Influence of Polymer Combination Concentration on the Characteristics, In Vitro Release, and In Vivo Lung Deposition of Alginate-Carrageenan Microspheres Encapsulating Ciprofloxacin HCl

Inhaled Ciprofloxacin HCl microspheres were formulated with a combination of alginate and kappa carrageenan with a total of 1% (Formula 1), 1.5% (Formula 2), and 2% (Formula 3). The aim of this research is to examine the effect of polymer concentration on the characteristics, release, and lung deposition of microspheres. The latter are characterized by qualities including loading, efficiency, yield, size, moisture content, mucoadhesivity, and release. Deposition was studied by means of fluorescence microscopy, the results of which showed it to be spherical, smooth and less than 2 mu m in size. Loading was between 21.29% and 38.18%, while entrapment efficiency ranged from 52.86% to 76.29%, and the yield amounted to between 49.83% and 70.72%. The swelling index was less than 10. For moisture content, all formulas recorded less than 6.5%. In terms of mucoadhesivity, F1, F2, and F3 showed 0.0090 kg, 0.0217 kg, and 0.0329 kg respectively. Increasing polymer concentration was found not to affect the size, loading, efficiency, and yield of microspheres. Cumulative release of F1, F2, and F3, with a burst release profile, was 72.64%, 59.25%, and 47.66% respectively after 10 min at PBS pH 7.4. In vivo analysis demonstrated that all formulas could be deposited in the lungs of rats, while a reduction in intensity occurred in the fourth hour due to increased levels of polymer. The remaining intensity indicated that microspheres were able to maintain the drugs loaded.