Treatment of aggressive cytomegalovirus retinitis with ganciclovir in combination with foscarnet in a child infected with human immunodeficiency virus

The role of ganciclovir for the management of cytomegalovirus retinitis in HIV patients: Pharmacological review and update on new developments

OBJECTIVE

To review the pharmacology and pharmacokinetics of intravenous, oral and intraocular ganciclovir, and to discuss the role of these various formulations in the management of cytomegalovirus (CMV) retinitis in AIDS patients.

DATA SOURCES

A MEDLINE search (1987 through November 1995) of English-language literature using the main medical subject headings 'ganciclovir' and 'cytomegalovirus', and the subheading 'acquired immunodeficiency syndrome'. Relevant articles were also selected from references of identified articles. Abstracts from recent medical conferences of infectious diseases, pharmacology and human immunodeficiency virus were screened for additional data.

STUDY SELECTION AND DATA EXTRACTION

All articles and abstracts discussing the use of ganciclovir for the management or prophylaxis of CMV retinitis in AIDS patients were considered for inclusion. Pertinent information, as judged by the authors, was selected and synthesized for discussion.

DATA SYNTHESIS

Ganciclovir has demonstrated virustatic activity against CMV, and is often administered 5 mg/kg intravenously every 12 h as first-line therapy for CMV retinitis. Intravenous maintenance therapy at 5 mg/kg daily is usually effective at delaying retinitis progression for approximately 60 to 70 days. Neutropenia and thrombocytopenia are observed frequently, often necessitating interruption or discontinuation of therapy. Local drug administration may delay disease progression even further, and may be considered for patients who are intolerant to or failing intravenous therapy. However, systemic ganciclovir should be encouraged to reduce the risk of developing contralateral eye or end-organ CMV disease. Oral ganciclovir at 1 g tid is almost as effective as intravenous ganciclovir 5 mg/kg/day in delaying retinitis progression and is associated with fewer line-related complications. Absorption, drug interactions, cost and compliance should also be considered.

CONCLUSIONS

Until recently, ganciclovir was available only for intravenous use. Recent developments allow for intraocular and oral administration of this agent. A clear understanding of the advantages and disadvantages of these new formulations is required in order to select the most appropriate product for managing CMV retinitis in AIDS patients.

Interactions among antiviral drugs acting late in the replication cycle of human cytomegalovirus

This study describes the extent of cross-resistance and interactions for selected inhibitors of human cytomegalovirus (HCMV) DNA synthesis and DNA processing. HCMV isolates resistant to the benzimidazole D-ribonucleoside viral DNA processing inhibitors TCRB and BDCRB were sensitive to BAY 38-4766, a non-nucleoside inhibitor of viral DNA processing. This indicates that these two drug types have distinct interactions with the products of HCMV genes UL56 and UL89 required for viral DNA cleavage and packaging. These virus isolates also were sensitive to ganciclovir (GCV) but slightly resistant to the L-benzimidazole ribonucleoside viral DNA synthesis inhibitor 1263W94. Virus resistant to 1263W94 remained sensitive to BDCRB, GCV, and BAY 38-4766. Examination of drug-drug interactions in cell culture assays measuring inhibition of HCMV replication revealed strong synergism for the combination of BDCRB with 1263W94, and for combinations of 1263W94 with cidofovir (CDV) and foscarnet (PFA), but not with GCV. Combinations of GCV with CDV and PFA were synergistic as well. The combination of GCV with 1263W94 showed additive antiviral interactions, whereas, a combination of BAY 38-4766 with GCV showed antagonism. Interaction of BDCRB with BAY 38-4766 showed a mixed pattern of synergy and antagonism. The antiviral synergy observed between GCV and PFA or CDV serves to validate clinical combination therapies for these drugs. Antagonism seen for BAY 38-4766 with GCV indicates that these two drugs are unlikely to be useful for combination therapies. Notably, 1263W94 demonstrated greater synergy in combination with PFA or CDV than did GCV, suggesting some promise for this benzimidazole L-riboside in such combination therapies.

