Pharmacokinetics of oral acyclovir (Zovirax) in the eye

Emerging drugs for the treatment of herpetic keratitis

INTRODUCTION

Herpes simplex keratitis stands as a prominent factor contributing to infectious blindness among developed nations. On a global scale, over 60% of the population tests positive for herpes simplex virus type-1 (HSV-1). Despite these statistics, there is currently no vaccine available for the virus. Moreover, the conventional nucleoside drugs prescribed to patients are proving ineffective in addressing issues related to drug resistance, recurrence, latency, and the escalating risk of vision loss. Hence, it is imperative to continually explore all potential avenues to restrict the virus. This review article centers on the present treatment methods for HSV-1 keratitis (HSK), highlighting the ongoing clinical trials. It delves into the emerging drugs, their mode-of-action and future therapeutics.

AREAS COVERED

The review focuses on the significance of a variety of small molecules targeting HSV-1 lifecycle at multiple steps. Peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase, and clinical trial websites.

EXPERT OPINION

The exploration of small molecules that target specific pathways within the herpes lifecycle holds the potential for substantial impact on the antiviral pharmaceutical market. Simultaneously, the pursuit of disease-specific biomarkers has the capacity to usher in a transformative era in diagnostics within the field.

Antiviral and Anti-Inflammatory Therapeutic Interventions for Treating Herpes Stromal Keratitis: A Systematic Review

PURPOSE

Herpes stromal keratitis (HSK) is an immune-mediated corneal inflammation that occurs after a herpes simplex virus infection. This paper aims to systematically identify and compare interventions for treating HSK and their patient outcomes.

METHODS

This systematic review followed the PRISMA methodology. Online databases were searched to obtain all relevant papers. Two independent reviewers screened through 168 records. Seven papers were included and used for data extraction. A qualitative analysis was conducted.

RESULTS

HSK patients receiving prednisolone phosphate and acyclovir showed a higher treatment success rate and significantly longer time to failure compared to patients receiving only acyclovir (P < .001). No difference in resolution time was found between oral and topical acyclovir. Between groups receiving dexamethasone and flurbiprofen, resolution occurred in 93% and 67% of patients, and BCVA (LogMAR) improved from 1.0 to 0.30 and 0.48, respectively. BCVA improved in both cyclosporine-A (P < .001) and its control (prednisolone) groups (P = .002). A tacrolimus treatment group showed greater improvement in BCVA compared to its control (prednisolone) group (P < .001).

CONCLUSION

Corticosteroids and antivirals managed HSK most effectively only when used concurrently. Oral acyclovir showed similar effectiveness to its ointment counterpart, a preferable alternative for easier administration. Corticosteroid use could induce greater therapeutic benefits when tapered in concentration and frequency and administrated for at least 10 weeks. Anti-inflammatory drugs including flurbiprofen, cyclosporine-A, and tacrolimus could be safe and effective for treating HSK. Future long-term follow-up and RCTs could provide insights on the therapeutic benefits of these potential alternatives.

Clinical Management of Herpes Simplex Virus Keratitis

Herpes simplex virus (HSV) keratitis is one of the leading causes of blindness worldwide. Additionally, up to 90% of the population in some countries is seropositive for HSV. HSV can cause a wide spectrum of ocular disease ranging from blepharitis to retinitis. Although the initial clinical expressions of HSV-1 and HSV-2 are similar, HSV-2 has been reported more frequently in association with recurrent HSV disease. Besides irreversible vision loss from keratitis, HSV also causes encephalitis and genital forms of the disease. Despite these statistics, there remains no vaccine against HSV. Current treatment therapies for related ocular diseases include the use of oral and topical antivirals and topical corticosteroids. While effective in many cases, they fail to address the latency and elimination of the virus, making it ineffective in addressing recurrences, a factor which increases the risk of vision loss. As such, there is a need for continued research of other potential therapeutic targets. This review utilized several published articles regarding the manifestations of HSV keratitis, antiviral immune responses to HSV infection, and clinical management of HSV keratitis. This review will summarize the current knowledge on the host–virus interaction in HSV infections, as well as highlighting the current and potential antiviral therapeutics.

Coin-shaped corneal endothelial scar in herpes zoster ophthalmicus: a case report

Background

Herpes zoster ophthalmicus includes a wide spectrum of lesions at the ocular surface, including epithelial, stromal, endothelial keratitis, and uveitis. Thus far, the occurrence of corneal endothelial disorder in herpes zoster ophthalmicus and the causative virus have not been confirmed, and the differential diagnosis and establishment of therapeutic strategies are challenging. Corneal endothelial coin-shaped lesions are well known to occur in cytomegalovirus-related corneal endotheliitis but have not been reported in patients with herpes zoster ophthalmicus.

Case presentation

A 39-year-old Asian female was referred to our ophthalmology department with recurrent anterior uveitis accompanied by coin-shaped corneal endothelial scar-like lesions that appeared after right facial herpes zoster. Diffuse corneal stromal haziness was mostly limited in the anterior stroma. The coin-shaped corneal endothelial lesions were separate from stromal lesions and showed a high-reflective scar-like line in sections of anterior segment optical coherence tomography. Anterior uveitis recurred each time she discontinued oral antiviral drug treatment for 12 months after the first event, but was remitted by the maintenance medications of combined topical ganciclovir gel with oral valaciclovir, at a dose lower than the usual adult dose, for acute or recurrent zoster-associated anterior uveitis. Corneal endothelial function remained normal and corneal endothelial and stromal lesions were unchanged throughout the treatment and follow-up period.

