NTP-CERHR Expert Panel Report on the reproductive and developmental toxicity of fluoxetine

Enduring sexual dysfunction after treatment with antidepressants, 5α-reductase inhibitors and isotretinoin: 300 cases

OBJECTIVE:

To investigate clinical reports of post-SSRI sexual dysfunction (PSSD), post-finasteride syndrome (PFS) and enduring sexual dysfunction following isotretinoin.

METHODS:

Data from RxISK.org, a global adverse event reporting website, have been used to establish the clinical features, demographic details and clinical trajectories of syndromes of persistent sexual difficulties following three superficially different treatment modalities.

RESULTS

We report on 300 cases of enduring sexual dysfunction from 37 countries following 14 different drugs comprised of serotonin reuptake inhibiting antidepressants, 5α-reductase inhibitors and isotretinoin. While reports of certain issues were unique to the antidepressants, such as the onset of premature ejaculation and persistent genital arousal disorder (PGAD), there was also a significant overlap in symptom profile between the drug groups, with common features including genital anaesthesia, pleasureless or weak orgasm, loss of libido and impotence. Secondary consequences included relationship breakdown and impaired quality of life.

CONCLUSIONS

These data point to a legacy syndrome or syndromes comprising a range of disturbances to sexual function. More detailed studies will require developments in coding systems that recognise the condition(s). Further exploration of these tardive sexual syndromes may yield greater understanding of tardive syndromes in general.

Depressing Antidepressant: Fluoxetine Affects Serotonin Neurons Causing Adverse Reproductive Responses in Daphnia magna

Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressants. As endocrine disruptive contaminants in the environment, SSRIs affect reproduction in aquatic organisms. In the water flea Daphnia magna, SSRIs increase offspring production in a food ration-dependent manner. At limiting food conditions, females exposed to SSRIs produce more but smaller offspring, which is a maladaptive life-history strategy. We asked whether increased serotonin levels in newly identified serotonin-neurons in the Daphnia brain mediate these effects. We provide strong evidence that exogenous SSRI fluoxetine selectively increases serotonin-immunoreactivity in identified brain neurons under limiting food conditions thereby leading to maladaptive offspring production. Fluoxetine increases serotonin-immunoreactivity at low food conditions to similar maximal levels as observed under high food conditions and concomitantly enhances offspring production. Sublethal amounts of the neurotoxin 5,7-dihydroxytryptamine known to specifically ablate serotonin-neurons markedly decrease serotonin-immunoreactivity and offspring production, strongly supporting the effect to be serotonin-specific by reversing the reproductive phenotype attained under fluoxetine. Thus, SSRIs impair serotonin-regulation of reproductive investment in a planktonic key organism causing inappropriately increased reproduction with potentially severe ecological impact.

Selective Serotonin Re-uptake Inhibitors (SSRIs) Induced Weight Changes: A Dose and Duration Dependent Study on Albino Rats

INTRODUCTION

Selective Serotonin Re-uptake Inhibitors (SSRIs) are the most significant and safe drugs among the antidepressants. Fluoxetine is the prototype drug of SSRIs. Various clinical studies showed that SSRI causes change in body weight in patients. This study was conducted to know the extent of weight change with different doses for different durations.

AIM

The aim of this study was to find out whether fluoxetine causes weight gain or weight loss, and to deduce the comparative weight change after intraperitoneal injection of fluoxetine for different duration and doses.

MATERIALS AND METHODS

Present study was conducted on 72 adult (36 males and 36 females) albino rats, in 3 phases of 2 weeks, 4 weeks and 12 weeks duration. Each phase consisted of 24 (12 males and 12 females) albino rats. These 24 rats were further randomly subdivided into 4 Groups of 6 albino rats each (3 males & 3 females). Group 1(Control) received normal saline (vehicle). Rest 18 rats of each phase were experimental rats, of Group 2, Group 3 and Group 4 (6 rats each). Group 2, group 3 and group 4 experimental rats received 10mg/kg, 20 mg/kg and 40mg/kg of intraperitoneal injection of fluoxetine respectively. All rats were weighed on each day for growth monitoring. Data was subjected to statistical analysis (Mean, standard deviation and Student's t-Test).