Plant-derived and semi-synthetic calanolide compounds with in vitro activity against both human immunodeficiency virus type 1 and human cytomegalovirus

Plant-derived and semi-synthetic calanolide compounds with anti-human immunodeficiency virus type 1 (HIV-1) activity were tested for anti-human cytomegalovirus (HCMV) activity in both cytopathic effect inhibition and plaque reduction assays. The results indicated that the anti-HCMV activity of calanolide compounds does not correlate with their activity against HIV-1. The semi-synthetic 12-keto derivatives tended to be more active against HCMV than the corresponding 12-OH congeners, which were more active against HIV-1. It appeared that the 7,8-unsaturated double bond in the chromene ring played a certain role in maintaining activities against both HCMV and HIV-1. Saturation of the double bond increased the EC50 values against both viruses, with concomitant increase in toxicity. The calanolide compounds reported here are the first non-nucleoside analogues capable of inhibiting both HIV-1 and HCMV and, therefore, may be useful chemoprophylactic agents for HCMV in HIV-infected people or vice versa.

Cytomegalovirus retinitis in immunosuppressed children

PURPOSE

To describe the ocular and systemic features of children with cytomegalovirus retinitis and their disease outcomes.

METHODS

Review of all cases of cytomegalovirus retinitis diagnosed or treated at a tertiary care pediatric hospital during a 10-year period.

RESULTS

Nine immunocompromised children younger than 16 years were diagnosed as having cytomegalovirus retinitis. The underlying causes of immunocompromise were severe combined immunodeficiency syndrome (n = 2), severe combined immunodeficiency syndrome after bone marrow transplantation (n = 1), acquired immunodeficiency syndrome (AIDS) (n = 2), AIDS and previous bone marrow transplantation for leukemia (n = 1), immunosuppressive therapy after renal transplantation (n = 1), chemotherapy for leukemia (n = 1), and congenital cytomegalovirus infection (n = 1). Five children (56%) had symptomatic extraocular cytomegalovirus infection. Only two children reported visual symptoms with cytomegalovirus retinitis at initial examination. Cytomegalovirus retinitis was bilateral in eight children (89%) and involved the posterior pole in at least one eye of all nine children. Four children (44%) died within 10 months of being diagnosed with cytomegalovirus retinitis. The remaining five children were alive, with follow-up ranging from 14 to 70 months. Successful bone marrow transplantation in one child and discontinuation of immunosuppressive medications in two children improved systemic immune function and permitted discontinuation of anticytomegaloviral therapy.

CONCLUSION

Pediatric cytomegalovirus retinitis is often asymptomatic and bilateral and involves the posterior pole at initial examination. Recovery of systemic immune function may occur in some children. Evaluation of children at risk and prompt treatment of cytomegalo. virus retinitis are important to prevent long-term visual morbidity.

Cytomegalovirus infection after intestinal transplantation in children

Sixteen episodes of cytomegalovirus (CMV) disease occurred in 10 of 41 children undergoing intestinal transplantation from 1990 to 1995. Stratification of CMV disease by donor (D)/recipient (R) serological status was as follows: 3 of 8, D+/R-; 3 of 9, D+/R+; 4 of 9, D-/R+; and 0 of 15, D-/R-. Treatment resulted in resolution of CMV disease in 93.3% of episodes. No deaths attributable to CMV disease occurred in this series. CMV in D+/R- children resulted in more extensive and persistent disease. However, patient and graft survival rates were similar in the different D/R subgroups and between children with and without CMV disease. Cumulative dose of steroid boluses (relative risk [RR], 1.59; 95% confidence interval [CI], 1.14-2.21) and history of steroid recycles (RR, 2.72; 95% CI, 1.21-6.13) were associated with CMV disease. These results suggest that although CMV-associated morbidity in pediatric intestinal transplant recipients was substantial, it was not associated with an increased rate of mortality or graft loss, even among high-risk D+/R- patients.

