Carbamazepine, phenytoin, sex hormones, and sexual function in men with epilepsy

Treatment of sexual disorders in people with epilepsy

Sexual dysfunction is underreported in persons with epilepsy. The evaluation of sexual physiology in small samples of epilepsy patients shows abnormal sexual functioning, and points to low free testosterone levels as a contributing factor. Abnormal sexual physiology in epilepsy patients may be due to antiseizure medication-related altered testosterone metabolism and abnormal central gonadotropin secretion due to epileptic physiology in the brain. More information exists on the sexual side effects of "classic" antiseizure medications than the "new generation" of antiseizure medications; barbiturates appear to have the greatest risk. More active surveying for sexual dysfunction should be undertaken in epilepsy clinics; a simple, self-reported scale of sexual functioning is available. Testosterone replacement for men, dehydroepiandrosterone for women, and sildenafil for restoring sexual performance are appropriate.

Sex differences in models of temporal lobe epilepsy: role of testosterone

Kainic acid and pilocarpine were used to assess sex differences in temporal lobe seizures. Adult Sprague-Dawley rats were injected with kainic acid (10-12 mg/kg) or with pilocarpine (380 mg/kg) and behavior was recorded for the next 3 h. Trunk blood was collected for hormonal measurements. Our data indicate that the male is more susceptible to the convulsant effects of agents that produce temporal lobe-like seizures. Males presented a higher amount of full limbic convulsions than females. To assess the role of plasma testosterone levels in kainate-induced seizures, a group of males was gonadectomized and half received testosterone replacement. The presence of testosterone, in intact and in gonadectomized males with testosterone replacement, increased the susceptibility to seizure. Seizures were either stronger (full limbic) or more frequent in animals with testosterone compared to animals devoid of testosterone. These results suggest that differences in plasma levels of testosterone may be partially responsible for the observed gender differences in seizure susceptibility. Our data reveal a reciprocal relationship between kainic acid-induced temporal lobe seizures and plasma testosterone. Testosterone enhances the occurrence and the severity of seizures. Conversely, kainic-acid-induced seizures decrease plasma testosterone. The higher plasma corticosterone levels found in these males suggest that kainic acid-induced seizures activate the hypothalamic-pituitary-adrenal axis which may induce alterations in plasma levels of male reproductive hormones.

Female sexual disorders: psychiatric aspects

OBJECTIVE

This manuscript reviews the current information concerning female sexual dysfunction that is relevant to general psychiatric practice.

METHOD

Research identified by the key words sexual dysfunction and prevalence, comorbidity, psychiatric drugs, or pharmacotherapy is reviewed.

RESULTS

Epidemiologic studies indicate that approximately 30% of female subjects between ages 18 and 59 years have sexual complaints of at least 3 months' duration in the past year. A high comorbidity with other psychiatric syndromes exists. Many psychiatric drugs are associated with sexual dysfunction. Drug treatments for female sexual dysfunction are being investigated.

CONCLUSION

Knowledge concerning the treatment of female sexual dysfunction is important to the general psychiatric clinician.

Early hormonal changes during valproate or carbamazepine treatment: a 3-month study

BACKGROUND

Long-term treatment with valproate (VPA) or carbamazepine (CBZ) may induce reproductive endocrine disorders in patients with epilepsy.

METHODS

Serum concentrations of reproductive hormones were studied in 17 women and 22 men with recently diagnosed epilepsy before they started either VPA or CBZ medication, and 1 and 3 months later.

RESULTS

No weight gain or clinical signs of hormonal disorders were observed during the follow-up. The mean serum levels of testosterone, luteinizing hormone, follicle-stimulating hormone, and sex hormone-binding globulin (SHBG) increased, and dehydroepiandrosterone sulfate (DHEAS) decreased, in women starting VPA. Serum testosterone levels increased in half of the women on VPA. Serum concentrations of progesterone and dehydroepiandrosterone increased, and gonadotropins decreased, in men on VPA during the follow-up. Serum SHBG levels increased and DHEAS decreased during the first months of CBZ treatment in both sexes. In addition, the free-androgen index decreased in men after starting CBZ.