RESULTS

All experimental group rats which received fluoxetine showed decrease of body weight. Rats which received high doses of fluoxetine could not tolerate the drug for more than two weeks and died due to excessive body weight loss, loose stools and muscle twitching.

CONCLUSION

Present study conclude that SSRIs can cause weight change in the form of decrease of body weight. This property of SSRIs can be used clinically by prescribing these drugs to obese psychiatric patient without any fear of withdrawal of drug.

In vitro modulation of estrogen receptor activity by norfluoxetine

Background and aims

Selective serotonin reuptake inhibitors (SSRIs) are antidepressants increasingly prescribed for pregnancy and postpartum depression. However, these compounds can cross the placenta and also pass into breast milk, thus reaching the fetus and infant during critical developmental stages, potentially causing adverse effects. Fluoxetine, a widely used SSRI, has been shown to affect (neuro)endocrine signaling in various organisms, including humans. This compound can also interact with estrogen receptors in vitro and cause an estrogen-dependent uterotrophic response in rodents. Consequently, the aim of the present study was to assess if the active metabolite of fluoxetine, namely norfluoxetine (NFLX), shares the same capacity for estrogen receptor interaction.

Methods

The in vitro (anti)estrogenic activity of norfluoxetine was assessed using a firefly luciferase reporter construct in the T47D-Kbluc breast cancer cell line. These cells express nuclear estrogen receptors (ERs) that can activate the transcription of the luciferase reporter gene upon binding of ER agonists. Light emission was monitored in case of cells exposed to norfluoxetine or mixtures of norfluoxetine-estradiol. Cell viability was assessed using a resazurin-based assay.

Results

During individual testing, NFLX was able to induce a significant increase in luciferase activity compared to control, but only at the highest concentration tested (10 μM). In binary mixtures with estradiol (30 pM constant concentration) a significant increase in luminescence was observed at low submicromolar norfluoxetine concentrations compared to estradiol alone.

Conclusion

Norfluoxetine can induce estrogenic effects in vitro and can potentiate the activity of estradiol. However, further studies are needed to clarify if these observed estrogenic effects may have detrimental consequences for human exposure.

The role of clomipramine in potentiating the teratogenic effects of caffeine in pregnant rats: a histopathological study

Since little is known about the teratogenic effects of clomipramine used concurrently with caffeine during the organogenesis period, the aim of this study was to test the teratogenic effects of a coadministration of caffeine and clomipramine on rat fetuses. We divided 42 pregnant rats into seven groups, randomly. The first group (control) received 0.5 mL of normal saline. Clomipramine was injected at 40 mg/kg and 80 mg/kg to the second and third groups, respectively. The fourth and fifth groups received caffeine in doses of 60 mg/kg and 120 mg/kg, respectively. The sixth group received a combination of 40 mg/kg clomipramine and 60 mg/kg caffeine, and the seventh group was given clomipramine and caffeine at 80 mg/kg and 120 mg/kg, respectively. The fetuses were removed on the 17th day of pregnancy and studied in terms of microscopic and macroscopic morphological features. Fetuses of rats receiving high doses of caffeine or combinations of caffeine and clomipramine showed a significant rate of cleft palate development, open eyelids, mortality, torsion anomalies, shrinkage of skin, and subcutaneous haemorrhage (P ≤ 0.001). This study concludes that caffeine in high doses or the simultaneous administration of caffeine and clomipramine leads to teratogenicity.

Disturbed development of the enteric nervous system after in utero exposure of selective serotonin re-uptake inhibitors and tricyclic antidepressants. Part 2: Testing the hypotheses

AIMS

Antidepressant use has increased in the last decade. Several studies have suggested a possible association between maternal antidepressant use and teratogenic effects.

