What has clinical research on the effects of inosin pranobex revealed, and what does it mean for practice?

Introduction

The effects of inosin pranobex (IP) on human immunity lie in its ability to support the proliferation of T lymphocytes, the activity of NK cells, and increase the levels of pro-inflammatory cytokines, thus restoring disrupted processes in immunocompromised patients. IP also has the potential to affect viral RNA and inhibit the growth of certain viruses. Thanks to its immunomodulatory and antiviral effects and good safety profile, it is applied in the treatment of a wide range of viral diseases, for instance, it is indicated in the treatment of herpes zoster. The total daily dose administered orally in one or more doses should not exceed 4 g/day, according to the summary of product characteristics (SPC).

Controlled studies with exposure to respiratory infections

A number of findings on the immunomodulatory effects of IP were obtained in so-called controlled challenge studies, in which healthy volunteers were exposed to respiratory viruses. For instance, a study with rhinovirus 21 showed that IP at a daily dose of 4 g significantly reduced the severity of infection symptoms after intranasal exposure to the virus (5 out of 19 volunteers in the IP group experienced cold symptoms, compared to 14 out of 20 in the placebo group; p < 0.01). A study with volunteers exposed to the influenza virus transnasally showed that inosin pranobex significantly reduced the intensity of flu symptoms in them.

Diseases caused by herpes simplex virus

HSV-1 virus primarily causes orofacial infectious diseases. It spreads most commonly via the oral route, mainly affecting children, with common manifestations including cold sores. HSV-2 primarily causes genital infections. The clinical presentation here is more variable; many infected individuals are unaware of their infection, and transmission mainly occurs through sexual contact. Diseases caused by HSV-2 mainly affect adults aged 15–49 years.

A multicenter randomized study from 2015 investigating the efficacy and safety of inosin pranobex and acyclovir in the treatment of labial and genital herpes showed that IP is as effective as acyclovir in the treatment of recurrent labial and genital herpes, but exhibits significantly higher efficacy in reducing the short-term recurrence rate of genital herpes as determined at a follow-up visit 3 months after the end of treatment.

Chronic fatigue syndrome as a symptom of immune dysfunction

Chronic fatigue syndrome primarily affects individuals between the ages of 40 and 60, manifesting as severe fatigue, intolerance to physical exertion, muscle pain, cognitive deficits, and sleep and concentration disorders. In 90% of cases, however, it is not correctly diagnosed. There are no established therapeutic procedures for this syndrome, and physicians usually focus only on treating the symptoms, not the underlying disease. Professional sources suggest that chronic fatigue syndrome may be driven by changes in the immune system, such as chronic cytokine production, decreased NK cell activity, and differences in T-lymphocyte function.

The potential use of inosin pranobex in patients with chronic fatigue syndrome was investigated in a placebo-controlled study involving 16 patients. Ten of them took IP for 12 weeks in a dose of 3 g daily in odd weeks and 1 g in even weeks, with six receiving a placebo. Both groups subsequently took IP for 16 weeks. In 6 out of 10 patients who took IP throughout the entire period, symptoms of the syndrome improved, and cognitive deficits improved by 16%. To more accurately evaluate the efficacy of IP in the treatment of chronic fatigue syndrome, studies with larger samples and longer monitoring periods are necessary.

Other uses of inosin pranobex

In the past, several studies have compared the efficacy of IP with conventional therapies (podophyllin, cryotherapy, electrocautery, laser or surgical procedures) in patients with genital warts caused by human papillomavirus (HPV). Therapy involving a combination of IP and conventional methods was associated with a higher proportion of cured individuals than conventional treatment alone.

A randomized placebo-controlled study with nearly 500 patients from 2016 confirmed the efficacy and safety of IP in individuals with clinically diagnosed influenza-like respiratory illness. In otherwise healthy non-obese patients under the age of 50, IP significantly shortened the time to symptom resolution compared to placebo.

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