Treatment of cytomegalovirus pneumonia with high-dose acyclovir

Serum and cerebrospinal fluid acyclovir pharmacokinetics in a neonate with HSV-2 meningoencephalitis

A neonatal patient with Herpes simplex virus type-2 meningoencephalitis was treated by high-dose intravenous acyclovir therapy. Serum and cerebrospinal fluid (CSF) concentrations were measured retrospectively, showing that the CSF-to-serum concentration ratio was 0.67-0.71, which was higher than the previously reported values in other age groups.

Predicting Pharmacokinetics of Multisource Acyclovir Oral Products Through Physiologically Based Biopharmaceutics Modeling

Highly variable disposition after oral ingestion of acyclovir has been reported, although little is known regarding the underlying mechanisms. Different studies using the same reference product (Zovirax ®) showed that C_max and AUC were respectively 44 and 35% lower in Saudi Arabians than Europeans, consistent with higher frequencies of reduced-activity polymorphs of the organic cation transporter (OCT1) in Europeans. In this study, the contribution of physiology (i.e., OCT1 activity) to the oral disposition of acyclovir immediate release (IR) tablets was hypothesized to be greater than dissolution. The potential role of OCT1 was studied in a validated physiologically-based biopharmaceutics model (PBBM), while dissolution of two Chilean generics (with demonstrated bioequivalence) and the reference product was assessed in vitro. The PBBM suggested that OCT1 activity could partially explain population-related pharmacokinetic differences. Further, dissolution of generics was slower than the regulatory criterion for BCS III IR products. Remarkably, virtual bioequivalence (incorporating in vitro dissolution into the PBBM) correctly and robustly predicted the bioequivalence of these products, showcasing its value in support of failed BCS biowaivers. These findings suggest that very-rapid dissolution for acyclovir IR products may not be critical for BCS biowaiver. They also endorse the relevance of cross-over designs in bioequivalence trials.

Novel Insights to Enhance Therapeutics With Acyclovir in the Management of Herpes Simplex Encephalitis

Acyclovir is an antiviral drug poorly absorbed in the gastrointestinal tract due to its hydrophilicity, with low oral bioavailability (~20%). Although acyclovir is prescribed in the management of herpes simplex encephalitis (HSE), the disease has a poor prognosis, particularly if the treatment is delayed, reaching mortality rates of 70% if left untreated. Thus, high acyclovir doses are administered by intravenous (IV) infusion, usually at a dosage of 10 mg kg^-1 8-hourly in adults with normal renal function. However, the mortality related to HSE treated with acyclovir remains high (~20%) and permanent sequelae are commonly reported after 1 year (~50%). This review analyzed clinical trials following IV acyclovir administration. Novel insights aiming to improve drug bioavailability were reviewed, including acyclovir or its prodrugs, leading to the systemic distribution of the drug or drug targeting. Much research effort has been made to improve antiviral therapy, searching for delivery systems increasing acyclovir bioavailability by non-invasive pathways, such as oral and nasal pathways, or parenterally administered nanotechnology-based systems leading to drug targeting. Nanocarriers administered by non-invasive pathways represent feasible alternatives to treat HSE, even though not be industrially manufactured yet.

Valaciclovir therapy for herpes encephalitis: caution advised

Recently some authors have suggested that oral valaciclovir 1 g q8h is a valid alternative to intravenous aciclovir for herpes encephalitis. We are concerned about numerous caveats that we think have not been sufficiently addressed to allow such use outside of a controlled research setting.

Anti-Herpetic Activity of (±)-(1α, 2β, 3α)-9-[2-Hydroxy-3-(Hydroxymethyl)Cyclobutyl]Guanine and Inhibition of HSV-1 DNA Polymerase

A novel nucleoside analogue, (±)-(1α, 2β, 3α)-9-[2-hydroxy -3-(hydroxymethyl)cyclobutyl]guanine [(±)-HHCG] was synthesized and has antiviral activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus (HCMV) and varicella-zoster virus (VZV) in plaque reduction assays. The antiviral activity of (±)-HHCG against HSV-2 shows a 10-40-fold dependence on the presence of a virally encoded thymidine kinase. (±)-HHCG is a substrate for HSV-1 thymidine kinase with a phosphorylation rate of 28 μm h−1 compared to 15 μm h−1 for acyclovir under identical conditions. Enzymatically prepared HHCG-triphosphate is a competitive inhibitor of dGTP incorporation into DNA by HSV-1 DNA polymerase with an inhibition constant corresponding to 0.0077 μm. Hybridization studies using an HSV-1-specific DNA probe indicated that DNA synthesis is reduced in HSV-1-infected WI-38 cells treated with (±)-HHCG, with an ED50 comparable to that of acyclovir. These results suggest that the antiviral activity of (±)-HHCG is due to preferential inhibition of viral DNA synthesis.