Conclusions

In patients with a history of facial herpes zoster with coin-shaped corneal endothelial scar accompanying recurrent anterior uveitis, suspicion for active varicella-zoster virus is warranted, and prolonged intake of oral antiviral agents is required despite varicella-zoster virus DNA not being detected in aqueous humor.

Evidence in the prevention of the recurrence of herpes simplex and herpes zoster keratitis after eye surgery

OBJECTIVE

Herpetic keratitis, either due to herpes simplex keratitis (HSK) or herpes zoster ophthalmicus (HZO), can recur after eye surgery.º Prophylaxis is postulated as necessary to avoid it. The objective of this study was to review the scientific evidence on the preventive methods used in the perioperative period in patients previously affected by HSK/HZO.

METHODS

An exhaustive search was carried out in the PubMed and Web of Science databases to identify relevant articles on prophylaxis and risk of recurrence of HSK/HZO in patients undergoing eye surgery up to 31 December 2019.

RESULTS

There is strong evidence that oral prophylaxis should be recommended after penetrating keratoplasty in patients who have previously had HSK/HZO. For other types of surgery, the evidence is less compelling. However, a latent period of inactivity should be considered between disease and oral prophylaxis.

CONCLUSIONS

Penetrating and lamellar keratoplasty, corneal crosslinking, cataract surgery, and photorefractive and phototherapeutic surgery cause an alteration of the subbasal nerve plexus of the cornea. Due to surgical trauma, as well as the modulation of the ocular immune response caused by steroids applied in the postoperative period, it is possible to induce the reactivation of HSK/HZO, which is common in some cases. Within this article, we discuss the available evidence for HSK/HZO prophylaxis in eye surgery. Further studies are necessary to define the real risk of HSK/HZO recurrence after ocular surgeries, particularly in cataract surgery, and to confirm the efficacy of perioperative prophylaxis with anti-HSK/HZO antivirals.

Adoption of Innovation in Herpes Simplex Virus Keratitis

Herpes simplex keratitis, caused primarily by human herpes simplex virus type 1 (HSV-1), remains the most common infectious cause of unilateral blindness and vision impairment in the industrialized world. Major advances in the care of HSV keratitis have been driven in large part by the landmark Herpetic Eye Disease Study randomized clinical trials, which were among the first in ophthalmology to reflect emerging trial conventions, including multicenter subject enrollment, double-masking, placebo controls, and a priori sample size determinations. The results of these trials now form much of the evidence basis for the management of this disease. However, management patterns in clinical practice often deviate from evidence-based care. These perceived quality gaps have given rise to the evolving field of implementation science, which is concerned with the methods of promoting the application of evidence-based medicine within routine care. To overcome variations in the quality and consistency of care for HSV keratitis, a range of clinical- and technology-based innovations are proposed. The most pressing needs include the following: a rational and tractable disease classification scheme that provides an immediate link between the anatomical localization of disease (corneal epithelial, stromal, or endothelial) and the appropriate treatment, and the actualization of an electronic medical record system capable of providing evidence-based treatment algorithms at relevant points of care. The latter would also input data to population-wide disease registries to identify implementation-rich targets for quality improvement, education, and research. These innovations may allow us to reduce the human and economic burdens of this highly morbid, and often blinding, disease.

20 years since the Herpetic Eye Disease Study: Lessons, developments and applications to clinical practice

Herpes Simplex Virus (HSV) is the most common virus that causes eye disease. Although around 60% of the world's population are seropositive for HSV antigens, fortunately, it is estimated that only 1% of seropositive individuals develop eye disease. The most common ocular manifestation of HSV is keratitis, while uveitis and retinal necrosis occur in a small number of cases. HSV keratitis is a debilitating disease, for several reasons: pain , photophobia, and vision loss in acute disease, latency of the virus which leads to infection reactivation from various triggers, scarring, and neovascularisation, leading to permanent vision loss with poor visual rehabilitation prospects. The Herpetic Eye Disease Study (HEDS) was a landmark series of randomised controlled trials in the 1990s that set the benchmark for evidence-based treatment guidelines for anterior eye herpetic disease. Since this time, there has been a change in the distribution of seroprevalence of herpes in the community, a simplified diagnostic classification, advances in treatment options, an emergence of new and a better understanding of risk factors, and discoveries in science that show promise for vaccine and novel future treatments. However, many of the principles of the HEDS study remain rightly entrenched in clinical practice. In this article, the HEDS study is revisited 20 years on through the lens of published literature, to determine current best practise and look towards the future.

Ocular surgery after herpes simplex and herpes zoster keratitis

PURPOSE

The recurrence of herpetic stromal keratitis (HSK) and herpes zoster ophthalmicus (HZO) has been reported after a variety of ocular surgeries. The aim of this study was to review the evidence on the preventive methods employed in the perioperative period in patients having undergone HSK/HZO.

METHODS

The PubMed and Web of Science databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the prophylaxis against and risk of HSK/HZO recurrence in patients undergoing ocular surgery up to December 31, 2019.

RESULTS

The disturbance of the corneal nerve plexus occurs during several ocular surgeries including penetrating keratoplasty, lamellar keratoplasty, corneal cross-linking, cataract surgery, as well as photorefractive and phototherapeutic procedures. Such trauma, as well as modulation of the ocular immunological response caused by steroids applied postoperatively, might engender the HSK/HZO reactivation which is not uncommon. There is strong evidence that oral prophylaxis should be recommended just after surgery in patients undergoing penetrating keratoplasty and having suffered from HSK/HZO. For other types of surgeries, the evidence is less compelling; nevertheless, a period of disease quiescence and oral prophylaxis should still be considered.

CONCLUSIONS

Within the article, we discuss the available evidence for HSK/HZO prophylaxis in ocular surgery. Additional studies would be required to define the real risk of HSK/HZO recurrence following eye surgeries, and particularly cataract surgery, and to confirm the utility of perioperative HSK/HZO prophylaxis.

