The European Commission granted a marketing authorisation valid throughout the European Union for Symtuza on 21 September 2017. The 4 active substances in this drugs have already been shown to be effective when used individually, and combining them in a single tablet simplifies treatment. It is an antiviral medicine used to treat human immunodeficiency virus type 1 (HIV-1) in adults and adolescents. Symtuza contains the active substances darunavir, cobicistat, emtricitabine and tenofovir alafenamide. Each tablet contains 800 mg darunavir, 150 mg cobicistat, 200 mg emtricitabine and 10 mg tenofovir alafenamide. The four active substances work in different ways against HIV:
Darunavir is a type of antiviral agent called a ‘protease inhibitor’. It blocks protease, an enzyme of the virus that allows it to reproduce itself in the cells it has infected. By blocking protease, Symtuza reduces the amount of HIV-1 in the blood and keeps it at a low level.
Cobicistat acts as a ‘booster’ to enhance the effects of darunavir, by slowing down the breakdown of darunavir and therefore prolonging the time it acts in the body.
Tenofovir alafenamide is a ‘prodrug’ of tenofovir, meaning that it is converted into the active substance tenofovir in the body. Tenofovir is a reverse transcriptase inhibitor, which means that it blocks the activity of reverse transcriptase, another enzyme of the virus that allows it to reproduce itself.
Emtricitabine is a reverse transcriptase inhibitor and it works in the same way as tenofovir. Symtuza does not cure HIV-1 infection or AIDS, but it may hold off the damage to the immune system and the development of infections and diseases associated with AIDS.
Because the individual active substances have previously been shown to be effective and are authorised for use in the treatment of HIV infection, studies were mainly carried out to show that Symtuza produced similar levels of active substances in the blood to the active substances given separately. In addition, one main study was carried out to compare the drug with another antiviral medicine containing darunavir, cobicistat, emtricitabine and tenofovir disoproxil in 153 adult patients with HIV who had not been previously treated. Effectiveness was measured by a reduction in viral load to less than 50 copies/ml. Overall, 75% of patients taking Symtuza achieved this reduction after 24 weeks of treatment, which was comparable to the 74% (37 of 50) of patients who achieved it with the comparator. The most common side effects with Symtuza are diarrhoea, nausea, tiredness, headache and rash.