Species Differences in the Metabolism and Disposition of Antiviral Nucleoside Analogues: 1. Acyclovir

The acyclic nucleoside analogue, acyclovir, is an antiviral drug with activity against the herpes group of DNA viruses. Clinically, it is used as a selective therapeutic agent for the treatment of herpes simplex and varicella-zoster virus infections. Studies on the disposition of acyclovir, during the course of its preclinical and clinical development, indicated significant species differences in the absorption, metabolism and elimination of the drug. Gastrointestinal absorption was adequate in dogs and in mice; but in rats and primates it was limited to less than 20% of the administered dose. Whereas in some species (mice, rats, and dogs), acyclovir was virtually unmetabolized, significant biotransformation was apparent in guinea pigs, rabbits, and some primates. Acyclovir tissue distribution was extensive and indicated few differences across species. This review summarizes diverse studies on acyclovir absorption, metabolism, and disposition in different species, including humans, and indicates the relevance and importance of such studies in drug development.

Overview of congenitally and perinatally acquired cytomegalovirus infections: recent advances in antiviral therapy

Congenital and perinatal infection with human cytomegalovirus (CMV) are commonly encountered in newborns. In recent years there has been increased awareness of the disabilities that result from congenital CMV infection, which in turn has prompted interest in examining the potential efficacy of antiviral agents to prevent or ameliorate neurodevelopmental injury. Currently, there are three licensed systemic antivirals for the treatment of CMV: ganciclovir (Cytovene, Roche] and its prodrug valganciclovir [Valcyte, Roche); foscarnet (Foscavir, AstraZeneca); and cidofovir (Vistide, Pharmacia). A CMV-specific immunoglobulin is also available. Experience with these agents in the setting of congenital and perinatal CMV infection is very limited, but there are encouraging data from a controlled clinical trial indicating that ganciclovir therapy may be of value in limiting one form of neurodevelopmental injury caused by congenital infection, that of sensorineural hearing loss. Licensed antivirals for the treatment of CMV all share the common mechanism of targeting the viral DNA polymerase, but novel therapies that employ alternative modes of action are in development. Ultimately, the problem of perinatal CMV infection may be best controlled by the development of CMV vaccines, which could be administered to young women of childbearing age to help control this important public health problem.

Population pharmacokinetics of intravenous acyclovir in preterm and term infants

BACKGROUND

Acyclovir is used to treat herpes infections in preterm and term infants; however, the influence of maturation on drug disposition and dosing requirements is poorly characterized in this population.

METHODS

We administered intravenous acyclovir to preterm and term infants <31 days postnatal age and collected plasma samples. We performed a population pharmacokinetic analysis. The primary pharmacodynamic target was acyclovir concentration ≥3 mg/L for ≥50% of the dosing interval. The final model was simulated using infant data from a clinical database.

RESULTS

The analysis included 28 infants (median 30 weeks gestation). Acyclovir pharmacokinetics was described by a 1-compartment model: clearance (L/h/kg) = 0.305 × [postmenstrual age (PMA)/31.3 weeks]. This equation predicts a 4.5-fold increase in clearance from 25 to 41 weeks PMA. With proposed dosing, the pharmacodynamic target was achieved in 91% of infants: 20 mg/kg every 12 hours in infants <30 weeks PMA; 20 mg/kg every 8 hours in infants 30 to <36 weeks PMA and 20 mg/kg every 6 hours in infants 36-41 weeks PMA.

CONCLUSIONS

Acyclovir clearance increased with infant maturation. A dosing strategy based on PMA accounted for developmental changes in acyclovir disposition to achieve the surrogate pharmacodynamic target in many infants.

Oral acyclovir suppression and neurodevelopment after neonatal herpes

BACKGROUND

Poor neurodevelopmental outcomes and recurrences of cutaneous lesions remain unacceptably frequent among survivors of neonatal herpes simplex virus (HSV) disease.

METHODS

We enrolled neonates with HSV disease in two parallel, identical, double-blind, placebo-controlled studies. Neonates with central nervous system (CNS) involvement were enrolled in one study, and neonates with skin, eye, and mouth involvement only were enrolled in the other. After completing a regimen of 14 to 21 days of parenteral acyclovir, the infants were randomly assigned to immediate acyclovir suppression (300 mg per square meter of body-surface area per dose orally, three times daily for 6 months) or placebo. Cutaneous recurrences were treated with open-label episodic therapy.

RESULTS

A total of 74 neonates were enrolled--45 with CNS involvement and 29 with skin, eye, and mouth disease. The Mental Development Index of the Bayley Scales of Infant Development (in which scores range from 50 to 150, with a mean of 100 and with higher scores indicating better neurodevelopmental outcomes) was assessed in 28 of the 45 infants with CNS involvement (62%) at 12 months of age. After adjustment for covariates, infants with CNS involvement who had been randomly assigned to acyclovir suppression had significantly higher mean Bayley mental-development scores at 12 months than did infants randomly assigned to placebo (88.24 vs. 68.12, P=0.046). Overall, there was a trend toward more neutropenia in the acyclovir group than in the placebo group (P=0.09).

