1. What is interferon?

Interferon (IFN) was discovered as an antiviral agent during studies on virus interference. Isaacs and Lindenmann reported in 1957 that influenza virus-infected chick cells produced a secreted factor that mediated the transfer of a virus-resistant state active against both homologous and heterologous viruses. Animal viruses are inducers of IFN, and are also sensitive to the antiviral actions of IFNs. The IFN family of cytokines is now recognized as a key component of the innate immune response and the first line of defence against viral infection. Accordingly, IFNs are currently used therapeutically, most notably to combat viral Hepatitis infections, but also against a range of other disorders, including numerous malignancies and multiple sclerosis.

2.How is  interferon classified?

The interferon (IFN) family can be classified into three main types of cytokines — type I, type II and type III IFNs. In humans, the type I IFN family is composed of 16 members, namely 12 IFNα subtypes, IFNβ, IFNε, IFNτ, IFNκ, IFNω, IFNδ and IFNζ. By contrast, the type II IFN family includes only one cytokine: IFNγ, which also exhibits antiviral activities. The third type of IFNs is the IFNλ family, which includes IFNλ1 (also known as IL‑29), IFNλ2 (also known as IL‑28A) and IFNλ3 (also known as IL‑28B). Type I IFNs have pleiotropic effects on cells - they induce an antiviral state,  can inhibit cell proliferation, modulate cell fate (survival/apoptosis), and differentiation and migration, while IFNα and IFNβ are the best-defined and most broadly expressed type I IFNs.

3.Which type is best for nebulization and intramuscular injection?

When IFN-a1b nebulized, the drug can reach and concentrate in lungs through bronchus and bronchioles, and slowly enter the blood. Thus, nebulization of IFN-a1b is more durable than intramuscular injection. Secondly, because of the direct effect on respiratory mucosa, nebulizing IFN-a1b shows better efficacy for respiratory virus infection. In addition, the increased safety and higher infant compliance of IFN-a1b make it widely used in pediatrics. Therefore, nebulization of IFN-a has been recommended in the Chinese National Formulary (2013) and  A Guide to Standardized Management of Children Atomization Center.

4.What can be combined with Hapgen® for nebulization?

The current clinical usage commonly uses nebulization preparation, such as salbutamol, budesonide, ambroxol, terbutaline and ipratropium bromide, all of which can be nebulized with Hapgen®.

5.What are  the effects on the efficacy of Hapgen® of improper preservation? 

The preservation has a direct impact on the drug activity, so keeping Hapgen® stored strictly according to the instructions is a prerequisite for the interferon's safety and efficacy. 

The suggested preservation condition is 2~8℃ and protected from the light. The valid time of the freeze-dried powder injection is 30 months, and the valid time of water injection is 24 months. Hapgen® is stable for a short time under room temperature (for example, the normal transfer of medicine in hospital and family) . Other severe conditions, such as freezing, long exposure to the light and high temperature will affect the activity and safety of the drug, and thus should be avoided.