Cell type-dependent effect of sodium valproate on human immunodeficiency virus type 1 replication in vitro

Pharmacokinetic Considerations with the Use of Antiepileptic Drugs in Patients with HIV and Organ Transplants

PURPOSE OF REVIEW

Antiepileptic drugs are frequently administered to patients with HIV infection or in recipients of organ transplants. The potentially serious drug-drug interactions between the "classic" antiepileptic drugs, antiretrovirals, and immunosuppressants have been extensively studied. Evidence-based information on the second and third generation of antiepileptic drugs is almost non-existent. The purpose of this review is to analyze the pharmacokinetic profile of these newer agents to assess their potential for drug interactions with antiretrovirals and immunosuppressants.

RECENT FINDINGS

As a group, the newer generations of antiepileptic drugs have shown a more favorable drug interaction potential compared to the "classic" ones. A group of moderate enzyme-inducing drugs includes eslicarbazepine acetate, oxcarbazepine, rufinamide, and topiramate. These drugs are not as potent inducers as the "classic" drugs but may potentially decrease the serum concentrations of some antiretrovirals and immunosuppressants. Antiepileptic drugs with no or minimal enzyme-inducing properties include brivaracetam, gabapentin, lacosamide, lamotrigine, levetiracetam, perampanel, pregabalin, and vigabatrin. The newer generations of antiepileptic drugs have expanded the therapeutic options in patients with HIV infection or organ transplants.

Post-translational Modification-Based Regulation of HIV Replication

Human immunodeficiency virus (HIV) relies heavily on the host cellular machinery for production of viral progeny. To exploit cellular proteins for replication and to overcome host factors with antiviral activity, HIV has evolved a set of regulatory and accessory proteins to shape an optimized environment for its replication and to facilitate evasion from the immune system. Several cellular pathways are hijacked by the virus to modulate critical steps during the viral life cycle. Thereby, post-translational modifications (PTMs) of viral and cellular proteins gain increasingly attention as modifying enzymes regulate virtually every step of the viral replication cycle. This review summarizes the current knowledge of HIV-host interactions influenced by PTMs with a special focus on acetylation, ubiquitination, and phosphorylation of proteins linked to cellular signaling and viral replication. Insights into these interactions are surmised to aid development of new intervention strategies.

The therapeutic potential of epigenetic manipulation during infectious diseases

Epigenetic modifications are increasingly recognized as playing an important role in the pathogenesis of infectious diseases. They represent a critical mechanism regulating transcriptional profiles in the immune system that contributes to the cell-type and stimulus specificity of the transcriptional response. Recent data highlight how epigenetic changes impact macrophage functional responses and polarization, influencing the innate immune system through macrophage tolerance and training. In this review we will explore how post-translational modifications of histone tails influence immune function to specific infectious diseases. We will describe how these may influence outcome, highlighting examples derived from responses to acute bacterial pathogens, models of sepsis, maintenance of viral latency and HIV infection. We will discuss how emerging classes of pharmacological agents, developed for use in oncology and other settings, have been applied to models of infectious diseases and their potential to modulate key aspects of the immune response to bacterial infection and HIV therapy.

Mood stabilizers inhibit cytomegalovirus infection

Cytomegalovirus (CMV) infection can generate debilitating disease in immunocompromised individuals and neonates. It is also the most common infectious cause of congenital birth defects in infected fetuses. Available anti-CMV drugs are partially effective but are limited by some toxicity, potential viral resistance, and are not recommended for fetal exposure. Valproate, valpromide, and valnoctamide have been used for many years to treat epilepsy and mood disorders. We report for the first time that, in contrast to the virus-enhancing actions of valproate, structurally related valpromide and valnoctamide evoke a substantial and specific inhibition of mouse and human CMV in vitro. In vivo, both drugs safely attenuate mouse CMV, improving survival, body weight, and developmental maturation of infected newborns. The compounds appear to act by a novel mechanism that interferes with CMV attachment to the cell. Our work provides a novel potential direction for CMV therapeutics through repositioning of agents already approved for use in psychiatric disorders.

