Introduction: Semisolid self-microemulsifying drug delivery systems (SMEDDSs) are isotropic mixtures of lipids (<20%), hydrophilic surfactants (20-50%) and cosolvents (20-50%), which form a fine o/w emulsion when introduced in the aqueous phase and under mild agitation such as digestive fluids and motility. 

Aim: The main objective of this study was to develop SMEDDSs as potential carriers for oral delivery of medicaments, in this case metformin hydrochloride, a poorly permeable antidiabetic drug.

Materials and Methods: Three SMEDDSs (F5P, F4G, F5G) were prepared by mixing CapryolTM 90 (lipid), Polysorbate 80 (surfactant), Transcutol°P (cosurfactant), propylene glycol or glycerol (hydrophilic surfactant). SMEDDSs were evaluated for their percentage transmittance, phase separation study and disperbilidy in aqueous media. Empty hard gel capsules were filled with either the developed SMEDDSs loaded with metformin hydrochloride or pure drug (60mg), equivalent to 60mg of metformin, and subjected to an in vitro dissolution test described in USP42-NF37.

Results: The prepared samples were uniform, clear and homogeneous systems with transmitance ≥ 99% and with no sings of phase separation. Dispersibility in aqueous media (0.1M HCL and PBS pH 6.8) was satisfying for all F4G and F5P formulations (transmittance ≥ 85%), droplet size between 92.25nm 139.7 nm and with PDI values lower than 0.3. Based on the calculated similarity factors, in vitro dissolution profiles of the tested samples were found not to be similar (f2 < 50). The highest amount of metformin was dissolved from the F4G formulation, while a lower drug dissolution from the F5P and F5G samples released suggested that a lower surfactant/cosurfactant ration enhanced drug dissolution. On the contrary, the cosolvent type seemed to have an insignificant role. 

Conclusion: Our research illustrated the potential use of SMEDDSs for oral administration of metformin. To confirm this, appropriate further studies are needed.

Zorana Tomić was born in Loznica, Serbia. She has completed her studies at Faculty of Medicine, Integrated studies of Pharmacy, Banja Luka, Bosnia and Herzegovina at 2024. During her studies she has been engaged in scientific research work within the Department of Pharmaceutical Technology. With research on the drug metformin hydrochloride, In vitro release of Metformin Hydrochloride from topical vehicles for Dermal Drug Delivery, she participated in VIII Serbian Congress of Pharmacy with International participation. This research also published in Vol. 72 no.suppl.4 (2022) Archives of Pharmacy - VIII Serbian Congress of Pharmacist of Serbia with International Participation. In 2022 she was research intern at Tokyo University of Science, Faculty of Pharmaceutical Sciences, Department of Medicinal and Life Sciences, Tokyo, Japan. Research topic was Design and Synthesis of Calixarene – Peptyde Hybrids as Amphiphilic Peptide Conjugates, under the mentorship of professor Shin Aoki. Currently she is based in Belgrade, Serbia, working as MPharm at pharmacy. From last year she has started Specialist academic studies in Cosmetology at University of Belgrade, Faculty of Pharmacy.