Trifluorothymidine and idoxuridine therapy of ocular herpes

In a coded study, we treated 40 patients who had active herpes simplex corneal ulcers with either 1% trifluorothymidine (F3T) or 0.1% idoxuridine (IDU) drops; we treated 15 similarly afflicted patients, who had failed on IDU or vidarabine, with open 1% F3T drops. All dosages were at therapeutically recommended frequency. In the coded study there was no statistically significant difference between the drugs in rate of healing; mean initial ulcer size in both groups was approximately 7 mm2 and mean healing time was approximately 5.5 days. There was a significant difference, however, in the chances of successful healing; 96% of all F3T treated eyes and only 75% of IDU treated eyes healed completely within 14 days. In the open study, 87% of patients healed completely on F3T eyedrops. Although an insufficient number of patients were on concomitant coricosteroid therapy to provide statistical analysis, F3T-corticosteroid treated eyes (eight masked and open) all healed. The one IDU-corticosteroid treated eye in the masked study failed to heal.

[Herpes simplex virus (hsv-1 and hsv-2) infection: its clinical and oncogenic properties (author's transl)]

The epidemiology and clinical features of diseases caused by the herpes simplex virus, are reviewed and recent results are discussed which give an insight into the complex mechanism of primary and chronic, recurrent HSV-1 infections. Immunological reactions in HSV infection and data concerning the oncogenic potential of HSV-1 and -2 are dealt with. Furthermore, current therapeutic possibilities are outlined.

Antiviral agents

Only a few agents with antiviral activity are available for regular clinical use. Amantadine hydrochloride is effective in the prophylaxis of influenza A2. Idoxuridine and adenine arabinoside have found application as topical agents in the treatment of herpes simplex keratitis. Adenine arabinoside is also under investigation in the treatment of disseminated infections due to herpes zoster and herpes simplex. Ribavirin, an agent with a wide spectrum of activity in vitro, has not fulfilled expectations in clinical trials. Because of the near eradication of smallpox, methisazone has become less important as a prophylactic agent in smallpox.

Treatment of herpetic keratitis

Idoxuridine which was first used in 1960 (Kaufman et al., 1962), has been for many years the only antiviral agent available in the treatment of herpetic keratitis. It is however no more successful than is mechanical removal of diseased epithelium (Patterson & Jones, 1967), and furthermore it may give rise to serious toxic side effects. The search for an alternative medication is therefore a pressing one. Trifluorothymidine (F3T) has, in recent years, been shown to be more effective than IDU and to be free from significant toxicity. Both of these drugs are pyrimidine nucleosides. Adenine Arabinoside or Arabinoside-A (Ara-A) is, by contrast, a purine nucleoside. It is thought to exert its antiviral effect by blocking DNA polymerase and ribonucleotide reductase.

Lysozyme tear level in patients with herpes simplex virus eye infection

The lysozyme level in tears of patients with HSV eye infection was examined and correlated with the clinical findings and presence of virus. The concentration of the enzyme in tears of patients during acute attack was 2.83 mg./ml. This value was significantly lower than that in tears from healthy controls (6.1 mg./ml.) and tears from the patient's healthy eye (4.46 mg./ml.). After termination of treatment with either IUDR or poly I:C, the lysozyme level rose to an average of 4.34 mg./ml. During the latent period of the disease the level increased (5.34 mg./ml.), but it remained lower than in healthy subjects who had never suffered from HSV eye infection. This may be an indicator of possible future recurrences.

The use of betadine antiseptic paint in the treatment of Herpes simplex and Herpes Zoster

Twenty-two patients with Herpes Simplex were treated with Betadine (povidone iodine) Antiseptic paint and seven with 5% idoxuridine in dimethyl sulphoxide, also one patient with bilateral lesions was treated with the two solutions, one on each side. The povidone iodine alcohol solution appeared to be at least as effective as the idoxuridine with minimal side-effects (some stinging in two patients). Good results were also obtained with this solution in twelve patients with Herpes Zoster.

