In vitro release study of azithromycin from the cationic liposomes

Cilj ovog rada bio je pripraviti kationske liposome s uklopljenim azitromicinom, provesti njihovu fizikalnu karakterizaciju te ispitati profil oslobađanja uklopljenog lijeka. Kationski liposomi (DOPC/DODAB; DPPC/DODAB; DPPC/DC-Chol) s uklopljenim azitromicinom su pripravljeni metodom hidratacije suhog fosfolipidnog sloja (filma). Homogenizacija liposomskih disperzija je provedena primjenom ultrazvučnog sonikatora sa sondom frekvencije 40 Hz tijekom 20 sekundi. Nakon soniciranja dobiveni su liposomi srednjeg promjera oko 300 nm, uz znatnu bolju razdiobu veličina liposoma (PI u rasponu od 0,360 do 0,471). Svim je preparacijama izmjeren zeta potencijal, a izmjerene pozitivne vrijednosti zeta potencijala u iznosu od +56,7 do +75,2 mV upućuju na fizičke stabilne liposomske disperzije. In vitro ispitivanje oslobađanja azitromicina je provedeno na Franz difuzijskoj ćeliji u trajanju od 24 sata te je količina oslobođenog azitromicina određena HPLC metodom. Za usporedbu su uzeti vodeno-etanolna otopina azitromicina kao kontrola i anionski SPC-liposomi. Nakon 24 sata iz testiranih kationskih liposoma se oslobodila približno ista količina (%) azitromicina. Iz ranije dobivenih podataka za anionske liposome, vidljivo je da se oslobodilo znatno manje azitromicina, ali je kod njih postignuto kontrolirano i produljeno oslobađanje, za razliku od kationskih gdje je takva vrsta oslobađanja postignuta samo djelomično. Može se zaključiti da je potrebno provesti dodatna in vitro ispitivanja oslobađanja kako bi se optimizirali uvjeti za postizanje potpunog kontroliranog i produženog oslobađanja kod kationskih liposoma.The aim of this study was to prepare cationic liposomes with encapsulated azithromycin, perform physical characterization and determine the drug release profile. Cationic liposomes (DOPC/DODAB; DPPC/DODAB; DPPC/DC-Chol) with encapsulated azithromycin were prepared by the film hydration method. Homogenization of liposome dispersions was performed using an ultrasonic probe sonicator with a frequency of 40 Hz for 20 seconds. After sonication, the resulting liposomes were with a mean diameter of 300 nm and with much better size distribution (PI ranging from 0.360 to 0.471). The measured positive value of zeta potential in a range of +56.7 to +75.2 mV indicated the formation of physically stable liposomal dispersions. In vitro release studies were performed on the Franz diffusion cell during 24 hours and the amount of the released azithromycin was determined by HPLC method. For comparison, aqueous-ethanolic solution of azithromycin as the control and the anionic-SPC liposomes were prepared and tested under the same conditions. After 24 hours, all of the tested cationic liposomes released approximately the same amount (%) of azithromycin. From the previously obtained data for anionic liposomes, it is evident that they have released significantly less amount of azithromycin, but they have achieved a controlled and prolonged release, as opposed to cationic liposomes where such release is achieved only partially. It could be concluded that it is necessary to do additional in vitro release testing in order to optimize the conditions for achieving complete controlled and prolonged release of the drug from cationic liposomes