted, as was patient or public involvement. Two reviewers extracted data synchronously and both cross-checked 10%. Extracted data were imported into EPPI-Reviewer software to create an evidence map.

OUTCOME MEASURES

The number and design of studies in the search yield, displayed per the published 10 priority questions.

RESULTS

Searches returned 4338 results for screening; 406 publications were included in the evidence map. 136 publications addressed multiple questions. Numerous studies address the immediate and long-term outcomes or possible markers for HG (question 8 and 9, respectively 164 and 82 studies). Very few studies seek a possible cure for HG (question 1, 8 studies), preventative treatment (question 4, 2 studies) or how to achieve nutritional requirements of pregnancy (question 10, 17 studies). Case reports/series were most numerous with 125 (30.7%) included. Few qualitative studies (9, 2.2%) were identified. 25 (6.1%) systematic reviews addressed eight questions, or aspects of them. 31 (7.6%) studies included patient involvement.

CONCLUSIONS

There are significant gaps and overlap in the current HG literature addressing priority questions. Researchers and funders should direct their efforts at addressing the gaps in the top 10 questions.

Clinical Conundrum: To Deliver or Not To Deliver a Patient With Pulmonary Edema and Preeclampsia

While admitted for management of hyperemesis gravidarum and preeclampsia, a 29-year-old gravida 1 para 0 patient with type 1 diabetes mellitus developed acute shortness of breath at 24 weeks gestation. Physical examination and chest X-ray findings were consistent with pulmonary edema, which in pregnancy is most often a severe complication of preeclampsia warranting delivery. The case is discussed with respect to diagnosis and management of pulmonary edema and acquired pulmonary hypertension in pregnancy, including timing and mode of delivery. Many case studies and guidelines advise caution when embarking on pregnancy with primary pulmonary hypertension; however, there is little available to guide clinical management when pulmonary hypertension secondary to fluid overload and preeclampsia develops during pregnancy.

The Management of Nausea and Vomiting Not Related to Anticancer Therapy in Patients with Cancer

OPINION STATEMENT

In cancer patients, the management of nausea and vomiting that is not directly related to treatment is challenging. Much current practice is based on expert opinion and anecdote. Fortunately, over recent years, a number of quality trials have been undertaken to strengthen the evidence base that guides the care of our patients with these distressing symptoms. Much is still unknown however. In this article, we present the latest literature that addresses some of the outstanding issues.

Effect of gabapentin on hyperemesis gravidarum: a double-blind, randomized controlled trial

BACKGROUND

Hyperemesis gravidarum is a disabling disease of nausea, vomiting, and undernutrition in early pregnancy for which there are no effective outpatient therapies. Poor weight gain in hyperemesis gravidarum is associated with several adverse fetal outcomes including preterm delivery, low birthweight, small for gestational age, low 5-minute Apgar scores, and neurodevelopmental delay. Gabapentin is most commonly used clinically for treating neuropathic pain but also substantially reduces chemotherapy-induced and postoperative nausea and vomiting. Pregnancy registry data have shown maternal first-trimester gabapentin monotherapy to be associated with a 1.2% rate of major congenital malformations among 659 infants, which compares favorably with the 1.6% to 2.2% major congenital malformation rate in the general population. Open-label gabapentin treatment in hyperemesis gravidarum was associated with reduced nausea and vomiting and improved oral nutrition.

OBJECTIVE

This study aimed to determine whether gabapentin is more effective than standard-of-care therapy for treating hyperemesis gravidarum.