Update on Herpes simplex keratitis management

Herpes simplex keratitis (HSK) is a common, potentially blinding condition characterised by recurrent infections of the cornea, seen by both general ophthalmologists and corneal specialists. Successful treatment of recurrences reduces disease duration, prevents progressive corneal scaring leading to vision loss and reduces risk of further recurrences. In this review we discuss the relative advantages of the diagnostic laboratory investigations including polymerase chain reaction, viral culture and fluorescence-based immunohistochemistry. We review treatment strategies in selected aspects of HSK and discuss the management options in cases not responding to treatment.

Self-Retained Amniotic Membrane Combined With Antiviral Therapy for Herpetic Epithelial Keratitis

PURPOSE

To evaluate the therapeutic benefit of self-retained cryopreserved amniotic membrane in conjunction with oral antiviral therapy in herpetic epithelial keratitis.

METHODS

Retrospective review of 4 patients with primary (1 eye) and recurrent (3 eyes) unilateral herpetic epithelial keratitis treated with cryopreserved amniotic membrane through the placement of the PROKERA Slim (PKS) (Bio-Tissue, Inc) in conjunction with oral acyclovir. Their symptoms, conjunctival inflammation, corneal staining, and visual acuity were compared before and after treatment.

RESULTS

Herpetic epithelial keratitis presented as dendritic (3 eyes) and geographic (1 eye) epithelial lesions. After epithelial debridement and placement of the PKS for 5 ± 3.7 days, all patients reported significant relief of symptoms, rapid corneal epithelialization, and reduction of ocular surface inflammation. The visual acuity was also improved in all eyes from 0.7 ± 0.7 to 0.4 ± 0.7 logarithm of the minimum angle of resolution (P = 0.2). They remained symptom-free during a follow-up period of 2.7 to 50.8 (20.3 ± 21.7) months.

CONCLUSIONS

The PKS in conjunction with oral acyclovir facilitates the ease of early intervention to accelerate restoration of a normal corneal epithelium in herpetic epithelial keratitis.

Clinical efficacy of oral and topical acyclovir in herpes simplex virus stromal necrotizing keratitis

Purpose:

To evaluate the efficacy of systemic and topical antiviral therapy in the treatment of active herpes simplex virus (HSV) necrotizing stromal keratitis (NSK).

Design:

Prospective interventional case series.

Methodology:

Patients with a diagnosis of HSV NSK based on history and clinical findings were enrolled in the study. A standard protocol was used for microbiologic investigations. Ten weeks regime of systemic acyclovir and 2 weeks of topical acyclovir was given. Complete ophthalmic examination was performed at every visit. Outcome measures were a reduction in the area of infiltration and improvement in visual acuity.

Results:

Fifteen patients were enrolled in the study. The mean age of presentation was 51.53 years. The duration of symptoms at presentation ranged from 2 to 8 weeks. HSV1 DNA polymerase chain reaction was positive in 70% cases of those tested. Area of infiltration at trial entry and at the end of 2 weeks of antiviral treatment reduced significantly (P = 0.007). All patients showed a complete resolution of keratitis at the end of study.

Conclusion:

Topical and systemic acyclovir for treatment of NSK facilitates healing of ulceration. Topical steroids after initial antiviral therapy are safe and decreases inflammation and improve visual recovery. Early initiation of therapy has better outcomes as compared to late presentations.

Infectious uveitis: An enigma

Infectious uveitis accounts for majority of the cases of uveitis in developing countries. It also encompasses an array of various microorganisms and their clinical presentations. Some of these infectious uveitic entities are familiar, while others are newly emerging in the global ophthalmic world. Many of these entities are also a major cause of morbidity and mortality, and appropriate, timely management is required to save not the eye, but life of the patient. This review highlights the ocular manifestations of various infectious uveitic entities, relevant to the ophthalmologist.

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.

Ocular herpes: the pathophysiology, management and treatment of herpetic eye diseases

Herpesviruses are a prominent cause of human viral disease, second only to the cold and influenza viruses. Most herpesvirus infections are mild or asymptomatic. However, when the virus invades the eye, a number of pathologies can develop and its associated sequelae have become a considerable source of ocular morbidity. The most common culprits of herpetic eye disease are the herpes simplex virus (HSV), varicella zoster virus (VZV), and cytomegalovirus (CMV). While primary infection can produce ocular disease, the most destructive manifestations tend to arise from recurrent infection. These recurrent infections can wreck devastating effects and lead to irreversible vision loss accompanied by a decreased quality of life, increased healthcare usage, and significant cost burden. Unfortunately, no method currently exists to eradicate herpesviruses from the body after infection. Treatment and management of herpes-related eye conditions continue to revolve around antiviral drugs, although corticosteroids, interferons, and other newer therapies may also be appropriate depending on the disease presentation. Ultimately, the advent of effective vaccines will be crucial to preventing herpesvirus diseases altogether and cutting the incidence of ocular complications.

Acute retinal necrosis after Boston type I keratoprosthesis

A case report of a 68-year-old male who developed acute retinal necrosis (ARN) after Boston type I keratoprosthesis is presented. The procedure was performed for multiple graft failure secondary to herpetic keratitis. Clinical data including visual acuity, color fundus photography, fluorescein angiography, laboratory tests findings, and management are presented. After exclusion of other causes by laboratory workup, the patient was diagnosed with ARN most likely secondary to herpetic infection. Intravenous acyclovir and oral prednisolone were administered to the patient resulting in marked improvement in visual acuity and regression in the size of the retinitis. The patient eventually developed a soft eye and choroidal detachment with light perception vision. In patients with a history of herpetic keratitis or keratouveitis, it is highly advisable to maintain prophylactic systemic antiviral treatment before and after any ocular procedure such as the Boston keratoprosthesis.

