Development and Evaluation of Bilayer Gastroretentive Floating Drug Delivery System for Baclofen

Baclofen, related to gamma-amino butyric acid (GABA), blocks the activity of nerves within the part of the brain that controls the contraction and relaxation of skeletal muscle. The oral bioavailability of baclofen is about 40%. It is stable and well absorbed within pH range 1-4. The short half life of baclofen (2-4 h) suggests that it is a suitable drug for sustained drug delivery. The objective of this research work was to develop bilayer floating tablets of baclofen to provide an immediate release of one-third of the baclofen content to achieve an effective plasma concentration and the sustained release layer to release the drug over several hours. Immediate release layer was prepared by using the superdisintegrant sodium starch glycolate while sustained release layer was prepared using gas generating agents like sodium bicarbonate, citric acid and release retardant polymer, hydroxypropyl methylcellulose K4M(HPMC K4M) by direct compression method. The drug release rate from the bilayer tablet was sustained up to 24 h (98% release) by incorporation of HPMC K4M in the concentration of 100 mg, which showed maximum swelling up to 240 % in 12 h as compared to other formulations. Sodium bicarbonate with citric acid in the ratio 2:1 caused the floating of tablet within 60 sec and maintained so for 24 h. Conclusively, the current study attained the successful design, preparation and evaluation of floating bilayer sustained release formulation of a slightly soluble drug baclofen with initial immediate release of one third of total drug content with gastric retention for the desired period of time by the second layer.