STUDY DESIGN

A double-blind, randomized, multicenter trial was conducted among patients with medically refractory hyperemesis gravidarum requiring intravenous hydration. Patients were randomized (1:1) to either oral gabapentin (1800-2400 mg/d) or an active comparator of either oral ondansetron (24-32 mg/d) or oral metoclopramide (45-60 mg/d) for 7 days. Differences in Motherisk-pregnancy-unique quantification of nausea and emesis total scores between treatment groups averaged over days 5 to 7, using intention-to-treat principle employing a linear mixed-effects model adjusted for baseline Motherisk-pregnancy-unique quantification of nausea and emesis scores, which served as the primary endpoint. Secondary outcomes included Motherisk-pregnancy-unique quantification of nausea and emesis nausea and vomit and retch subscores, oral nutrition, global satisfaction of treatment, relief, desire to continue therapy, Nausea and Vomiting of Pregnancy Quality of Life, and Hyperemesis Gravidarum Pregnancy Termination Consideration. Adjustments for multiple comparisons were made employing the false discovery rate.

RESULTS

A total of 31 patients with hyperemesis gravidarum were enrolled from October 2014 to May 2019. Among the 21 patients providing primary outcome data (12 assigned to gabapentin and 9 to the active comparator arm), 18 were enrolled as outpatients and all 21 were outpatients from days 5 to 7. The study groups' baseline characteristics were well matched. Gabapentin treatment provided a 52% greater reduction in days 5 to 7 baseline adjusted Motherisk-pregnancy-unique quantification of nausea and emesis total scores than treatment with active comparator (95% confidence interval, 16-88; P=.01). Most secondary outcomes also favored gabapentin over active comparator treatment including 46% and 49% decreases in baseline adjusted Motherisk-pregnancy-unique quantification of nausea and emesis nausea (95% confidence interval, 19-72; P=.005) and vomit and retch subscores (95% confidence interval, 21-77; P=.005), respectively; a 96% increase in baseline adjusted oral nutrition scores (95% confidence interval, 27-165; P=.01); and a 254% difference in global satisfaction of treatment (95% confidence interval, 48-459; P=.03). Relief (P=.06) and desire to continue therapy (P=.06) both showed trends favoring gabapentin treatment but Nausea and Vomiting of Pregnancy Quality of Life (P=.68) and Hyperemesis Gravidarum Pregnancy Termination Consideration (P=.58) did not. Adverse events were roughly equivalent between the groups. There were no serious adverse events.

CONCLUSION

In this small trial, gabapentin was more effective than standard-of-care therapy for reducing nausea and vomiting and increasing oral nutrition and global satisfaction in outpatients with hyperemesis gravidarum. These data build on previous findings in other patient populations supporting gabapentin as a novel antinausea and antiemetic therapy and support further research on gabapentin for this challenging complication of pregnancy.

A Comparative Study Between Ondansetron and Gabapentin for Prevention of Postoperative Nausea and Vomiting Following Maxillofacial Surgery

Background and Aim

Gabapentin is an antiepileptic drug with antiemetic properties. We evaluated prophylactic oral gabapentin as compared with ondansetron for postoperative nausea and vomiting (PONV) in patients undergoing maxillo facial surgery.

Settings and Design

A double-blind, randomized study in a teaching hospital.

Materials and Methods

Seventy patients of ASA physical status I and II, scheduled to undergo maxillofacial surgery, were randomly assigned into two groups to receive 300 mg gabapentin or 8 mg ondansetron 1 h before surgery. Standard anaesthesia technique was used in all patients. Students' t test for difference of means between two groups was used for continuous variables. Chi square or Fisher's exact test was used for comparing proportion between two groups. Kaplan-Meier survival analysis was performed to compare the time to event observed between ondansetron and gabapentin groups. Log-rank test was performed to detect statistical significance of time to events between two groups.

Results

There was no significant difference in incidence of PONV between two groups within 2 h postoperatively. No incidence of PONV was observed in gabapentin group within 2-24 h as compared to ondansetron group in which PONV was observed in five cases.

Conclusion

Gabapentin effectively suppresses PONV in maxillo facial surgery.

Gabapentin in pregnancy and the risk of adverse neonatal and maternal outcomes: A population-based cohort study nested in the US Medicaid Analytic eXtract dataset

BACKGROUND

Despite the widespread use, only sparse information is available on the safety of gabapentin during pregnancy. We sought to evaluate the association between gabapentin exposure during pregnancy and risk of adverse neonatal and maternal outcomes.