Antiviral selection in the management of acute retinal necrosis

There is no consensus on the optimal antiviral regimen in the management of acute retinal necrosis, a disease caused by herpetic viruses with devastating consequences for the eye. The current gold standard is based on retrospective case series. Because the incidence of disease is low, few well-designed, randomized trials have evaluated treatment dosage and duration. Newer oral antiviral agents are emerging as alternatives to high-dose intravenous acyclovir, avoiding the need for inpatient intravenous treatment. Drug resistance is uncommon but may also be difficult to identify. Antiviral drugs have few side effects, but special attention needs to be paid to patients who have underlying renal disease, are pregnant or are immunocompromised.

Evidence-based treatment of herpes simplex virus keratitis: a systematic review

Herpes simplex virus (HSV) keratitis is a common cause of ocular and visual morbidity. In this article, we systematically review published randomized clinical trials (RCTs) for HSV epithelial and stromal keratitis in order to establish a rational evidence-based foundation for treatment of these disorders. Articles for review were identified in the MEDLINE database from January 1, 1966, to May 30, 2006. Our review criteria stipulated that each study be performed in prospective, randomized, and double-blinded fashion, that it be controlled, and that it rely on specific clinical criteria for diagnosis and outcome. Of articles thus identified in the English language press, 38 articles met our review criteria, 30 for HSV epithelial keratitis and 8 (comprising 7 RCTs) for HSV stromal keratitis. From these studies, we concluded that the best evidence from treatment trials on HSV epithelial keratitis supports the use of topical trifluridine and topical or oral acyclovir, and suggests a possible additional benefit for topical interferon. The best evidence from RCTs for HSV stromal keratitis supports the use of topical corticosteroids given together with a prophylactic antiviral to shorten the duration of active HSV stromal keratitis, and the use of long-term suppressive oral acyclovir therapy to reduce the incidence of recurrent HSV keratitis.

Bioequivalence assessment of Lovrak (Julphar, UAE) compared with Zovirax (Glaxo Wellcome, UK)-Two brands of Acyclovir-in healthy human volunteers

Two studies were performed to assess the relative bioavailability of Lovrak (Julphar, UAE) compared with Zovirax (Glaxo Wellcome, UK) at the International Pharmaceutical Research Center (IPRC), Amman, Jordan. One study involved acyclovir tablets and the other acyclovir suspension. Each study enrolled 24 volunteers and in both studies, after an overnight fasting, the two brands of acyclovir were administered as a single dose on 2 treatment days separated by 1 week washout period. After dosing, serial blood samples were collected for a period of 16 h. Plasma harvested from blood, was analysed for acyclovir by an HPLC method with UV detection. Various pharmacokinetic parameters including AUC0-t, AUC0-infinity, Cmax, Tmax, T1/2 and Kelm were determined from plasma concentrations for both formulations and found to be in good agreement with the reported values. AUC0-t, AUC(0-proportional to), and Cmax were tested for bioequivalence after log-transformation of data. No significant difference was found based on ANOVA; 90% confidence intervals for the test/reference ratio of these parameters were found within the bioequivalence acceptance range 80%-125%. Based on these statistical inferences it was concluded that a Lovrak tablet is bioequivalent to a Zovirax tablet and that Lovrak suspension is bioequivalent to Zovirax suspension.

[The latest in herpes simplex keratitis therapy]

Herpetic keratitis is characterized by spontaneous recurrences and a risk of vision loss, the latter being more serious when relapses are frequent and severe. Two clinical forms are commonly distinguished: epithelial keratitis, usually quickly resolved with topical antivirals, and stromal keratitis, which has a slower progression, even when both steroids and antivirals are used. Great strides have been made during the last 20 Years in the therapy of herpes keratitis, which is now considered and treated as a chronic disease. Randomized controlled studies definitively showed the decrease in spontaneous herpetic ocular events in patients treated with long-term oral acyclovir. The effectiveness of preventive treatment has also been shown during high-risk periods, especially ocular surgery, in patients with a history of herpes keratitis. However, the optimal duration and dosage of antiviral prevention have yet to be defined. We can also hope that in the future novel antiviral strategies such as vaccination will reduce the place of herpes keratitis as an indication for corneal graft.

The outcome of corneal grafting in patients with stromal keratitis of herpetic and non-herpetic origin

AIM

To evaluate the outcome of corneal grafting in patients with stromal keratitis of herpetic (HSK) and non-herpetic origin, using predefined diagnostic criteria and standardised postoperative therapeutic strategies.

METHODS

384 adult immunocompetent recipients of a corneal graft for herpetic (n = 186) or non-herpetic (n = 198) keratitis were followed up prospectively for up to 5 years.

RESULTS

The herpetic group displayed significantly more corneal vascularisation (p = 0.013), more epithelial defects (p = 0.049), lower corneal sensitivity (p <0.001), more graft rejection episodes (p = 0.002), and required larger grafts (p<0.001). However, the postoperative course of visual acuity, endothelial cell numerical density, and rate of graft failures were similar in both groups. After 5 years, cumulative probability of graft survival in HSK patients (40.85%) was similar to that observed in individuals with non-herpetic keratitis (50.15%; log rank = 0.874; relative risk: 1.04).

CONCLUSION

Despite a markedly higher preoperative risk profile in herpetic eyes, the functional outcomes of grafts in individuals with keratitis of herpetic or non-herpetic origin were similar. Probably the most important contribution is a consequent close follow up and a therapeutic strategy including systemic prophylaxis of viral recurrence and of graft rejection by well adopted local steroid therapy.