CONCLUSIONS

Hormonal changes occur after only 1 month's use of VPA or CBZ. VPA-treatment seems to be associated with increased serum androgen levels, but the profile of hormonal changes appears to be different in women than in men. The use of CBZ, in turn, was associated with increased SHBG concentrations and thus with diminished sex steroid function in both sexes. The women with increased serum testosterone levels in the early phase of VPA medication may be at increased risk for VPA-related endocrine disorders later during treatment.

Seizures, hormones and sexuality

Sexual disorders (both hyposexuality and sexual dysfunction) are common in people with epilepsy, occurring in up to two-thirds of patients. However, characteristically, patients do not spontaneously report these problems. Nocturnal penile tumescence testing suggests that the erectile dysfunction has a neurophysiological component. The aetiology remains uncertain but is likely to be multifactorial, involving neurological, endocrine, iatrogenic, cognitive, psychiatric and psychosocial factors. Epilepsy-related factors include the age of onset/duration of epilepsy along with the seizure type and focus. In addition, seizure frequency might be relevant as successful epilepsy surgery can result in an improvement in sexual functioning despite remaining on anticonvulsant medication. Endocrine changes (raised sex hormone binding globulin and reduced free testosterone) have been reported in men with epilepsy, especially when treated with hepatic-enzyme inducing antiepileptic drugs. Studies have not been performed evaluating anticonvulsants that do not induce hepatic enzymes such as lamotrigine. The association between these endocrine changes and hyposexuality is not known. The relationship between seizures, hormones and anticonvulsant medication in women is explored, focusing on issues such as catamenial epilepsy, the menopause, hormone replacement therapy and the polycystic ovarian syndrome. Suggestions for future research and treatment issues are discussed.

Interictal hyposexuality in male patients with epilepsy

The purpose of this study was to compare the serum levels of androgens between hyposexual and non-hyposexual patients with epilepsy. Adult male patients with epilepsy were investigated. Serum levels of testosterone (T) and free-T, estradiol, and sex hormone binding globulin (SHBG) were measured and the free androgen index (FAI) was calculated. While there were no differences between hyposexual and non-hyposexual patients in the serum levels of T, free-T, and estradiol, or to the FAI, the serum levels of SHBG were significantly higher in hyposexual patients than in non-hyposexual patients. Thus, the effects of increased SHBG upon serum levels of testosterone biologically active in patients with epilepsy and hyposexuality were not detected by the methods used in this study. Four (44%) of nine hyposexual patients who were re-evaluated after two years follow-up improved sexual performance. Thus, clinical treatment that results in good seizure control may improve sexual performance in some patients with epilepsy.

Phenytoin inhibits both the first ovulation and uterine development in gonadotropin-primed immature rats

This study was planned to determine the effects and possible mechanism of action of phenytoin on development of the reproductive tract and first ovulation in immature rats. Rats were injected s.c. with 5 IU of equine chorionic gonadotrophin (equine CG) on day 26 to induce ovarian and uterine development. Treatment with phenytoin (140 mg/kg) at 1200 h on day 28, which induces serum levels approximately twice those reached with the clinical dose as anticorvulsant drug for humans, was effective for inhibiting the first ovulation and normal secretion of serum follicle - stimulating hormone and luteinizing hormone (LH) on day 29 as well as the preovulatory gonadotrophin surge on day 28. The block of ovulation was overcome by administration of human chorionic gonadotrophin or LH-releasing hormone on day 28. Simultaneous treatment with equine CG and phenytoin at 0800 h on day 26 did not affect either ovarian weight or ovarian hormones secretion, whereas phenytoin clearly inhibited the normal increase in uterine weight on day 27. Furthermore, phenytoin suppressed uterine growth after 17beta-oestradiol injection. These results indicate that phenytoin inhibits the first ovulation by inhibiting the gonadotrophin surge and further, that the drug impairs the stimulatory effects of oestrogen on uterine proliferation in the gonadotropin-induced ovulation model.