Characterization of the influence of mediator complex in HIV-1 transcription

HIV-1 exploits multiple host proteins during infection. siRNA-based screenings have identified new proteins implicated in different pathways of the viral cycle that participate in a broad range of cellular functions. The human Mediator complex (MED) is composed of 28 elements and represents a fundamental component of the transcription machinery, interacting with the RNA polymerase II enzyme and regulating its ability to express genes. Here, we provide an evaluation of the MED activity on HIV replication. Knockdown of 9 out of 28 human MED proteins significantly impaired viral replication without affecting cell viability, including MED6, MED7, MED11, MED14, MED21, MED26, MED27, MED28, and MED30. Impairment of viral replication by MED subunits was at a post-integration step. Inhibition of early HIV transcripts was observed by siRNA-mediated knockdown of MED6, MED7, MED11, MED14, and MED28, specifically affecting the transcription of the nascent viral mRNA transactivation-responsive element. In addition, MED14 and MED30 were shown to have special relevance during the formation of unspliced viral transcripts (p < 0.0005). Knockdown of the selected MED factors compromised HIV transcription induced by Tat, with the strongest inhibitory effect shown by siMED6 and siMED14 cells. Co-immunoprecipitation experiments suggested physical interaction between MED14 and HIV-1 Tat protein. A better understanding of the mechanisms and factors controlling HIV-1 transcription is key to addressing the development of new strategies required to inhibit HIV replication or reactivate HIV-1 from the latent reservoirs.

Safe Treatment of Seizures in the Setting of HIV/AIDS

OPINION STATEMENT

HIV(+) patients are at increased risk for developing seizures due to the vulnerability of the central nervous system to HIV-associated diseases, immune dysfunction, and metabolic disturbances. In patients with acute seizures, standard protocols still apply with urgent seizure cessation being the priority. Management of the person with established epilepsy who contracts HIV is challenging, but the decision to initiate chronic antiepileptic drug (AED) therapy in an HIV(+) patient is also difficult. Chronic treatment guidelines emphasize the interactions between AEDs and antiretroviral (ARV) medications, but provide no explicit advice regarding when to initiate an AED, what medication to select, and/or the duration of treatment. Epidemiologic data regarding seizure recurrence risk in HIV(+) individuals is not available. The risk of further seizures likely depends upon the underlying etiology for the seizure(s) and patients' immune status and may be increased by the use of efavirenz (an ARV). The issues for consideration include AED-ARV interactions, organ dysfunction, seizure type, and drug side effects, which may worsen or be confused with symptoms of HIV and/or epilepsy. Co-administration of enzyme inducing (EI)-AEDs and ARVs can result in virological failure, breakthrough seizure activity, AED toxicity, and/or ARV toxicity. Where available, the AED of choice in HIV(+) patients is levetiracetam due to its broad spectrum activity, ease of use, minimal drug interactions, and favorable side effect profile. Lacosamide, gabapentin, and pregabalin are also favored choices in patients with partial onset seizures and/or those failing levetiracetam. Where newer AEDs are not available, valproic acid may be the treatment of choice in terms of an AED, which will not cause enzyme induction-associated ARV failure, but its side effect profile causes other obvious problems. In resource-limited settings (RLS) where only EI-AEDs are available, there are no good treatment options and further pressure needs to be placed upon policymakers to address this care gap and public health threat.

Antiretroviral agents effectively block HIV replication after cell-to-cell transfer

Cell-to-cell transmission of HIV has been proposed as a mechanism contributing to virus escape to the action of antiretrovirals and a mode of HIV persistence during antiretroviral therapy. Here, cocultures of infected HIV-1 cells with primary CD4(+) T cells or lymphoid cells were used to evaluate virus transmission and the effect of known antiretrovirals. Transfer of HIV antigen from infected to uninfected cells was resistant to the reverse transcriptase inhibitors (RTIs) zidovudine (AZT) and tenofovir, but was blocked by the attachment inhibitor IgGb12. However, quantitative measurement of viral DNA production demonstrated that all anti-HIV agents blocked virus replication with similar potency to cell-free virus infections. Cell-free and cell-associated infections were equally sensitive to inhibition of viral replication when HIV-1 long terminal repeat (LTR)-driven green fluorescent protein (GFP) expression in target cells was measured. However, detection of GFP by flow cytometry may incorrectly estimate the efficacy of antiretrovirals in cell-associated virus transmission, due to replication-independent Tat-mediated LTR transactivation as a consequence of cell-to-cell events that did not occur in short-term (48-h) cell-free virus infections. In conclusion, common markers of virus replication may not accurately correlate and measure infectivity or drug efficacy in cell-to-cell virus transmission. When accurately quantified, active drugs blocked proviral DNA and virus replication in cell-to-cell transmission, recapitulating the efficacy of antiretrovirals in cell-free virus infections and in vivo.

