The active ingredients in the liquid extract of elderflower are responsible for the antibacterial, antioxidant and anti-inflammatory effects of the plant. The main objective of the investigation was to design semisolid formulations with the elderflower extract and evaluate their quality using the biopharmaceutical research method in vitro. The quality of the elderflower (Sambucus nigra L.) extracts was evaluated spectrophotometrically by determining the total amount of polyphenols and flavonoids. The antiradical activity was determined spectrophotometrically by employing the DPPH free radical scavenging method. The agar diffusion method was used to determine antibacterial activity in vitro. The modified diffusion cells of Franz type were used to perform the biopharmaceutical experiment in vitro of semisolid pharmaceutical formulations. The results revealed that the highest amount of active compounds were found in the extracts when 70% (v/v) ethanol was used for the extraction of raw material. The obtained extracts had antiradical activity and antimicrobial effects against S. aureus and B. cereus. An inverse correlation was found between the total amount of flavonoids released after 6 hours in vitro experiment and the dynamic viscosity of the formulations. The base and the amount of excipients affected the release of active compounds from the formulations during the experiment. The results of the study showed that, as the lipophilicity and viscosity of the base increased, the performance in formulations slowed down. The released amount of active compounds decreased when oleogel concentration in the formulation increased. The hydrophilic base was confirmed as the best carrier of the liquid extract of elderflower.