Advances in diagnosis and management of herpetic uveitis

Herpetic eye disease is common and is frequently associated with intraocular inflammation or uveitis. Despite recent advances in measuring anti-herpes virus antibodies and viral DNA in ocular fluids, diagnosis remains largely clinical. The two more common syndromes include anterior uveitis, often associated with keratitis, and the acute retinal necrosis (ARN) syndrome. Treatment is complex and requires careful monitoring to provide the appropriate balance of antiviral medication and corticosteroids. Long-term prophylaxis with oral antiviral agents may be required in selected patients to help prevent the vision-compromising complications associated with recurrences.

Treatment of viral diseases of the cornea and external eye

Ocular virus infections remain an important cause of corneal and external disease. Herpes simplex, the most important, is easily treated when it is confined to the epithelium. New studies indicate that herpetic stromal disease and iritis are effectively treated with a combination of corticosteroid and antiviral without additional risk. Recurrences of ocular herpetic disease can be reduced with acyclovir given orally; the benefit seems to be greatest in patients who have had at least one episode of stromal keratitis. Herpes zoster can be treated with either acyclovir or famciclovir, but to be effective, treatment must be initiated within 72 hours of onset. Early treatment reduces the risk of post-herpetic neuralgia and may reduce the risk of ocular complications. Adenovirus infection (epidemic keratoconjunctivitis) is often spread by the ophthalmologist. New medications such as cidofovir appear to be effective against the adenoviruses in non-human systems and may have some effect in man, although previously, drugs that appeared to have an effect in vitro have proven to be ineffective in the clinical setting.

Risk factors for herpes simplex virus epithelial keratitis recurring during treatment of stromal keratitis or iridocyclitis. Herpetic Eye Disease Study Group

AIMS

Possible risk factors were evaluated for herpes simplex virus (HSV) epithelial keratitis in patients with stromal keratouveitis.

METHODS

The study population included 260 patients who had active stromal keratitis and/or iridocyclitis without epithelial disease and who were enrolled in one of three clinical trials of the Herpetic Eye Disease Study. Study treatment involved a 10 week course of topical placebo, topical prednisolone phosphate, or topical prednisolone phosphate with oral acyclovir. All groups received topical trifluridine four times daily for 3 weeks then twice daily for another 7 weeks. Patients were examined for HSV epithelial keratitis for 16 weeks.

RESULTS

Dendritic or geographic epithelial keratitis occurred in 12 (4.6%) study patients. Adverse effects attributable to trifluridine prophylaxis were acute allergic blepharoconjunctivitis in 10 (3.8%) study patients and corneal epithelial erosions in 11 (4.2%) study patients. No significant difference in the occurrence of HSV epithelial keratitis was found among the study treatment groups: one (2.0%) of 49 topical placebo treated patients, nine (6.5%) of 138 patients treated with topical corticosteroids without acyclovir, and two (2.7%) of 73 patients treated with topical corticosteroids and oral acyclovir. Univariate exponential models suggested that patients with a history of previous HSV epithelial keratitis and non-white patients were more likely to develop HSV epithelial keratitis during treatment of stromal keratouveitis.

CONCLUSION

Individuals with prior HSV epithelial keratitis and certain ethnic groups may have a higher rate of recurrent epithelial keratitis during the acute treatment of HSV stromal keratouveitis.

Recurrence and rejection rates following corneal transplantation for herpes simplex keratitis

Seventy-two penetrating primary keratoplasties for herpes simplex keratitis performed from 1970 to 1993 were reviewed. Postoperative follow-up periods ranged from 6 months to 16 years with 2 years median. Epithelial herpetic recurrence occurred in 25% of the transplants the first year and in 44% during the first 2 years. Primary allograft rejection was observed in 29% of the grafts the first year and in 46% during the first 2 years. Preoperative inflammation was a risk factor for preservation of a clear cornea (p < 0.10). The degree of corneal vascularization prior to operation did not influence the survival of the grafts. The overall one-year survival rate of a clear graft was 84% and the 2-year survival rate was 67%. Prophylactic antiviral treatment is discussed.

Herpetic Eye Disease Study. A controlled trial of oral acyclovir for herpes simplex stromal keratitis

PURPOSE

To evaluate the efficacy of oral acyclovir in treating stromal keratitis caused by herpes simplex virus (HSV) in patients receiving concomitant topical corticosteroids and trifluridine.

METHODS

The authors performed a randomized, double-masked, placebo-controlled, multicenter trial in 104 patients with HSV stromal keratitis without accompanying HSV epithelial keratitis. Sample size was chosen so that a 5%, one-tailed test would have an 80% chance of detecting a doubling of the median time to treatment failure. Patients were randomized to receive a 10-week course of either oral acyclovir (400 mg 5 times daily, n = 51) or placebo (n = 53). All patients also received a standard regimen of topical prednisolone phosphate and trifluridine. Ophthalmologic examinations were performed weekly during the 10-week treatment period, every 2 weeks for an additional 6 weeks, and at 6 months after entry into the trial.

RESULTS

The median time to treatment failure (defined as worsening or no improvement of stromal keratitis or an adverse event) was 84 days (95% confidence interval, 69-93 days) for the acyclovir group and 62 days (95% confidence interval, 57-90 days) for the placebo group. By 16 weeks, 38 patients (75%) in the acyclovir group and 39 patients (74%) in the placebo group had failed treatment. Also by that time, the keratitis had resolved with trial medications, and there was no subsequent worsening in nine patients (18%) in the acyclovir group and ten (19%) in the placebo group. None of these results were significantly different between the two groups. However, visual acuity improved over 6 months in significantly more patients in the acyclovir group than in the placebo group.