METHODS

The pharmacy prescription database IADB.nl was used for a cohort study in which laxative and antidiarrhoeal medication use in children after in utero exposure to antidepressants (TCA, SSRI, fluoxetine or paroxetine exposed) was compared with no antidepressant exposure. Laxatives and antidiarrhoeal medication use were applied as a proxy for constipation and diarrhoea respectively, which may be associated with disturbed enteric nervous system (ENS) development.

RESULTS

Children exposed in utero to SSRIs (mainly fluoxetine and paroxetine) in the second and third trimester or to TCAs in the first trimester, more often received laxatives. Combined exposure to TCAs and SSRIs in pregnancy was associated with a 10-fold increase in laxative use. In utero exposure to SSRIs is not associated with antidiarrhoeal medication use compared with non-exposed children. In contrast, antidiarrhoeal medication use was significantly higher in children exposed to TCAs anytime in pregnancy.

CONCLUSIONS

The increased laxative use after second and third trimester exposure to SSRIs might be explained through the inhibitory effect of the serotonin re-uptake transporter (SERT) and because of selectivity for the 5-HT(2B) receptor which affects the ENS. TCA exposure during the first trimester leads to increased laxative use probably through inhibition of the norepinephrine transporter (NET). Exposure of TCAs anytime in pregnancy leads to increase diarrhoeal use possibly through down-regulation of α₂-adrenoceptors or up-regulation of the pore forming α(1c) subunit.

Delivery outcome after maternal use of antidepressant drugs in pregnancy: an update using Swedish data

BACKGROUND

Concerns have been expressed about possible adverse effects of the use of antidepressant medication during pregnancy, including risk for neonatal pathology and the presence of congenital malformations.

METHOD

Data from the Swedish Medical Birth Register (MBR) from 1 July 1995 up to 2007 were used to identify women who reported the use of antidepressants in early pregnancy or were prescribed antidepressants during pregnancy by antenatal care: a total of 14 821 women with 15 017 infants. Maternal characteristics, maternal delivery diagnoses, infant neonatal diagnoses and the presence of congenital malformations were compared with all other women who gave birth, using the Mantel-Haenszel technique and with adjustments for certain characteristics.

RESULTS

There was an association between antidepressant treatment and pre-existing diabetes and chronic hypertension but also with many pregnancy complications. Rates of induced delivery and caesarean section were increased. The preterm birth rate was increased but not that of intrauterine growth retardation. Neonatal complications were common, notably after tricyclic antidepressant (TCA) use. An increased risk of persistent pulmonary hypertension of the newborn (PPHN) was verified. The congenital malformation rate was increased after TCAs. An association between use of paroxetine and congenital heart defects was verified and a similar effect on hypospadias was seen.

CONCLUSIONS

Women using antidepressants during pregnancy and their newborns have increased pathology. It is not clear how much of this is due to drug use or underlying pathology. Use of TCAs was found to carry a higher risk than other antidepressants and paroxetine seems to be associated with a specific teratogenic property.

Modest effects of repeated fluoxetine on estrous cyclicity and sexual behavior in Sprague Dawley female rats

In an earlier study, we reported that daily fluoxetine treatment (10 mg/kg/day) rapidly disrupted estrous cyclicity and sexual receptivity in adult, regularly cycling Fischer rats. The current study was designed to investigate if comparable fluoxetine treatment would similarly affect intact, regularly cycling Sprague Dawley rats. In the first experiment, fluoxetine was injected for 24 days. After 11-14 days of daily fluoxetine treatment, 40% of the rats showed a transient disturbance of the estrous cycle with elimination of sexual receptivity. In these affected rats, reduced sexual receptivity generally preceded disruption of vaginal cyclicity. In a second experiment, a shorter exposure was used to attempt to dissociate effects of fluoxetine on behavior and estrous cyclicity. Nine days of fluoxetine treatment eliminated sexual receptivity and proceptivity (hops/darts) in 40% and 46%, respectively, of rats without altering the estrous cycle. Female rats then received a 10th fluoxetine injection 30 min prior to assessment of sexual motivation (measured with the male preference paradigm). There was no effect of fluoxetine on male preference, but fluoxetine significantly reduced the number of crossings and seconds of grooming during preference testing. Therefore, effects of fluoxetine on estrous cyclicity and behavior of Sprague Dawley female rats were smaller and required longer to develop than previously reported in Fischer female rats. These findings reinforce a probable relationship between fluoxetine's effect on sexual activity and neuroendocrine disturbances and illustrate the importance of strain selection in attempting to model human disease.