The spectrum of eye disease in children with AIDS due to vertically transmitted HIV disease: clinical findings, virology and recommendations for surveillance

BACKGROUND

Eye disease in children infected with HIV is uncommon, but there is little information on which children require screening or surveillance and the management of those with retinitis.

METHODS

We examined 12 children with symptomatic HIV disease (of a cohort of 98 HIV-positive children) using indirect ophthalmoscopy. When retinitis was found it was documented photographically at the time of diagnosis and on follow-up.

RESULTS

Four cases of infective retinitis were diagnosed: three with probable cytomegalovirus retinitis and one with progressive outer retinal necrosis.

CONCLUSION

Detection of reactivation is difficult and we recommend fundus photography under general anaesthesia wherever possible. Children with other end-organ disease, symptomatic eye disease and advanced HIV disease with severe immunosuppression require ophthalmological surveillance.

Treatment of bilateral cytomegalovirus retinitis with sustained-release ganciclovir implants in a child

PURPOSE

To report treatment of bilateral cytomegalovirus (CMV) retinitis in an 11-year-old girl with acquired immunodeficiency syndrome (AIDS).

METHOD

Case report describing the use of intravitreal ganciclovir sustained-release devices to treat CMV retinitis, involving zones 1 through 3, which progressed despite single and combination intravenous therapy with ganciclovir and foscarnet.

RESULTS

Stabilization with no active CMV retinitis was achieved after bilateral implantation of intravitreal sustained-release ganciclovir devices. There was no reactivation of the retinitis during the 5 months of follow-up.

CONCLUSION

Sustained-release ganciclovir implants can be used to achieve local control of CMV retinitis in the pediatric patient.

Pediatric human immunodeficiency virus infection

In the past decade, an increase in pediatric human immunodeficiency virus (HIV) infection has had a substantial impact on childhood morbidity and mortality worldwide. The vertical transmission of HIV from mother to infant accounts for the vast majority of these cases. Identification of HIV-infected pregnant women needs to be impoved so that appropriate therapy can be initiated for both mothers and infants. While recent data demonstrate a dramatic decrease in HIV transmission from a subset of women treated with zidovudine during pregnancy, further efforts at reducing transmission are desperately needed. This review focuses on vertically transmitted HIV infection in children, its epidemiology, diagnostic criteria, natural history, and clinical manifestations including infectious and noninfectious complications. An overview of the complex medical management of these children ensues, including the use of antiretroviral therapy. Opportunistic infection prophylaxis is reviewed, along with the important role of other supportive therapies.

Report of a case of aggressive cytomegalovirus retinitis in an infant with AIDS

A case of aggressive cytomegalovirus retinitis is reported in an infant with acquired immunodeficiency syndrome. Intravenous treatment with ganciclovir did not control the infection. The combination of ganciclovir and foscarnet was needed to obtain a complete response.

Combined intravenous ganciclovir and foscarnet for children with recurrent cytomegalovirus retinitis

PURPOSE

Children with the acquired immune deficiency syndrome (AIDS) and cytomegalovirus (CMV) retinitis may not complain of symptoms despite the presence of advanced sight-threatening disease. Although little data exist regarding CMV retinitis in this population, the treatment of this disease may be difficult because of frequent, extensive recurrences after reduction of drug dose from induction to maintenance levels. The authors reported the results of the use of combined ganciclovir and foscarnet for treatment of recurrent CMV retinitis in three children with AIDS.

METHODS

Three children with recurrent CMV retinitis were treated with combined ganciclovir and foscarnet administered intravenously. All patients initially received induction dosages of ganciclovir followed by maintenance therapy, at which time they experienced reactivation of their disease. The dosing regimen for induction with the combined therapy was foscarnet (60 mg/kg every 8 hours) and ganciclovir (5 mg/kg daily for 3 weeks). Maintenance with combined therapy consisted of foscarnet (90 mg/ kg daily) and ganciclovir (5 mg/kg daily).

