A team of experts led by Slobodan Đokić from the Croatian pharmaceutical company "Pliva" discovered in 1980 formulation of the azithromycin chemical compound. Beside Đokić, Gorjana Radoboja-Lazarevski, Zrinka Tamburašev and Gabrijela Kobrehel were in the team. Azithromycin has been shown to be extremely effective in therapeutic treatment of bacterial infections. It removes the ability of the bacterium to grow and multiply, and it is targeted at the site of infection due to the transfer of white blood cells. Azithromycin in inflammatory tissues achieves high concentrations and the therapy remains effective for five to seven days after discontinuation of the drug. Azithromycin rarely causes side effects.

The discovered antibiotic azithromycin, known under the trademark name Sumamed, Pliva, in collaboration with the American pharmaceutical company Pfizer, put into the market in 1988. Under the protected names Sumamed (Pliva) and Zithromax (Pfizer), azithromycin has become one of the best-selling antibiotics worldwide for its highly successful therapeutic action. 

The discovery of azithromycin, a wide-scale macrolide antibiotic, is the greatest success in the history of Pliva and the Croatian pharmaceutical industry.