Daily male exposure attenuates estrous cycle disruption by fluoxetine

Fluoxetine (Prozac) produces sexual dysfunction in a substantial number of patients. In the few animal studies designed to address this sexual dysfunction in females, data have been inconsistent. Some investigators report that the drug disrupts sexual behavior without affecting the estrous cycle while we have reported robust effects of fluoxetine on the estrous cycle. The current studies were designed to initiate examination of procedural differences that may account for these contradictory outcomes. In the first experiment, intact, regularly cycling female rats were injected daily for 10 days with 10 mg/kg fluoxetine (intraperitoneally) or vehicle. Male-exposed, fluoxetine- or vehicle-treated rats were housed in a room with males and placed for 5 min/day into a male's cage. Other fluoxetine-treated females were housed in a room separate from males. In the second experiment, this protocol was repeated for 20 days and an additional group of females were exposed to male bedding for 5 min/day. Without male exposure, fluoxetine rapidly disrupted vaginal estrus and sexual receptivity so that approximately 50% of the rats failed to show vaginal estrus during the first 5 days; and the majority of the rats had a blocked cycle by 10 days of treatment. With male exposure, these reproductive effects were attenuated. The majority of rats cycled normally during the first 5 days of treatment and more than half cycled throughout the experiment. Loss of behavioral receptivity occurred even when normal estrous cyclicity was present. Although exposure to the male's bedding may have delayed the onset of estrous cycle disruption, five min daily exposure to a male's bedding did not prevent the disruptive effects of fluoxetine. These findings are consistent with evidence that fluoxetine's effect on female sexual dysfunction may result, in part, from the drugs' disruption of the hypothalamic-pituitary-gonadal axis. However, the data also evidence dissociation between the effects of fluoxetine on vaginal and behavioral estrus. These findings may also explain why different laboratories have reported the presence or absence of estrous cycle disturbances following daily treatment with fluoxetine.

The safety of antidepressant drugs during pregnancy

This article discusses known or suspected effects of maternal use of antidepressants during pregnancy on pregnancy outcome. It is unlikely that any marked teratogenic effect occurs with the possible exception of an increased risk for cardiovascular defects after maternal use of clomipramine or paroxetine. An increased risk for preterm birth is seen. Transient neonatal symptoms are common after the use of antidepressants in late pregnancy. Few firm data are available on the possible impact on the long-term neuropsychological development of the infants. The magnitude of the actual contribution from drug therapy is unclear; it is likely that the underlying pathology of the mother explains part of the anomalies. Selective serotonin re-uptake inhibitor drugs seem to represent a smaller hazard than tricyclic antidepressants. Further research to separate the effects of the drug and underlying pathology is urgently needed as are large-scale studies on long-term development. When a pregnant woman has a major depressive disease and non-pharmacological treatments are not enough, the relatively small risk with drug therapy has to be weighed against the considerable risk for a relapse of the disease if therapy is interrupted.

Maternal use of selective serotonin re-uptake inhibitors in early pregnancy and infant congenital malformations

BACKGROUND

Maternal use of selective serotonin re-uptake inhibitors (SSRIs) has recently been associated with an increased risk for certain malformations.

METHODS

Using the Swedish Medical Birth Register, we identified women who had reported the use of SSRIs in early pregnancy and studied their infants, born between July 1, 1995 and the end of 2004. Congenital malformations were identified from that register, from the Register of Congenital Malformations, and from the Hospital Discharge Register. The effect of drug exposure was studied after adjustment for a number of identified maternal characteristics that could act as confounders.