RESULTS

All patients showed complete healing of the retinitis during the first 3 weeks of combined therapy. Median survival after initiation of combined therapy was 15 weeks (range, 12-33 weeks). None of the children experienced reactivation of CMV retinitis during combined therapy with ganciclovir and foscarnet. Combined therapy was well tolerated in all patients without major side effects. No patient required discontinuation or interruption of either drug during combined therapy.

CONCLUSION

Children with recurrent CMV retinitis may not report visual symptoms, which can delay therapeutic intervention. Therefore, recurrent disease in children should be treated aggressively to avoid potentially devastating visual loss. A combination of ganciclovir and foscarnet appears to be a safe and effective therapeutic option for treatment of recurrent CMV retinitis in children with AIDS. This approach causes no additional toxic reactions and may provide improved long-term control of recurrent CMV retinitis in children.

Double resistance to ganciclovir and foscarnet of four human cytomegalovirus strains recovered from AIDS patients

Four human cytomegalovirus (HCMV) isolates from four different AIDS patients treated with both ganciclovir and foscarnet and not responding clinically to antiviral treatment, were studied in order to verify the occurrence of double resistance to both drugs, and to define whether single or multiple HCMV strains could be responsible for the double resistance. Peripheral blood leukocytes (PBL), the relevant conventional viral isolates, and plaque-purified strains from all four patients were examined by antiviral drug susceptibility testing by an immediate-early antigen plaque reduction assay and by restriction fragment length polymorphism (RFLP) analysis using polymerase chain reaction (PCR)-amplified multiple genome regions and endonucleases. All four HCMV strains had a high level of resistance to both ganciclovir and foscarnet. A single HCMV strain was shown to be responsible for the dual resistance in each patient. HCMV strain identity and uniqueness were shown for each of the four patients in blood samples, viral isolates, and plaque-purified strains. In addition, in two patients the same single HCMV strain shifted progressively from drug sensitivity to ganciclovir and then to ganciclovir-foscarnet resistance. These findings document that resistance to both ganciclovir and foscarnet of HCMV strains recovered from blood of AIDS patients represents an emerging problem. Although it is known that multiple HCMV strains may cocirculate in the blood of AIDS patients, single strains appear to be responsible for the dual resistance. Molecular mechanisms responsible for the double resistance of the four reported strains are under study.

Foscarnet and ganciclovir pharmacokinetics during concomitant or alternating maintenance therapy for AIDS-related cytomegalovirus retinitis

INTRODUCTION

The use of foscarnet and ganciclovir as a combination treatment for cytomegalovirus retinitis is increasing because of limitations associated with single agent therapy.

METHODS

The pharmacokinetics of foscarnet and ganciclovir were determined in 13 patients receiving either concomitant therapy (regimen A) or daily alternating therapy (regimen B) for maintenance of cytomegalovirus disease. For regimen A, 60 mg/kg intravenous foscarnet and 3.75 mg/kg ganciclovir were sequentially administered daily; for regimen B, 120 mg/kg foscarnet and 6 mg/kg ganciclovir were administered on alternating days. For both regimens, serial blood sampling for pharmacokinetic analysis was performed for each drug alone (day 1 or 2) and after 2 weeks of combination therapy. Plasma samples for foscarnet and ganciclovir analysis were performed by means of high-performance liquid chromatography. Pharmacokinetic analysis was performed with noncompartmental methods.

RESULTS

For regimen A, the plasma clearance (CL) of foscarnet did not change in the presence of ganciclovir, averaging 0.12 +/- 0.08 and 0.11 +/- 0.02 L/hr/kg on study days 2 and 14, respectively (p = 0.34). The volume of distribution (VSS) and mean residence time (MRT) also did not change significantly. CL and MRT of foscarnet did not change for regimen B, although a slight increase in VSS was observed before (0.38 +/- 0.05 L/kg) and after (0.46 +/- 0.07 L/kg) alternating therapy (p = 0.03). Ganciclovir CL did not change for either regimen, with mean values of 0.21 +/- 0.10 and 0.25 +/- 0.10 L/hr/kg (regimen A, p = 0.17) and 0.32 +/- 0.10 and 0.34 +/- 0.11 L/hr/kg (regimen B, p = 0.24). MRT and VSS were also not significantly different.

