Osmotically controlled oral delivery of ciprofloxacin through asymmetric membrane capsules.

Asymmetric membrane capsules (AMCs) are based on the concept of osmotic pressure but are much simpler to manufacture. Further, they can be suitably optimized by varying the parameters like concentration of pore former, polymer, osmotic agents and solubility enhancers to cater the specific needs of a particular formulation. The main objective of the present work was to exploit the concept of AMCs for the controlled delivery of poorly soluble anti-infective drugs. Ciprofloxacin was chosen as the model drug. Nine AMCs (F1-F9) with varying concentrations of cellulose acetate [CA] (polymer-12% w/v, 16% w/v and 20% w/v) and glycerol (pore former- 50% w/w, 60% w/w and 70% w/w of polymer) were prepared. AMCs F1-F3 were discarded because of poor rigidity. 18 formulations (F4A-F9C) were prepared with the remaining 6 AMCs by varying concentrations of mannitol in the core (osmogen-15% w/w, 25% w/w and 50 % w/w of drug). F6C prepared with 16% CA, 70% glycerol and 50% mannitol gave highest release (57.93 +/- 0.93 %) after 12 h. Scanning electron microscopy revealed asymmetric structure of the membrane and osmotic release (zero order) through pores formed in situ was confirmed. Three concentrations of tartaric acid were used in F6C (T1-5%, T2-15%, T3-20%) for further optimization. T3 gave maximum release after 12 h (82.21 +/- 0.71%) and was selected as final optimized formulation. The study concluded that AMCs containing a suitable osmogen and a solublizer, can successfully deliver poorly soluble anti-infective drugs in a controlled manner.