The effects of valproate, carbamazepine, and oxcarbazepine on growth and sexual maturation in girls with epilepsy

OBJECTIVE

Antiepileptic drugs (AEDs) have endocrine effects that may interfere with growth and sexual maturation in children. The aim of this study was to evaluate the effects of AEDs on growth and pubertal development in girls with epilepsy.

STUDY DESIGN

Forty girls taking valproate (VPA), 19 girls taking carbamazepine (CBZ), and 18 girls taking oxcarbazepine (OXC) for epilepsy and 49 healthy control girls participated in the study, which included a cross-sectional clinical examination when the girls were 8 to 18 years old and a longitudinal growth analysis from the age of 1 year.

RESULTS

VPA, CBZ, or OXC did not affect linear growth or pubertal development in girls with epilepsy. However, the patients taking VPA gained weight, and an increase in relative weight was seen in girls who started their medication before as well as during puberty. The body mass index of the VPA-treated girls (19.8 +/- 4.8 kg/m2) was higher than that of the control girls (18.0 +/- 2.5 kg/m2) at clinical examination. The weight of the girls taking CBZ or OXC for epilepsy was similar to that of the control girls. Plasma insulin-like growth factor-I (IGF-I) levels were higher in girls treated with CBZ and OXC than in the control girls, but AEDs did not affect fasting serum insulin, IGF-binding protein-1, or IGF-binding protein-3 concentrations in girls on VPA, CBZ, or OXC medication during the period of exposure (average 2.8, 4.1, and 1.9 years, respectively) in this study.

CONCLUSIONS

AEDs do not seem to have any adverse effects on linear growth or sexual maturation in girls with epilepsy. VPA-related weight gain can be seen already in prepuberty and it is not associated with hyperinsulinemia in these young patients. The clinical significance of high circulating concentrations of IGF-I in patients taking CBZ or OXC remains to be defined.

Characterization of phenytoin-resistant kindled rats, a new model of drug-resistant partial epilepsy: influence of genetic factors

It has been recently shown that a subpopulation of amygdala-kindled Wistar rats can be selected which do not respond to phenytoin with an increase in afterdischarge threshold (ADT). Such non-responders could be a perfect model for studying the mechanisms of pharmacoresistance of complex partial seizures. Further studies on these rats suggested that the lack of anticonvulsant response was not due to the influence of experimental factors, but is an inherent property of each rat. In this study the influence of genetic factors on the pharmacoresistance to phenytoin by breeding Wistar rats which have been selected for their ability to consistently respond or not respond to phenytoin is examined. Male and female Wistar rats were implanted with bipolar electrodes in the basolateral amygdala and kindled. The fully kindled rats were repeatedly tested for their ability to respond to phenytoin (75 mg/kg i.p.) with an ADT increase. Responders and non-responders were mated and the offspring underwent the same kindling and repeated phenytoin testing procedure. Altogether, four generations of kindled rats were studied. The incidence of responses to phenytoin, i.e. ADT increased by more than 20% of control, was significantly higher in the F2 generation of the responder line compared to the non-responder line, but the number of responders and non-responders in the offspring generations F1-F3 did not significantly increase. The data suggest that the ability to respond or not to respond to phenytoin is genetically determined, although it does not follow a simple scheme of inheritance. The low reproductive success of the kindled and phenytoin-treated rats made it impossible to achieve a strain of phenytoin non-responders.

Hyposexuality produced by temporal lobe epilepsy in the cat

PURPOSE

The hypothesis tested in this study was that a unilateral irritative focal epileptic lesion in the temporal lobe results in hyposexuality.

METHODS

Focal epilepsy was produced in male cats by unilateral injection of aluminum hydroxide into either the basolateral amygdala (temporal lobe group) or anterior sigmoid gyrus (motor cortex group). Weekly sex testing trials with estrous females were conducted prior to and after aluminum hydroxide injection, and mating performance scores were compared with those of normal, unoperated cats (normal control group).