CONCLUSIONS

Infants surviving neonatal HSV disease with CNS involvement had improved neurodevelopmental outcomes when they received suppressive therapy with oral acyclovir for 6 months. (Funded by the National Institute of Allergy and Infectious Diseases; CASG 103 and CASG 104 ClinicalTrials.gov numbers, NCT00031460 and NCT00031447, respectively.).

Acyclovir levels in serum and cerebrospinal fluid after oral administration of valacyclovir

The possible involvement of herpesviruses in the pathogenesis of multiple sclerosis (MS) was recently investigated in a clinical trial of valacyclovir in patients with MS. As an important part of that survey we performed an independent pharmacokinetic study in order to determine the concentration of acyclovir in cerebrospinal fluid (CSF). The concentrations of acyclovir in serum and CSF were measured at steady state after 6 days of oral treatment with 1,000 mg of valacyclovir three times a day. Samples were obtained from 10 patients with MS. All patients had normal renal function, and none had signs of a damaged blood-CSF barrier. The maximum concentration of acyclovir in serum was reached after 1 to 3 h (mean +/- standard deviation [SD], 27.1 +/- 5.6 micro M), and the minimum concentration in serum was 3.1 +/- 1.1 micro M (mean +/- SD). The acyclovir concentrations in CSF at 2 and 8 h were essentially stable, with the mean +/- SD levels being 2.5 +/- 0.9 and 2.3 +/- 0.7 micro M, respectively. Similar levels were recorded in serum and CSF samples from five other MS patients after 6 months of oral treatment with valacyclovir at identical dosages. The area under the concentration-time curve (AUC) for acyclovir in CSF to the AUC for acyclovir in serum (CSF/serum AUC ratio) was approximately 20%. We conclude that the improved bioavailability previously reported for valacyclovir in plasma results in higher concentrations in CSF, while the CSF/serum AUC ratio remains constant.

Separation methods for acyclovir and related antiviral compounds

Acyclovir (ACV) is an antiviral drug, which selectively inhibits replication of members of the herpes group of DNA viruses with low cell toxicity. Valaciclovir (VACV), a prodrug of ACV is usually preferred in the oral treatment of viral infections, mainly herpes simplex virus (HSV). Also other analogues such as ganciclovir and penciclovir are discussed here. The former acts against cytomegalovirus (CMV) in general and the latter against CMV retinitis. The action mechanism of these antiviral drugs is presented briefly here, mainly via phosphorylation and inhibition of the viral DNA polymerase. The therapeutic use and the pharmacokinetics are also outlined. The measurement of the concentration of acyclovir and related compounds in biological samples poses a particularly significant challenge because these drugs tend to be structurally similar to endogenous substances. The analysis requires the use of highly selective analytical techniques and chromatography methods are a first choice to determine drug content in pharmaceuticals and to measure them in body fluids. Chromatography can be considered the procedure of choice for the bio-analysis of this class of antiviral compounds, as this methodology is characterised by good specificity and accuracy and it is particularly useful when metabolites need to be monitored. Among chromatographic techniques, the reversed-phase (RP) HPLC is widely used for the analysis. C18 Silica columns from 7.5 to 30 cm in length are used, the separation is carried out mainly at room temperature and less than 10 min is sufficient for the analysis at 1.0-1.5 ml/min of flow-rate. The separation methods require an isocratic system, and various authors have proposed a variety of mobile phases. The detection requires absorbance or fluorescence measurements carried out at 250-254 nm and at lambdaex=260-285 nm, lambdaem=375-380 nm, respectively. The detection limit is about 0.3-10 ng/ml but the most important aspect is related to the sample treatment, mainly when body fluids are under examination. The plasma samples obtained from human blood are pre-treated with an acid or acetonitrile deproteinization and the supernatant after centrifugation is successively extracted before RP-HPLC injection. Capillary Electrophoresis methods are also discussed. This new analytical approach might be the expected evolution, in fact the analyses are improved with regard to time and performance, in particular coated capillary as well as addition of stabilisers have been employed. The time of analysis is shortened arriving at less than half a minute. Furthermore by using an electrochemical detection, and having a calibration linearity in the range of 0.2-20.0 ng/ml, the detection limit is 0.15 microg/ml. The measurements of acyclovir and penciclovir have been presented but in the future other related drugs will probably be available using CE methods.