New approaches in HIV eradication research

PURPOSE OF REVIEW

Despite the proven efficacy of highly active antiretroviral therapy in reducing mortality and morbidity of HIV infection, longer-term strategies are less well defined and there is renewed interest in HIV eradication. This review will describe the major obstacles that need to be overcome and the key new advances and strategies designed to achieve an HIV cure.

RECENT FINDINGS

Characterization of the HIV viral reservoir over the past few years has led to a better understanding of which approaches might successfully lead to eradication. A number of approaches such as histone modification, immunotoxins, gene therapy and gene knockout strategies have resulted and have been explored initially in vitro. There has been progression from both laboratory and animal model studies, and clinical trials are now underway using new approaches such as histone deacetylase inhibitors and zinc finger nucleases.

SUMMARY

Although there is currently no cure for HIV infection, there has been a resurgence of interest in the field with the development of a number of potential new approaches, some of which have entered clinical trials.

Histone deacetylase inhibitors for purging HIV-1 from the latent reservoir

A reservoir of latently infected memory CD4(+) T cells is believed to be the source of HIV-1 reemergence after discontinuation of antiretroviral therapy. HIV-1 eradication may depend on depletion of this reservoir. Integrated HIV-1 is inaccessible for expression, in part because of histone deacetylases (HDACs). One approach is to exploit the ability of HDAC inhibitors to induce HIV-1 expression from an integrated virus. With effective antiretroviral therapy, newly expressed HIV-1 is incapable of reinfecting naive cells. With HIV-1 expression, one assumes the infected cell dies and there is a progressive reduction in the size of the reservoir. The concept was tested using the HDAC inhibitor valproic acid. However, valproic acid is weak in inducing HIV-1 from latency in vitro. As such, clinical trials revealed a small or no effect on reducing the number of latently infected T cells in the peripheral blood. However, the new HDAC inhibitors vorinostat, belinostat and givinostat are more effective at targeting specific HDACs for HIV-1 expression than valproic acid. Here, we review studies on HDAC inhibitor-induced expression of latent HIV-1, with an emphasis on new and specific HDAC inhibitors. With increased potency for HIV-1 expression as well as safety and ease of oral administration, new HDAC inhibitors offer a unique opportunity to deplete the latent reservoir. An additional benefit is the antiinflammatory properties of HDAC inhibitors, including downregulation of HIV-1 coreceptor expression.

Immune and neuroimmune alterations in mood disorders and schizophrenia

A large number of publications over the past 20 years have indicated that immune system function is altered in schizophrenia and mood disorder patients. This chapter reviews the evidence, which suggests that a proinflammatory state of the cytokine network induces psychopathologic symptoms and may be involved in the pathogenesis and pathophysiology of these major mental illnesses. The authors also present recent data, which relates immune activation to present theories on the influence of activated immune cells in altering brain function. They also focus on the role of the environment in immune activation and on the role of the microbiome and gut flora. Increased understanding of such factors could help in the development of novel treatment strategies and improved clinical management of mental disorders.

Molecular and therapeutic potential and toxicity of valproic acid

Valproic acid (VPA), a branched short-chain fatty acid, is widely used as an antiepileptic drug and a mood stabilizer. Antiepileptic properties have been attributed to inhibition of Gamma Amino Butyrate (GABA) transaminobutyrate and of ion channels. VPA was recently classified among the Histone Deacetylase Inhibitors, acting directly at the level of gene transcription by inhibiting histone deacetylation and making transcription sites more accessible. VPA is a widely used drug, particularly for children suffering from epilepsy. Due to the increasing number of clinical trials involving VPA, and interesting results obtained, this molecule will be implicated in an increasing number of therapies. However side effects of VPA are substantially described in the literature whereas they are poorly discussed in articles focusing on its therapeutic use. This paper aims to give an overview of the different clinical-trials involving VPA and its side effects encountered during treatment as well as its molecular properties.