CONCLUSION

There was no statistically or clinically significant beneficial effect of oral acyclovir in treating HSV stromal keratitis in patients receiving concomitant topical corticosteroids and trifluridine with regard to time to treatment failure, proportion of patients who failed treatment, proportion of patients whose keratitis resolved, time to resolution, or 6-month best-corrected visual acuity. Visual acuity improved over 6 months in more patients in the acyclovir group than in the placebo group.

Aciclovir. A reappraisal of its antiviral activity, pharmacokinetic properties and therapeutic efficacy

Aciclovir (acyclovir) is a nucleoside analogue with antiviral activity in vitro against the herpes simplex viruses (HSV), varicella zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6). Topical, oral or intravenous aciclovir is well established in the treatment of ophthalmic, mucocutaneous and other HSV infections, with intravenous aciclovir the accepted treatment of choice in herpes simplex encephalitis. The efficacy of aciclovir is increased with early (preferably during the prodromal period) initiation of treatment but, despite significant clinical benefit, viral latency is not eradicated, and pretreatment frequencies of recurrence usually continue after episodic acute treatment is completed. Intravenous administration has also shown benefit in the treatment of severe complications of HSV infection in pregnancy, and neonatal HSV infections. Recurrence of HSV has been completely prevented or significantly reduced during suppressive therapy with oral aciclovir in immunocompetent patients. Use of oral aciclovir is effective but controversial in the treatment of otherwise healthy individuals with varicella (chickenpox), and in some countries it has been recommended for use only in cases which may be potentially severe. The development of rash and pain associated with herpes zoster (shingles) is attenuated with oral or intravenous aciclovir therapy, ocular involvement is prevented, and post-herpetic neuralgia appears to be decreased. Similarly, in a few patients with zoster ophthalmicus, oral aciclovir has reduced the frequency and severity of long term ocular complications and post-herpetic neuralgia, and herpes zoster oticus is improved with intravenous aciclovir. Oral aciclovir has prevented recurrence of HSV genital or orofacial infections during suppressive therapy in > 70% of immunocompetent patients in most clinical trials. Suppression of latent HSV, VZV and CMV infections has been achieved in many immunocompromised patients receiving the oral or intravenous formulations. Aciclovir also appears to offer partial protection from invasive CMV disease in CMV-seropositive bone marrow transplant recipients. The few comparative trials published have shown aciclovir to be at least as effective as other investigated antivirals in the treatment of HSV infections in immunocompetent patients, and more effective than inosine pranobex in the prophylaxis of genital herpes. Similarly, in isolated clinical trials, oral aciclovir appears as effective as topical idoxuridine and oral brivudine in some parameters in immunocompetent patients with VZV infections, and the intravenous formulation appears at least as effective as oral brivudine and intravenous vidarabine in treating these infections in immunocompromised patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Systemic viral infections and their retinal and choroidal manifestations

Viruses are one of the most common causes of infections involving the posterior segment of the eye. Such infections can occur either on a congenital or an acquired basis, and may affect primarily the retina or the choroid. Congenital cytomegalovirus (CMV) and rubella infections may result in retinitis. CMV retinitis is also the most common cause of acquired viral retinitis, primarily because of the acquired immunodeficiency syndrome (AIDS). Other types of viral retinitis, such as those caused by herpes simplex or herpes zoster, can occur in immunocompromised or immunocompetent individuals. Retinitis or choroiditis caused by viruses such as measles, influenza, Epstein-Barr virus, and Rift Valley fever virus, typically occurs subsequent to an acute viral systemic illness. The systemic and ocular manifestations, as well as the histopathology, laboratory tests, differential diagnoses, and treatment regimens for each of the individual viruses are discussed in detail.

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.

Oral acyclovir for herpes zoster ophthalmicus

BACKGROUND

Reports on the natural history of herpes zoster ophthalmicus stress its high morbidity related to vicious scars on eyelids, ocular complications, and post-herpetic neuralgia. Early treatment with oral acyclovir is effective, but the optimal duration of treatment has not been defined.

METHODS

The authors performed a bicentric, prospective, randomized, double-masked study of 86 patients with acute herpes zoster ophthalmicus, within 72 hours of skin eruption, who received oral acyclovir (800 mg 5 times daily), either for 7 days (plus 7 days oral placebo) or for 14 days. All patients concomitantly received ophthalmic 3% acyclovir ointment; follow-up was at least 6 months.

RESULTS

Statistical analyses of subjective symptoms, skin lesions, and ocular complications showed no significant differences between the groups, suggesting that a 7-day course of treatment was sufficient. Drug tolerance was good. Pooled data from both groups corroborated earlier reports that prompt treatment with oral acyclovir reduces the severity of the skin eruption, the incidence and severity of late ocular manifestations, and the intensity of postherpetic neuralgia. At 6 months, late ocular inflammatory complications were seen in 29.1% of our 86 patients, versus 50% to 71% of untreated patients described by others. Only 13% of our patients experienced post-herpetic neuralgia, which in no case required the use of analgesics.

CONCLUSION

The authors believe it is not useful to prolong treatment with 800 mg of oral acyclovir 5 times daily for more than 7 days in herpes zoster ophthalmicus. This study confirms the efficacy of oral acyclovir not only against skin lesions and ocular complications, but also against postherpetic neuralgia in herpes zoster ophthalmicus.