METHODS AND FINDINGS

Using the United States Medicaid Analytic eXtract (MAX) dataset, we conducted a population-based study of 1,753,865 Medicaid-eligible pregnancies between January 2000 and December 2013. We examined the risk of major congenital malformations and cardiac defects associated with gabapentin exposure during the first trimester (T1), and the risk of preeclampsia (PE), preterm birth (PTB), small for gestational age (SGA), and neonatal intensive care unit admission (NICUa) associated with gabapentin exposure early, late, or both early and late in pregnancy. Gabapentin-unexposed pregnancies served as the reference. We estimated relative risks (RRs) and 95% confidence intervals (CIs) using fine stratification on the propensity score (PS) to control for over 70 confounders (e.g., maternal age, race/ethnicity, indications for gabapentin, other pain conditions, hypertension, diabetes, use of opioids, and specific morphine equivalents). We identified 4,642 pregnancies exposed in T1 (mean age = 28 years; 69% white), 3,745 exposed in early pregnancy only (28 years; 67% white), 556 exposed in late pregnancy only (27 years; 60% white), and 1,275 exposed in both early and late pregnancy (29 years; 75% white). The reference group consisted of 1,744,447 unexposed pregnancies (24 years; 40% white). The adjusted RR for major malformations was 1.07 (95% CI 0.94-1.21, p = 0.33) and for cardiac defects 1.12 (0.89-1.40, p = 0.35). Requiring ≥2 gabapentin dispensings moved the RR to 1.40 (1.03-1.90, p = 0.03) for cardiac defects. There was a higher risk of preterm birth among women exposed to gabapentin either late (RR, 1.28 [1.08-1.52], p < 0.01) or both early and late in pregnancy (RR, 1.22 [1.09-1.36], p < 0.001), SGA among women exposed to gabapentin early (1.17 [1.02-1.33], p = 0.02), late (1.39 [1.01-1.91], p = 0.05), or both early and late in pregnancy (RR, 1.32 [1.08-1.60], p < 0.01), and NICU admission among women exposed to gabapentin both early and late in pregnancy (RR, 1.35 [1.20-1.52], p < 0.001). There was no higher risk of preeclampsia among women exposed to gabapentin after adjustment. Study limitations include the potential for residual confounding and exposure misclassification.

CONCLUSIONS

In this large population-based study, we did not find evidence for an association between gabapentin exposure during early pregnancy and major malformations overall, although there was some evidence of a higher risk of cardiac malformations. Maternal use of gabapentin, particularly late in pregnancy, was associated with a higher risk of PTB, SGA, and NICUa.

Practical Perspectives in the Treatment of Nausea and Vomiting

Nausea and vomiting result from complex interactions between afferent and efferent pathways of the gastrointestinal tract, central nervous system, and autonomic nervous system. Afferent pathways from the vagus nerve, vestibular system, and chemoreceptor trigger zone project to nucleus tractus solitarius, which in turn relays signals to the central pattern generator to initiate multiple downstream pathways resulting in symptoms of nausea and vomiting. There is increasing evidence that the central pathway of chronic nausea is different from that of acute nausea and vomiting-and closely resembles that of neuropathic pain. This improved understanding of chronic nausea has resulted in a paradigm shift with regard to management strategy. Although conventional therapies such as antiemetics and prokinetics are commonly used to manage acute nausea and vomiting, they are historically not as effective in treating chronic nausea. Recently, neuromodulator agents, such as tricyclic antidepressants, gabapentin, olanzapine, mirtazapine, and benzodiazepines, and cannabinoids have been shown to be efficacious in the treatment of nausea and vomiting, and may be useful in the treatment of chronic symptoms. There is a need to study these agents, especially in the management of chronic functional nausea. Improved understanding of the central and peripheral circuitry of nausea and vomiting symptoms will allow for enhanced utilization of the currently available medications, and the development of novel therapeutic options.