CONCLUSION

These plasma data suggest that further dosage adjustments are unnecessary for or alternating maintenance therapy.

Rapid screening for resistance to ganciclovir and foscarnet of primary isolates of human cytomegalovirus from culture-positive blood samples

A rapid screening assay for the detection of resistance to ganciclovir and foscarnet of primary isolates of human cytomegalovirus from culture-positive blood samples was developed by using single doses of both drugs and an immediate-early antigen plaque reduction assay. Results of the rapid assay with peripheral blood leukocytes as the viral inoculum were compared with those of a conventional assay with cell-free virus from the relevant viral isolates. Both assays gave overlapping results. The rapid assay offers the following major advantages: (i) it provides results within 4 to 6 days, (ii) it can be performed with peripheral blood leukocytes, and (iii) it reliably detects drug-resistant human cytomegalovirus strains.

Ganciclovir. An update of its therapeutic use in cytomegalovirus infection

The antiviral nucleoside analogue ganciclovir has demonstrated in vitro activity against human cytomegalovirus and effectively treats infection caused by this organism in various immunocompromised patient groups. The drug prolongs time to progression in patients with acquired immune deficiency syndrome (AIDS)-related cytomegalovirus retinitis although life-long maintenance therapy is required. Direct comparisons between ganciclovir and foscarnet in this indication are few; nevertheless, the 2 drugs appear to have equal therapeutic efficacy in treating cytomegalovirus retinitis although results from 1 study in this indication suggest that foscarnet has an advantage in terms of patient survival. AIDS-related gastrointestinal and, to a lesser extent, pulmonary cytomegalovirus infection also respond to treatment with ganciclovir; maintenance therapy does not appear to be required in these latter 2 indications. Ganciclovir is also useful against cytomegalovirus infection in organ transplant recipients. The drug is most effective when given prophylactically or as early treatment for asymptomatic infection in bone marrow transplant recipients; treatment of established infection is less effective in this patient group. However, established infection in solid organ transplant recipients appears to respond to treatment with ganciclovir. The most common adverse event during ganciclovir therapy is haematological toxicity but this appears to be readily reversible on discontinuation of the drug. In addition, coadministration of granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage CSF (GM-CSF) has been shown to prevent ganciclovir-associated neutropenia. Thus, ganciclovir is a valuable treatment for cytomegalovirus infection in patients with AIDS and in organ transplant recipients. Further studies comparing ganciclovir and foscarnet-ideally incorporating the use of G-CSF or GM-CSF to prevent ganciclovir-associated neutropenia and assessing survival as 1 endpoint--should further clarify the relative role of ganciclovir as treatment or prophylaxis for cytomegalovirus infection.

Foscarnet. A reappraisal of its antiviral activity, pharmacokinetic properties and therapeutic use in immunocompromised patients with viral infections

The DNA polymerase of human herpes viruses, including cytomegalovirus (CMV), and the reverse transcriptase of human immunodeficiency virus (HIV) are selectively inhibited in vitro by the pyrophosphate analogue foscarnet. Inhibition is reversible on withdrawal of foscarnet and additive or synergistic effects have been demonstrated in vitro with other antiviral drugs, including ganciclovir and zidovudine. Foscarnet appears to have negligible effects on host enzymes and cells. Complete or partial clinical resolution of ocular symptoms is obtained in more than 89% of patients with acquired immunodeficiency syndrome (AIDS) and CMV retinitis during foscarnet induction therapy, but relapse occurs soon after ceasing treatment. Maintenance treatment given daily can extend the period of remission considerably. Foscarnet and ganciclovir monotherapy had similar efficacy in the treatment of CMV retinitis in patients with AIDS in several studies, and have been used concomitantly in immunocompromised patients with recalcitrant CMV infections. In 1 trial, patients receiving foscarnet survived for significantly longer than those receiving ganciclovir. Foscarnet has been used successfully in the treatment of limited numbers of immunocompromised patients with CMV-associated gastrointestinal (improvement in over 67% of patients) and other infections. Aciclovir-resistant herpes simplex infections in immunocompromised patients have also been treated successfully with foscarnet. Almost 90% of a foscarnet dose is excreted in the urine. Reversible nephrotoxicity is common during foscarnet therapy, but may be reduced by dosage adjustment and adequate hydration. Anaemia, nausea and vomiting, disturbances in electrolyte levels and genital ulceration have also been associated with administration of the drug. The different tolerability profiles of foscarnet and zidovudine facilitate the use of these agents in combination in patients with AIDS and CMV infection; whereas ganciclovir, like zidovudine, is associated with dose-limiting haematological toxicity. The apparent survival benefits seen in these patients when receiving foscarnet and zidovudine (possibly linked to synergy between zidovudine and foscarnet and/or the inherent anti-HIV activity of foscarnet), appear to offer potentially important advantages for foscarnet over ganciclovir in the treatment of selected patients with AIDS and CMV infections.

