This study demonstrates the results of experimental studies aimed at the development of technology and assessment of quality of drug substance containing a dry extract of a flavonoid-containing herb and silver nanoparticles, as well as the optimal technological parameters of the phytosynthesis process and methods for the qualitative and quantitative content of biologically active substances have been developed. Phytosynthesis of silver nanoparticles was carried out using plant extracts, in which biologically active substances, flavonoids, act as an agent that reduces silver ions to nanoparticles. The optimal technology for the production of silver nanoparticles was chosen and the sample obtained at t =50 °C and the ratio of extract: silver nitrate = 1:4 was chosen as the optimal one. Additionally, the expiration date of the drug was determined for the development of regulatory documentation. During quality assessment, it was found that the quantitative content of silver nanoparticles should be at least 2 mg/g. As a result, it became possible to produce a substance used in the preparation of local antibacterial and antifungal drugs for the treatment of skin diseases.