The histone deacetylase inhibitor ITF2357 decreases surface CXCR4 and CCR5 expression on CD4(+) T-cells and monocytes and is superior to valproic acid for latent HIV-1 expression in vitro

OBJECTIVES

Chromatin-associated repression is one mechanism that maintains HIV-1 latency. Inhibition of histone deacetylases (HDAC) reverses this repression resulting in viral expression from quiescently infected cells. Clinical studies with the HDAC inhibitor valproic acid (VPA) failed to substantially decrease the latent pool within resting CD4(+) cells. Here we compared the efficacy of ITF2357, an orally active and safe HDAC inhibitor, with VPA for HIV-1 expression from latently infected cells in vitro. We also evaluated the effect of ITF2357 on the surface expression of CXCR4 and CCR5.

METHODS

Latently infected cell lines were incubated with either ITF2357 or VPA and p24 levels were measured. Peripheral blood mononuclear cells of uninfected donors were treated with ITF2357 and HIV-1 coreceptors expression was assessed by flow cytometry.

RESULTS

At clinically relevant concentrations, ITF2357 increased p24 by 15-fold in ACH2 cells and by 9-fold in U1 cells, whereas VPA increased expression less than 2-fold. Analogues of ITF2357 primarily targeting HDAC-1 increased p24 up to 30-fold. In CD4(+) T cells treated with ITF2357, CXCR4 expression decreased by 54% (P < 0.001).

CONCLUSION

ITF2357 is superior to VPA in inducing HIV-1 from latently infected cells. Safely used in humans, ITF2357 is an attractive candidate for HIV-1 clinical purging.

Pharmaceutical approaches to eradication of persistent HIV infection

Highly active antiretroviral therapy (HAART) has markedly decreased morbidity and mortality in human immunodeficiency virus type 1 (HIV-1)-infected individuals in the developed world. Successful therapy often results in stable plasma levels of HIV-1 RNA below the limits of detection of commercial assays. Nonetheless, HIV-1 has not been cured by HAART. The causes of persistence of HIV infection in the face of current therapy appear to be multifactorial: latent but replication-competent provirus in resting CD4+ T cells, cryptic viral expression below the limits of detection of clinical assays, and viral sanctuary sites might all contribute to persistence. Clearance of HIV infection will almost certainly require a multimodality approach that includes potent suppression of HIV replication, therapies that reach all compartments of residual HIV replication and depletion of any reservoirs of persistent, quiescent proviral infection. This review highlights the basic mechanisms for the establishment and maintenance of viral reservoirs and pharmaceutical approaches towards their elimination.

Modulation of human immunodeficiency virus infection by anticonvulsant drugs

Patients with human immunodeficiency virus (HIV) infection often require treatment with anticonvulsants either for treatment of seizures or occasionally for pain control. In this study, the authors determined if the anticonvulsants phenytoin, carbamazepine, and valproate could modulate HIV replication. These drugs activated HIV replication in latently infected monocytic cells but not in latently infected lymphocytic cells at clinically relevant dosages. The activation in the monocytic cells was as a result of transactivation of HIV long terminal repeat (LTR) and could be seen at therapeutic dosages whereas no effect was seen on LTR activation in lymphocytic cells. When the drugs were used in conjunction with known transactivators of HIV LTR such as Tat and phorbol-12-myristate-13-acetate (PMA), no additive or synergistic effect was noted. Although the clinical relevance of these observations needs to be determined, these observations may suggest that monitoring of cerebrospinal fluid (CSF) viral load maybe needed in HIV-infected patients treated with anticonvulsants, because HIV-infected macrophages are important in mediating HIV dementia.

TDM: Therapeutic Drug Measuring or Therapeutic Drug Monitoring?

The third round of the International Interlaboratory Quality Control Program for Therapeutic Drug Monitoring in HIV infection (QC-program) consisted of the analysis not only of plasma samples but also of patient cases. The case was composed of different topics related to the therapeutic drug monitoring of antiretroviral drugs. The participants were asked to give recommendations concerning dose adjustments, changes to the regimen, and drug-drug interactions to observe whether the expert recommendations were comparable. Of the 30 participants of the QC-program, 16 returned their comments and recommendations with regard to the patient case. The drug level was easy to judge: approximately 90% were able to correctly do so. Almost half of the recommendations (44%) given were satisfactory. Levels of knowledge regarding HIV treatment appeared to be variable among the respondents and for this reason were partly incomparable.