Treatments for hyperemesis gravidarum and nausea and vomiting in pregnancy: a systematic review and economic assessment

BACKGROUND

Nausea and vomiting in pregnancy (NVP) affects up to 85% of all women during pregnancy, but for the majority self-management suffices. For the remainder, symptoms are more severe and the most severe form of NVP - hyperemesis gravidarum (HG) - affects 0.3-1.0% of pregnant women. There is no widely accepted point at which NVP becomes HG.

OBJECTIVES

This study aimed to determine the relative clinical effectiveness and cost-effectiveness of treatments for NVP and HG.

DATA SOURCES

MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials, PsycINFO, Commonwealth Agricultural Bureaux (CAB) Abstracts, Latin American and Caribbean Health Sciences Literature, Allied and Complementary Medicine Database, British Nursing Index, Science Citation Index, Social Sciences Citation Index, Scopus, Conference Proceedings Index, NHS Economic Evaluation Database, Health Economic Evaluations Database, China National Knowledge Infrastructure, Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effects were searched from inception to September 2014. References from studies and literature reviews identified were also examined. Obstetric Medicine was hand-searched, as were websites of relevant organisations. Costs came from NHS sources.

REVIEW METHODS

A systematic review of randomised and non-randomised controlled trials (RCTs) for effectiveness, and population-based case series for adverse events and fetal outcomes. Treatments: vitamins B6 and B12, ginger, acupressure/acupuncture, hypnotherapy, antiemetics, dopamine antagonists, 5-hydroxytryptamine receptor antagonists, intravenous (i.v.) fluids, corticosteroids, enteral and parenteral feeding or other novel treatment. Two reviewers extracted data and quality assessed studies. Results were narratively synthesised; planned meta-analysis was not possible due to heterogeneity and incomplete reporting. A simple economic evaluation considered the implied values of treatments.

RESULTS

Seventy-three studies (75 reports) met the inclusion criteria. For RCTs, 33 and 11 studies had a low and high risk of bias respectively. For the remainder (n = 20) it was unclear. The non-randomised studies (n = 9) were low quality. There were 33 separate comparators. The most common were acupressure versus placebo (n = 12); steroid versus usual treatment (n = 7); ginger versus placebo (n = 6); ginger versus vitamin B6 (n = 6); and vitamin B6 versus placebo (n = 4). There was evidence that ginger, antihistamines, metoclopramide (mild disease) and vitamin B6 (mild to severe disease) are better than placebo. Diclectin^® [Duchesnay Inc.; doxylamine succinate (10 mg) plus pyridoxine hydrochloride (10 mg) slow release tablet] is more effective than placebo and ondansetron is more effective at reducing nausea than pyridoxine plus doxylamine. Diclectin before symptoms of NVP begin for women at high risk of severe NVP recurrence reduces risk of moderate/severe NVP compared with taking Diclectin once symptoms begin. Promethazine is as, and ondansetron is more, effective than metoclopramide for severe NVP/HG. I.v. fluids help correct dehydration and improve symptoms. Dextrose saline may be more effective at reducing nausea than normal saline. Transdermal clonidine patches may be effective for severe HG. Enteral feeding is effective but extreme method treatment for very severe symptoms. Day case management for moderate/severe symptoms is feasible, acceptable and as effective as inpatient care. For all other interventions and comparisons, evidence is unclear. The economic analysis was limited by lack of effectiveness data, but comparison of costs between treatments highlights the implications of different choices.

LIMITATIONS

The main limitations were the quantity and quality of the data available.

