a pharmaceutical composition for controlled drug delivery comprising a β - lactam antibiotic or its pharmaceutically acceptable hydrates , salts or esters , and one or more carbomers . the above β - lactam antibiotics formulation avoids the limitations of known β - lactam controlled release form which are found to be either complex and / or cost - extensive to obtain requiring multiphase and / or selective coatings or fail to achieve the desired controlled release for once daily dosage form . importantly , in the β - lactam antibiotic form of the above the rate - controlling polymer wherein the c max of the formulation is substantially the same as that of a single dose of the immediate release formulation . also advantageously the formulation achieves a rate controlling polymer wherein the t & gt ; mic for the formulation is more than 17 hours when the mic is 0 . 25 mcg / ml and more than 10 hours when the mic is 2 mcg / ml . the above β - lactam antibiotic form is thus directed to serve as the much desired simple and cost - effective controlled release form suitable for once daily administration .