Administration of HDAC inhibitors to reactivate HIV-1 expression in latent cellular reservoirs: implications for the development of therapeutic strategies

The discovery of powerful antiviral compounds in the 90's raised the hope that the human immunodeficiency virus type 1 (HIV-1) might be eradicated. However, if these drugs succeed in decreasing and controlling viral replication, complete eradication of the virus is nowadays impossible. The persistence of virus even after long periods of highly active antiretroviral therapy (HAART) mainly results from the presence of cellular reservoirs that contain transcriptionally competent latent viruses capable of producing infectious particles after cellular activation. These latently infected cells are a permanent source for virus reactivation and lead to a rebound of the viral load after interruption of HAART. Activation of HIV gene expression in these cells combined with an effective HAART has been proposed as an adjuvant therapy that could lead to the elimination of the latently infected cells and then to the eradication of the infection. In this context, we have previously demonstrated that deacetylase inhibitors (HDACi) synergize with TNF-induced NF-kappaB to activate the HIV-1 promoter. The physiological relevance of the TNF/HDACi synergism was shown on HIV-1 replication in both acutely and latently HIV-infected cell lines. Based on these results, we propose the administration of deacetylase inhibitor(s) together with continuous HAART as a new potential therapeutic perspective to decrease the pool of latent HIV reservoirs by forcing viral expression.

Increased human cytomegalovirus replication in fibroblasts after treatment with therapeutical plasma concentrations of valproic acid

Valproic acid (2-propylpentanoic acid, VPA), an effective inhibitor of histone deacetylases (HDAC) is used for the treatment of epilepsia. In this study, structure-activity relationships for the action of structurally modified VPA derivatives on human cytomegalovirus (HCMV) replication and HDAC inhibition were defined. Pretreatment of human foreskin fibroblasts with VPA (0.125-1mM) caused a concentration-dependent increase of HCMV immediate early and antigen late antigen expression. Structure-activity relationships of VPA derivatives for HCMV stimulation were compared to those for teratogenic action and those for HDAC inhibition. Side chain elongation and introduction of a triple bond in 4-position of the other chain caused teratogenicity, stimulated HCMV replication, and increased HDAC inhibition, as demonstrated by enhanced levels of acetylated histones. Teratogenic VPA derivatives with a branched chain in 3-position as well as a non-teratogenic anticonvulsive active VPA derivative did not stimulate HCMV or accumulation of acetylated histones. This demonstrates a strict correlation between inhibition of HDAC and increased HCMV replication.

Special populations: the management of seizures in HIV-positive patients

An increasing percentage of patients with new-onset seizures are HIV positive. The evaluation and management is distinctly different from managing the non-HIV-infected patient. Clinicians must be familiar with comorbid infectious etiologies and the relative value of electroencephalogram, imaging, and serum and cerebrospinal fluid laboratory tests. Traditional antiepileptic drug (AED) therapies are contraindicated and may lead to increased HIV viral replication through either directed cellular mechanisms or interference with antiretroviral therapies. Newer AEDs have pharmacokinetic properties that make them reasonable choices, although none have been specifically studied for efficacy or safety in HIV. Lastly, optimal choice of an AED should reflect commonly encountered neurologic and psychiatric comorbidities.

Coaxing HIV-1 from resting CD4 T cells: histone deacetylase inhibition allows latent viral expression

BACKGROUND

Histone deacetylase (HDAC), a host mediator of gene repression, inhibits HIV gene expression and virus production and may contribute to quiescence of HIV within resting CD4 T cells.

OBJECTIVES

To test the ability of valproic acid (VPA), an inhibitor of HDAC in clinical use, to induce expression of HIV from resting CD4 T cells.

METHODS

Chromatin immunoprecipitation measured the capability of VPA to deacetylate the HIV promoter, a remodeling of chromatin linked to gene expression. The effect of VPA on resting CD4 T cell phenotype was measured by flow cytometric analysis, and its effect on de novo HIV infection of peripheral blood mononuclear cells was measured ex vivo. Outgrowth of HIV from resting CD4 T cells of aviremic, HIV-infected donors treated with highly active antiretroviral therapy was compared in limiting-dilution cultures after mitogen stimulation or exposure to VPA.