New strategies for prevention and therapy of cytomegalovirus infection and disease in solid-organ transplant recipients

In the past three decades since the inception of human organ transplantation, cytomegalovirus (CMV) has gained increasing clinical import because it is a common pathogen in the immunocompromised transplant recipient. Patients may suffer from severe manifestations of this infection along with the threat of potential fatality. Additionally, the dynamic evolution of immunosuppressive and antiviral agents has brought forth changes in the natural history of CMV infection and disease. Transplant physicians now face the daunting task of recognizing and managing the changing spectrum of CMV infection and its consequences in the organ recipient. For the microbiology laboratory, the emphasis has been geared toward the development of more sophisticated detection assays, including methods to detect emerging antiviral resistance. The discovery of novel antiviral chemotherapy is an important theme of clinical research. Investigations have also focused on preventative measures for CMV disease in the solid-organ transplant population. In all, while much has been achieved in the overall management of CMV infection, the current understanding of CMV pathogenesis and therapy still leaves much to be learned before success can be claimed.

Antiviral agents for non-human immunodeficiency virus infections

Several new agents for treating viral infections have been developed in recent years. All available agents are virustatic, inhibiting specific steps in the process of viral replication. No agent is active against nonreplicating or latent viruses. Acyclovir is useful in the treatment of genital herpes, herpes simplex encephalitis, mucocutaneous herpetic infection, varicella infection in the immunosuppressed host, and herpes zoster infection in the normal and the immunosuppressed host. It can also be used for prevention of herpesvirus infection in immunocompromised patients. Ganciclovir is indicated for the treatment of cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome and is effective in the treatment and prevention of cytomegalovirus infection in other immunocompromised patients. Famciclovir and valacyclovir are effective in the management of herpes simplex and varicella-zoster infection. Amantadine and rimantadine are useful therapeutically and prophylactically in the management of influenza A virus infection. Chronic hepatitis B infection can respond to lamivudine therapy, and the optimal treatment of hepatitis C is the combination of interferon alfa and ribavirin. Despite pronounced toxic effects, foscarnet and cidofovir are effective antiviral agents in specific settings.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.

Cytomegalovirus prophylaxis and treatment following bone marrow transplantation

OBJECTIVE

To provide an overview of the role of cytomegalovirus (CMV) in the bone marrow transplant (BMT) population and update the current methods of prevention and treatment of CMV infection and disease, with emphasis on CMV interstitial pneumonia (CMV-IP).

DATA SOURCES

The current medical literature, including abstracts presented at recent national and international meetings, is reviewed. References were identified by searching the MEDLINE database from January 1988 through June 1994. The reference lists of the published studies and reviews obtained from the initial literature search were reviewed as well.

STUDY SELECTION

Data regarding the epidemiology of CMV, the risk factor associated with CMV infection and disease, as well as data on the prevention and the treatment of CMV infection and disease in the BMT population are cited. Specific attention was focused on randomized, placebo-controlled studies pertaining to the prevention of CMV infection and disease in CMV-immunoglobulin G positive recipients undergoing allogeneic BMT. Information from nonrandomized, placebo-controlled studies was included in the absence of stronger data.

DATA EXTRACTION

Information contributing to CMV in the BMT population was reviewed. Data supporting and disputing specific preventive and treatment modalities are presented.

DATA SYNTHESIS

The incidence of CMV seropositivity in the general population is high and while BMT becomes a widely accepted treatment modality, CMV reactivation and subsequent disease, especially CMV-IP, becomes a significant prognostic factor of morbidity and mortality. Even though antiviral agents such as ganciclovir and foscarnet can inhibit the viral replication in vivo, they have not been able to treat CMV-IP effectively. It has been suggested that CMV-IP is an immunopathologic process that can cause irreversible damage, hence, the low efficacy of antiviral therapy and the associated high mortality. Immunomodulating agents such as intravenous immune globulin and cytomegalovirus hyperimmune globulin can increase the efficacy of antivirals in the treatment of CMV-IP. This further supports the postulated immunopathologic process of this disease. The lack of understanding of the pathophysiology of the disease compromised the efforts of treatment and led to the development of preventive interventions with antiviral and immunomodulatory regimens that resulted in a significantly lower incidence of infection and disease. As a result of current data, the Eastern Cooperative Oncology Group has published guidelines for the prevention and treatment of CMV infection and disease.

CONCLUSIONS

The prognosis of CMV disease in the BMT recipients has improved as a result of a wide variety of modifications in the management of BMT recipients. These include an increased understanding of the risk factors associated with CMV infection, routine screening for CMV replication and excretion, and more effective prophylactic regimens. Still, more than half of the patients who develop pneumonia will die, indicating that more studies are needed to increase the understanding of the pathophysiology and refine the preventive and therapeutic regimens against CMV.

Administration of oral acyclovir suppressive therapy after neonatal herpes simplex virus disease limited to the skin, eyes and mouth: results of a phase I/II trial

BACKGROUND

Neonatal herpes simplex virus (HSV) infections limited to the skin, eyes and mouth (SEM) can result in neurologic impairment. A direct correlation exists between the development of neurologic deficits and the frequency of cutaneous HSV recurrences. Thus, the National Institutes of Allergy and Infectious Diseases Collaborative Antiviral Study Group conducted a Phase I/II trial of oral acyclovir therapy for the suppression of cutaneous recurrences after SEM disease in 26 neonates.