RESULTS

We identified 6,481 women who reported the use of SSRIs in early pregnancy and their 6,555 infants. There was no general increase in malformation risk. An increased risk for cystic kidneys was seen, but this was based on only nine malformed infants, and the pathology varied between these cases. An in-depth study of cardiovascular defects identified an association between such defects and notably ventricular and atrial septum defects and maternal use of paroxetine but not other SSRIs. No support for a postulated association between SSRI use and infant craniostenosis or omphalocele was found.

CONCLUSIONS

Use of SSRIs in early pregnancy does not seem to be a major risk factor for infant malformations. The association between paroxetine use and infant cardiovascular defects may be a result of multiple testing, but is supported by other studies.

Prevalence and patterns of antidepressant drug use during pregnancy

OBJECTIVE

The aim of this study was to determine the extent and patterns of antidepressant use before, during and after pregnancy in a large population in The Netherlands.

METHODS

Health care records and prescription data from one of the largest Dutch health insurance companies were analysed. The study cohort consisted of 29,005 women who had live births in the period between January 2000 and July 2003. Antidepressant drug use during a specified period was defined as there being a record of a prescription during that period.

RESULTS

During the first trimester of pregnancy 2% of all pregnant women of the study cohort were found to have taken antidepressants; in the second and third trimesters, this figure had dropped to 1.8% of all pregnancies. Antidepressant use before as well as during pregnancy was almost twofold higher in women over 35 years of age than in those under 35 years. Almost 60% of the women who used antidepressants before pregnancy stopped taking them in the first trimester, and a smaller number stopped thereafter. Of all women using antidepressants during pregnancy, one third started this medication during gestation. In the 3 months following delivery, the prevalence of antidepressant use was the same as before pregnancy (2.9%). There was no shift to benzodiazepines in the group of women who stopped taking antidepressants during pregnancy. Although paroxetine and fluoxetine were the most frequently used antidepressants among the study group, all modern antidepressants were used.

CONCLUSION

A considerable number of women are being exposed to antidepressants throughout pregnancy up until delivery. One consequence of this is that their newborns need special care and supervision during the first days of life. However, women who stop taking the medication may risk a relapse of their illness, and this may also have a negative effect on the child.

Gender differences in depression and response to psychotropic medication

BACKGROUND

In the United States, depression is approximately twice as common among women as among men, across all age groups.

OBJECTIVE

This review examines gender differences in the epidemiology and clinical presentation of depression, and explores whether women respond differently than men to antidepressant medications.

METHODS

This is a selective review focusing on current issues in the management of depression, with particular attention to gender differences in the epidemiology, diagnosis, and treatment of the disease.

RESULTS

Women are more likely than men to have atypical symptoms of depression (eg, hypersomnia, hyperphagia), to have comorbid anxiety disorders, and to attempt suicide. Women are also more likely to have seasonal affective disorder. Mood and anxiety symptoms that seem to be related to the menstrual cycle do not often represent genuine premenstrual dysphoria, but when premenstrual dysphoric disorder does occur, its impact on quality of life is similar to that of major depressive disorder. There is ongoing controversy about whether men and women respond equally well to antidepressant medications, and preliminary evidence suggests that selective serotonin reuptake inhibitors (SSRIs) are more effective in the presence of estrogen. Depression affects about 10% of pregnant women. Antidepressant medication should be considered during pregnancy if depression is moderate or severe, or if withdrawal of maintenance medication is likely to result in recurrent depression. The potential benefits of using antidepressant medications in a pregnant or breastfeeding woman should be balanced against the potential risks to the newborn. Because of the risk of neonatal withdrawal syndrome, SSRIs should be used at the lowest effective dose during the third trimester of pregnancy and should be tapered before delivery.

CONCLUSIONS

Continuing research is needed to determine how gender influences the risk, clinical presentation, and response to treatment of depression. Exploration of sex differences in animals and humans should aid in efforts to treat depression as an organic disorder rather than a psychological maladaptation.