Treatment of fatal disseminated vaccinia virus infection in immunosuppressed mice

Studies were performed to compare the therapeutic effectiveness of three antiviral drugs (ARA-A, ARA-C and IDU) on the course of fatal disseminated vaccinia virus infection in immunosuppressed mice. Treatment with ARA-A begun as late as 7 days after virus infection was significantly effective in preventing death; no antiviral effect of the other two drugs was demonstrated.

Herpes simplex: treatment today

Past and current therapies for recurrent mucocutaneous herpes simplex infections are reviewed. At present, no topical or systemic therapy has been proved safe and effective in scientific double-blind studies. Recent treatment with flexible collodion is discussed.

Effect of phosphonoacetic acid in the treatment of experimental herpes simplex keratitis

In the rabbit 5% phosphonoacetic acid ointment suppressed herpetic keratitis as well as 0-5% idoxuridine ointment. After 5 days of treatment quantitative virus titres showed that phosphonoacetic acid was superior to idoxuridine in the inhibition of herpes virus replication. Phosphonoacetic acid was found to be nontoxic to the eye in both clinical and histopathological studies. Recent reports suggest that the mechanism of action of phosphonoacetic acid appears to be the blocking of the virus DNA polymerase, which is essential for the synthesis of herpes virus DNA.

Potential role of amphotericin B methyl ester in the prevention and therapy of herpetic keratitis

Amphotericin B methyl ester (AME), a semisynthetic derivative of amphotericin B, was studied in the rabbit cornea for its potential role in prevention and therapy of HSV, vaccinia virus, and vesicular stomatitis virus. It was effective in the prevention of lesion formation by these three viruses and dose-related antiviral effects were shown. Of these viruses HSV was the most sensitive to AME. The antiviral effect of AME was additive with those of IDU and ribavirin. However, it was not effective in treating established lesions due to HSV and vaccinia virus. Since its mode of action is to bind to the sterol sites of the viral envelope, it is suggested that AME should also be effective against other enveloped DNA and RNA viruses. A new method of therapy for epithelial herpetic keratitis in humans using a combination of AME with MWD is proposed.

Double--blind clinical trial of adenine arabinoside and idoxuridine in herpetic corneal ulcers

The results are reported of a fully controlled randomized double-blind clincial trial of adenine arabinoside and idoxuridine ointment in sixty patients with herpetic ulceration of the cornea. Although both antivirals showed a trend towards superiority over placebo, the therapeutic effect did not reach statistical significance in spite of the known efficacy in laboratory animals. Further studies in rabbits are reported; these indicate that systemic immunity may play a role in combating virus proliferation in recurrent disease, and it is considered this disguises the efficacy of topical antiviral therapy in clinical trials, thus necessitating an estimated requirement for approximately fifty patients per treatment group to obtain significant effects. It is concluded that an antiviral is valuable in the treatment of ulcerative herpetic keratitis, particularly in primary disease and in the presence of systemic and local immunosuppression after the use of topical adrenocorticosteroid. In recurrent disease, where a trigger factor is known, experience has shown that therapy can be profitably administered before the onset of clinical disease.

Management of herpetic eye disease

We define in this paper a rational approach to the management of the various stages of herpetic eye disease. We consider in more detail comparisons between idoxuridine (IDU), trifluorothymidine (F3T), and adenine arabinoside (Ara-a) (derived largely from clinical trials in herpetic ulcers). We discuss metaherpetic ulcers and certain aspects of keratoplasty.

[Herpes therapy and prophylaxis. II. Results of a survey of practicing ophthalmologists (author's transl)]

Between December 1975 and April 1976, 2,300 ophthalmologists in the Federal Republic of Germany and West-Berlin were asked about their experiences with different forms of therapy and prophylaxis for herpetic eye diseases. 15 questions were answered by 965 ophthalmologists (42%). The answers not only reflect their preferences and experiences, but could also initiate a new evaluation of many diagnostic, therapeutic and prophylactic methods.