METHODS

Infants < or = 1 month of age with virologically confirmed HSV-2 SEM disease were eligible for enrollment. Suppressive oral acyclovir therapy (300 mg/m2/dose given either twice daily or three times per day) was administered for 6 months.

RESULTS

Twelve (46%) of the 26 infants developed neutropenia (< 1000 cells/mm3) while receiving acyclovir. Thirteen (81%) of the 16 infants who received drug 3 times per day experienced no recurrences of skin lesions while receiving therapy. In comparison, a previous Collaborative Antiviral Study Group study found that only 54% of infants have no cutaneous recurrences in the 6 months after resolution of neonatal HSV disease if oral acyclovir suppressive therapy is not initiated. In one infant, HSV DNA was detected in the cerebrospinal fluid during a cutaneous recurrence, and an acyclovir-resistant HSV mutant was isolated from another patient during the course of the study.

CONCLUSIONS

Administration of oral acyclovir can prevent cutaneous recurrences of HSV after neonatal SEM disease. The effect of such therapy on neurologic outcome must be assessed in a larger, Phase III study. As such, additional investigation is necessary before routine use of suppressive therapy in this population can be recommended.

Viral infections in severely immunocompromised cancer patients

Immunocompromised cancer patients are susceptible to infection by many viral pathogens. The most serious morbidity results from active infection by members of the herpes virus family. Reactivation of latent virus occurs as a sequela of cytotoxic therapy and deficiency of cell-mediated immunity, especially cytotoxic responses, the major host protective defense. Herpes simplex virus and varicella zoster virus infections are problematic in patients with all types of cancer; cytomegalovirus infections cause life-threatening morbidity in bone marrow transplant patients. Several antiviral agents are highly active against these pathogens and different strategies of using them have resulted in reduced morbidity and mortality. Ultimately, the resolution of these infections is dependent on the control of the malignancy and the ability of the patient to mount an adequate immune response.

Effects of tumor necrosis factor-alpha treatment on mortality in murine cytomegalovirus-infected mice

The effects of treatment with recombinant DNA-derived Tumor Necrosis Factor-alpha (TNF-alpha) in a murine model of cytomegalovirus infection were investigated. Treatment of 3-week-old Swiss Webster mice with murine TNF-alpha prior to infection with murine cytomegalovirus (MCMV) had no demonstrable effect on mortality. However, if mice were treated prior to infection with a combination of murine IFN-gamma and murine TNF-alpha, the dose of IFN-gamma required to achieve significant reduction in mortality was reduced by a factor > 10. In contrast to the beneficial effects of prophylactic TNF-alpha treatment in combination with IFN-gamma, TNF-alpha treatment of mice after MCMV infection resulted in increased mortality. The increased mortality occurred when nonlethal doses of TNF-alpha were used and required virus replication. The effects of TNF-alpha treatment on mortality in MCMV-infected mice were not predicted from cell culture experiments which evaluated the effects of TNF-alpha treatment on MCMV replication in primary mouse embryo fibroblasts.

Viral infections in leukemia and bone marrow transplant patients

Infections by herpesviruses are common phenomena in patients being treated for acute leukemia and those undergoing bone marrow transplantation. Reactivation of endogenous latent virus caused by the immunosuppressive and cytotoxic effects of cytoreductive therapies is a common mechanism of infection. With cytomegalovirus (CMV), acquisition of exogenous virus by transfusion of blood products containing virus and from the bone marrow graft in the case of bone marrow transplantation can occur. Serious morbidity can result and occasional mortality. CMV infections in allogeneic BMT recipients have high case fatality rates. Treatment and preventive strategies for herpes simplex virus (HSV), CMV, and varicella zoster virus (VZV) have been developed to reduce morbidity. Acyclovir, either given prophylactically or as treatment of active infection, has been highly successful in reducing illness from HSV and VZV infection. For CMV, provision of CMV-seronegative blood products is the mainstay of prevention of morbidity in seronegative patients and is especially important in the care of patients undergoing allogeneic BMT. Ganciclovir given either prophylactically or as early therapy for patients detected to be shedding CMV appears to be a promising strategy. Bolstering host immunity through augmentation of anti-CMV cytotoxic T-cell responses appears to be an exciting candidate therapy under development.