RESULTS

All animals receiving aluminum hydroxide developed electroencephalographic and behavioral manifestations of epilepsy; i.e., interictal EEG spiking and partial or generalized seizures. Cats in the temporal lobe group exhibited a dramatic and complete suppression of sexual behavior at periods from 6 to 26 weeks after aluminum hydroxide injection. The duration of the hyposexuality varied between individual animals and returned to normal as suddenly as the onset occurred, despite the use of AEDs to prevent or control generalized seizure activity. Interictal EEG epileptiform spiking in the amygdala preceded the onset of hyposexuality by 1-12 weeks. By contrast, cats in the motor cortex and normal control groups showed no sign of sexual dysfunction throughout the experimental period, independent of seizure activity and/or antiepileptic drug (AED) treatment.

CONCLUSIONS

These data support the hypothesis that hyposexuality occurs as a result of epileptiform activity in the temporal lobe, but not in the motor cortex. The precise mechanisms by which this occurs are unknown, but are likely to involve abnormally high-frequency neuronal activity in temporal lobe structures known to connect with and/or to regulate hypothalamic nuclei that organize male sexual behavior toward receptive females.

Reproductive activity and offspring health of young adults with childhood-onset epilepsy: a controlled study

PURPOSE

To study reproductive activity and offspring health in a prospective follow-up setting.

METHODS

After a 35-year follow-up of a population-based patient cohort with childhood-onset "epilepsy only," 100 (56.8%) of 176 surviving patients were shown to have "epilepsy only", i.e., recurrent unprovoked seizures with no associated neuroimpairment. Their reproductivity and offspring health were compared with those of matched controls.

RESULTS

The marriage rate and fertility of patients with "epilepsy only" were significantly reduced as compared with those of matched controls. Continuation of antiepileptic drug (AED) treatment was significantly associated with reduced reproduction, whereas occurrence of seizures during the previous 5 years was not. The incidence of epilepsy was nine times greater among the children of patients than among those of controls. No higher risks were observed in pregnancy or delivery in patients, nor were increased rates of birth defects in their offspring than in those of controls. Exposure to AEDs during pregnancy did not increase these risks.

CONCLUSIONS

Patients with "epilepsy only" since childhood have fewer marriages and fewer children than expected. However, when they marry, their pregnancies and deliveries are unremarkable and their children do not have increased congenital health problems. Obviously, etiologies causative of both epilepsy and associated neurological impairments are more harmful to the course of pregnancy and delivery and offspring health than are those resulting in "epilepsy only".

The new antiepileptic drugs and women: efficacy, reproductive health, pregnancy, and fetal outcome

As new antiepileptic drugs (AEDs) become available, physicians will define their appropriate use in particular patient populations. For women, the issues include gender-specific efficacy and tolerability, including the impact of the AED on reproductive health. Women with epilepsy who are treated with established AEDs appear to be at risk for compromised bone health, for disturbances in fertility, menstrual cyclicity, ovulatory function, and sexuality and, with some AEDs, for failure of hormonal contraception. Finally, pregnancy outcome may be adversely affected by the established AEDs, all of which are human teratogens. Felbamate (FBM), gabapentin (GBP), lamotrigine (LTG), oxcarbazepine (OCBZ), tiagabine (TGB), topiramate (TPM), and vigabatrin (VGB) were reviewed. The preclinical development process had not addressed all the issues of concern to women. Although gender-specific efficacy is routinely evaluated, impact on reproductive health is not. FBM, GBP, LTG, TGB, TPM, and VGB have similar efficacy in women and men. It is not known whether the new AEDs will affect bone health, fertility, the menstrual cycle, and sexuality. FBM, GBP, LTG, TGB, and probably VGB do not interfere with hormonal contraception. Whether these new AEDs are good choices for the pregnant woman with epilepsy awaits further experience in human pregnancy. However, animal reproductive toxicology studies appear promising. The limited number of human pregnancy exposures do not, thus far, signal a significant number or particular type of adverse outcomes. However, only with improved postmarketing surveillance can essential information about teratogenic effects by acquired in an acceptably short time.