RESULTS

VPA induced acetylation at the integrated HIV proviral promoter, but CD4 cells exposed to VPA did not become activated or more permissive for de novo HIV infection. VPA induced outgrowth of HIV from the resting CD4 cells of aviremic patients at concentrations achievable in vivo as frequently as did mitogen stimulation.

CONCLUSIONS

With advances in antiretroviral therapy, HIV infection might be cleared by intensive time-limited treatment coupled with practical strategies that disrupt latency without enhancing new infection. HDAC inhibitors are capable of inducing expression of quiescent provirus, without fully activating cells or enhancing de novo infection, and may be useful in future clinical protocols that seek to eradicate HIV infection.

Anticonvulsant and antiretroviral interactions

OBJECTIVE

To evaluate the clinical significance of interactions between anticonvulsant and antiretroviral agents and provide recommendations regarding their concurrent use.

DATA SOURCES

A PubMed search (1966 to April 2003) was conducted using individual anticonvulsant and antiretroviral drug names and the following key search terms: anticonvulsant, antiepileptic, antiretroviral, protease inhibitor, and pharmacokinetic. Abstracts from scientific meetings that pertained to drug interactions were manually reviewed.

STUDY SELECTION AND DATA EXTRACTION

All articles identified by the PubMed search were examined. Articles and abstracts from scientific meetings with relevant information were included.

DATA SYNTHESIS

Six case reports were identified that describe interactions between anticonvulsant agents and protease inhibitors. In several reports, carbamazepine serum concentrations increased by approximately two- to threefold with concurrent ritonavir, resulting in carbamazepine-related toxicity. Carbamazepine was also associated with loss of viral suppression when combined with indinavir. Phenytoin serum concentrations were decreased with nelfinavir in a patient who developed recurrent seizures. The effect of ritonavir on phenytoin was variable; a 30% reduction in phenytoin serum concentration occurred in one patient, while no apparent change was observed in another. Interactions with nonnucleoside reverse-transcriptase inhibitors are poorly characterized because existing data involve concurrent protease inhibitor therapy. The utility of newer anticonvulsant agents is explored. Experience with newer anticonvulsant agents in 2 patients at our site is also described.

CONCLUSIONS

Limited data exist regarding interactions between anticonvulsant and antiretroviral agents. Valproic acid and newer anticonvulsant agents may provide useful alternatives to first-generation agents. Clinicians need to be diligent when monitoring for anticonvulsant-antiretroviral interactions because of the potential for toxicity, loss of seizure control, and incomplete viral suppression.

Infection, treatment and immune response in patients with bipolar disorder versus patients with major depression, schizophrenia or healthy controls

Bipolar disorder is the least studied among the three major psychiatric disorders of schizophrenia, major depression and bipolar disorder. Furthermore, investigations on infection and immunity in bipolar disorder make up only a small portion of the sparse research done on this disorder. However, there are reports that modulation of the immune system and certain infections might be associated with bipolar disorder and that there might be differences between bipolar and the other disorders. The purpose of this paper is to briefly review published data on these issues in bipolar versus the other disorders, and to present an ongoing clinical study on the putative involvement of infection with the parasite Toxoplasma gondii in these three major psychiatric disorders.

Diversity of acetylation targets and roles in transcriptional regulation: the human immunodeficiency virus type 1 promoter as a model system

Persuasive evidence has accumulated that reversible acetylation of proteins is key post-translational modification regulating transcription in eukaryotes. Deacetylase inhibitors (such as trichostatin A) modulate the expression of approximately 2% of all cellular genes. We and others have demonstrated a marked transcriptional activation of the human immunodeficiency virus type 1 (HIV-1) promoter in response to deacetylase inhibitors. Deacetylation events seem to be an important mechanism of HIV-1 transcriptional repression during latency, whereas acetylation events play critical functional roles in HIV-1 reactivation from latency. These deacetylation/acetylation events are implicated in chromatin remodeling of the viral promoter region, as well as in modulating the functional properties of cellular and viral transcription factors binding to this promoter region. Thereby, the HIV-1 promoter constitutes a unique regulatory model system to study the complex relationship between acetylation processes and transcriptional activity.