Systemic antiviral drugs used in ophthalmology

Over the past two decades, the recognition of viral enzymes and proteins that can serve as molecular targets of drugs has revolutionized the treatment of viral infections. Beginning with acyclovir, a number of systemically administered agents which are both relatively safe and effective for the treatment of herpetic infections and human immunodeficiency virus (HIV) infections have become widely available. Because of increased numbers of herpes virus infections, as well as the rising epidemic of HIV infections, the ophthalmologist is, more likely than ever before to be involved in the treatment of severe and frequent ocular infections caused by herpes viruses. In addition, the acute retinal necrosis (ARN) syndrome has been demonstrated to be caused by herpes viruses and a once rare retinal infection caused by cytomegalovirus is common in patients with the acquired immunodeficiency syndrome (AIDS). In this article, four systemic antiviral drugs (Vidarabine, Acyclovir, Ganciclovir, and Foscarnet) that have demonstrated usefulness in the treatment of ophthalmic disease are reviewed in detail with regard to their mechanisms, applications, effectiveness, and side effects.

Herpes zoster ophthalmicus

Herpes zoster ophthalmicus occurs worldwide, usually in healthy adults, but, increasingly in patients who are immunocompromised. After primary varicella infection (chickenpox), the virus lies dormant in the sensory ganglion until it becomes reactivated as zoster. Involvement of the ophthalmic branch of the trigeminal nerve is characterized early by corneal dysesthesia and dendritiform keratopathy, and these are self-limited. However, smoldering disease may cause pathological changes in the ocular structures through direct invasion of virus, secondary inflammation, and alterations of autoimmune mechanisms. Antiviral agents have demonstrated some success in resolving early signs and symptoms, but their role in preventing and treating late complications remains to be fully studied. Until a definitive antiviral agent is established, the benefits of steroid use in certain acute inflammatory processes outweight its risk of reducing host immunity. Corneal complications of herpes zoster ophthalmicus sometimes require surgical intervention.

Antiviral agents

In recent years, the antiviral armamentarium has expanded considerably. Currently available agents are virustatic, inhibiting specific steps in the process of viral replication. No agent is active against nonreplicating or latent viruses. Acyclovir is useful in the treatment of genital herpes, herpes simplex encephalitis, mucocutaneous herpetic infection, varicella infection in the immunosuppressed host, and herpes zoster infection in the normal and the immunosuppressed host. It can also be used for prevention of herpesvirus infection in immunocompromised patients. Ganciclovir is indicated for the treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome (AIDS) and is effective in the management of organ-specific cytomegalovirus infection in other immunocompromised patients. Chronic hepatitis C and condyloma acuminatum due to human papillomavirus respond to therapy with interferon alfa-2b. Patients with human immunodeficiency virus infection and CD4 lymphocyte counts of less than 500 cells/mm3 should be treated with zidovudine. Amantadine is useful in a therapeutic and prophylactic role in the management of influenza A virus infection. With the expanded use of and indications for antiviral therapy, clinically significant resistance to these agents has been encountered with increasing frequency.

Foscarnet for treatment of cytomegalovirus infections in bone marrow transplant recipients

42 episodes of verified or clinically suspected cytomegalovirus (CMV) infection in 40 bone marrow transplant (BMT) recipients were treated with foscarnet (trisodium phosphonophormate hexahydrate). CMV infection was verified in 31/42 treatment episodes. Symptoms treated were pneumonia (n = 17), pancytopenia with or without fever (n = 12), enteritis (n = 5), fever (n = 4), encephalitis (n = 2), retinitis (n = 1) and hepatitis (n = 1). Foscarnet was given as a continuous intravenous infusion. Side-effects observed were increase in serum creatinine (38%), decrease in serum calcium (19%), increase in serum bilirubin (12%), decrease in hemoglobin concentration (7%), increase in serum calcium (5%), increase in serum transaminase (5%), hypophosphatemia (2%) and tremor (2%). CMV was eradicated from blood and/or urine in 11/25 (44%) of assessable treatment episodes with infection verified by isolation. Overall clinical improvements including eradication of CMV, afebrility and/or improvements in laboratory abnormalities were seen in 14/31 (45%) episodes of verified infection. All 15 patients with CMV interstitial pneumonia (CMV IP) died. We conclude that foscarnet is nephrotoxic but otherwise well tolerated with moderate clinical and virostatic effects on CMV infection. The effect on CMV IP is discouraging.

Early treatment with ganciclovir to prevent cytomegalovirus disease after allogeneic bone marrow transplantation

BACKGROUND

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after allogeneic bone marrow transplantation. We conducted a controlled trial of ganciclovir for the early treatment of CMV infection in asymptomatic recipients of bone marrow transplants whose surveillance cultures for CMV became positive.

METHODS

Bone marrow--allograft recipients who were seropositive for CMV antibodies or who received seropositive marrow were screened for CMV excretion by culture of throat swabs, blood, urine, or bronchoalveolar-lavage fluid. In this double-blind trial, 72 patients who had marrow engraftment and were excreting virus were randomly assigned to receive either placebo or ganciclovir (5 mg per kilogram of body weight twice a day for one week, followed by 5 mg per kilogram per day) for the first 100 days after transplantation. Patients were followed for the development of biopsy-confirmed CMV disease, ganciclovir-related toxicity, and survival.

