ABSTRACT
Bilayer/multilayer tablets have been introduced to formulate incompatible components for compound preparations, but they are now more commonly used to tailor drug release. This research aimed to formulate a novel gastro-retentive tablet to deliver a combination of a fixed dose of two drugs to eliminate Helicobacter pylori (H. pylori) in the gastrointestinal tract. The bilayer tablets were prepared by means of the direct compression technique. The controlled-release bilayer tablets were prepared using various hydrophilic swellable polymers (sodium alginate, chitosan, and HPMC-K15M) alone and in combination to investigate the percent of swelling behavior and average drug release. The weight of the controlled-release floating layer was 500 mg, whereas the weight of the floating tablets of pantoprazole was 100 mg. To develop the most-effective formulation, the effects of the experimental components on the floating lag time, the total floating time, T 50%, and the amount of drug release were investigated. The drugs' and excipients' compatibilities were evaluated using ATR-FTIR and DSC. Pre-compression and post-compression testing were carried out for the prepared tablets, and they were subjected to in vitro characterization studies. The pantoprazole layer of the prepared tablet demonstrated drug release (95%) in 2 h, whereas clarithromycin demonstrated sustained drug release (83%) for up to 24 h (F7). The present study concluded that the combination of sodium alginate, chitosan, and HPMC polymers (1:1:1) resulted in a gastro-retentive and controlled-release drug delivery system of the drug combination. Thus, the formulation of the floating bilayer tablets successfully resulted in a biphasic drug release. Moreover, the formulation (F7) offered the combination of two drugs in a single-tablet formulation containing various polymers (sodium alginate, chitosan, and HPMC polymers) as the best treatment option for local infections such as gastric ulcers.
ABSTRACT
Balkhi, Michni and Hashtnagri populations are the three fat-tailed phenotypes native to Khyber Pakhtunkhwa Province of Pakistan, harbouring the central valley. Their distribution, breeding trend and performances were evaluated through a survey using a pre-tested questionnaire during August, 2008. Out of the total populations, 70.7% were mixed flocks and 5.8%, 3.1% and 9.2% were purebred flocks belonging to Balkhi, Hashtnagri and Michni populations, respectively. Sheep flocks were reared under three different production systems, i.e. sedentary, transhumant and nomadic. Nomads keep Balkhi and are sole responsible for their development as a mutton breed. They practise autumn breeding only, for which they select the heaviest ram/s available within the community. Sedentary and transhumant shepherds had mixed flock, who were constantly replacing their native breed stock, i.e. Michni and Hashtnagri through outcrossing with Balkhi. The size of Balkhi and Michni populations warrants no immediate threat to their existence and diversity. However, in case of increased popularity of crossbreeding, Michni could pose threats of extinction. Hashtnagri on the other hand can be declared as breed at risk. Age at first lambing was significantly lower in Hashtnagri ewes, followed by Michni, crossbred and Balkhi. Hashtnagri ewes outperformed other populations in lambing twice per annum.