Diagnosis and therapy of herpes zoster ophthalmicus

Studies in the basic and clinical sciences have yielded new information about the biology, infection, latency, and recurrence of the varicella-zoster virus. Contrast is made with the herpes simplex virus. The host-viral relationship is an extremely dynamic one with clinical disease being determined primarily by the host cellular immune system. The complications of herpes zoster ophthalmicus are related to multiple mechanisms including viral growth, vascular and neural damage, and the host-immune response to infection. There are several laboratory tests available for confirming the diagnosis or determining the immune status. Systemic acyclovir administered early in the course alleviates many of the symptoms of herpes zoster ophthalmicus. Acute and postherpetic neuralgia remain significant and enigmatic problems; an update of therapeutic options is offered. The role of corticosteroids in herpes zoster ophthalmicus is scrutinized along with the potential and uncertainties of a varicella-zoster virus vaccine.

Design and organization of the herpetic eye disease study (HEDS)

The Herpetic Eye Disease Study (HEDS) includes three double-masked, placebo-controlled clinical trials for potentially blinding herpes simplex virus (HSV) eye infections. One study compares a tapering dosage of topical prednisolone or placebo eye drops for HSV stromal keratitis (HEDS-SKN). Two other trials compare oral acyclovir to placebo capsules for HSV stromal keratitis (HEDS-SKS) or iridocyclitis (HEDS-IRT) in patients on a tapering dosage of topical prednisolone drops. All medications are administered for 10 weeks. Outcome is judged by time to recurrent disease or treatment failure. This paper presents the design, estimated sample size and recruitment as of July 25, 1990.

Collagen shield delivery of trifluorothymidine

Corneal and aqueous levels of topically applied trifluorothymidine (F3T) were compared with and without the collagen shield in normal and damaged rabbit eyes. Shields were presoaked in 1% F3T for 15 minutes prior to application. Rabbits received either a presoaked shield, 1% F3T drops every two hours, or both. Corneal and aqueous levels of F3T were measured at 30 minutes, two, four, and eight hours. If 5 mm epithelial defects were created, the collagen shield and topical F3T drops produced significantly higher levels of F3T than drops alone at all periods tested (P less than .05). A presoaked shield alone produced greater levels of F3T than drops alone at 30 minutes and two hours (P less than .05). Collagen shields did not enhance F3T levels in eyes with intact epithelium. Implications for treatment of herpetic keratouveitis are discussed.

Treatment of ocular disease in eczema herpeticum

Individuals with atopic dermatitis are particularly susceptible to herpes simplex viral infection and may develop dissemination (eczema herpeticum). Additionally, they may develop severe and bilateral herpetic ocular disease. The keratitis is commonly complicated by stromal scarring and slow epithelial healing despite topical antiviral therapy. We treated three patients who had herpetic keratoconjunctivitis associated with eczema herpeticum. In all three cases the keratitis resolved promptly (48 to 72 hours) without residual scarring after treatment with systemic acyclovir and topical trifluridine. The combined use of systemic acyclovir and topical trifluridine may be of similar value in treating all cases of atopic herpetic keratitis.

A comparison of local and systemic acyclovir in the management of herpetic disciform keratitis

Forty-three patients with active herpetic disciform keratitis were entered into an open study to compare the efficacy of oral acyclovir (400 mg) with acyclovir ophthalmic ointment (3%) to inhibit viral replication during treatment with 0.05% prednisolone eye drops. All patients, regardless of the mode of therapy, were treated five times a day until they were healed. The mean time to heal in the oral group was 25.9 days and in the topical group was 25.3 days. Resolution of lacrimation was significantly faster in the oral group (12.1 days versus 27.6 days). The patients on tablets also showed a greater improvement in visual acuity. No statistically significant differences were found between the two groups in the incidence of recurrences over a three-year post-treatment period. It is concluded that oral acyclovir treatment is an effective alternative to ophthalmic ointment in the management of herpetic disciform keratitis.

Acyclovir. An updated review of its antiviral activity, pharmacokinetic properties and therapeutic efficacy

Acyclovir (aciclovir) is a nucleoside antiviral drug with antiviral activity in vitro against members of the herpes group of DNA viruses. As an established treatment of herpes simplex infection, intravenous, oral and to a lesser extent topical formulations of acyclovir provide significant therapeutic benefit in genital herpes simplex and recurrent orofacial herpes simplex. The effect of acyclovir therapy is maximised by early initiation of treatment, especially in non-primary infection which tends to have a less protracted course than the primary episode. Long term prophylactic oral acyclovir, in patients with frequent episodes of genital herpes simplex, totally suppresses recurrences in the majority of subjects; as with other infections responding to acyclovir, viral latency is not eradicated and pretreatment frequencies of recurrence return after discontinuation of treatment. Caution should accompany the prophylactic use of acyclovir in the general population, due to the theoretical risk of the emergence of viral strains resistant to acyclovir and other agents whose mechanism of action is dependent on viral thymidine kinase. Intravenous acyclovir is the treatment of choice in biopsy-proven herpes simplex encephalitis in adults, and has also been successful in the treatment of disseminated herpes simplex in pregnancy and herpes neonatorium. Intravenous and oral acyclovir protect against dissemination and progression of varicella zoster virus infection, but do not protect against post-herpetic neuralgia. In immunocompromised patients, intravenous, oral and topical acyclovir shorten the clinical course of herpes simplex infections while prophylaxis with oral or intravenous dosage forms suppresses reactivation of infection during the period of drug administration. Ophthalmic application of 3% acyclovir ointment rapidly heals herpetic dendritic corneal ulcers and superficial herpetic keratitis. Thus, despite an inability to eradicate latent virus, acyclovir administered in therapeutic or prophylactic fashion is now the standard antiviral therapy in several manifestations of herpes simplex virus infection, and indeed represents a major advance in this regard. With the exception of varicella zoster virus infections, early optimism concerning the use of the drug in diseases due to other herpes viruses has generally not been supported in clinical investigations.