Combined daily therapy with intravenous ganciclovir and foscarnet for patients with recurrent cytomegalovirus retinitis

We treated seven patients (nine eyes) who had cytomegalovirus retinitis with daily intravenous ganciclovir plus foscarnet. All patients had demonstrated multiple progressions of retinitis on single-drug therapy, and some were intolerant to induction doses of one or both medications. Before combination therapy, the median number of progressions was five per patient. The mean interval between progressions was 11 weeks, and the mean interval before the final progression was four weeks. While taking combination therapy, two patients showed progression after 14 and 34 weeks. Two patients showed no progression after 17 and 36 weeks of follow-up. Three patients died after five, 14, and 23 weeks, respectively, without progression of retinitis. In every patient, the progression-free interval was longer during combination therapy than the previous progression-free interval during single-drug therapy. In no case was combination therapy stopped because of toxicity. Combination therapy was fairly well tolerated and appeared to prolong the interval to progression and to preserve vision in our patients.

Cytomegalovirus retinitis in pediatric acquired immunodeficiency syndrome: report of two cases

Two cases of cytomegalovirus retinitis in pediatric acquired immunodeficiency syndrome (AIDS) are described. The first case was a 7-month-old infant who received an HIV-infected blood transfusion in 1983. The infant was treated with specific anti-cytomegalovirus immunoglobulin. The second case was an 8-year-old hemophiliac child who received HIV-infected factor VIII concentrates. Intravenous ganciclovir therapy resulted in marked improvement of ocular lesions. This is, to our best knowledge, the first report of pediatric AIDS-induced retinopathy resulting from postnatal intravenous causes.

Considerations in the Treatment of Patients With Acquired Immunodeficiency Syndrome at Home

The rapidly growing acquired immunodeficiency syndrome (AIDS) population faces frequent, expensive hospitalization due to the debilitating sequelae of the disease. Home care offers these patients an opportunity to receive or complete their therapy in comfortable surroundings, allowing them to realize the psychosocial and financial benefits of outpatient care. A myriad of sophisticated drug therapies has been successfully administered in the home setting. Therapy for frequently occurring opportunistic infections often requires treatment with highly toxic drugs such as amphotericin, pentamidine, and ganciclovir. With thorough patient training and diligent monitoring by the home-care pharmacist and nurse, these agents can be safely administered at home. Conventional and investigational chemotherapy and immunomodulator therapy, such as interferon or erythropoietin, can also be administered at home. Providing total parenteral nutrition to AIDS patients is a controversial treatment modality, but if indicated, it can also be accomplished at home. Outpatient pain management has allowed many patients with terminal or chronic illnesses to minimize time spent in hospitals or extended care facilities, and it can offer the same advantages to patients with AIDS. The psychosocial ramifications of AIDS and its impact on patients and health care professionals must be understood in order to effectively provide total patient care at home. The challenge to the home-care pharmacist is to acquire and maintain a comprehensive knowledge of the treatment options currently available for the management of AIDS.