Seizures in HIV-seropositive individuals: epidemiology and treatment

Seizures are a relatively common occurrence in patients with HIV infection. They may be a result of HIV infection of the CNS or a manifestation of an opportunistic infection. Because seizures are likely to recur in patients infected with HIV and because they are a poor prognostic indicator, it is generally recommended that all HIV-seropositive patients experiencing a first seizure without a recognisable and reversible cause be treated. Clinicians faced with treating seizures in HIV-seropositive patients often encounter a therapeutic dilemma since few data exist in this area. In selecting appropriate anticonvulsant therapy, clinicians must consider both therapy-compromising drug-drug and drug-disease interactions. Ideal anticonvulsants for this setting are those that do not effect viral replication, have limited protein binding and have no effects on the cytochrome P450 system, such as gabapentin, topiramate and tiagabine. Unless the benefits outweigh the risks, valproic acid (sodium valproate) should be avoided as it has been shown to stimulate HIV replication. Since few data exist, controlled trials examining pharmacokinetic and pharmacodynamic interactions between anticonvulsants and antiretrovirals are needed. Until such time, clinicians caring for these patients should examine existing data carefully and employ vigilant monitoring.

The effect of divalproex sodium on viral load: a retrospective review of HIV-positive patients with manic syndromes

OBJECTIVE

In vitro studies report that valproic acid causes an increase in HIV-1 replication. This retrospective study examines a sample of patients with HIV disease and behavioural disturbances, for which the treatment of choice is divalproex sodium (DVP), to determine whether DVP causes an increase in HIV-1 replication.

METHOD

A chart and database review identified 15 patients with HIV disease presenting with either 1) mania or hypomania or 2) dementia with mania or with hypomania or behavioural disturbances. HIV-1 viral load was compared before and after mood stabilizer initiation.

RESULTS

Eleven patients started therapy with DVP, and 4 patients declined treatment with a mood stabilizer. Nine of the 11 patients taking DVP were also receiving antiretroviral therapy. HIV-1 viral load did not increase in 6 of the 9 patients who had measurements between 1 week and 3.5 months after DVP initiation. No follow-up was available for the other 3 patients. Of the 2 patients receiving DVP but not antiretroviral medication, 1 had an increase of 0.17 log in HIV-1 viral load at 4 months. No follow-up record was available for the second patient. The 4 patients not taking DVP were all on antiretroviral therapy; viral loads in 2 of them remained nondetectable over 3 to 4 months, and 1 had an increase of 0.32 log in HIV-1 viral load at 3 months. No follow-up record was available for the fourth patient.

CONCLUSIONS

These preliminary data suggest that, in the presence of effective antiretroviral therapy, HIV-1 viral load appears not to be adversely affected by the administration of DVP. The results for the patients receiving DVP in the absence of antiretroviral medication remain indeterminate. Further prospective study is required.

Neurotoxicity and dysfunction of dopaminergic systems associated with AIDS dementia

Infection with the human immunodeficiency virus (HIV) selectively targets the basal ganglia resulting in loss of dopaminergic neurons. Although frequently asymptomatic, some patients may develop signs of dopamine deficiency de novo. Accordingly, they are highly susceptible to drugs that act on dopaminergic systems. Both neuroleptics and psychostimulants may exacerbate these symptoms. Experimental evidence suggests that viral proteins such as gp120 and Tat can cause toxicity to dopaminergic neurons, and this toxicity is synergistic with compounds such as methamphetamine and cocaine that also act on the dopaminergic system. In addition, other neurotransmitters that modulate dopaminergic function, such as glutamate and opioids, may also modify the susceptibility of the dopamine system to HIV. Therefore, a thorough understanding of the mechanisms that lead to this selective neurotoxicity of dopaminergic neurons would also likely lead to the development of therapeutic modalities for patients with HIV dementia.

The use of valproic acid in HIV-positive patients

OBJECTIVE

To review the use of valproic acid in HIV-positive patients.

DATA SOURCES

Clinical literature was accessed through a MEDLINE search (January 1966-November 1998). Key search terms included HIV, AIDS, seizures, valproic acid, and glutathione.

DATA SYNTHESIS

Patients with HIV often develop neurologic manifestations; therefore, valproic acid may be considered in the management of this population. It has been demonstrated that valproate may increase viral burden by potentiating replication. An evaluation of studies addressing the use of valproic acid in HIV-positive patients was conducted.

CONCLUSIONS

The potential for valproate-induced increases in viral replication exists. Although further studies are warranted, clinicians should exercise caution when using valproate in HIV-positive patients.