RESULTS

Between assignment to the study drug and day 100 after transplantation, CMV disease developed in only 1 of the 37 patients assigned to receive ganciclovir (3 percent), but in 15 of the 35 patients assigned to receive placebo (43 percent, P less than 0.00001). The ganciclovir recipients had rapid suppression of virus excretion; 85 percent had negative cultures after one week of treatment, as compared with 44 percent of the placebo group (P = 0.001). The principal toxic reaction was neutropenia; 11 ganciclovir recipients had an absolute neutrophil count below 0.75 x 10(9) per liter, as compared with 3 placebo recipients (P = 0.052). Treatment was discontinued in 11 ganciclovir recipients and 1 placebo recipient because of neutropenia (P = 0.003). After treatment was stopped, the neutrophil count recovered in all patients. Overall survival was significantly greater in the ganciclovir group than in the placebo group both 100 days and 180 days after transplantation (P = 0.041 and 0.027, respectively).

CONCLUSIONS

Early treatment with ganciclovir in patients with positive surveillance cultures reduces the incidence of CMV disease and improves survival after allogeneic bone marrow transplantation.

A randomized, controlled trial of prophylactic ganciclovir for cytomegalovirus pulmonary infection in recipients of allogeneic bone marrow transplants; The City of Hope-Stanford-Syntex CMV Study Group

BACKGROUND

Cytomegalovirus (CMV)-associated interstitial pneumonia is a major cause of death after allogeneic bone marrow transplantation. We conducted a controlled trial of ganciclovir in recipients of bone marrow transplants who had asymptomatic pulmonary CMV infection. We also sought to identify risk factors for the development of CMV interstitial pneumonia.

METHODS

After bone marrow transplantation, 104 patients who had no evidence of respiratory disease underwent routine bronchoalveolar lavage on day 35. The 40 patients who had positive cultures for CMV were randomly assigned to either prophylactic ganciclovir or observation alone. Ganciclovir (5 mg per kilogram of body weight intravenously) was given twice daily for two weeks and then five times per week until day 120.

RESULTS

Of the 20 culture-positive patients who received prophylactic ganciclovir, 5 (25 percent) died or had CMV pneumonia before day 120, as compared with 14 of the 20 culture-positive control patients (70 percent) who were not treated prophylactically (relative risk, 0.36; P = 0.01). No patient who received the full course of ganciclovir prophylaxis went on to have CMV interstitial pneumonia. Four patients treated with ganciclovir had maximal serum creatinine levels greater than or equal to 221 mumol per liter (2.5 mg per deciliter), as compared with none of the controls (P = 0.029). Of the 55 CMV-negative patients who could be evaluated, 12 (22 percent) had CMV pneumonia--a significantly lower rate than in the untreated CMV-positive control patients (relative risk, 0.33; P = 0.003). The strongest predictors of CMV pneumonia were a lavage-fluid culture that was positive for CMV and a CMV-positive blood culture, both from specimens obtained on day 35.

CONCLUSION

In recipients of allogeneic bone marrow, asymptomatic CMV infection of the lung is a major risk factor for subsequent CMV interstitial pneumonia. Prophylactic ganciclovir is effective in preventing the development of CMV interstitial pneumonia in patients with asymptomatic infection.

Successful treatment of disseminated cutaneous cytomegalic inclusion disease associated with Hodgkin's disease

A case of disseminated cutaneous cytomegalic inclusion disease associated with Hodgkin's disease is described. The patient had a diffuse eruption of pruritic, erosive erythematous nodules. Histologically, many inclusion bodies were observed in perivascular areas of the skin lesions. Immunohistologically, the inclusion bodies positively stained with both anticytomegalovirus antibody and anti-factor VIII-related antibody. On electron microscopy many virus particles and dense bodies were found in the area where inclusion bodies were observed. Treatment with high-dose intravenous acyclovir and a large amount of immunoglobulin resulted in prompt healing of the skin lesions. Subsequently, the patient's Hodgkin's disease was well controlled on chemotherapy. The patient steadily improved without relapse of skin lesions 1 year after antiviral therapy was administered.

Synergistic effect of ganciclovir and foscarnet on cytomegalovirus replication in vitro

Ganciclovir and foscarnet possess substantial activity against cytomegalovirus. Both exhibit dose-limiting toxicity, which reduces their clinical usefulness. We demonstrated synergistic inhibition of cytomegalovirus replication in vitro by ganciclovir and foscarnet. Reduced-dose combination therapy may provide a means to treat patients with cytomegalovirus infection while reducing drug toxicity.