CONCLUSION

There was evidence of some improvement in symptoms for some treatments, but these data may not be transferable across disease severities. Methodologically sound and larger trials of the main therapies considered within the UK NHS are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013006642.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The neurotoxic effects of prenatal gabapentin and oxcarbazepine exposure on newborn rats

AIM

Teratogenicity is a problematic issue for pregnant women because of X-ray radiation, drugs, and genetic and unknown variables. First-generation antiepileptic drugs (AED) like valproic acid are well-known teratogens for developing fetuses. However, their usage is necessary in order to prevent maternal seizures. The underlying mechanism of birth defects associated with AED exposure remains unclear and information about the neurotoxic effects of prenatal exposure to AED is still limited. Oxcarbazepine (OXC) and gabapentin (GBP) are second-generation AED. It still remains unclear how much these drugs are safe during pregnancy. This study aimed to investigate whether any neurotoxic effect of OXC and GBP in utero exposure on the developing brain.

METHODS

Eighteen pregnant Wistar albino rats were divided into six groups. The first group was exposed to OXC at 100 mg/kg/day, the second to GBP at 50 mg/kg/day, and third to saline (0.9% NaCl) at 1.5 ml/day between the first and the fifth days of gestation. The same procedure was applied at the same dosages between the 6th and the 15th days of gestation for the 2nd three groups. Five female offspring (total n = 30, 45 days old) were taken from each group and stereological methods were applied in order to analyze the total and dopaminergic neuron number of the substantia nigra pars compacta (SNc).

CONCLUSION

The result is that the OXC and GBP exposure at different gestational periods may not give rise to congenital malformation and it appears that the GBP exposure during the organogenesis period proliferatively affects the total number of neurons.

Treatment options for hyperemesis gravidarum

Hyperemesis gravidarum (HG) is a severe and prolonged form of nausea and/or vomiting during pregnancy. HG affects 0.3-2% of pregnancies and is defined by dehydration, ketonuria, and more than 5% body weight loss. Initial pharmacologic treatment for HG includes a combination of doxylamine and pyridoxine. Additional interventions include ondansetron or dopamine antagonists such as metoclopramide or promethazine. The options are limited for women who are not adequately treated with these medications. We suggest that mirtazapine is a useful drug in this context and its efficacy has been described in case studies. Mirtazapine acts on noradrenergic, serotonergic, histaminergic, and muscarinic receptors to produce antidepressant, anxiolytic, antiemetic, sedative, and appetite-stimulating effects. Mirtazapine is not associated with an independent increased risk of birth defects. Further investigation of mirtazapine as a treatment for HG holds promise to expand treatment options for women suffering from HG.

Newest Drugs for Chronic Unexplained Nausea and Vomiting

OPINION STATEMENT

Chronic unexplained nausea and vomiting (CUNV) refers to a symptom complex defined by nausea and/or vomiting with normal diagnostic testing, including anatomic assessments (including upper endoscopy) and measures of upper gut function (e.g., gastric emptying testing). Nausea and vomiting in this condition are postulated to result from aberrant peripheral or central neurohumoral activity. A substantial subset of patients satisfies this diagnosis as more than half of individuals referred for scintigraphic testing exhibit normal gastric emptying rates. No randomized, placebo-controlled trials of any medication treatment have been performed in CUNV. However, agents with potential therapeutic benefits in CUNV include antiemetic drugs, neuromodulatory treatments which are proposed to act by reducing gastric sensitivity, and medications with prokinetic action to stimulate upper gut propulsion. Recently approved drugs with antiemetic capability include serotonin antagonists with novel modes of delivery and neurokinin antagonists with or without additional serotonergic blocking capabilities. Existing neuroleptics and pain-modifying neuromodulatory therapies with fortuitous antiemetic benefits are being considered for their benefits in this disorder. Furthermore, current investigations will define potential therapeutic actions of agents that stimulate gastric emptying via action on gastroduodenal serotonin, motilin, and ghrelin receptors. This current research may broaden the treatment options for refractory cases of unexplained nausea and vomiting.

