Inosine pranobex in the treatment of influenza and other respiratory infections of viral etiology
The antiviral inosine pranobex is a clinically proven immunomodulator for the treatment of patients from 1 year of age, indicated for a wide range of diseases with manifestations of immune insufficiency and viral infections. It acts by a direct antiviral effect, modulates the immune system, and also finds application in the treatment of acute viral respiratory diseases, such as influenza and other seasonal viral infections.
Inosine pranobex complex
Isoprinosine, or inosine pranobex, is a purine derivative of inosine with antiviral and immunomodulatory effects. The nucleoside inosine is naturally present in food, such as brewer's yeast and organ meats. Inosine pranobex is a tricomponent molecular complex of inosine, N,N-dimethylamino-2-propanol (DIP), and p-acetoamidobenzoate (PAcBA) in a ratio of 1:3:3. Inosine pranobex is rapidly and well absorbed after oral administration and is evenly distributed in the body without signs of accumulation.
Inosine pranobex is used in the treatment of immunodeficiency states with recurrent viral infections, subacute sclerosing panencephalitis, viral infections including varicella and measles, infections caused by herpes simplex virus (HSV), human papillomavirus (HPV), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and lastly in the treatment of influenza-like viral respiratory infections. Specific indications vary in different countries where the drug is registered.
Mechanism of action
Inosine pranobex directly affects viral replication through the so-called wobble mechanism, which leads to disruption in the transcription of viral nucleic acids and the protein synthesis of viral proteins at the tRNA level. The inhibition of viral RNA is nonspecific, affecting a wide range of viruses.
Immunomodulatory effect
Inosine pranobex affects the immune system at multiple levels. It has been shown to activate T-cell immunity, particularly the TH1 type response, which is associated with increased production of inflammatory factors such as interleukin 2 (IL-2) and interferon gamma (IFN-γ). The effect of inosine pranobex also stimulates IL-10 production, which is involved in the homeostatic regulation of inflammation.
The effect of inosine pranobex leads to a favorable influence on nonspecific natural immunity - an increase in the number of NK cells of the immune system and an increase in their functionality. A high number of NK cells positively affects the prognosis of viral infections and the speed of immune system engagement in eliminating virus-infected cells.
Therapy of acute viral respiratory infection
The dissertation by Jelena Ermanová from 2009 evaluated the use of inosine pranobex in influenza and acute respiratory viral infections (ARVI). It was shown that isoprinosine reduces the duration and severity of disease symptoms (duration of fever, intoxication, catarrhal symptoms in the nasopharynx). In ARVI (rhinopharyngitis, acute rhinopharyngitis) in children aged 1 month to 12 years, the duration of the disease was shortened, and the disease symptoms were suppressed 48–72 hours after the drug was prescribed. In treated patients, the fever was not excessively high and remained elevated for no more than 2 days. Overall symptoms disappeared within 1–2 days.
The results of this work coincide with the systematic review and meta-analysis published a year later - the use of inosine pranobex in the treatment of ARVI in immunocompromised patients reduced the need for antibiotic prescription, did not require the prescription of other medications, and shortened hospital stay duration.
In 2016, results were published from a phase IV clinical study aimed at monitoring the benefits of inosine pranobex in the treatment of patients with confirmed acute viral respiratory infections. The most common causes of these infections include influenza viruses, parainfluenza viruses, adenoviruses, coronaviruses, and enteroviruses. The placebo-controlled study (n = 463) randomized patients in a 1:1 ratio. Patients in the active arm received the drug at a dose of 1000 mg 3 times daily for 1 week, exhibiting faster improvement compared to the placebo. This confirmed the efficacy of this therapy in otherwise healthy non-obese patients under 50 years of age with clinically diagnosed influenza-like illnesses.
Conclusion
Inosine pranobex stimulates the human immune system and enhances the body's resistance to viruses, giving it broad therapeutic use. The different mechanism of action also allows it to be used concurrently with antibiotics or other antivirals. Although clinical results have proven its efficacy in treating acute viral respiratory illnesses, it is not registered for such treatment in the Czech Republic, unlike in some other countries.
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Sources:
1. Erman E. S. Evaluation of the clinical and epidemiological efficacy of new drugs for the prevention of influenza and ARI of other etiologies in frequently ill children. Dissertation. St. Petersburg, 2009.
2. Eliseeva M. Y., Tsarev V. N., Masikhi K. N. et al. An efficiency of adjuvant immunotherapy in patients with immunodeficiency and frequently ill children: systematic review and meta-analysis of inosine pranobex administration. Russian Medical Journal 2010; 18 (5): 313–320.
3. Beran J., Šalapová E., Špajdel M. Inosine pranobex is safe and effective for the treatment of subjects with confirmed acute respiratory viral infections: analysis and subgroup analysis from a phase 4, randomised, placebo-controlled, double-blind study. BMC Infect Dis 2016; 16 (1): 648, doi: 10.1186/s12879-016-1965-5.
4. Krejsek J. Inosine pranobex, clinically proven effective immunomodulator; possible mechanisms of action. Remedia 2018; 4: 396–400.
5. SPC Isoprinosine. Available at: www.sukl.cz/modules/medication/detail.php?code=0107676&tab=texts
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