Ocular herpes simplex infection: pathogenesis and current therapy

Ocular herpes simplex disease has a variable pattern of manifestations and recurrences as a result of the site and extent of the infection, the host immunologic events, the trophic damage within ocular tissues, and the toxic effects of antiviral medications. Laboratory research has established a clinical model and a working hypothesis about the complex pathophysiologic features of the disease and the interaction of the virus with its host tissue. Recent studies have further defined the viral genome and its role in virulence and pathogenicity. Antiviral therapy is effective in some but not all aspects of the ocular infection. A proposed clinical classification of ocular herpes simplex is based on the manifestations associated with viral disease and those associated with the host response and the subsequent structural damage. A plan for medical and surgical management of ocular herpes simplex, based on current knowledge of the disease process, relates to the integrity of the epithelium and the presence of active viral disease.

Oral acyclovir in the management of herpes simplex ocular infections

Acyclovir, an oral antiviral agent that inhibits viral DNA replication, was used to treat 27 patients (16 males, 11 females) (mean age, 50 years) with vision-threatening herpes simplex virus (HSV) infections. Twenty patients had active stromal keratitis or keratouveitis, four had controlled nonnecrotizing stromal keratitis but could not taper topical medications, and four eczema patients with previous HSV infections had intraocular surgery (1 of these patients also is included in the 20 with active stromal keratitis). All 20 patients with active stromal keratitis or keratouveitis improved on acyclovir, all four patients using acyclovir postoperatively were disease-free while on the drug, but only two of the four patients using acyclovir to assist tapering topical medications were successful. There has been only one recurrence during a cumulative 194 months while on acyclovir. Thirteen patients have remained on acyclovir, and three who stopped acyclovir had prompt recurrences. Acyclovir seems to be a promising adjunct antiviral agent for the treatment of recalcitrant epithelial, stromal, or uveal disease secondary to HSV.

Rational acyclovir therapy in herpetic eye disease

Acyclovir has been widely used against the various manifestations of eye disease due to herpes simplex since it first became generally available in the UK nearly five years ago. This paper discusses the rational indications for its use, through considerations of its pharmacology and pharmacokinetics, and through results of the many clinical trials that have been carried out to investigate its effects since its clinical efficacy was first demonstrated in 1979.

A double-blind comparative trial of acyclovir and adenine arabinoside in combination with dilute betamethasone in the management of herpetic disciform keratitis

A double-blind comparative trial of acyclovir (ACV) and adenine arabinoside (ARA-A) in combination with dilute betamethasone was carried out in 30 patients with herpetic disciform keratitis. Of those receiving ACV and betamethasone, 86.7% healed in a mean time of 22.5 days, while 76.9% of those receiving the Ara-A combination healed in a mean time of 26.7 days. There was no statistical difference between the two treatment groups for efficacy parameters. However, the proportion of patients developing superficial punctate keratopathy (SPK) was significantly greater in the Ara-A treatment group.

Oral acyclovir (Zovirax) in herpes simplex dendritic corneal ulceration

Sixty patients with simple dendritic corneal ulceration were randomly assigned to double blind treatment with either acyclovir tablets (400 mg) or acyclovir ophthalmic ointment administered five times daily. There was no significant difference in the proportions of patients healed in either treatment group (88.9% on oral acyclovir and 96.6% on acyclovir ointment). The median healing time was five days in both groups. No systemic or significant local side effects were noted in either treatment group. Trough levels of acyclovir in the tear fluid of those who received the oral preparation were within or above the range of mean in-vitro ID50 levels for herpes simplex virus type 1. We conclude that oral administration of acyclovir (400 mg, five times daily) may be an effective alternative to topical therapy in selected patients.

Treatment of the acute retinal necrosis syndrome with intravenous acyclovir

We treated 13 eyes of 12 patients with the acute retinal necrosis syndrome (ARN) with intravenous acyclovir (1500 mg/M2/day) for an average of 10.9 days. All patients were also treated with oral aspirin or Coumadin. in an attempt to prevent thrombotic complications and nine of twelve patients were treated with oral prednisone after intravenous acyclovir had been initiated. Regression of retinal lesions was first seen on average 3.9 days after initiation of therapy and required 32.5 days on average for completion. No eye developed new retinal lesions or progressive optic nerve involvement 48 hours or more after initiation of therapy, although progression within the first 48 hours was occasionally seen. Treatment did not ameliorate vitritis or prevent retinal detachment, which occurred in 11 of 13 eyes, an average of 59 days after the initiation of therapy. There were no evident ocular or systemic complications of therapy. Our data suggest the need for a prospective randomized clinical trial to evaluate the efficacy of intravenous or oral acyclovir in the treatment of the acute retinal necrosis syndrome.

Oral acyclovir in the therapy of acute herpes zoster ophthalmicus. An interim report

A prospective, randomized, double-masked, placebo-controlled clinical trial was conducted to study the effects of oral acyclovir on 55 patients with acute herpes zoster ophthalmicus. Treatment with oral acyclovir resulted in more prompt resolution of signs and symptoms, particularly in patients treated within 72 hours after onset of skin rash (P less than 0.05), and shortened the duration of viral shedding (P = 0.02). Vesicular skin lesions involving other dermatomes (microdissemination) occurred in five (19%) placebo-treated patients but in no acyclovir-treated patients (P = 0.03). Interim analysis of this longitudinal study suggests that the incidence and severity of secondary ocular inflammatory disease was reduced by acyclovir. Prolonged observation of these patients is ongoing to determine if oral acyclovir reduces post-herpes zoster neuralgia or the late ocular complications of ophthalmic zoster.