Central Aspects of Nausea and Vomiting in GI Disorders

OPINION STATEMENT

Nausea and vomiting result from continuous interactions among gastrointestinal, central nervous system, and autonomic nervous system. Despite being closely associated, central pathways of nausea and vomiting appear to be at least partly different and nausea is no longer considered only a penultimate step of vomiting. Although our understanding of central pathways of nausea has improved over the last one decade, it is still very basic. Afferent pathways from gastrointestinal tract via vagus, vestibular system, and chemoreceptor trigger zone project to nucleus tractus solitarius which, in turn, relays the signal to central pattern generator initiating multiple downstream pathways. This central nausea pathway appears to be under constant modulation by autonomic nervous system and cerebral cortex. There is also some evidence that central pathway of chronic nausea is different from that of acute nausea and closely resembles that of neuropathic pain. This improved understanding has modified the way we can approach the treatment of acute and chronic nausea. While conventional therapies such as antiemetics (antiserotoninergic, antihistaminic, antidopaminergic) and prokinetics are commonly used to manage acute nausea, they are not as effective in improving chronic nausea. Recently, neuromodulators such as tricyclic antidepressants, gabapentin, olanzapine, benzodiazepines, and cannabinoids have been shown to have antinausea effect. There is a need to study the utility of these drugs in managing chronic functional nausea. Improving our understanding of central and peripheral circuitry of nausea will allow us to better utilize the currently available drugs and develop new therapeutic options.

The Effect of Preoperative Gabapentin on Postoperative Nausea and Vomiting: A Meta-Analysis

BACKGROUND

Preoperative gabapentin has been shown to improve postoperative pain and limit reliance on opioid analgesia. On the basis of an alternative mechanism, our group investigated the ability of preoperative gabapentin to prevent postoperative nausea and vomiting (PONV).

METHODS

We performed a meta-analysis of trials that reported outcomes on the effect of preoperative gabapentin on PONV end points in patients undergoing general anesthesia. In our primary analysis, we calculated the pooled antiemetic effects of preoperative gabapentin in studies with PONV as the primary end point. In our secondary analysis, we calculated the pooled effects in trials involving preoperative gabapentin that reported on the side effects, nausea and vomiting.

RESULTS

Among the trials designed with PONV as a primary end point (8 trials; n = 838), preoperative gabapentin was associated with a significant reduction in PONV (risk ratio [RR] = 0.60; 99% confidence interval [CI], 0.50-0.72; P < 0.0001), nausea (RR = 0.34; 99% CI, 0.20-0.56; P < 0.0001), and vomiting (RR = 0.34; 99% CI, 0.19-0.61; P = 0.0002) at 24 hours. Among all included trials (44 trials; n = 3489) that reported on the side effects, nausea and vomiting, similar reductions were noted in PONV with preoperative gabapentin administration. Subgroup analysis of trials excluding repeat dosing, thiopental induction, and nitrous oxide maintenance and including high-risk surgery resulted in similar PONV efficacy. Preoperative gabapentin is also associated with significantly increased rates of postoperative sedation (RR = 1.22; 95% CI, 1.02-1.47; P = 0.03) compared with control.

CONCLUSIONS

Preoperative gabapentin is associated with a significant reduction in PONV among studies designed to investigate this end point. Preoperative gabapentin should be considered not only as part of a multimodal approach to postoperative analgesia, but also for prevention of PONV.

The Risk of Specific Congenital Anomalies in Relation to Newer Antiepileptic Drugs: A Literature Review

BACKGROUND

More information is needed about possible associations between the newer anti-epileptic drugs (AEDs) in the first trimester of pregnancy and specific congenital anomalies of the fetus.

OBJECTIVES

We performed a literature review to find signals for potential associations between newer AEDs (lamotrigine, topiramate, levetiracetam, gabapentin, oxcarbazepine, eslicarbazepine, felbamate, lacosamide, pregabalin, retigabine, rufinamide, stiripentol, tiagabine, vigabatrin, and zonisamide) and specific congenital anomalies.