Cytomegalovirus infection after organ transplantation: an update with special emphasis on renal transplantation

Cytomegalovirus infections are still the most important infectious complications after organ transplantation. Besides historical notes this review will deal with new aspects concerning the epidemiology of the CMV, diagnostic modalities of CMV infection, the delicate counterbalance between the immune system and the CMV, as well as the symptomatology of this infection. Furthermore, aspects like prophylaxis and new, promising therapeutic regimes for treatment of infection will be dealt with. Although this update is applicable for all types of solid organ transplantation, emphasis will be on renal transplantation.

Effect of 2'-nor-cyclic GMP against guinea pig cytomegalovirus infection

Cyclic phosphate derivative of DHPG, 2'-nor-cGMP [9-[(2-hydroxy-1,3,2-dioxaphosphorinan-5-yl)oxymethyl]-guani ne phosphate-oxide] was evaluated for activity against guinea pig cytomegalovirus (GPCMV) infection in cultured guinea pig embryo cells and in guinea pigs. By virus yield reduction and plaque reduction assays, 2'-nor-cGMP was demonstrated to be 15- to 20-fold more potent against GPCMV infection than its parental drug DHPG. The selectivity index of 2-nor-cGMP was 110, which was 10-fold higher than that of DHPG. In cultured cells, 2'-nor-cGMP attained maximal antiviral activity when added to the cells within 12 h postinfection. In the studies on GPCMV infection in guinea pigs, 2'-nor-cGMP administered subcutaneously once daily (5 mg/kg per day) for 8 days, starting 24 after virus inoculation, significantly suppressed GPCMV infectivity titers in the blood, spleen, lung, and salivary gland during acute infection (10 days postinfection) as compared with sham-treated infected animals. A greater reduction of GPCMV infectivity titers in the salivary gland was noted during chronic infection (i.e., 24 days postinfection). Clinically, splenomegaly and peripheral lymphocytosis were significantly modified as compared with the sham-treated animals (P less than 0.05). The drug, administered at this dosage, was reasonably tolerated by the guinea pigs and showed clinical benefit.

Evaluation of ganciclovir for cytomegalovirus disease

Cytomegalovirus (CMV) infections are a common cause of morbidity and mortality in immunosuppressed patients. Ganciclovir is an acyclic deoxyguanosine analog structurally similar to acyclovir but with superior activity against CMV. The median ganciclovir concentration required to inhibit viral replication by 50 percent is 2.15 mumol versus 72 mumol for acyclovir. Pharmacokinetic properties of ganciclovir include biexponential decay with a terminal half-life of 2.5 hours, tissue uptake, cerebrospinal fluid penetration, and renal dependence for elimination. CMV treatment approaches have commonly used dosages of 3-15 mg/kg/d. In uncontrolled trials, the response rate of CMV retinitis is approximately 80 percent. The overall response rate for CMV pneumonitis has been approximately 50 percent. However, AIDS (acquired immunodeficiency syndrome) and other immunosuppressed patients appear to respond more favorably (approximately 70 percent) than do marrow transplant recipients. Relapse is common once ganciclovir is stopped and maintenance therapy may be required for sustained benefit. Neutropenia appears to be the drug-limiting adverse reaction. Although the development of ganciclovir-resistant CMV, risk factors for neutropenia, and alternative administration strategies all need further study, ganciclovir appears to have a role in the treatment of cytomegalovirus disease.

Treatment of cytomegalovirus pneumonitis with ganciclovir in renal transplantation

Ganciclovir, also called DHPG, was administered intravenously to eight renal transplant recipients with life-threatening cytomegalovirus (CMV) pneumonitis. One patient died of pulmonary failure; a favorable clinical response was observed in the seven others. In one patient, CMV pneumonitis recurred but responded well to a second course of the drug. At no time was the immunosuppressive regimen completely stopped in the seven surviving patients. Six of them maintained a good renal function 1-11 months after treatment with ganciclovir. No toxic effect was detected during therapy. We conclude that ganciclovir appears to be a promising and effective treatment for CMV pneumonitis after renal transplantation.

Reduced mortality in murine cytomegalovirus infected mice following prophylactic murine interferon-gamma treatment

Efficacy of recombinant DNA-derived murine IFN-gamma was investigated in a murine model of cytomegalovirus infection. Treatment of 3-week-old Swiss Webster mice with murine IFN-gamma prior to infection with murine cytomegalovirus (MCMV) significantly reduced mortality due to MCMV infection. Efficacy was dose-dependent and was observed using either intraperitoneal or intramuscular injection as the route of administration. Two doses, one at 24 h and one at 4 h prior to MCMV infection, were required for optimum efficacy, and doses administered after MCMV infection had no apparent effect. Reduced infectious MCMV titers were observed in critical organs of IFN-gamma treated mice and histopathologic lesions induced by MCMV infection were in general less severe and resolved sooner than lesions in untreated mice. Results in this murine model of cytomegalovirus infection suggest that IFN-gamma treatment may be useful as prophylactic therapy for human cytomegalovirus infections when a high probability of exposure to the virus exists and consequences of infection may be severe.