95PHYSICO-CHEMICAL CHARACTERISTICS OF AMPICILLIN TRIHYDRATE AND A CARRIER IN THE FORMULATION OF SUSTAINED DOSAGE FORMFormulation of sustained release dosage forms has focused attention on a wide range of drugs, especially those with relatively short biological half life and drugs used for long term treatments, such as antih ypertensive, antidiabetic and antimicrobial agents. Ampicillin trihydrate is an acid stable broad spectrum antibiotic with short half life. This study is a imed at assessing the possibility of achieving sustained release formulations for this drug. Ampicill in trihydrate powder was heated in a buffered solution with a trace of a copper salt at a fixed temperature for a period of time. The sample is then analysed spectrophotometrically. A buffer ‘A’ solution was prepared in which 30 µg/ml solution of ampicilli n trihydrate was added and incubated at 75 0 C for 30 minutes, cooled to room temperature, while the other portion was left fresh and untreated. The sample solution and that of pure Eudragit (R) RS were scanned against the reference solution from 400-220 nm using a UV spectrophotometer. Standard curve of ampicillin trihydrate following Lambert -Beer’s law was constructed by using prepared solutions of 5-60 µg/ml through a serial dilution from a 1 mg/ml stock solution with a pH 5.2 buffer solution containing 15 µg/ml copper II. The absorbance was measured at 320 nm against the un-incubated part in the reference cell. No appreciable absorption of the polymer was recorded at this wavelength, indicating non interference of the polymer used. The observed absorbances are plotted against concentration at which the slope of the plot was calculated by linear regression analysis and its value was found to be 0.02114 with an intercept of zero. The plot shows that drug concentrations up to 50 µg/ml can be measured with accuracy since the Lambert-Beer’s law is obeyed. Therefore, physical and chemical characteristics of ampicillin trihydrate and its carrier observed in this study may be appropriate in formulating the sustained release tablet ifeanyivemenike@yahoo.comResearch612016Ampicillin,Acrylic resins,Sustained release tabletEmenike IV,Lauwo JAK,Timothy SY,Musa HDepartment of Pharmaceutics and Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Gombe State University, Gombe, Nigeria.,Division of Health Sciences, College of Medicine and Medical Sciences, Papau New Gueine,Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Maiduguri, Maiduguri, Nigeria,Department of Pharmaceutics and Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ahmadu Bello University Zaria, Kaduna, Nigeria