METHODS

We searched PubMed and EMBASE to find observational studies with pregnancies exposed to newer AEDs and detailed information on congenital anomalies. The congenital anomalies in the studies were classified according to the congenital anomaly subgroups of European Surveillance of Congenital Anomalies (EUROCAT). We compared the prevalence of specific congenital anomalies in fetuses exposed to individual AEDs in the combined studies with that of the general population in a reference database. A significantly higher prevalence based on three or more fetuses with anomalies was considered a signal.

RESULTS

Topiramate showed a higher rate of congenital anomalies than the other newer AEDs. Four signals were found. The signals for associations between topiramate and cleft lip with/without cleft palate and hypospadias were considered strong. Associations between lamotrigine and anencephaly and transposition of great vessels were found within one study and were not supported by other studies. No signals were found for the other newer AEDs, or the information was too limited to provide such a signal.

CONCLUSION

In terms of associations between monotherapy with a newer AED in the first trimester of pregnancy and a specific congenital anomaly, the signals for topiramate and cleft lip with/without cleft palate and hypospadias should be investigated further.

Gabapentin for Postoperative Vomiting in Children Requiring Posterior Fossa Tumor Resection

Gabapentin is well known for its pain control and antiepileptic effect, but its antiemetic effect is poorly investigated. Here we report on effective gabapentin use for refractory vomiting after craniotomy in two children with medulloblastoma in the fourth ventricle. The two pediatric patients (an 11-year-old girl and a 4-year-old boy) underwent near-total excision of the tumor via craniotomy. Both patients suffered from refractory postoperative nausea and vomiting, treated with multiple traditional antiemetic drugs but without relief. After gabapentin intake, their nausea and vomiting improved from one to two episodes per day to complete resolution of symptoms. This report suggests that gabapentin may be a novel antiemetic therapeutic intervention for patients with refractory nausea and vomiting after craniotomy.

Potential maternal symptomatic benefit of gabapentin and review of its safety in pregnancy

Restless legs syndrome (RLS) and nausea and vomiting of pregnancy (NVP) are both common maternal conditions affecting quality of life. Gabapentin is currently FDA-approved for treating RLS and preliminary results have shown it may be effective for treating the most severe form of NVP, hyperemesis gravidarum (HG). Because NVP and HG symptoms peak early in pregnancy, the potential teratogenicity of gabapentin needs to be considered. We reviewed published pregnancy registries and cohorts for pregnancy outcomes associated with maternal gabapentin use. Gabapentin exposures from 5 pregnancy registries, 1 HG pilot study and 2 additional cases were reviewed. Among 294 first trimester gabapentin-monotherapy exposures, there were 5 major congenital malformations (MCMs) reported (1.7%), which favorably compares to the MCM rate in the general population (1.6-2.2%). Two of the registries reported maternal gabapentin use among 261 singleton pregnancies to be associated with roughly equivalent rates of premature birth, birth weight after correction for gestational age at delivery and maternal hypertension/eclampsia as those that have been reported in the general population. These data support the safety of gabapentin use in pregnancy; however, the number of exposures to date is still small. If future pregnancy registry data confirm this positive safety profile, gabapentin therapy would likely be a safe and effective treatment for RLS during pregnancy. Controlled, clinical trials are needed to assess gabapentin's effectiveness for HG.

Gabapentin's anti-nausea and anti-emetic effects: a review

Gabapentin's main clinical use is in the treatment of neuropathic pain where its binding to neuronal alpha-2/delta subunits of voltage-gated calcium channels (VGCCs) is critical to its mechanism of action. Over the past 10 years, there have been several reports of gabapentin also having anti-nausea and anti-emetic effects in conditions including postoperative nausea and vomiting (PONV), chemotherapy-induced nausea and vomiting (CINV), and hyperemesis gravidarum (HG). In this report, a MEDLINE electronic search was performed, and relevant citations were reviewed and classified by level of evidence; a grade of recommendation was then assigned for gabapentin's use for each studied indication. Out of 33 clinical trials reviewed, 12 assessed nausea and/or vomiting (N/V) associated with gabapentin therapy as primary outcome measures. These 12 studies provided a Grade A recommendation for gabapentin use in treating PONV, a Grade B recommendation for use in treating CINV, and a Grade C recommendation for use in treating HG. Further research is needed to confirm these initial promising results, which implicate the alpha-2/delta VGCC subunit as a novel therapeutic target in the treatment of several N/V-associated clinical conditions.

Pregnancy outcomes following gabapentin use: results of a prospective comparative cohort study

OBJECTIVES

Our objectives were to 1) determine whether first-trimester use of gabapentin is associated with an increased risk for major malformations; 2) examine rates of spontaneous abortions, therapeutic abortions, stillbirths, mean birth weight and gestational age at delivery; and 3) examine rates of poor neonatal adaptation syndrome following late pregnancy exposure.

METHODS

The study design was prospective. Women were included who initially contacted the services between 5 and 8 weeks with a comparison group of women exposed to nonteratogens, collected in a similar manner.

RESULTS

We have data on 223 pregnancy outcomes exposed to gabapentin and 223 unexposed pregnancies. The rates of major malformations were similar in both groups (p = 0.845). There was a higher rate of preterm births (p = 0.019) and low birth weight <2,500 g (p = 0.033) in the gabapentin group. Among infants who were exposed to gabapentin up until delivery, 23 of 61 (38%) were admitted to either the neonatal intensive care unit or special care nursery for observation and/or treatment, vs 6 of 201 (2.9%) live births in the comparison group (p < 0.001). There were 2 cases of possible poor neonatal adaptation syndrome in neonates exposed to gabapentin close to delivery, compared with none in the comparison group, although it must be noted that these infants were concomitantly exposed to other psychotropic drugs. Among the women who took gabapentin, the major indications were pain (n = 90; 43%) and epilepsy (n = 71; 34%); the remainder were for other indications, mostly psychiatric.

CONCLUSION

Our results suggest that although this sample size is not large enough to make any definitive conclusions, and there was no comparator group treated with other antiepileptic drugs, gabapentin use in pregnancy does not appear to increase the risk for major malformations. This finding and the increased risk for low birth weight and preterm birth require further investigation.

Newer anticonvulsants: lamotrigine, topiramate and gabapentin

BACKGROUND The second generation antiepileptic drugs (AEDs), which include lamotrigine, topiramate, and gabapentin, have been introduced during the past 20 years. Because the newer AEDs differ in their pharmacokinetics from the first generation AEDs, it is hoped that the second generation AEDs will be less teratogenic. METHODS The findings in pregnancy cohorts and case-control studies concerning lamotrigine, topiramate and gabapentin-exposed pregnancies have been analyzed. RESULTS The rate of all malformations in lamotrigine monotherapy-exposed pregnancies has been between 2.0 and 5.6%, in comparison to baseline rates of 1.1 to 3.6% in two unexposed comparison groups. Compared to reference populations, a higher risk (0.4%) of isolated oral clefts has been observed in one cohort of 1562 lamotrigine-exposed pregnancies, but the risk was lower (0.1%) in other studies. In topiramate-exposed pregnancies, the rate of all malformations has been 4.2 to 4.9%, with an increase in oral clefts with and without other anomalies. The limited information available now for gabapentin has shown no evidence of teratogenicity. Concerning other developmental effects of these drugs, young children exposed to lamotrigine in utero have shown no deficits in cognitive function. Prenatal exposure to topiramate has been associated with an elevated frequency of small size for gestational age newborns. CONCLUSIONS The information available suggests an increased risk of oral clefts in infants exposed to topiramate, and perhaps lamotrigine, early in pregnancy, and of growth retardation for topiramate-exposed infants. Larger sample sizes are needed to clarify the questions that have been raised.